SERUM FRACTION OF PLATELET-RICH FIBRIN AS A CELL CULTURE ADDITIVE

Abstract

A method of preparing an isolated serum fraction of platelet rich fibrin, cell cultures comprising said serum fraction and its use as a cell culture additive. The invention also relates to increasing proliferation rate of chondrocytes, to the treatment of articular or joint diseases and to increasing the proliferation rate of mesenchymal stem cells. The isolated serum fraction of platelet rich fibrin (PRF), is prepared by providing platelet rich plasma (PRP) without the addition of an anticoagulant; clotting the PRP to obtain a coagel of PRF; and separating the coagel to isolate the serum fraction which comprises an activated platelet releasate; and further provides for the isolated serum fraction obtained by such method, and its medical use.

Claims

1. A cell culture comprising mammalian cells, a cell culture medium, a serum fraction containing the fluid fraction of platelet-rich fibrin, i.e. serum fraction of PRF (SPRF), wherein said SPRF being obtained by a method comprising the steps of a. separating and removing the red blood cell fraction from a venous blood sample to provide a plasma without the addition of an anticoagulant; b. clotting said plasma to obtain a coagel of PRF spontaneously by centrifugation carried out at 1000 to 5000 g and a supernatant, wherein in said method the centrifugation is carried out for 2 to 20 minutes; c. pressing or squeezing the coagel to obtain fluid fraction from the coagel, thereby obtaining said SPRF; wherein said SPRF is added to the medium, said SPRF comprising a platelet releasate from activated platelets and said SPRF comprising a reduced content of red blood cells, platelets or fibrinogen as compared to whole blood or a reduced content of fibrin as compared to said plasma, and wherein said SPRF is capable of inducing cell proliferation or restoring cell proliferation capacities.

2. The cell culture of claim 1 wherein said cell culture does not comprise fetal bovine serum (FBS) or fetal calf serum (FCS), and does not comprise platelet rich plasma (PRP) and does not comprise any other growth factor either, only those which are present in the SPRF.

3. The cell culture according to claim 1 wherein said SPRF is depleted in a growth factor selected from the group consisting of PDGF-AB, PDGF-BB and TGF beta-1 as compared to platelet rich plasma (PRP).

4. The cell culture according to claim 1 wherein said cells are mammalian cells.

5. The cell culture according to claim 4 wherein said mammalian cells are selected from the group consisting of stem cells, epithelial cells, cells of the periosteum, osteogenic cells, angiogenic cells, stromal cells, mesenchymal cells, e.g. mesenchymal cells of bone marrow, adipose tissue, microvascular tissue or other mesenchymal tissue origin, osteoprogenitor cells and bone cells.

6. The cell culture of claim 1 wherein in said cell culture the SPRF is prepared by a method wherein centrifugation is carried out at 1000 to 2000 g.

7. The cell culture of claim 1 wherein said medium comprises 2-20% (v/v), preferably 5-15% (v/v), highly preferably 8 to 12% (v/v) or about 10% (v/v) SPRF and wherein said medium comprises besides SPRF, no FBS (FCS) and no other serum derived product or supplement and preferably no other growth factors.

8. The cell culture of claim 7 wherein the medium is a derivative of Dulbecco's modified Eagle's medium (DMEM) which differs from DMEM in that it is supplemented with 2-20% (v/v), preferably 5-15% (v/v), highly preferably with 8 to 12% (v/v) or about 10% (v/v) SPRF and comprises no other serum derived product or supplement and no other growth factors.

9. The cell culture of claim 7 wherein the cells in the culture are MSCs that are contacted or maintained in contact with SPRF, preferably for until at least a time-period when osteoblast direction differentiation occurs, preferably for until at least a time-period when the expression of at least one, preferably two or at least two osteoblast specific marker gene(s) is/are increased in a medium supplemented with SPRF.

10. The cell culture of claim 7 wherein the cells are chondrocytes and SPRF is added to the culturing medium of chondrocytes.

11. A method for using an isolated serum fraction of platelet rich fibrin (SPRF) as a cell culture additive, said method comprising the steps of culturing cells by incubating said cells in a medium, and adding the SPRF to the medium, said SPRF being obtained by a method comprising the steps of a. separating and removing the red blood cell fraction from a venous blood sample without the addition of an anticoagulant, to provide a plasma; b. clotting said plasma to obtain a coagel of PRF spontaneously by centrifugation carried out at 1000 to 5000 g and a supernatant, wherein in said method the centrifugation is carried out for 2 to 20 minutes; c. pressing or squeezing the coagel to obtain fluid fraction from the coagel, thereby obtaining said SPRF; said SPRF comprising a platelet releasate from activated platelets and said SPRF comprising a reduced content of red blood cells, platelets or fibrinogen as compared to whole blood or a reduced content of fibrin as compared to said plasma, and wherein said SPRF is capable of inducing cell proliferation or restoring cell proliferation capacities.

12. The method of claim 11 for using an isolated serum fraction of platelet rich fibrin (SPRF) as a cell culture additive, said method comprising the steps of contacting the isolated serum fraction with a culture of cells in vitro, incubating said cells in vitro for a period of time sufficient to promote cell growth or regeneration, thereby promoting proliferation of cells.

13. The method of claim 11 wherein said medium or said cell culture does not comprise fetal bovine serum (FBS) or fetal calf serum (FCS), and does not comprise platelet rich plasma (PRP) and does not comprise any other growth factor either, only those which are present in the SPRF, wherein said SPRF enhances the proliferation rate of said cells in vitro, ex vivo or in vivo, while maintaining their potential to differentiate into several cell types.

14. The method according to claim 11 wherein said isolated serum fraction is depleted in a growth factor selected from the group consisting of PDGF-AB, PDGF-BB and TGF beta-1 as compared to said plasma or whole blood.

15. The method according to claim 11 wherein said cells are mammalian cells.

16. The method according to claim 15 wherein said mammalian cells are selected from the group consisting of stem cells, epithelial cells, cells of the periosteum, osteogenic cells, angiogenic cells, stromal cells, mesenchymal cells of bone marrow, adipose tissue, microvascular tissue or other mesenchymal tissue origin, osteoprogenitor cells, bone cells and chondrocytes.

17. The method according to claim 11 wherein the serum fraction is freshly prepared and ready-for-use.

18. The method according to claim 11 wherein the serum fraction is provided in an application device.

19. The method according to claim 11 wherein the serum fraction is prepared as an autologous pharmaceutical or medicinal product.

20. The method according to claim 11, wherein the cells in the medium comprising SPRF as a cell culture additive are administered to a patient.

21. The method according to claim 11 for increasing proliferation rate of dedifferentiated chondrocytes comprising contacting a serum fraction of platelet rich fibrin (SPRF) with dedifferentiated chondrocytes, said SPRF being prepared from whole blood obtained from one or more donor subject(s).

22. The method according to claim 11 wherein SPRF does not redifferentiate chondrocytes from the dedifferentiated state or provides a lesser extent of redifferentiation than PRP, preferably measured by the col II/col I ratio.

23. The method according to claim 11 wherein SPRF obtained from a donor subject is used for increasing proliferation rate of chondrocytes in vitro before transplantation thereof, wherein preferably SPRF is applied in the cell culture in a concentration between 1-25% or 2-20%, preferably 5 to 15%, highly preferably 8 to 12% or in particular about 10%, wherein the percentage of concentration is given in v/v %.

24. The method according to claim 11 wherein said method is a method of transplantation or implantation of chondrocytes into a patient in need thereof, wherein said SPRF is an SPRF prepared from whole blood obtained from a donor subject and wherein said SPRF is contacted with the dedifferentiated chondrocytes to be transplanted or implanted to said patient in vitro, to use for increasing proliferation rate of said chondrocytes.

25. The method according to claim 24 wherein the patient is a subject in need of cartilage repair, in particular articular cartilage repair and/or cartilage replacement therapy, preferably articular cartilage repair, or in more particular the patient is a subject with cartilage failure, osteoarthritis, cartilage damage, osteochondral damage, rheumatoid arthritic damage, autoimmune arthritis, reactive arthritis, cellular matrix linkage rupture, chondrocyte protein synthesis inhibition, and chondrocyte apoptosis, a condition requiring cartilage regeneration in particular in cartilage ulcer, osteoarthritis or traumatic cartilage loss, a condition requiring subchondral bone regeneration in osteoarthritis, Ahlback's disease or osteochondral lesions.

26. The method according to claim 11 for use of serum fraction of platelet rich fibrin (SPRF) for selectively increasing MSC proliferation rate in vitro, in vivo or ex vivo wherein said differentiated MSCs maintain their potential to differentiate into several cell types, preferably MSCs are obtained from a subject.

27. The method according to claim 26, said method comprising i. providing SPRF, ii. adding SPRF to a pool of MSCs, iii. allowing MSCs to proliferate, for at least 5 days.

28. The method according to claim 26 for use of SPRF as a cell medium supplement instead of PRP and FBS wherein said SPRF enhances the proliferation rate of human mesenchymal stem cells in vitro, ex vivo or in vivo, while maintaining their potential to differentiate into several cell types, wherein upon proliferation of MSCs expression of one or both of the following osteogenic marker genes is increased: COL1A1 and ALPL, and wherein said medium comprises SPRF, preferably 2-20% (v/v), preferably 5-15% (v/v), highly preferably 8 to 12% (v/v) or about 10% (v/v) SPRF, as a supplement and the medium does not comprise fetal bovine serum (FBS) or fetal calf serum (FCS), and does not comprise platelet rich plasma (PRP) and preferably does not comprise FGF (e.g. bFGF) and preferably does not comprise any other growth factor either, only those which are present in the SPRF.

29. The method according to claim 26 for use of SPRF in therapy, preferably in stem cell therapy, wherein in said therapy SPRF obtained from a donor subject is used to increase proliferation rate of the patient's MSCs expanded in vitro, ex vivo or in vivo, wherein the MSCs so proliferated maintain their undifferentiated character with the potential to differentiate into several cell types, wherein proliferation of MSCs is carried out for at least 5 days.

30. The method according to claim 26 wherein the MSCs are bone marrow derived mesenchymal stem cells (BM-MSCs or bone marrow stromal stem cells), or the MSCs are adipose derived mesenchymal stem cells (AD-MSCs), wherein preferably the MSC culturing medium normally comprises a carbon source, preferably a sugar source and preferably a glutamine source and preferably pyruvate.

31. A medium comprising a cell culture medium and a serum fraction containing the fluid fraction of platelet-rich fibrin, i.e. serum fraction of PRF (SPRF), wherein said SPRF being obtained by a method comprising the steps of a. separating and removing the red blood cell fraction from a venous blood sample to provide a plasma without the addition of an anticoagulant; b. clotting said plasma to obtain a coagel of PRF spontaneously by centrifugation carried out at 1000 to 5000 g and a supernatant, wherein in said method the centrifugation is carried out for 2 to 20 minutes; c. pressing or squeezing the coagel to obtain fluid fraction from the coagel, thereby obtaining said SPRF; wherein said SPRF is added to the cell culture medium, said SPRF comprising a platelet releasate from activated platelets and said SPRF comprising a reduced content of red blood cells, platelets or fibrinogen as compared to whole blood or a reduced content of fibrin as compared to said plasma, and wherein said SPRF is capable of inducing cell proliferation or restoring cell proliferation capacities.

32. The medium, according to claim 31 wherein said cell culture medium does not comprise fetal bovine serum (FBS) or fetal calf serum (FCS), and does not comprise platelet rich plasma (PRP) and does not comprise any other growth factor either, only those which are present in the SPRF.

33. The medium according to claim 31 wherein said isolated SPRF is depleted in a growth factor selected from the group consisting of PDGF-AB, PDGF-BB and TGF beta-1 as compared to platelet rich plasma (PRP).

34. The medium according to claim 31 wherein said cell culture medium is a stem cell culture medium.

35. The medium according to claim 31 wherein said mammalian cells are selected from the group consisting of stem cells, epithelial cells, cells of the periosteum, osteogenic cells, angiogenic cells, stromal cells, mesenchymal cells of bone marrow, adipose tissue, microvascular tissue or other mesenchymal tissue origin, osteoprogenitor cells, bone cells and chondrocytes.

36. The medium according to claim 31 wherein in said cell culture the SPRF is prepared by a method wherein centrifugation is carried out at 1000 to 2000 g.

37. The medium of claim 31 wherein said medium comprises 2-20% (v/v), preferably 5-15% (v/v), highly preferably 8 to 12% (v/v) or about 10% (v/v) SPRF and wherein said medium comprises besides SPRF no FBS (FCS) and no other serum derived product or supplement and preferably no other growth factors.

38. The medium of claim 37 wherein the cell culture medium is a derivative of Dulbecco's modified Eagle's medium (DMEM) which differs from DMEM in that it is supplemented with 2-20% (v/v), preferably 5-15% (v/v), highly preferably with 8 to 12% (v/v) or about 10% (v/v) SPRF and said medium comprises no other serum derived product or supplement and no other growth factors.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0386] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0387] FIG. 1. Protocol of simulated ischemia and reperfusion in human bone explants. Bone tissue pieces were isolated at day 0 at total hip replacement procedures and kept in culture for 3 days. Cells were subjected to damage through oxygen glucose deprivation (OGD) for 7 hours on day 3, followed by the replacement of normal stem cell medium and a return of oxygen levels to normal. Serum fractions were added to the explanted cultures at just before OGD and replaced at medium changes when necessary until the end of the experiment. Cell viability was measured on either the 6th or the 9th days by replacing the tissues in a fresh well and thus measuring the cells on the bone matrix only.

[0388] FIGS. 2A to 2D. Effect of PRP treatment on bone explants after OGD. FIG. 2A and FIG. 2B show that neither PRP nor heparinized PRP has any effect on cell viability after 3 or 6 days reperfusion (n=24/group). FIG. 2D shows that increasing the concentration of PRP to the technically feasibly maximum level without affecting the native preparation has still no effect on the proliferation, and FIG. 2C shows that PRP activated by different ways such as adding Calcium, Calcium+Thrombin, or subjecting the preparation to 3 cycles of freezing and thawing was also without effect. Data are presented as averageSEM.

[0389] FIGS. 3A and 3B. Effect of SPRF on bone explants after OGD. FIG. 3A shows that there is no effect immediately after 7-hours OGD (n=18-24/group), but cells started to proliferate significantly better after 6 days. FIG. 3B shows the effect of SPRF-pretreatment when the serum fraction was present in the medium from day 0 (n=24/group). Data are presented as averageSEM, ** represents p<0.01, *** represents p<0.001.

[0390] FIGS. 4A and 4B. Constituents of serum fractions measured by the Proteome Profiler array. Protein levels are measured by the intensity of spots in arbitrary units, compared between SPRF and PRP. Data are split between FIG. 4A and FIG. 4B for legibility. Data are presented as averageSEM, n=3 subjects, each spot is measured in duplicates.

[0391] FIG. 5. Schematic comparison of exemplary isolation of Platelet rich plasma (PRP) and SPRF.

[0392] FIG. 6. Exemplary isolation of Platelet rich plasma (PRP)

[0393] FIGS. 7A and 7B. Multiplex arrayprotein quantification. FIG. 7A. Human blood donors; n=10, data represented as interquartile median. FIG. 7B. Human blood donors; n=6, data represented as interquartile median

[0394] FIG. 8. Multiplex arrayprotein quantification. SPRF or PRP pooled from 10 individual donors; data represented as interquartile median.

[0395] FIGS. 9A and 9B. Cell proliferation of chondrocytes from OA patients. * represents p<0.05.

[0396] FIGS. 10A-D. Col I gene expression of OA chondrocytes under conditions of normoxia and hypoxia.

[0397] FIGS. 11A-D. Col II gene expression of OA chondrocytes under conditions of normoxia and hypoxia. *** represents p<0.001.

[0398] FIGS. 12A-D. Index of cell differentiation (redifferentiation). The Col II/Col I ratio is indicative of the cell-cell differentiation (in dedifferentiated cell the redifferentiation) potential of cells. * represents p<0.05 and ** represents p<0.01.

[0399] FIGS. 13A-D. Matrix metalloproteinase 3 (MMP 3) gene expression of OA chondrocytes under conditions of normoxia and hypoxia.

[0400] FIGS. 14A-D. Matrix metalloproteinase 13 (MMP 13) gene expression of OA chondrocytes under conditions of normoxia and hypoxia. ** represents p<0.01.

[0401] FIGS. 15A and 15B. Proliferative effect of serum derivatives in isolated human chondrocytes. ** represents p<0.01 and *** represents p<0.001.

[0402] FIGS. 16A and 16B. FIG. 16A. Representation of the mean results from 3 different experiments with XTT assay after 8 days, performed in 96-well cell culture plate based monolayer culture with 2000 cells/well seeded, cultured in serum free DMEM (SF) or DMEM media supplemented with 10% SPRF, 10% PRP or 10% FCS. *** represents p<0.001. FIG. 16B. Pictures of OA chondrocyte cultures after 0, 4, 8 days with different media supplementation.

[0403] FIG. 17. Autologous chondrocyte implantation process scheme.

[0404] FIG. 18. Time-course effect of serum supplements on hMSCs. Subconfluent hMSCs were cultured in DMEM in the absence of supplement (col. 1 at day 2 and 5), 10% (v/v) of FCS (col. 2 at day 2 and 5) or 10% (v/v) FCS+1 ng/mL bFGF (col. 3 at day 2 and 5), or 10% (v/v) PRP (col. 4 at day 2 and 5) or 10% (v/v) SPRF (col. 5 at day 2 and 5). Results are presented as means of triplicate samples in three experimentsSD. *** represents p<0.001.

[0405] FIG. 19. Cell morphology of hMSCs in differently supplemented media, using phase contrast microscopy (magnification 10). Cells were cultured in 10% (v/v) of FCS (upper row, left); 10% (v/v) FCS+1 ng/mL bFGF (upper row, right); 10% (v/v) PRP (lower row, left) or 10% (v/v) SPRF (lower row, right).

[0406] FIGS. 20A to 20D. Cell immunophenotypes of hMSCs cultured in differently supplemented media. Mesenchymal stem cells were cultured in 10% (v/v) of FCS () or 10% (v/v) FCS+1 ng/mL bFGF (), or 10% (v/v) PRP (.square-solid.) or 10% (v/v) SPRF (.square-solid.) and stained with specific antibodies. In the first three pages of FACS diagrams (FIG. 20A, FIG. 20B and FIG. 20C) representative images of expression of hMSC markers CD90, CD105, and CD73, respectively, are shown. On the fourth page of FACS diagrams (FIG. 20D) representative images of expression of hematopoietic markers CD34, CD11b, CD19 and CD45 are shown. The fluorochromes applied were FITC (fluorescein isothiocyanate), Cy5 cyanine dye, APC (Allophycocyanin) and PE (Phycoerythrin), respectively.

[0407] FIGS. 21A-D. Gene expression analysis of differently supplemented hMSCs cultures. In these figures hMSC (FIG. 21A), adipocyte (FIG. 21B), osteoblast (FIG. 21C) and apoptotic (FIG. 21D) marker levels are shown in hMSC cultures after 5 days culturing. Mesenchymal stem cells were cultured in 10% (v/v) of FCS (background color, control) or 10% (v/v) FCS+1 ng/mL bFGF (col. 1), or 10% (v/v) PRP (col. 2) or 10% (v/v) SPRF (col. 3). On the Y axis the relative protein expression level ratio is presented, the base of comparison is the level in 10% FCS cultures (background color).

[0408] Data are presented as fold change values to the expression of hMSCs cultured in 10% (v/v) FCS-supplemented medium that was considered as the standard growing medium.

[0409] FIG. 22. Culture of human subchondral bone chips. Following 5 days incubation cells in SPRF show alike if not better viability increase as cells in FCS medium. Blood serum free medium did not induce proliferation of cells. Serum-free medium (), 10% (v/v) of FCS (), 10% (v/v) SPRF ().

[0410] FIG. 23. Histological analysis of hSBPs. Culturing hSBPs in 10% (v/v) SPRF supplemented medium for 5 days preserved bone marrow integrity as hematoxylin and eosin-stained sections (A) and Masson's trichrome sections (B) show. 10% (v/v) FCS supplementation for 5 days appeared less effective therein (E, F). That means, SPRF revealed higher level of hMSC accumulation (C) compared to FCS (G), and preserved better the local vasculature (D, H).

[0411] FIGS. 24A-E. Gene expression analysis of human subchondral bone chips. Relative gene expression level is shown on Y axis, compared to the values measured right after the bone chip explanation. Serum-free medium (), 10% (v/v) of FCS (), 10% (v/v) SPRF ().

[0412] FIG. 24A: demonstrates that hMSC markers did not change in average.

[0413] FIG. 24A1: ENG, FIG. 24A2: ITGB1, FIG. 24A3: ANPEP, FIG. 24A4: ALCAM

[0414] FIG. 24B: indicates that the hematopoetic cells were not induced, however they could be present in bone chips.

[0415] FIG. 24B1: CD34, FIG. 24B2: CD14, FIG. 24B3: PTPRC

[0416] FIG. 24C: shows that adipocytes were not induced in SPRF medium.

[0417] FIG. 24C1: PPARG, FIG. 24C2: FABP4, FIG. 24C3: ADIPOQ

[0418] FIG. 24D: the increase of the expression level of osteoblastic genes is demonstrated.

[0419] FIG. 24D1: COL1A1, FIG. 24D2: P4HA2, FIG. 24D3: ALPL, FIG. 24D4: RUNX2

[0420] FIG. 24E: presents the expression level of osteocytic genes.

[0421] FIG. 24E1: DMP1, FIG. 24E2: MEPE, FIG. 24E3: PDPN.

DEFINITIONS

[0422] The term clotting as used herein in relation to blood coagulation is herein understood in the following way. Platelet activation and subsequent degranulation and aggregation play a pivotal role in blood clotting. Coagulation can be activated through the intrinsic or contact activation pathway which is initiated when blood coagulation factor XII comes into contact with negatively charged surfaces in a reaction involving high molecular weight kininogen and plasma kallikrein. FXII can be activated by so-called contact activators, e.g. the biological macromolecular constituents of the subendothelial matrix such as glycosaminoglycans and collagens, sulfatides, nucleotides, and other soluble polyanions or non-physiological material such as glass, or polymers, in particular artificial negatively charges surfaces, such as glass beads. Besides, the coagulation cascade supports the blood coagulation process. The coagulation cascade involves a series, i.e. cascade of reactions, in which a zymogen is activated, e.g. by enzymes supported by co-factors, to become an active enzyme that then catalyzes the next reaction in the reaction cascade, ultimately resulting in the formation of a fibrin clot, which strengthens the platelet aggregate. The zymogens are also known as coagulation factors or clotting factors.

[0423] As a result of coagulation activation, a blood clot is formed, which is herein referred to as a coagel. A coagel is specifically understood as the coagulated phase of blood, i.e. the soft, coherent, jelly-like mass resulting from the conversion of fibrinogen to fibrin mainly consisting of fibrin fibers associated to form a fibrin gel or clot. The coagel as described herein specifically is entrapping platelets and further components of coagulated plasma.

[0424] The coagel emanated from PRP is specifically understood as platelet rich fibrin (PRF) which may specifically include aggregated fibrin and blood cells, such as platelets, white blood cells, and/or red blood cells.

[0425] The coagel of PRF is herein understood to be composed of two fractions, the fluid fraction and the solid fraction, which may be physically separated to isolate the liquid phase and discard the solid mass.

[0426] Coagulation is specifically activated in a suitable container, such as a clot container or clot activating container, e.g. a tube. The container is suitably a glass or plastic container, with or without additional means to initiate or accelerate clotting, e.g. blood collection tubes generally used in the medical practice. In particular, the clot container does not contain anticoagulants, and is used without adding anticoagulants, so to support the clotting in situ. According to a specific embodiment, the clot container is suitably equipped with contact activating surfaces to activate the intrinsic coagulation pathway.

[0427] The term platelet rich plasma or PRP is herein understood as a volume of plasma that has a platelet concentration above baseline. Normal platelet counts in blood range between 150,000/microliter and 350,000/microliter. The platelet concentration is specifically increased by centrifugation, and/or otherwise fractionation or separation of the red blood cell fraction, e.g. centrifugation of whole blood first by a soft spin such as 8 min at 460 g and the buffy coat is used or further pelleted by a hard spin at higher g values. PRP typically comprises an increased platelet concentration, which is about a 1.5-20 fold increase as compared to venous blood.

[0428] Alternatively, Platelet rich plasma (PRP) is a blood fraction prepared by separating the red blood cell fraction from a venous blood sample, removing the red blood cell fraction and, if appropriate, the buffy coat, obtaining thereby a platelet poor plasma fraction (PPP), separatingpreferably by centrifugationa platelet rich fraction from the PPP or pelleting platelets, and recovering the platelets in a platelet rich plasma (PRP) fraction, optionally by resuspending the pelleted platelets in an appropriate medium, optionally in PPP.

[0429] Such centrifugation and/or fractionation will separate the red blood cells from the other components of blood, and further separate the platelet rich fraction (PRP) including platelets, with or without white blood cells together with a few red blood cells from the platelet poor plasma. PRP may be further concentrated by ultrafiltration, where the protein content of the platelet-rich plasma is concentrated from about 5% to about 20%.

[0430] PRP of the prior art typically comprises anticoagulant and clotting is carried out by a clotting agent. However, platelet rich plasma prepared by centrifuging blood without an anticoagulant may be activated by the method as described herein, in particular by clotting, which specifically activates the platelets contained in PRP in the absence of exogenous anticoagulant additives. The present invention specifically provides for activation of PRP, e.g. such that the majority of the platelets are activated. Thus, at least 50% of the platelets in the PRP are activated through the activation of coagulation.

[0431] Platelet rich fibrin is clotting spontaneously during its preparation by centrifuging a blood sample, preferably accelerated upon contact with negatively charged surfaces and with adding exogenous coagulation activators.

[0432] Preferably, upon clotting and formation of the platelet rich fibrin clot, the acellular or clear supernatant from the PRF may be isolated, or may be removed before fractionating the PRF to isolate the PRF fluid fraction. Such fluid fraction turned out to contain a high concentration of activated platelet releasate and growth factors contained therein.

[0433] Preferably, the SPRF may be obtained from a blood sample from a single donor or from multiple donors and mixed together to obtain a single blood sample. According to a specific aspect, the SPRF is obtained from venous blood collected from a single donor. In a preferred embodiment the donor is the patient to whom, once proliferated, the MSCs are reintroduced.

[0434] Preferably, the SPRF is employed herein without exogenous anticoagulants that are commonly used in the prior art when preparing PRP, thereby an effective activation of platelets and a content of an activated platelet releasate in the isolated serum fraction is obtained according to the invention.

[0435] Preferably, SPRF comprises significantly less bFGF than PRP. Preferably, SPRF comprises less than 100 pg/mL, more preferably less than 50 or 20 pg/mL, highly preferably less than 10 pg/mL, even more preferably less than 5 pg/mL bFGF or essentially comprises no bFGF.

[0436] Preferably, SPRF comprises significantly less G-CSF than PRP. Preferably, SPRF comprises less than 100 pg/mL, more preferably less than 50 or 20 pg/mL, highly preferably less than 10 pg/mL G-CSF.

[0437] Preferably, SPRF comprises less pro-inflammatory factors than PRP. In particular, SPRF comprises less pro-inflammatory factor(s) than PRP, said pro-inflammatory factor(s) being selected from the group comprising at least IL-6, IL-8, IL-12, TNF-.

[0438] Culture as used herein refers to the cultivation of biological material in an artificial environment, i.e. in vitro. Culturing thus may include maintenance and/or propagation of the biological material. The biological material may comprise cells or tissues, including artificial tissues or tissues taken out from an animal body or organs or partial organs or organ parts.

[0439] The term administration as used herein shall include routes of introducing or applying activated a preparation, such as the serum fraction of the invention, to a subject in need thereof to perform their intended function.

[0440] Preferred routes of administration are local, including topical or mucosal application, or application to a wound site or a site of intervention, e.g. surgical intervention, or application to an injured cartilage site or a site of (surgical) intervention at or near to cartilage, or a site in or near to the bone, e.g. under the cartilage. Administration may be carried out e.g. by using a fluid, spray, hydrogel, cream or ointment, or else by any other convenient route, including systemic administration, for example, injections, such as by subcutaneous, or intra-articular injections, by injecting into the layers of skin, under the skin into the epidermis, into fat pads, into muscles of various soft tissues, into cancellous bone and bone marrow, sprayed onto tissue surfaces, mixed with bodily fluids, etc. Various known delivery systems, including syringes, needles, tubing, bags, etc., can be used. Specific or alternative delivery systems employ patches for topical delivery, or implants. Specifically preferred are slow-release preparations, e.g. in the form of a hydrogel, a semisolid or solid gel or formulations and delivery systems to provide for the long-acting treatment. In a preferred embodiment administration is performed in the form of a fluid, in a hydrogel or collagen matrix or an artificial scaffold (matrix).

[0441] In one embodiment, the serum fraction of the present invention is the only therapeutically active agent administered to a subject, e.g. as a disease modifying or preventing monotherapy.

[0442] The serum fraction can be administered alone, or in combination or conjunction with either another agent or any other therapeutic treatment used in the indication, e.g. used to treat patients suffering from osteoarthritis, osteoarthrosis, bone necrosis, or bone ischemia or a patient in need of cultured cells, e.g. proliferated cells, in particular chondrocytes and/or mesenchymal stem cells.

[0443] In another embodiment, the serum fraction of the present invention is combined, e.g. combined in a mixture or kit of parts.

[0444] The serum fraction of the present invention may be administered in combination with one or more other therapeutic or prophylactic active agents or regimens, including but not limited to standard treatment, e.g. antibiotics, steroid and non-steroid inhibitors of inflammation, anti-inflammatory agents, vitamins, or minerals.

[0445] The serum fraction can be administered prior to the administration of the other agent, simultaneously with the agent, or after the administration of the agent. An alternative delivery system provide for the serum fraction associated with or bound to a carrier material, e.g. a gel or an implant.

[0446] The term in vitro is understood herein as outside the animal body in an artificial (or laboratory) environment or equipment. Preferably an in vitro environment is a controlled environment.

[0447] In a preferred embodiment an in vitro environment is a cell culture in an artificial vessel.

[0448] In a further preferred embodiment in vitro environment is an ex vivo environment. Ex vivo is understood herein as a body part e.g. tissue or organ or part thereof taken out from the animal body and present in an artificial (or laboratory) environment or equipment. Typically ex vivo refers to experimentation or measurements done in or on tissue from an organism in an external environment. The animal as understood herein is preferably a warm-blooded mammalian, particularly a human being.

[0449] The term isolated as used herein with respect to a serum fraction shall refer to such fraction of blood, plasma or serum that has been sufficiently separated from other fractions or blood components with which it would naturally be associated. In particular, the serum fraction of the invention is isolated so as to be separated from the PRF coagel and/or from the solid fraction of the PRF coagel. Isolated does not necessarily mean the exclusion of artificial or synthetic mixtures with other fractions, compounds or materials, or the presence of impurities that do not interfere with the fundamental activity. In particular, active substances and surgical materials may be combined with the isolated serum fraction of the invention.

[0450] The term pharmaceutically acceptable carrier as used herein shall specifically refer to any and all suitable solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like that are physiologically compatible with a serum fraction provided by the invention. Further examples of pharmaceutically acceptable carriers include sterile water, saline, phosphate buffered saline, dextrose, glycerol, ethanol, and the like, as well as combinations of any thereof. In one such aspect, a serum fraction can be combined with one or more carriers appropriate for a desired route of administration. Such carriers and modes of administration are well known in the pharmaceutical arts. A carrier may include a gel or hydrogel, or gellifying agent or gelling agent, controlled release material or time delay material, or other materials well known in the art.

[0451] Additional pharmaceutically acceptable carriers are known in the art and described in, e.g. REMINGTON'S PHARMACEUTICAL SCIENCES. Liquid formulations can be solutions, emulsions or suspensions and can include excipients such as suspending agents, solubilizers, surfactants, preservatives, gelling and chelating agents. Exemplary formulations may be provided, e.g. as a hydrogel including more than 50% water by weight.

[0452] The term subject or individual as used herein shall refer to a warm-blooded mammalian, particularly a human being. In particular, the medical use of the invention or the respective method of treatment applies to a subject in need of prophylaxis or treatment of a disorder or disease condition, e.g. associated with damaged tissue, a wound, an injury, a burn, an incision or an ischemic event, such as osteoarthritis, osteoarthrosis, bone necrosis or bone ischemia, or suffering from such disease condition; in an embodiment the respective method of treatment applies to a subject in need of treatment of a cartilage disorder or disease condition, e.g. associated with damaged cartilage tissue; in a further embodiment the respective method of treatment applies to a subject in need of administration of a pool of MSCs.

[0453] The term patient includes human and other mammalian, preferably warm-blooded mammalian subjects that receive either prophylactic or therapeutic treatment. The term treatment is thus meant to include both prophylactic and therapeutic treatment, in particular to treat, repair or augment a tissue at a target site.

[0454] Stem cells are undifferentiated or partially differentiated cells with a strong potential to differentiate into several or multiple differentiated cell types and which are also capable of a limited number of cell division to maintain themselves. Thus, stem cells have a limited capability to proliferate and a high potential to differentiate.

[0455] Adult stem cells (somatic stem cells or tissue stem cells) are partially differentiated stem cells capable of proliferation, self-renewal, production of a large number of differentiated functional progeny, and are capable of regenerating tissue after injury and having a flexibility in the use of these options.

[0456] Without limitation, adult stem cells are e.g.:

[0457] Hematopoietic stem cells,

[0458] Mammary stem cells,

[0459] Intestinal stem cells,

[0460] Mesenchymal stem cells,

[0461] Endothelial stem cells,

[0462] Neural stem cells,

[0463] Olfactory adult stem cells,

[0464] Neural crest stem cells,

[0465] Testicular cells.

[0466] Mesenchymal stem cells (MSCs) are stem cells of stromal origin and/or localization which have the potential to differentiate into several cell types, and are [0467] adherent, [0468] capable of differentiation into mesenchymal tissue, preferably bone, cartilage or adipose tissue in vitro, and preferably are [0469] CD105, CD73 and CD90 positive, do not carry surface markers of blood progenitor cells or heamatopoietic stem cells, and preferably are CD45, CD34, CD14, CD11b, CD79a and CD19 negative.

[0470] Cell therapy is the transplantation of human or animal cells to a patient to replace or repair damaged tissue.

[0471] MSC therapy is a cell therapy wherein MSCs are administered to a patient having an impaired tissue and wherein said MSCs are differentiated into cells of said tissue or tissue-specific cells or tissue-resident cells in the patient.

[0472] Osteoarthritis is a degenerative disease characterized by erosion of articular cartilage, which becomes soft, frayed, and thinned with eburnation of subchondral bone and outgrowths of marginal osteophytes; results in pain and loss of function; mainly affects weight-bearing joints. Osteoarthritis is also called degenerative joint disease, or osteoarthrosis. Osteoarthrosis may be considered as a chronic noninflammatory bone disease variant and also may be a synonym for osteoarthritis.

[0473] Spongy bone is the tissue that makes up the interior of bones; compact bone is the tissue that forms the surface of bones. In long bones, spongy bone forms the interior of the epiphyses.

[0474] Osteonecrosis is bone death in particular caused by poor blood supply.

[0475] Chondrocyte dedifferentiation is a process which involves the switching of the cell phenotype towards a state where extracellular matrix production no longer occurs. Chondrocyte dedifferentiation is also understood herein as a phenomenon that occurs during chondrocyte expansion in culture on 2D substrates.

[0476] Chondrocyte redifferentiation is a process which involves the switching of the cell phenotype from a dedifferentiated state (e.g. a state obtained by chondrocyte expansion in culture on 2D substrates) into a more differentiated state.

[0477] The dedifferentiation or the redifferentiation process can be monitored by differentiation markers e.g. by the Col II/Col I ratio.

[0478] Dedifferentiated chondrocytes as used herein are chondrocytes wherein the Col II/Col I ratio (CONSTANS-LIKE 1 and 2 are zinc finger proteins) is significantly lower than in healthy control chondrocytes.

[0479] In particular, dedifferentiated chondrocytes show reduced extracellular matrix production in comparison with healthy chondrocytes; in particular, dedifferentiated chondrocytes show reduced expression of aggrecan and collagen type II, in particular collagent type IIB in comparison with healthy chondrocytes.

[0480] Preferably dedifferentiated chondrocytes are chondrocytes which have been subjected to 2-dimensional culturing and/or cell expansion.

[0481] In an embodiment dedifferentiated chondrocytes are arthritic chondrocytes or chondrocytes dedifferentiated due to a cartilage disease or in impaired cartilage.

[0482] Chondrocyte proliferation (or chondrocyte expansion) is a process which, upon culturing (and expansion) of chondrocytes, involves the propagation or multiplication of the cultured chondrocyte cells.

[0483] The term comprise(s) or comprising or including are to be construed herein as having a non-exhaustive meaning and to allow the addition or involvement of further features or method steps or components to anything which comprises the listed features or method steps or components. Such terms can be limited to consisting essentially of or comprising substantially which is to be understood as consisting of mandatory features or method steps or components listed in a list, e.g. in a claim, whereas allowing to contain additionally other features or method steps or components which do not materially affect the essential characteristics of the use, method, composition or other subject matter.

[0484] As used in this specification and the appended claims, the singular forms a, an and the include plural references, and should be construed as including the meaning one or more, unless the content clearly dictates otherwise. In general, it is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

DETAILED DESCRIPTION OF THE INVENTION

[0485] The biological properties of the serum fraction or the respective pharmaceutical preparations of the invention may be characterized in vitro, preferably ex vivo in cell or tissue experiments or in whole organism experiments. As is known in the art, drugs are often tested in vivo in animals, including but not limited to mice, rats, rabbits, dogs, cats, pigs, and monkeys, in order to measure a drug's efficacy for treatment against a disease or disease model, or to measure a drug's pharmacokinetics, pharmacodynamics, toxicity, and other properties. The animals may be referred to as disease models. The serum fraction and respective pharmaceutical compositions of the present invention may further be tested in humans to determine their therapeutic or prophylactic efficacy, toxicity, immunogenicity, pharmacokinetics, and/or other clinical properties.

[0486] The terminology of these platelet concentrates, including PRP, PRF, platelet gel, fibrin glue and also platelet poor plasma (PPP) remains uncertain and their effectdespite the several positive results obtained in certain situations, controversial. A general classification of these products is suggested by Dohan et al. (In search of a consensus terminology in the field of platelet concentrates for surgical use: platelet-rich plasma (PRP), platelet-rich fibrin (PRF), fibrin gel polymerization and leukocytes. Curr Pharm Biotechnol. 2012 June; 13(7):1131-7.). Bone ischemia or ischemic bone necrosis (avascular necrosis, osteonecrosis, bone infarction, aseptic necrosis) is a disease wherein cellular death (necrosis) of bone components is due to an interruption of the blood supply of the bone tissue. As a result, the bone tissue dies; this necrosis of cell touches at the first place hematopoietic cells. If the disease affects the bones of a joint, it probably leads to destruction of the joint articular surfaces. Ischemic bone necrosis may be caused e.g. by traumatic injury, fracture or dislocation of the bones, dislocated hip or excessive alcohol consumption or use of steroids.

[0487] Upon reperfusion, repair of ischemic bone occurs. At first, mesenchymal cells and macrophages migrate from the living bone tissue grow into the dead bone marrow spaces and then the mesenchymal cells differentiate into osteoblasts and fibroblasts.

[0488] Possible treatment includes the replacement of the dead tissue and/or the use of compounds, which may reduce the rate of bone breakdown. There is still a need, however, for materials, which facilitate bone regeneration after the ischemic event.

[0489] Recent advances in regenerative medicine shed light on the capabilities of various growth factors, which have remarkable effects as inducers of bone formation. In addition to bone morphogenic proteins, platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), insulin-like growth factor (IGF) and epidermal growth factor (EGF) also have a positive effect on bone regeneration. Single factor therapies are available as recombinant products, currently BMP-2, -7, and PDGF have marketing approval, or as natural extracts typically isolated from venous blood.

[0490] Activation

[0491] In the prior art, the PRP was typically produced as anticoagulated preparation, e.g. from blood or PRP collected with anticoagulants, such as heparin, citrate, acid citrate dextrose (ACD) and/or citrate-theophylline-adenosine-dipyridamole (CTAD). Such anticoagulants were known to preserve the platelets maintaining the integrity of platelet structures. In contrast, the present invention is based on the PRP plasma activation wherein said PRP does not contain such anticoagulants, which was found to be supporting the effective production of invaluable growth factors and cytokines which are released by the platelets activated according to the method of the present invention.

[0492] The serum fraction of the invention is prepared without exogenous anticoagulants that are commonly used when preparing PRP, thereby an effective activation of platelets and a content of an activated platelet releasate in the isolated serum fraction is obtained according to the invention.

[0493] Specifically, the PRP is clotting spontaneously during its preparation by centrifuging a blood sample, preferably accelerated upon contact with negatively charged surfaces and with adding exogenous coagulation activators.

[0494] According to a specific aspect, the blood sample is collected in a clot device such as a clot tube or clot syringe, optionally wherein the PRP is prepared and clotted to obtain the coagel, e.g. a clot activating tube or syringe, which is typically equipped with appropriate coagulation initiators or accelerators, herein referred to as coagulation activators or contact activators.

[0495] Particularly preferred contact activators are anorganic, physical and/or biologic contact activators. According to a specific aspect, coagulation is accelerated or activated through the contact activation pathway, specifically upon contact with negatively charged surfaces, preferably glass e.g. silicate, borosilicate; kalomel, diatomaceous earth polymers with a polar structure, e.g. acrylates, carbonates, or polyacrylamides, specifically those which are physical contact activators.

[0496] Alternative activators may be biological, or chemicals like collagen, CaCl.sub.2, Ca-gluconate, MgCl.sub.2, thromboxane A2, ADP, thrombin, D-glucose, dextran, glycerol. These activators may be present as a coating, bead, or porous sponge. The activator may also be an enzyme or amino acid, like thrombin, thromboplastin or coagulation factors e.g. FIIa, FXa, FVIIa, FIXa, FXIa, FXIIa, FXIVa.

[0497] According to specific embodiments, it is preferred to prepare the serum fraction by endogenous clotting of the PRP, i.e. by physical contact with suitable surfaces only, thereby avoiding exogenous additives which would possibly contaminate the serum preparation. Such endogenous clotting would provide for the endogenously activated platelets, allowing the collection and isolation of the fluid fraction of PRF or the serum fraction of the invention containing the activated platelet releasate obtained from such activated platelets without exogenous contaminants. Specifically, in such embodiment the addition of exogenous thrombin or other coagulation factors is avoided.

[0498] For example, typical clot tubes may provide a negatively charged contact surface, such as glass, which would accelerate spontaneous clotting of the PRP during separation of the red blood cell fraction. The device may not only be used for collecting the blood, but also for preparing the PRP, e.g. by centrifugation of the blood sample in one or more consecutive steps.

[0499] According to a specific aspect, the serum fraction is freshly prepared without adding preservatives, such as ethanol, and e.g. prepared without any intermediate storage or freezing/thawing step. Typically, the preparation method would be carried out during a short period of time to obtain a freshly prepared serum fraction, e.g. a period up to 10 hours, preferably less than 6 hours.

[0500] Preservation

[0501] Such serum fraction is e.g. prepared ready-to-use for the purpose of treating a patient without using a preservative. Thus, stabilizing agents, such as high concentrations of alcohol or further preservatives are avoided. Yet, the freshly prepared serum fraction is storage stable at lower temperatures and may be stored at refrigerating temperatures or frozen over a longer period of time, e.g. at 2 C.-12 C. for up to 1-24 months, or at 80 C. to 25 C. for up to 0-5 years.

[0502] In the present invention SPRF showed surprisingly consistently better results than PRP and similar to or even better than the gold standard cell medium supplement FBS plus growth factors. However, FBS obviously is not appropriate for medicine and is not advisable in cell cultures in transplantation applications.

[0503] The invention relates to in vitro, ex vivo or in vivo methods of treatment of cells which comprise a cell culture and an incubation step, e.g. in solution or on a solid support, e.g. an implant or bone graft material. Such cell culture or treatment is preferably performed in the following way: Cells are cultured under regular cell culture conditions and the serum fraction of the invention is added to the medium. The addition of the serum fraction specifically induces cell proliferation, prevents cell death or damage and may induce differentiation in specific cell types. Cell proliferation is typically measured by cell counting or surrogate methods.

[0504] It was also unexpectedly found that certain blood derived preparations accelerate and improve cell proliferation, regeneration and healing of tissue, in particular osteoarthritic material or the bone tissue after ischemic bone damage.

[0505] Blood cells, upon activation by injury, secrete a plethora of proliferation factors into the serum. This raises the possibility of using serum products for therapeutic targets other than acute injury, thus applying a more physiological growth factor mix than the monotherapy of recombinant proteins. Investigations of PRP and related serum fractions in an ex-vivo model of bone ischemia were made. Small bone pieces of 10 mm.sup.3 were isolated from the discarded femoral heads during hip replacement operations. The explants were grown in culture for 3 days then subjected to transient oxygen glucose deprivation (OGD) for simulating ischemia. The majority of the cells on the bone explants died and the survivors did not proliferate. Adding PRP that is either native or anticoagulated (heparinized) or activated by chemical or physical means, did not have any effect on the postischemic cells. However, the serum fraction of the invention, in particular containing the fluid fraction of the coagel of PRF, in particular the serum pressed from platelet rich fibrin (SPRF), induced cell proliferation of the post-ischemic osteoblasts. Proteome-profiler analysis showed that PRP and SPRF have diverging growth factor profiles, with platelet factor 4 being a key one which has a higher concentration in SPRF than PRP. Another significant difference is the lack of fibrin or fibrinogen in SPRF. It is concluded that the serum fraction of the invention, in particular the SPRF, is a blood derivative which can restore the cell proliferation capacities, e.g. of post-ischemic bone and thus can be a new therapeutic tool, with a specific use in degenerative bone diseases.

[0506] The serum fraction of the invention is specifically provided for treating osteoarthritis, osteoarthrosis, bone necrosis or bone ischemia, for implants or autologous bone grafts to prevent or treat ischemia after implantation, or to increase proliferation of cells after an ischemic episode.

[0507] Bone ischemia or avascular necrosis (AVN) for example of the femoral head still presents a challenge for the orthopedic surgeons, mainly for the progressive characters of the disease and the relative young age of the patients. Presently available specific and efficient treatments are: [0508] core decompression [0509] autologous bone [0510] demineralized bone-matrix [0511] BMP (Bone morphogenic proteins) [0512] osteotomia [0513] application of promising agents of human blood, e.g. PRP [0514] any combination of the foregoing.

[0515] A human in vitro model was set-up and the effects of blood plasma derived preparations in the pathomechanism of bone ischemia were tested.

[0516] Experiments with various plasma fractions were carried out and it was surprisingly found that preparations can be obtained which are effective for accelerating and facilitating bone regeneration after bone ischemia.

[0517] The ex vivo results showed that the serum derived preparation of the invention directly induces proliferation of bone cells even after severe ischemia. Proliferation of cells has been found to be significantly improved by the fluid fraction of PRF, which comprises or consists of the liquid content in PRF, but not by PRP of the prior art.

[0518] The experimental results were surprising in view of the prior art. It was specifically surprising that the starting material, which is PRP without the addition of anticoagulants, and the clotting according to the invention affects the final result. Specifically, the freshly prepared serum fraction of the invention could be provided as an improved material for medical use.

[0519] Activated fibrin has a strong pro-inflammatory effect which is beneficial in case of acute injuries but may be harmful in chronic cases where regeneration of the tissues is inhibited by persistent inflammation. Therefore, matching the right kind of proliferation factor mix with a certain pathology is necessary in order to develop a reliable clinical protocol. In the present study a novel ex vivo human model of bone ischemia was used, which closely resembles the tissue states of transplanted bone or tissue damaged by end-stage degenerative diseases. The constituents of various platelet-rich serum fractions were analyzed and their effects as proliferation factors on postischemic human bone explants were investigated, to confirm the positive effects of the serum fraction of the invention.

[0520] Without being bound by theory this is possibly the mechanism behind the clinical observation that PRP augmented bone grafts have a markedly better 6-year result than decompression therapy in femoral head necrosis.

[0521] Specific method steps applicable in the present invention are as follows:

[0522] 1. Obtain venous blood. No additives, e.g. anticoagulants, are necessary.

[0523] 2. Remove red blood cells.

[0524] 3. Obtain platelet rich fibrin (a yellowish coagulum floats on top of the red blood cell fraction).

[0525] 4. From PRF separate the fluid fraction and the matrix (solid fraction). This can be done by pressing (squeezing) the PRF or by centrifugation at an increased, appropriate force.

[0526] In a preferred embodiment spinning down is carried out within 20 minutes, preferably within 15, 10, 5 minutes, or shorter period from obtaining venous blood.

[0527] Preferably, centrifugation is carried out at 1000 g to 5000 g, preferably at 2000 g to 4000 g or 1000 g to 3000 g or 1000 g to 4000 g, more preferably at about 1200 g to 2500 g or at about 1500 g to 2000 g. Preferably, centrifugation is carried out for 2 to 20 minutes, preferably for 4 to 15 minutes, highly preferably to about 5 to 12 minutes, preferably about 10 minutes (+/2 minutes).

[0528] The clot obtained (i.e. the coagel) can be removed by any appropriate method, e.g. by filtering or other physical means. In a preferred embodiment continuous centrifugation is applied and the clot is removed at an opening on the wall of the centrifugation space.

[0529] The fluid fraction from the clot can be removed by squeezing, pressing, filtering, vacuum filtering or any other appropriate method.

[0530] The process can be carried out in an application device e.g. a syringe. Preferably, according to a specific aspect, the serum fraction is freshly prepared and ready-to-use, optionally wherein the serum fraction is provided in the application device. A particular embodiment refers to an autologous serum fraction, i.e. a serum fraction prepared from blood of a single individual donor which is for administration to the same individual. Alternatively, a pooled serum fraction is prepared from multiple patients. In a preferred embodiment the SPRF is prepared from donors of young age, e.g. by donors from 19 to 40 years old e.g. by donors from 20 to 35 years old.

[0531] In a preferred embodiment the donor subject is different from the patient. Preferably, the age of the donor subject is below 50 years, preferably below 40 years, more preferably below 35 or 30 years. In a preferred embodiment the age of the patient is above 50 years or above 55 years or above 60 years.

[0532] The serum fraction may be conveniently prepared in an appropriate preparation device suitable for aseptic collection of the blood. Negatively charged surfaces are preferred. The isolated serum fraction may be produced in the application device in an aseptic way and may conveniently be directly and immediately administered to the individual, e.g. by an applicator aseptically connected to the preparation device, or by a separate application device or kit which allows the aseptic transfer of the prepared serum fraction to the application device and/or to administer the preparation to the individual.

[0533] According to the invention, the serum fraction is specifically provided for use in the manufacturing of an autologous pharmaceutical or medicinal product. Such product may be in the form of a pharmaceutical preparation or a medical device preparation.

[0534] Specifically, the serum fraction is provided for the treatment of the serum fraction's donor. Specifically, the autologous use of the serum fraction is preferred.

[0535] The invention is particularly useful in helping, facilitating or allowing the regeneration of the bone tissue of a subject. Bone tissue can be acutely damaged such as in case of trauma or surgery or can be chronically impaired e.g. in case of degenerative bone diseases such as osteoarthrosis, bone necrosis, or bone ischemia. As an example, ischemia can be present during transplantation of bone tissue or organs containing bone such as osteochondral plugs. Specific methods, which can be improved by using the serum fraction of the invention, are e.g. methods to apply plasma preparations in surgery such as taught in the following publications. [0536] Jun Araki et al.: Optimized Preparation Method of Platelet-Concentrated Plasma and Noncoagulating Platelet-Derived Factor Concentrates: Maximization of Platelet Concentration and Removal of Fibrinogen (Tissue Eng Part C Methods. 2012 March; 18(3):176-85). [0537] Dohan, D. M. et al.: Platelet-rich fibrin (PRF): A second-generation platelet concentrate. Part I: Technological concepts and evolution. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2006; 101(3):E37-44.

[0538] Mesenchymal Stem Cells (MSCs)

[0539] In a particular aspect, the cells cultured in the presence of SPRF are mesenchymal stem cells.

[0540] One of the most important functions of MSCs is natural tissue repair, which is mainly the result of the wide distribution and multipotent differentiation in the human body. Clinical and preclinical models already proved this reparative effect and the critical role of MSCs in injury healing was strongly suggested as well. MSCs are believed to be responsible for replacing cells that are lost in diseases or pathological conditions. Due to these functions the approach of supplementing stem cells to enhance tissue regeneration and treat degenerative diseases were also successfully tested and were shown to be effective. MSCs are also responsible for therapeutic effects in the musculoskeletal system, and were found to be effective in periodontal tissue and bone damage caused by e.g. osteonecrosis and has been successfully applied in cartilage and long bone repair. Besides supplementing MSCs, which were harvested from the patient and either injected or cultured and injected back to the patient, there may be an alternative solution as well. The distribution of stem cells may alternatively be redistributed using our method, which basically enables selective proliferation of the available stem cells, which means that the proliferative effect can be localized and thus a selective tissue repairing treatment can be realized. In order to overcome the uncertainty, which is posed by the circulating excess stem cell concentration, we focus on local therapeutic effect, which means that musculoskeletal and degenerative bone and joint diseases are the main therapeutical targets. This solves the majority of the circulation problems as the circulation of these parts of the body is limited thus the effect of the enhanced proliferation of the stem cells is concentrated on local tissue repair. In our case these tissues are mainly musculoskeletal tissues, more specifically bone and joint tissue.

[0541] Another important aspect of our application is that the MSCs preserve their stem cell character during the first 5 days of culturing as no differentiation occurs into adipocyte direction with the use of our SPRF culture supplement except the increase in osteoblast factors after 5 days of culture or further culturing. This enables the advantage of not interfering with the MSCs, thus the MSCs will only differentiate as an effect of the surrounding cells at site of the treatment. This gives the opportunity that the stem cells will differentiate in a manner that accelerates the regeneration of the treated tissue.

[0542] In case of diseases of the bone and cartilage this osteogenic differentiation indicates a further unforeseen advantage as it shows that SPRF in a surprising manner prepares the cells for osteogenic differentiation whereas no other direction of differentiation is observed. This means that SPRF and MSCs proliferated thereby are particularly suitable for treatment of diseases of the bone, in particular osteoarthrosis and osteoarthritis.

[0543] Source of MSCs

[0544] While MSCs are available from various sources it appears the present invention is not limited to BM derived MSCs and also for example adipose derived MSCs could be applied. Literature opinions vary in assessing the capabilities of MSCs of various sources, an advantage of the present invention may be that due to culturing as disclosed herein multiple sources may become useful and available.

[0545] Culturing MSCs

[0546] In the present invention MSCs are obtained from a subject and said MSCs are cultured by an in vitro method, as disclosed in the Brief Description of the Invention.

[0547] In the invention usual MSC culturing conditions can be applied, for example a DMEM basal medium with sugar source like high glucose, glutamate source like GlutaMax Supplement, pyruvate and antibiotics or selective agents like penicillin/streptomycin and 1% amphotericin. Instead of FBS regularly used in media like DMEM, SPRF and only SPRF are to be used. In a particular embodiment even no further growth factors are to be used.

[0548] SPRF as an MSC Medium Supplement/Additive

[0549] Pressing out the fluid content from PRF leads to an autologous blood separation product, which does not contain fibrinogen, anticoagulants and the inflammation markers are low. After testing it as a stem cell medium supplement, the inventors have surprisingly found that use of a serum from platelet rich fibrin (SPRF) instead of PRP and FBS enhanced the proliferation rate of human mesenchymal stem cells in vitro while phenotypical changes were not observed and differentiation potential of proliferated MSCs was maintained. Moreover, culturing human subchondral bone pieces in SPRF supplemented medium cell viability was not only retained, but also significantly increased in 7-days culture without any measurable cell differentiation. The inventors revealed that predominantly mesenchymal stem cells were multiplicated in the course of the incubation time.

[0550] Treatment with MSCs

[0551] Osteoarthritis (OA) is one of the most prevalent joint diseases with prominent symptoms affecting the daily life of millions of middle aged and elderly people. Despite this, there are no successful medical interventions that can prevent the progressive destruction of OA joints.

[0552] Administration of SPRF in Osteoarthritis

[0553] Administration of SPRF is conveniently carried out by injection at the site of impaired bone or chondrocyte tissue. In order to maintain an appropriate level so as to maintain contact with MSCs multiple injections can be applied. For example, injection can be added regularly, e.g. every day or in every 2 days or 1, 2 or 3 times a week.

[0554] Another possibility to maintain the level of SPRF may be e.g. matrix assisted administration.

[0555] Effect of SPRF on Chondrocytes

[0556] Chondrocytes are the main cell type found within cartilage. They are responsible for the synthesis and maintenance of the extracellular matrix (ECM) and are themselves isolated from each other by a large quantity of ECM. Chondrocytes therefore must exist in a low oxygen environment; all this explains the unitary nature of chondrocytes, cartilage and its low reparative potential and thus the problems arising in clinical conditions like osteoarthritis (OA).

[0557] Although articular cartilage can well tolerate physical stress, its ability to heal even a minor injury is particularly low which makes the cartilage tissue particularly sensitive to degenerative processes. Ageing also leads to alterations in ECM composition and alters the activity of the chondrocytes, including their ability to respond to stimuli such as growth factors. Moreover, chondrocytes gradually decline in number with age.

[0558] Other typical conditions wherein damage or injury of cartilage occurs are e.g. the following:

[0559] Cartilage damage like mechanical cartilage injury, traumatic cartilage loss, cellular matrix linkage rupture, chondrocyte protein synthesis inhibition, chondrocyte apoptosis, cartilage ulcer, subchondral bone damage, Ahlback's disease, osteochondral lesions.

[0560] In any of these situations the patient may be a subject in need of cartilage repair, preferably articular cartilage repair, e.g. cartilage replacement therapy.

[0561] Autologous chondrocyte implantation (ACI) is one of the most widely used cell based repair strategies for articular cartilage [Brittberg, M. et al. Treatment of deep cartilage defects in the knee with autologous chondrocyte transplantation. N Engl J Med. 1994, 331(4): 889-95; Brittberg M. Autologous chondrocyte implantationtechnique and long-term follow-up. Injury. 2008, 39(Suppl. 1):S40-9.]

[0562] In this method cartilage biopsy is taken from the patient from an area which is not weight bearing and preferably which is intact. Then chondrocytes are isolated and transferred into a 2 dimensional culture wherein they are cultured (expanded) to increase their number (multiply them). The so cultured chondrocytes then introduced into the affected (damaged, impaired) area of the cartilage wherein they are fixed.

[0563] Chondrocyte Dedifferentiation

[0564] The zones of cartilage are based on the shape of the chondrocytes, the composition of the extracellular matrix (ECM) and the orientation of the type II collagen with respect to the articulating surface and the subchondral bone. [Mobasheri, A. et al. Chondrocyte and mesenchymal stem cell-based therapies for cartilage repair in osteoarthritis and related orthopaedic conditions. Maturitas, 2014, 78: 188-198.]. Damaged ECM or its complete absence will result in a major shift in chondrocyte gene expression. Instead of producing cartilage specific proteoglycans and collagen type II, chondrocytes switch to making non-specific proteoglycans and collagen type I.

[0565] Chondrocyte dedifferentiation is known to influence cell mechanics leading to alterations in cell function. Dedifferentiation occurs in diseased, e.g. OA cells as well. Typically metabolically active OA chondrocytes no longer express aggrecan and collagen type II. However, chondrocytes in OA cartilage express collagens type I and III, which are rare in normal articular cartilage. OA chondrocytes also express type IIA collagen, a marker of prechondrocyte phenotype. This expression is enhanced by transforming growth factor-1 (TGF-1). Bone morphogenetic protein-2 (BMP-2), on the other hand, favors the expression of type IIB collagen isoform, a normal component of articular cartilage. Thus, despite their high synthetic activity, dedifferentiated chondrocytes do not express cartilage-specific anabolic genes such as aggrecan or type II collagen, associated with an impairment in anabolic function.

[0566] Thus, damaged or ostearthritic chondrocytes show signs of dedifferentiation which is modeled in 2 dimensional chondrocyte cultures used for autologous cell based repair of articular cartilage. While the US Food and Drug Administration has approved the clinical use of chondrocytes that have been expanded in vitro to obtain larger number of cells, cells cultured using traditional 2D monolayer conditions undergo dedifferentiation indicated by a phenotypic shift. Dedifferentiated cells are larger, spread and acquire actin stress fibers. They express fibroblastic matrix (such as type I collagen; COL1A1) as well as contractile (alpha smooth muscle actin; aSMA) molecules resulting in biomechanically inferior tissue capable of shrinkage. [Parreno, J. et al., Chondrocyte Dedifferentiation: Actin Regulates the Passaged Cell Phenotype Through MRTFa. Osteoarthritis and Cartilage, 22 (2014), S57-S489, abstract].

[0567] The term dedifferentiation as used herein includes both dedifferentiation due to a disease process and the process as occurs in vitro, preferably the latter.

[0568] In this study, we have investigated the effect of serum from platelet rich fibrin (SPRF) donor age variation on osteoarthritic (OA) chondrocyte culture expansion. SPRF was prepared from 10 individual donors aged 25 to 59 years and added to chondrocyte cultures started from explants harvested at knee replacement surgery.

[0569] Multiplex Array

[0570] We have performed a multiplex arrayprotein quantification (FIGS. 7A, 7B and 8) to characterize the fractions.

[0571] In cell proliferation experiments of chondrocytes from OA patients we have surprisingly seen that SPRF was slightly more effective than PRP in particular from younger donors in promoting proliferation (see e.g. FIGS. 9A and 9B).

[0572] Col I and COL II (CONSTANS-LIKE 1 and 2) are zinc finger proteins playing role in gene regulation. The Col II/Col I ratio is indicative of the cell-cell differentiation (in dedifferentiated cell the redifferentiation) potential of cells. Measurement may be made at the mRNA or protein level. We have shown that this index of differentiation is very low when SPRF is used both under conditions of normoxia and hypoxia (FIGS. 10A-D, 11A-D and 12A-D).

[0573] Proteins of the matrix metalloproteinase (MMP) family are involved in the breakdown of extracellular matrix proteins and during tissue remodeling in normal physiological processes, such as embryonic development and reproduction. MMP 3 is involved in normal collagen breakdown. MMP13 is expressed in the skeleton as required for restructuring the collagen matrix for bone mineralization. In pathological situations it is highly overexpressed; this occurs in human carcinomas, rheumatoid arthritis and osteoarthritis [Johansson, N., Ahonen, M., Kahari, V.M. (2000). Matrix metalloproteinases in tumor invasion. Cell Mol Life Sci. 57 (1): 5-15].

[0574] FIGS. 13A-D and 14A-D show a normal expression of these genes under the condition of normoxia. Matrix metalloproteinase 3 (MMP 3) gene expression was normally regulated also under conditions of hypoxia. Matrix metalloproteinase 13 (MMP 13) gene expression was reduced under conditions of hypoxia in case of SPRF and PRP which is normal and suggest that SPRF is safe.

[0575] Chondrocyte Transplantation or Implantation

[0576] FIG. 17 shows an autologous chondrocyte implantation process scheme. Such methods are known e.g. in the literature below, the content of which is incorporated herein by reference, as far as treatment of cartilage with chondrocytes is disclosed. Autologous chondrocyte implantation is described e.g. in Robi et al, Current Issues in Sports and Exercise Medicine (2013)/978-953-51-1031-6.]. Also, a review is provided by Vasiliadis, H. et al. [Vasiliadis, H.; Wasiak, J.; Salanti, G. (2010). Autologous chondrocyte implantation for the treatment of cartilage lesions of the knee: a systematic review of randomized studies. Knee Surgery, Sports Traumatology, Arthroscopy 18 (12): 1645-1655.]. A further summary is provided by Mobasheri, Ali et al. [Mobasheri, Ali et al. Chondrocyte and mesenchymal stem cell-based therapies for cartilage repair in osteoarthritis and related orthopaedic conditions. Maturitas 78 (2014) 188-198]. Peterson, Lars et al. [Peterson, Lars et al. Autologous Chondrocyte Implantation: A Long-term Follow-up. The American Journal of Sports Medicine, 2010, 38(6) 1117-1124.] report on a long term follow of patients treated by first generation ACI and conclude that ACI is an effective and durable solution for the treatment of large full-thickness cartilage and osteochondral lesions of the knee joint. They add that second- and third-generation ACI techniques have been developed since 1987, using either manufactured coverings or scaffolds for the 3-dimensional culturing of the chondrocytes or, in third generation

[0577] ACI, fully arthroscopical administration can further improve outcomes in the future.

[0578] The present inventive methods provided herein seamlessly fit into such scheme by adding SPRF to the chondrocyte culturing medium. SPRF is added to the culturing medium of chondrocytes so as to improve their proliferation rate, preferably in vitro. SPRF is in one embodiment simply mixed into the media. Upon implantation of the cells SPRF may be administered simultaneously.

[0579] Autologous Chondrocyte Implantation with Scaffold (Matrix) or Cover

[0580] Variants of the autologous chondrocyte implantation method are methods using a cover for the chondrocyte, e.g. a periosteum-cover technique e.g. wherein type I/type III collagen is used as a cover (ACI-C) and matrix-induced autologous chondrocyte implantation (MACI) using a collagen bilayer seeded with chondrocytes. The methods are described e.g. in Bartlett W. et al. [Bartlett W. et al. Autologous chondrocyte implantation versus matrix-induced autologous chondrocyte implantation for osteochondral defects of the knee. J Bone Joint Surg [Br] 2005; 87-B:640-5.]. A more recent report on MACI is provided by Schneider, T., E. and Karaikudi S. [Schneider, T., E., Matrix-Induced Autologous Chondrocyte Implantation (MACI) Grafting for Osteochondral Lesions of the Talus. Foot & Ankle International 30(9) 2009]. The studies report that the MACI technique is a basically reliable treatment method. According to the invention such method can be used with a minimal adaptation wherein the chondrocytes are to be cultured in SPRF.

[0581] Upon culturing the chondrocytes the SPRF is preferably used in a concentration of between 1-25% or 2-20%, preferably 5 to 15%, highly preferably 8 to 12% or in particular about 10%, wherein the percentage of concentration is given in v/v %.

[0582] Administration SPRF to the Site of Cartilage Damage

[0583] An alternative method for the treatment of cartilage injuries is the administration of SPRF to the site of cartilage damage. This method should be preceded by a diagnosis of the cartilage injury. Very seriously damaged cartilage may not be successfully treated by this technique. Also, some healthy cartilage may be necessary to be present.

[0584] The SPRF is prepared as described herein, and included into an appropriate physiologically acceptable buffer system. In an embodiment the SPRF

[0585] Matrix (Scaffold) Assisted Administration of SPRF

[0586] In an embodiment SPRF can be added to a matrix analogously to a matrix-induced autologous chondrocyte implantation matrix, with or without chondrocytes.

[0587] The foregoing description will be more fully understood with reference to the following examples. Such examples are, however, merely representative of methods of practicing one or more embodiments of the present invention and should not be read as limiting the scope of invention.

EXAMPLES

Example 1: Platelet-Rich Plasma as an Adjuvant Therapy in Aseptic Femoral Head Necrosis

[0588] In a retrospective clinical observational study two surgical treatments were compared for avascular femoral head necrosis. Patients of the control group (n=13) were treated with core decompression alone, in the PRP group (n=19) core decompression was completed with the impaction of autologous bone chips mixed with autologous PRP. hi the clinical observational study six years after the operation the PRP group had significantly lower failure rate (21% vs 67%, p<0.05) indicated by prosthesis implantation.

[0589] However, the exact role and cellular mechanisms are unknown and further data are necessary to prove the effect of the method.

Example 2: Preparation of an SPRF Composition, which is an Exemplary Serum Fraction of the Invention

[0590] A preparation was prepared which was free of platelets, however was rich in platelet-derived factors. The description of the procedure applied is as follows:

[0591] 1. Venous blood was drawn into a standard, native tube without any additives.

[0592] 2. Spinned it down instantly, preferably within 3 minutes, in a centrifuge at 1600-1700 G, for 5-10 minutes.

[0593] 3. The red blood cells were collected at the bottom of the tubes, a yellowish coagulum floats on top of the red blood cell fraction in clear plasma. This clot (coagulum or coagel) was removed with a forceps and put on a clean petri dish.

[0594] 4. The clot was gently squeezed to obtain the fluid out of the clot: The fluid obtained from the clot is essentially the final SPRF composition. As an estimate 0.4 ml final product can be gained from 6 ml of blood.

[0595] In order to speed up the clotting mechanism a silica-coated blood collection tube or a glass tube can also be used for drawing blood.

Example 3: Bone Explants and Oxygen Glucose Deprivation (OGD)

[0596] In this in vitro study, bone samples were obtained from the removed femoral head during total hip replacements for primary osteoarthritis. Femoral heads were obtained from patients suffering from coxarthrosis and undergoing hip replacement surgery, during which the femoral head is extracted in its entirety and discarded as surgical waste. [0597] Average 0,004 g weight explants (n=40 pieces/patient) were harvested from the femoral heads [0598] The explants were transported into cell culture conditions at 37 C. in Dulbecco's Modified Eagle Medium containing 1 g/l glucose, 5% Penicillin-streptomycin and 10% fetal bovine serum (Stem cell medium).

[0599] After an incubation of 3 days of the femoral heads oxygen-glucose deprivation (OGD) was used to model the poor circulation of the femoral head. At a tissue level OGD models cellular damage and impaired regeneration which is characteristic for degenerative bone diseases such as aseptic necrosis, osteochondrosis, osteoarthrosis, etc. The femoral heads were placed into glucose and amino-acid free medium at an oxygen level of O.sub.2<0.5 mmHg (replaced with N2 gas). The tests have been continued at 1, 2.5, 3.5, 4, 5, and 7 hours after which the normal cell culture conditions were restored.

[0600] For qualitative testing of cell viability live and dead cells were labeled with

[0601] Calcein-AM (488 nm) and Ethidium-Homodimer-2 (546 nm) fluorescent dyes, then evaluated by confocal microscopy (ZEISS LSM confocal microscopy, 20).

[0602] For quantitative analysis of cell viability the methyl-thiazol-tetrasolium (MTT) assay was used with the following parameters: 1 h incubation in MTT solution, 1 h solubilization in isopropanol, absorbance measures at 570 and 690 nm.sub.5 correcteted with the dry weight of bones. Assay was carried out at 37 C. In preliminary experiments, incubation was tested for 10 minutes, 1, 2, 5 hours, and solubilization in isopropanol was tested for 10 minutes, 1, 2, 3, 4, 5, 6, 20 hours.

Example 4: Preparation of an Exemplary Serum Fraction of the Invention

[0603] (SPRF) And its Characterization

[0604] In an early variant of the method, Platelet-rich plasma was isolated by the double-centrifugation protocol. Blood from healthy adult donors was collected in EDTA tubes (BD Vacutainer, K2E EDTA) and centrifuged at 1300 rpm (320 g) for 12 minutes. The supernatant was removed and centrifuged at 3000 rpm (1710 g) for 10 minutes. The pellet was resuspended in stem cell medium at a 1:4 ratio during the OGD therapy and after that. Heparinized PRP was created by adding 100 l fractionated heparine (Clexane 4000 NE/0.4 ml) to 1200 l PRP after the isolation. Platelet-rich fibrin was prepared by centrifugation without anticoagulants for 5 minutes at 3000 rpm (1710 g). A fibrinous gel was removed from the tube and the fluid gently squeezed out of the gel to obtain isolated SPRF, which was added to the stem cell medium in 1:10 ratio. The amount of serum was about 500 l of final product from 6 ml of blood) and 2 ml of final product from 6 ml of blood

Example 5: Effect of Serum Fractions on Bone Explants after Oxygen Glucose Deprivation

[0605] Bone explants were harvested from the discarded femoral heads from patients undergoing hip replacement. Bone grafts of about 10 mm.sup.3 were collected and transferred immediately into Dulbecco's Modified Eagle Medium containing 1 g/l of glucose, 1% penicillin-streptomycin, and 10% fetal bovine serum. The explants were cultured in this medium under standard cell culture conditions in 24-well plates. Oxygen-glucose deprivation (OGD) was performed in a Pecon incubation system (Erbach-Bach, Germany) on the third day after explantation. The bone pieces were transferred into stem cell medium lacking glucose and amino acids and the oxygen was flushed with nitrogen to 0.5% O.sub.2 level for 7 hours. After completion of OGD the medium was replaced and the explants were cultured in 20% oxygen and 5% CO.sub.2. Blood fractions were added to the medium in a ratio of 1:4 just before OGD and was refreshed at medium changes. Both PRP and SPRF was prepared fresh just before use and never stored or frozen.

[0606] The grafts were incubated in a 1:9 diluted mixture of 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT, #M5655, Sigma) and stem cell medium at 37 C. for 60 min then diluted with isopropanol. Absorbance of the solution was measured by a PowerWave XS spectrophotometer at 570 nm and noise was filtered out by measuring the absorbance at 690 nm. The MTT-assay was performed on the third and sixth days after OGD.

[0607] There were only a few living cells on the bone chips on the day of the operation, and these cells were damaged. The samples were obtained from different patients. To get the various bone chips into a similar state, they were incubated in stem cell medium at 37 C. and 5% CO.sub.2 for 3 days. Sufficient number of cells were detected on the 3.sup.rd day, therefore OGD was started to model the ischemic condition. Based on the data of four patients significant difference was shown by t-test between cell viability of the bone chips on the day of surgery and after 3 days of incubation (81.7547.72 vs. 106.2855.24).

[0608] To achieve the ischemic state OGD was applied for many different intervals. Bone samples were observed for one, two and a half, three and a half, five and seven hours of OGD. After the OGD treatment lasting 5 hours, cell viability of the OGD treated and untreated groups were determined by MTT assay and it was found that 5 hours of treatment is not enough to damage cells (n=12 explants/groups, control: 50.366.66 vs. OGD: 36.973.00, t-test, not significant). Before OGD healthy adherent cells could be seen in green, and with increasing the time of OGD to 7 hours these cells lost their branches, changed their shape, got damaged or killed, so their color turned red. Significant difference was shown between the control group and the OGD-treated group by our quantitative measurement.

[0609] During the PRP treatment explants of the treated group received a mixture of PRP and stem cell medium in a 1:4 ratio.

[0610] PRP cannot improve the viability of the cells after the ischemic condition (FIGS. 2A-D). As PRP was put into the stem cell medium, red blood cells in PRP were coagulated and the consistence of the solution became jelly-like. To avoid this consistency heparin was put into the PRP solution and cell viability was examined based on the protocol described earlier. A tendential growth was observed on the 6th day after the OGD compared to the untreated group, but this was not significant. Significant difference was not observed after testing the PRP in higher and lower concentrations (FIGS. 2A-D). To activate platelets, three methods were tried: freeze and thaw, added CaCA or CaCA and thrombin, but none of them changed the earlier results (FIGS. 2A-D).

[0611] The effect of SPRF during the OGD was examined. Treated explants were incubated in stem cell medium containing SPRF 1:4 scale for 7 hours. Based on the result of MTT assay, it is concluded that the group treated with SPRF did not have higher cell viability compared to the untreated group. SPRF cannot protect the immediate, acute effect of OGD (Data from 2 patients, control group: 70.186.64, OGD group: 24.852.49, SPRF group: 26.783.49, not significant difference).

[0612] After that long-term effect of SPRF was examined. Explants were treated during OGD and continuously for 6 days after OGD. On the 3rd day the medium was changed and cell viability assay was done and tendencial growth was shown in the SPRF-treated group. After another 3 days of incubation after the OGD the difference was significant (FIGS. 3A-B).

[0613] In the pre-treated groups explants have received SPRF from the day of the surgery. In these cases the positive effect of SPRF can be declared, because significant difference was already detected between the treated and untreated groups after 3 days of OGD (4 patients, n=24 explants/groups, **:p<0.01), which difference was more pronounced on the 6th day after OGD (4 patients, n=24 explants/groups, ***:p<0.0001) (FIGS. 3A-B). In our study two rather similar blood fractions were compared in a model of bone ischemia. Unexpectedly, a positive effect from PRP could not be observed even at high concentrations, while SPRF significantly improved the proliferation capacity of osteoblast cells damaged by ischemia. It is also of note that the proliferative effect was additive to the effect of FBS, a normal constituent of stem cell culture media, and was only observed at the postischemic state.

Example 6: Analysis of the Composition of Serum Fractions

[0614] For determination the growth factors and angiogenesis-related proteins in the SPRF and PRP Proteome Profiler Human Angiogenesis Array Kit (R&D System, #ARY 007) was applied and Adobe Photoshop was used for quantitation of protein expression. For the quantitative determination of platelets and ions in SPRF Sysmex XT 4000i and Beckman Coulter AU5800 was used. Results are reported as meanSEM. Statistical significances were determined by t-test or one-way ANOVA with Tukey's post-hoc tests as appropriate with the Graphpad Prism software. Significance values of p<0.05 were considered significant.

TABLE-US-00001 TABLE 1 Laboratory parameters of blood fractions. Salts and proteins were measured by a Sysmex XT 4000i device, cell counts were determined by a Beckman Coulter AU5800 device. Data is presented as average SEM, n = 3. Normal range in SPRF PRP PPP whole blood Unit Sodium 141.00 0.58 138.33 0.67 139.00 1.00 133-146 mmol/l Potassium 4.04 0.19 4.38 0.26 3.90 0.19 3.5-5.3 mmol/l Calcium 2.31 0.01 2.33 0.04 2.30 0.02 2.12-2.57 mmol/l Magnesium 0.84 0.01 0.88 0.04 0.83 0.00 0.6-1.1 mmol/l Chloride 105.67 0.88 103.00 0.58 102.67 0.88 99-111 mmol/l Phosphor 1.21 0.08 1.31 0.08 1.16 0.08 0.87-1.45 mmol/l Glucose 5.36 0.32 4.61 0.34 5.26 0.3 3.6-6.0 mmol/l Total protein 74.87 1.53 75.77 1.7 74.03 2.4 60-80 g/l Albumin 49.67 0.07 48.27 0.33 47.57 0.82 35-52 g/l IgG 12.04 1.34 10.22 1.17 12.95 1.17 6.9-14 g/l Hemoglobin 0.00 0.00 6.33 0.88 0.33 0.33 115-155 g/l Fibrinogen 0.00 0.00 1.07 0.09 0.00 0.00 1.5-4 g/l Red blood cells 0.00 0.00 0.28 0.04 0.00 0.00 4.2-6.1 T/l White blood cells 0.01 0.01 14.85 2.61 0.01 0.01 4.8-10.8 G/l Platelets 1.33 0.33 242.33 75.9 16.00 4.93 150-400 G/l

[0615] There are several key differences between PRP and SPRF measured by the proteome profiler assay (FIGS. 4A-B). The differences between the two fractions are limited to a handful of proteins, and it is a straightforward explanation that those factors that have higher levels in the SPRF fraction are responsible for the effect. It is noted that the full proteomics analysis of platelet release has just been compiled and it contains 3500 proteins, significantly more than those measured by the Proteome Profiler assay. However, two important proteins are often overlooked in these analyses: albumin and fibrin (Table 1). Both proteins are abundant in serum and have rather well-described effects on cell proliferation. It was previously described that the in vitro and in vivo bone inducting effects of serum albumin, which raises the possibility that albumin itself is the active factor in PRP and SPRF. However, since albumin is present in both PRP and SPRF at comparable levels, plus it is also added to the culture medium in the form of FBS, it is concluded that it would not be responsible for the effects of SPRF observed in the current study.

[0616] A clear difference between PRP and SPRF preparations is the presence of fibrin (Table 1). Fibrin or the inactivated form fibrinogen is the second most abundant protein in serum and is present in both native and heparinized PRP while it is missing in SPRF. Several studies described that fibrin has a very strong pro-inflammatory reaction by specifically activating macrophages. Fibrin is also known as a key factor in the bone healing process after a fracture as the first step of enchondral bone formation. Although not all details of the cellular connections of fibrin is clear, it is reasonable to hypothesize that it is at least partly responsible for the differences in the proliferative action of SPRF versus PRP. It is also of importance that the model used in the present study is not designed to mimic bone healing under normal conditions, but rather regeneration potential of a damaged tissue. While the inflammatory response during an acute injury of a broken healthy bone may be beneficial, it has an opposite effect in a degenerative tissue where the remodelling capacity of the cells is impaired. It is believed that the current model resembles this later situation by mimicking an ischemic period. The observation that serum fractions had no effect on the healthy state of the bone explants but in the postischemic period also supports the idea that the current model, with its limitations as an ex vivo system, more resembles degenerative bone tissues. Furthermore, since the bone stock was femoral heads explanted at total hip replacement procedures in end-stage osteoarthosis, the current results should be interpreted in this context.

[0617] It is concluded that isolating serum from platelet rich fibrin has unique regenerative properties in damaged bone tissues. The isolation of SPRF is a simple procedure which can be performed at the bedside, providing an autologous mix of growth factors which may even be used in degenerative bone diseases. The fact that SPRF is devoid of fibrin and has generally fewer constituents than PRP, but better effects in this specific case is a further step in the standardization of serum products. Based on the current ex vivo human study, the clinical translation of the use of SPRF is initiated in degenerative and ischemic bone diseases.

[0618] The short term safety of PRP is well-established by numerous clinical studies, however, concerns emerged regarding its efficacy. Attempts at compiling a meta-analysis face the problem of non-standardized nomenclature, diverse isolation protocols and treatment regimens. Even well-designed studies focusing on a niche indication struggle with the very high variation of growth factor levels in PRP. Since PRP is essentially a mixture of known and yet unknown active agents, it is not evident which can be used as a reference compound for dosing. Therefore, currently the best way of standardization is defining the product by the isolation protocol rather than its constituents.

Example 7: SDF-1 Determination in SPRF

[0619] SDF-1 (Stromal cell-derived factor-1), also known as PBSF (pre-B-cell growth-stimulating factor), is a recently discovered protein belonging to the alpha chemokine (CXC) family of cytokines. SDF-1 alpha and SDF-1 beta are the first cytokines initially identified using the signal sequence trap cloning strategy from a human bone-marrow stromal cell line. SDF-1 has chemotactic activity on resting T lymphocytes and monocytes. The SDF-1 ELISA (Enzyme-Linked Immunosorbent Assay) kits [Sigma-Adrich, RAB0123, Human SDF 1 alpha ELISA Kit and RAB0124 SIGMA Human SDF-1 beta ELISA Kit] are in vitro enzyme-linked immunosorbent assays for the quantitative measurement of human SDF-1 in plasma (serum samples are not recommended for use in this assay as human SDF-1 concentration is low in normal plasma, it may not be detected in this assay), cell culture supernatants, and urine. This assay employs an antibody specific for human SDF-1 coated on a 96-well plate. Standards and samples are pipetted into the wells and SDF-1 present in a sample is bound to the wells by the immobilized antibody. The wells are washed and biotinylated anti-human SDF-1 antibody is added. After washing away unbound biotinylated antibody, HRP-conjugated streptavidin is pipetted to the wells. The wells are again washed, a TMB substrate solution is added to the wells and color develops in proportion to the amount of SDF-1 bound. The Stop Solution changes the color from blue to yellow, and the intensity of the color is measured at 450 nm. The standard dilution curve was prepared using the following SDF-1 concentrations (pg/ml): 6000, 3000, 1500, 750, 375, 187.5, 93.75.

Example 8

[0620] Serum from platelet-rich fibrin (SPRF) and the platelet-rich plasma (PRP) were obtained from whole blood of 11 donors. Isolated SPRF and PRP will be stored at 80 C. as stocks and aliquots for cell-culture experiments and GF, cytokine quantification assays by Luminex

[0621] Materials

[0622] Sterile

[0623] Tweezers (sharp and thin tweezer), Sharp scissor

[0624] VACUETTE 9 ml K3 EDTA Blood Collection Tube (REF. 455036, Greiner Bio-one)

[0625] VACUETTE 9 ml Z Serum C/A (REF.no. 455092, Greiner Bio-one)

[0626] Polypropylene falcon tubes 15 ml

[0627] Eppendorf tubes 2 ml

[0628] Non-Sterile

[0629] Centrifuge

[0630] Method

[0631] Isolation of SPRF:

[0632] a) Whole blood obtained from donors was centrifuged at 1700 g for 10 mins at RT in the VACUETTE 9 ml Z Serum C/A.

[0633] b) The fibrin clot from the tube was gently removed with a sharp tweezer and placed onto a sterile petri dish and the red blood cells at the bottom of the fibrin clot were cut with a sharp scissor and discarded.

[0634] c) Now, using a flat forceps the lysate was squeezed out of the fibrin clot, collected, stored at 80 C.

[0635] Isolation of PRP:

[0636] d) Whole blood obtained from donors was centrifuged at 320 g for 12 mins at RT in the VACUETTE 9 ml K3 EDTA blood collection tube.

[0637] e) Three layers were formed in the collection tube. A bottom layer containing red blood cells, middle layer containing the buffy coat and top layer containing Platelet-Poor plasma (PPP).

[0638] f) The top layer (PPP) was aspirated along the middle layer (buffy coat) and transferred into a 15 mL falcon tube and centrifuged at 1700 g for 10 mins, the pellet was resuspended into an corresponding volume to the isolated SPRF in the supernatant (PPP), stored at 80 C.

[0639] Data from Informed Consent and Parameters for Isolation

TABLE-US-00002 TABLE 2.0 Isolation of SPRF with defined parameters Volume *vials Volume stored *tubes Centrifugation Collected Volume at 80 C. Donor ID Total blood centrifuged period for G- serum from stored at 80 C. for No. Gender Age collected for SPRF SPRF Force/RPM PRF for Luminex Donor 1 F 57 36 mL 9 mL* 2 10 mins 1710 g/3000 1 1 mL NIL Donor 2 F 40 36 mL 9 mL* 2 10 mins 1710 g/3000 1.5 1.5 mL NIL Donor 3 F 24 36 mL 9 mL* 2 10 mins 1710 g/3000 0.2 0.2 mL NIL Donor 4 M 25 36 mL 9 mL* 2 10 mins 1710 g/3000 1.8 1.8 mL NIL Donor 5 M 32 36 mL 9 mL* 2 10 mins 1710 g/3000 2.4 2.4 mL NIL Donor 6 M 34 36 mL 9 mL* 2 10 mins 1710 g/3000 2.5 2.5 mL NIL Donor 7 M 29 36 mL 9 mL* 2 10 mins 1710 g/3000 1.1 1.1 mL NIL Donor 8 F 31 36 mL 9 mL* 2 10 mins 1710 g/3000 1 1.0 mL NIL Donor 9 F 39 36 mL 9 mL* 2 10 mins 1710 g/3000 1.05 0.8 mL 75 ul*2 Donor 10 M 30 36 mL 9 mL* 2 10 mins 1710 g/3000 2.65 2.5 mL 75 ul*2 Donor 11 F 36 36 mL 9 mL* 2 10 mins 1710 g/3000 2.15 2.0 mL 75 ul*2 Donor 12 M 36 36 mL 9 mL* 2 10 mins 1710 g/3000 1.45 1.3 mL 75 ul*2 Donor 13 F 58 36 mL 9 mL* 2 10 mins 1710 g/3000 1.625 1.5 mL 125 ul*1 Donor 14 F 53 36 mL 9 mL* 2 10 mins 1710 g/3000 3.725 3.6 mL 125 ul*1 Donor 15 F 52 36 mL 9 mL* 2 10 mins 1710 g/3000 2.425 2.3 mL 125 ul*1 Donor 16 F 58 36 mL 9 mL* 2 10 mins 1710 g/3000 1.0 0.875 mL 125 ul*1 (not sterile) Donor 17 F 27 36 mL 9 mL* 2 10 mins 1710 g/3000 1.8 1.675 mL 125 ul*1 Donor 18 F 50 36 mL 9 mL* 2 10 mins 1710 g/3000 2.3 2.175 mL 125 ul*1 Donor 19 M 57 36 mL 9 mL* 2 10 mins 1710 g/3000 2.0 1.875 mL 125 ul*1 Donor 20 M 61 36 mL 9 mL* 2 10 mins 1710 g/3000 2.4 2.275 mL 125 ul*1

TABLE-US-00003 TABLE 3.0 Isolation of PRP with defined parameters Vol. Volume* stored vials Volum. 80 C. stored at Total *tubes Centrif. Coll. Centrif. for 80 C. Donor blood centrifuged period 1 G- S. nat. period 2 G- Stock for ID No. Gender Age collected for PRP (mins) Force/RPM (mL) (mins) Force/RPM (mL) Luminex Donor 1 F 57 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 1 NIL Donor 2 F 40 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 1.5 NIL Donor 3 F 24 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 0.2 NIL Donor 4 M 25 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 1.8 NIL Donor 5 M 32 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.4 NIL Donor 6 M 34 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.5 NIL Donor 7 M 29 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 1.1 NIL Donor 8 F 31 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 1 NIL Donor 9 F 39 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 0.8 75 ul*2 Donor 10 M 30 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.5 75 ul*2 Donor 11 F 36 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 2.5 75 ul*2 Donor 12 M 36 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 1.3 75 ul*2 Donor 13 F 58 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 1.5 125 ul*1 Donor 14 F 53 36 mL 9 mL* 2 12 320/1200 4 10 1710/3000 3.6 125 ul*1 Donor 15 F 52 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.3 125 ul*1 Donor 16 F 58 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 0.875 125 ul*1 (not sterile) Donor 17 F 27 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 1.675 125 ul*1 Donor 18 F 50 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.175 mL 125 ul*1 Donor 19 M 57 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 1.875 mL 125 ul*1 Donor 20 M 61 36 mL 9 mL* 2 12 320/1200 6 10 1710/3000 2.275 mL 125 ul*1 *After centrifugation period 2, the pellet (PRP) was re-suspended in an equal amount of PPP (Supernatant) in a volume corresponding to the obtained volume from SPRF

[0640] Observations During Experiments [0641] In the preparation of SPRF, it was noted that clot formation in a particular donor is dependent on the time factor; i.e., Whole blood fractions obtained from donors not centrifuged within 10, 5, 2 or preferably 1 minute(s) or immediately resulted in impaired clot formation. [0642] In an example, we tested this observation, by obtaining two vials from a donor, that were centrifuged immediately (less than a minute) and one vial from the same donor, which was centrifuged after 5 minutes. It was observed that the vials centrifuged immediately (within 1 minutes) had a clot formation, whereas the vial centrifuged after 5 mins had no clot formation. [0643] It has also been observed that the amount of PRF derived serum (quantity) isolated from each donor is donor dependent. It varies from each individual.

Example 9the Proliferative Effect of Serum Derivatives on Isolated Human Chondrocytes Obtaining and Culturing Chondrocytes

[0644] Human osteoarthritic articular cartilage was obtained from patients (n=3; age 60-80 years) undergoing total knee arthroplasty. For chondrocyte isolation, articular cartilage was minced into 2 mm3 pieces prior to enzymatic digestion with Liberase Blendzyme 3 (0.2 WU/mL, Roche Diagnostics GmbH, Mannheim, Germany) in medium (GIBCO DMEM/F12 GlutaMAX-I, Invitrogen, LifeTech Austria, Vienna, Austria) with antibiotics (penicillin 200 U/mL; streptomycin 0.2 mg/mL, and amphotericin B 2.5 g/mL (Sigma-Aldrich Chemie GmbH, Steinheim, Germany)) under permanent agitation for 18 to 22 hours at 37 C. Subsequently, cell suspensions were passed through a 40 m filter (BD, Franklin Lakes, N.J.) to remove debris, washed with phosphate-buffered saline (PBS), centrifuged (10 minutes, 500g, room temperature) and resuspended in PBS. Cells were seeded into 75 cm2 culture flasks (Nunc, Rochester, N.Y.) at a density of 100 cells/cm2 and further cultivated in medium supplemented with antibiotics (see above), 10% fetal calf serum (PAA Laboratories GmbH, Linz, Austria), and 1-ascorbic acid (50 g/mL; Sigma-Aldrich Chemie GmbH, Steinheim, Germany) at 37 C. in a humid environment with 5% CO2. Medium was changed every 3 days. For passaging, cells grown to 80% confluency were harvested by use of accutase (1.5 mL/flask; PAA Laboratories GmbH, Linz, Austria) counted, and seeded again (all experiments were performed in passage 1)

[0645] Proliferation Assay

[0646] OA chondrocytes (passage 1) were seeded in three 96-well plate (2000 cells/well) For obtaining reliable results, cells for every tested group were seeded in 20 wells (in few different rows placed on the 96-well plateto eliminate any disruptions in the data that could be associated with the possible mistake in pipetting, resulting in differences with the number of cells in wells)and for each group 12 wells should remain without cells only with media (to check the absorbance of medium). After seeding the cells were fed for 48 hours with 100 l of standard growing medium (described above). 48 hours after seeding (day 0) standard growing medium was replaced with 100 l of following growth medium per well: group with SPRF-DMEM medium (GIBCODMEM/F12 GlutaMAX-I, Invitrogen, Vienna, Austria) with 10% SPRF, 2% Penicilin/Streptomycin, 1% Amphotericin; group with PRP-DMEM medium (GIBCODMEM/F12 GlutaMAX-I, Invitrogen, Vienna, Austria) with 10% PRP, 2% Penicilin/Streptomycin, 1% Amphotericin, Heparine (2 U/ml); FCS group: standard growing medium as described above; serum free group (SF): DMEM medium (GIBCODMEM/F12 GlutaMAX-I, Invitrogen, Vienna, Austria) with 2% Penicilin/Streptomycin, 1% Amphotericin. Experiments lasted 8 days and measurements were taken at three different time points (days 0, 4, 81 plate was used at one time point). Metabolic activity and proliferation rate of OA chondrocytes were investigated through XTT assay (Roche, Mainheim, Germany) according to the manufacturer's instructions. Relative fluorescence was measured using plate reader The BioTek's Synergy 2.

[0647] In a preliminary experiment, FIG. 15A and FIG. 15B, the proliferative effect of serum derivatives is shown in isolated human chondrocytes.

[0648] In FIG. 16A the mean results from 3 different experiments with XTT assay after 8 days is shown, performed in 96-well cell culture plate based monolayer culture with 2000 cells/well seeded, cultured in serum free DMEM (SF) or DMEM media supplemented with 10% SPRF, 10% PRP or 10% FCS. In FIG. 16B pictures of OA chondrocytes culture after 0, 4, 8 days with different media supplementation are shown.

[0649] Cells were harvested from either healthy or osteoarthritic human knee hyalin cartilage and grown in culture. In terms of proliferation support, FCS and SPRF are comparably effective, while PRP has no effect in healthy chondroytes. In osteoarthritic chondrocytes the differences are even more pronounced, SPRF outperforms FCS and PRP shows some effect.

Example 10SPRF Preparation in a Syringe Ready for Intraarticular Injection

[0650] 18 mL blood (without anticoagulant) from the right or left forearm vein of the patient is taken using e hypodermic needle (e.g. butterfly needle) into glass or silica-coated tubes then spun in a centrifuge at 1714 g for 8 min (5-10 min). The red blood cell fraction is removed and the remaining yellowish clotted plasma (=platelet rich fibrin, PRF) is gently squeezed to harvest the SprF fraction. Alternatively, SPRF can be prepared in the hypACT Inject Auto medical device using the same method. The SPRF fraction is then transferred into a standard 5 mL syringe ready for intraarticular injection.

Example 11Autologous Chondrocyte Implantation

[0651] It is confirmed that the lesion is eligible for autologous chondrocyte implantation. Then a biopsy is taken from the cartilage and is sent for chondrocyte culturing (cell proliferation) in the laboratory. Chondrocyte proliferation is carried out as described above.

[0652] Cell implantation is performed in the following stage, consisting of arthrotomy, preparation of the chondral defect, harvesting of periosteum, hermetic fixation of periosteum over the lesion with stitches and fibrin glue, injection of chondrocyte concentrate and closing of the operative wound.

[0653] In a further variant, second generation ACI is applied, i.e. after cell expansion in a monolayer, the cells are deposited on a carrier membrane/matrix, obtaining a membrane sown with MACI (chondrocytes (Verigen AG, Leverkusen, Germany).

[0654] In a further variant of the example, a third generation of ACI is applied, i.e the chondrocyte culture is deposited on a matrix of hyaluronic acid structured in three dimensions (Hyalograft-C, Fidia Advanced Biopolymers, Abano Term, Italy), thus enabling homogeneous distribution of the chondrocytes inside the lesion.

[0655] Conclusions of Results with Chondrocytes

[0656] SPRF increases the proliferation rate of OA chondrocytes as observed with PRP on 2D substrates but is very donor dependent. However, SPRF does not redifferentiate the OA chondrocyte from the dedifferentiated state either under normoxic and hypoxic (physiological) conditions. However, PRP enhances proliferation & redifferentiation both under normoxic and hypoxic conditions from 24h to 72h.

[0657] Moreover, as an example, over a culture period of 9 days SPRF from younger donors (35 years) reached a higher proliferation rate compared to older donors (55 years). In contrast to the biological activity, growth factor concentrations (PDGF-BB, Leptin) were not age-dependent in the SPRF preparations. However, the growth factor concentrations of individual SPRF donors measured at two different time points were highly variable as quantified with a multiplex screening array. Our results indicate that SPRF from younger donors expedite proliferation of OA chondrocytes derived from older patients and can be a relevant serum replacement during cell culture expansion or in vivo therapy.

[0658] We have also found that FCS does not retain the redifferentiated state (Col2/Col1 differentiation index) under normoxic/hypoxic conditions from 24h to 72h.

[0659] Thus, SPRF increased the proliferation rate of dedifferentiated, preferably osteoarthritic chondrocytes to a larger extent than PRP, and also to a larger extent than FCS.

[0660] Moreover, proliferation and differentiation of chondrocytes can be separated and therefore a more regulated handling of the procedure. The inventors have also noticed that the effect of SPRF obtained from younger donors is stronger than dose obtained from elder donors.

Example 12Cell and Tissue Cultures for Experiments with Mesenchymal Stem Cells (MSCs)

[0661] All tissue culture procedures were carried out in a sterile laminar flow tissue culture hood. Cells and ex vivo explant cultures were maintained in an incubator at 37 C. and 5% CO.sub.2 and 95% of humidity. hMSC proliferation assay

[0662] Cells were seeded in standard growing medium into 5 parallel wells of a 96-well plate (2000 cells/well). Cell-free wells were used as background control. 48 hours after the start of the incubation standard growing medium was refreshed only in a group (same medium type was kept), in the others the 10% (v/v) FCS supplement was changed for 10% (v/v) FCS+bFGF, or 10% (v/v) platelet rich plasma (PRP), or 10% (v/v) serum from platelet rich fibrin (SPRF). PRP-supplemented medium contained 2 U/mL heparine (Clexane, Sanofi Aventis, Paris, France). As negative control, serum-free medium was used. Following 2 and 5 days incubation cell viability assay was performed.

[0663] Human Mesenchymal Stem Cell (hMSC) 2D Culture Human mesenchymal stem cells (hMSCs) purchased from LONZA were seeded at 5000 cells/cm.sup.2 in normal T-75 tissue culture flasks and maintained in standard growing medium: Dulbecco's modified Eagle's medium (DMEM), high glucose, GlutaMAX Supplement, pyruvate (Gibco, Paisley, Scotland), supplemented with 10% (v/v) fetal calf serum (FCS, Gibco, Paisley, Scotland), fibroblast growth factor (bFGF) 1 ng/ml (Sigma-Aldrich, St. Louis, USA), 2% Penicillin/Streptomycin (Sigma-Aldrich, St. Louis, USA) and 1% Amphotericin (Sigma-Aldrich, St. Louis, USA). Cell culture medium was refreshed twice a week.

[0664] Cell Culture Conditions for hMSCs

[0665] Four different media were used in the course of the experiments with hMSCs. (1) Basal medium: DMEM, high glucose, GlutaMax Supplement, pyruvate containing 10% FBS, 2% penicillin/streptomycin and 1% amphotericin. (2) Serum-free medium: DMEM, high glucose, GlutaMax Supplement, pyruvate (Gibco, Paisley, Scotland), containing 2% penicillin/streptomycin and 1% penicillin/streptomycin. (3) SPRF-medium: DMEM, high glucose, GlutaMax Supplement, pyruvate containing 10% SPRF, 2% penicillin/streptomycin and 1% amphotericin. (4) PRP-medium: DMEM, high glucose, GlutaMax Supplement, pyruvate containing 10% PRP, 2% penicillin/streptomycin and 1% amphotericin. Media were changed every 48 hours (support for 2 days injection). Cells were incubated in normal cell culture conditions (5% CO2, humidified atmosphere, 37 C.). 2000-3000 cells/well were seeded in 5 parallel wells for all sample type and for all time point. Percentage ratios are given in respect of the total volume.

[0666] Isolation and Culture of Human Subchondral Bone Pieces (Bone Explants; hSBEs)

[0667] hSBEs, 2 mm in diameter were harvested from patients undergoing total hip replacement surgery at the Orthopedic Clinics of Semmelweis University (Budapest, Hungary). All procedures were performed with permission of hungarian Ethical Committee. The donors had osteoarthritis, otherwise they were diagnosed not to have cancer, or any infectious or autoimmune disease. Only tissue that would have otherwise been discarded was used.

[0668] In an embodiment femoral heads (those would have been otherwise discarded) are sawn off that results in intense cell death at the sawn surface due to friction based heat shock. Therefore, bone explanted from the body was cut in half with a bone chisel and hSBEs were picked from the cut surface with a small chisel.

[0669] Explants were delivered to the laboratory in the same medium that was used for hMSC culture.

[0670] All further experiments were started following 48 hours of preincubation in the medium described above.

[0671] In an embodiment tissue cultures were maintained in basal medium (DMEM containing 10% FBS and 1% penicillin/streptomycin) at 37 C. and 5% CO.sub.2 in a humidified atmosphere. After 2 days incubation samples were used for experiments with special media or harvested for RNA.

Example 13Viability Test for Cell Culture and Bone Explants

[0672] Cell viability of hMSCs and hSBEs was determined using Cell Proliferation Kit II (XTT; Roche, Mannheim, Germany) according to the manufacturer's instructions. Absorbance were measured after 4 hours incubation in the staining solution using a PowerWave Microplate Spectrophotometer (BioTek, Winooski, Vt., USA) at 480 nm with a reference wavelength at 650 nm. In case of hSBEs, bone pieces were removed from the labeling mixture right before absorbance measurement. Results were normalized with the weight of the chips considering that the bone size is proportional to the number of active cells.

[0673] On FIG. 18. growth for the hMSC cells grown with FCS+bFGF or with FCS, only SPRF or PRP and without serum on plastic surface are shown. On the first day 2000-3000 cells were seeded pro well into a 96-well plate. Viability of cells was measured by XTT viability test. The viability on the 5.sup.th day in case of cells supplemented with FCS+bFGF showed OD.sub.450=1.4280.064 absorbance values, only FCS supplemented OD.sub.450=1.3060.069, only SPRF supplemented OD.sub.450=1.4580.098, only PRP supplemented OD.sub.450=0.9540.075. The values are the average of five parallel measurements. It can be seen that the medium supplemented with SPRF provided the best result in terms of cell viability.

[0674] Tissue Culture Conditions for hSBPs

[0675] Three different media were used in the course of the experiments with hSBPs (1) Basal medium: DMEM containing 10% FBS and 1% penicillin/streptomycin. (2) Serum-free medium: DMEM containing 1% penicillin/streptomycin. (3) SPRF-medium: DMEM containing 10% SPRF and 1% penicillin/streptomycin. Media were changed every 48 hours. Tissue cultures were incubated in normal cell culture conditions (5% CO2, humidified atmosphere, 37 C.).

[0676] Cell Viability Test of hMSCs and hSBPs

[0677] XTT (sodium 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)-carbonyl]-2H-tetrazolium)) assay (Roche, Cell Proliferation Kit II) was performed to measure the viability of cells. XTT Labeling Mixture was added to the culture medium and bones or cell monolayers in 0.3 mg/ml final concentration on a 96-well plate and the plate was placed back into the incubator for 4 hours. Bone pieces were removed and absorbance was measured on 450 nm on a plate reader. In case of hSBPs absorbance values were normalized to the dry weight of the bone pieces.

Example 14RNA Extraction and Reverse Transcription

[0678] Total RNA was isolated from 5 bone pieces with TRIzol Reagent (Ambion) following homogenization with liquid nitrogen in a mortar. 500 l of TRIzol reagent was added to the homogenized tissue. Following 5 min incubation on room temperature centrifugation was carried out (12000 g, 1 minute, room temperature) to remove particulate debris from homogenized samples. The supernatant was transferred into a new tube and RNA was purified with Direct-zol RNA MiniPrep Kit (Zymo Research). RNA was eluted in 40 l diethylpyrocarbonate-treated (DEPC) water. Measurement of RNA yield was performed by agarose gel electrophoresis and using a NanoDrop 1000A Spectrophotometer (Thermo Fisher Scientific, Waltham, Mass., USA). The purity of RNA was accepted, when values A260/280>2.0 and A260/230>2.0 were measured. Reverse transcription was performed using the first-strand cDNA synthesis kit as instructed by the manufacturer (ReadyScript, Sigma Aldrich), i.e. reverse transcription to synthesize first strand cDNA was carried out for 30 min at 42 C., primed with an oligo (dT) primer bearing a T7 promoter.

[0679] Quantitative PCR

[0680] Real-time quantitative PCR was performed using ABI for quantifying the expression of activated leukocyte cell adhesion molecule (ALCAM/CD166: Hs00977641_m1). Values were calculated using the comparative threshold cycle (C.sub.t) method and normalized to GAPDH (Hs02758991_g1) expression. Values were expressed as the meanSD. Experiments were performed at least three times. Statistical analysis was performed using one-way analysis of variance (ANOVA) with Tukey-Kramer Multiple Comparison post-test.

Example 15

[0681] Assessment of MSC Proliferation on Bone Explants

[0682] hSBPs were incubated in basal medium two days long. On the second day their viability showed 48.26715.626 (n=3). On this day medium was changed for fresh basal medium, serum-free medium or SPRF-medium. Viability values on the 4th day were 92.99717.025 (n=19), 117.35719.383 (n=24) and 187.52718.814 (n=24) in serum-free medium, basal medium and SPRF-medium, respectively. Viability values on the 7th day were 77.71121.734 (n=7), 199.0227.367 (n=15) and 224.21228.023 (n=15) in serum-free medium, basal medium and SPRF-medium, respectively. Statistically significant differences at p<0.05 were determined by one-way analysis of variance (ANOVA).

[0683] Quantitative reverse transcription-polymerase chain reaction analysis was used to evaluate the expression of the hMSC associated gene CD166 (ALCAM). Compared to the second day expression of CD166 (ALCAM) molecule expression was 2.2-times higher in case of basal medium, and 2.1-times higher in case of SPRF-medium. All expression values are normalized to the expression of GAPDH. Our SPRF supplemented medium was as effective as the one, which was supplemented with specific stem cell media (FBS supplemented basal medium), however SPRF is from human autologous origin. All expression values are normalized to the expression of GAPDH.

Example 16Isolation of SPRF

[0684] a) Whole blood obtained from donors was immediately centrifuged at 1700 g for 10 mins at RT in BD Vacutainer Z. [0685] b) The fibrin clot from the tube was gently removed with a tweezer and placed onto a sterile Petri-dish and the red blood cells at the bottom of the fibrin clot were cut with a sharp scissor and discarded. [0686] c) The lysate was squeezed out of the fibrin clot, collected and stored at 20 C.

[0687] Isolation of PRP [0688] a) Whole blood obtained from donors was centrifuged at 320 g for 12 mins at RT in the BD Vacutainer 6 ml K2E (EDTA). [0689] b) Three layers had been formed in the collection tube. The bottom layer containing the red blood cells, middle layer containing the buffy coat and the top layer containing the platelet-poor plasma (PPP). [0690] c) PPP was aspirated along the middle layer and transferred into a 15 ml Falcon tube and centrifuged at 1700 g for 10 mins [0691] d) The pellet was resuspended into a corresponding volume to the isolated SPRF in the supernatant. Stored at 20 C.

Example 17Mesenchymal Stem Cell Proliferation Assay and Cell Morphology

[0692] To examine cell proliferation in presence of different serum derivatives, subconfluent hMSC cultures were incubated for 2 or 5 days in serum-free DMEM (SF) or in DMEM supplemented either with FCS, FCS+bFGF, PRP or SPRF, 10% (v/v) each. Viability of the samples was measured with XTT assay on the 1.sup.st, 2.sup.nd and 5.sup.th day of the experiment.

[0693] SF, FCS and FCS+bFGF had no mitogenic effect after 2 days incubation. In the presence of PRP and SPRF viability of cells was elevated 7.18-fold and 9.57-fold, respectively. This significant proliferation could be due to the human origin of the applied supplement.

[0694] In SF medium viability was not significantly higher as on day 2. In the period between the 2.sup.nd similar viability to FCS+bFGF for the 5.sup.th day, 11.83-fold and 15.53-fold, respectively. Clearly the strongest effect had SPRF in the medium, where the cell viability 20.1-fold higher was compared to the zero day. This effect is very remarkable considering that the official culture medium and a treatment with a growth factor were less effective (FIG. 18).

[0695] The morphology of the cells was not visibly altered by the various treatments, all preserved the typical hMSC morphology (FIG. 19).

Example 18Flow Cytometry Analysis of hMSC Cultured in Different Serum Supplements

[0696] Immunophenotyping analysis was used to characterize that hMSCs cultured 5 days long in differently supplemented media preserved their hMSC-characteristic. hMSCs cultured in 10% (v/v) FCS or 10% (v/v) FCS+1 ng/mL bFGF, or 10% (v/v) PRP or 10% (v/v) SPRF were positive for CD90-FITC, CD105-PerCP-Cy5.5 and CD73-APC in more than 93.94%. While CD90-FITC and CD73-APC expression was above 99% in case of the PRP-supplemented samples (FIGS. 20A and 20C). CD105-PerCP-Cy5.5 level decreased by 13.99% and two cell populations were appeared. This thought to be the result of an unknown differentiation process in connection with PRP (FIG. 20B).

[0697] No expression of hematopoietic markers (CD34/CD11b/CD19/CD45/HLA-DR-PE) was detected in any of the experiments with 10% (v/v) FCS-, 10% (v/v) PRP- and 10% (v/v) SPRF-supplemented samples (FIG. 20D), showing that no hematopoietic differentiation occurs; however 10% (v/v) FCS+1 ng/mL bFGF supplement caused the formation of a positive subpopulation for those markers (16.2%) (FIG. 20D). This finding suggests that not hematopoietic stem cells (HSCs) but MSCs are proliferated according to the invention.

Example 19Gene Expression Analysis of Differently Supplemented hMSCs Cultures

[0698] The result of this analysis is shown on FIGS. 21A-D.

[0699] FIG. 21A shows that mesenchymal stem cell marker levels remained compared to standard culture medium (10 v/v % FCS). On the Y axis the protein expression level ratio is presented, the base of comparison is the level in 10% FCS cultures.

[0700] MSCs may differentiate in either to osteoblasts or adipocytes, consequently both cell type markers have been checked to complete the study. In FIGS. 21B and 21C it is shown that PPARGG and ADIPOQ expression level did not show any change in contrast with osteoblast markers ALPL and COL1A1 which have been significantly increased in case of SPRF supplementation.

[0701] FIG. 21D. Apoptotic genes' expression levels were analyzed as well: BCL2 is antiapoptotic, while BAX is an apoptotic protein. BAX/BCL2 ratio is in equilibrium under normal physiological conditions (taken as 100% in FCS). Increase is demonstrable if cells undergo apoptotic process due to inner or under external effects. FCS+BFGF and SPRF supplementation results in an approximate 80-90%, while PRP cultured cells show a tremendous increase.

[0702] hMSC-Specific Genes Stayed Intensely Expressed in Culture of Mesenchymal Stem Cells Supplemented with 10% (v/v) SPRF

[0703] The expression of hMSC-specific genes was confirmed by real time qPCR after 5 days incubation in the media indicated above. ALCAM (CD166), ITGB1, CD105 and ANPEP expression showed significant increase in the 10% (v/v) SPRF supplemented samples when compared with 10% (v/v) FCS supplemented group 1.68-fold, 2.03-fold, 1.29-fold and 1.37-fold, respectively. While ALCAM (CD166), ITGB1, CD105 and ANPEP expressions were almost unchanged after culturing in 10% (v/v) FCS+1 ng/mL bFGF (0.95-fold, 1.35-fold, 0.98-fold and 1.29-fold, respectively), the expression of the same markers decreased in case of the 10% (v/v) PRP culturing at CD105 0.87-fold and ALCAM (CD166) 0.55-fold. Increase was found when 10% (v/v) PRP culturing in case of ITGB1 (1.67-fold) and ANPEP (2.19-fold) expression. (FIG. 24A)

[0704] Adipose Differentiation was not Observed but Osteoblastic Gene Expression was Elevated when hMSCs were Cultured in 10% (v/v) SPRF

[0705] Since hMSCs are the common progenitor cells of adipocytes and osteoblasts, adipocyte-specific and osteoblast-specific gene expression was investigated in the variously supplemented hMSC cultures by RT-qPCR. FABP4, PPARG and ADIPOQ expression, that are markers of adipogenic differentiation were not elevated when 10% (v/v) FCS supplementation was changed for 10% (v/v) FCS+1 ng/mL bFGF, 10% (v/v) PRP or 10% (v/v) SPRF, i.e. the expression level stayed unvaried compared to standard culturing method (FIG. 24C). COL1A1, ALPL and RUNX expression was slightly changed in cultures supplemented with 10% (v/v) FCS+1 ng/mL bFGF, 0.78-fold, 1.3-fold and 1.49-fold respectively. 10% (v/v) PRP had almost the same effect 1.43-fold change in COL1A1 expression, 3.11-fold change in ALPL expression and RUNX2 expression decreased 0.47-fold compared to the control group. 10% (v/v) SPRF supplement showed a significant increase in osteblastic gene expression. COL1A1 mRNA level elevated 8.38-fold, ALPL level 8.28-fold and RUNX2 level 1.31-fold compared to control (FIG. 24D).

[0706] BAX/BCL2 Ratio was Highly Increased when hMSC Culture Supplemented with 10% (v/v) PRP

[0707] BAX/BCL2 ratio was elevated 29.97-fold in case of 10% (v/v) FCS+1 ng/mL bFGF supplement, 31.99-fold when 10% (v/v) SPRF supplementation was used (FIG. 21D).

[0708] Example 20Histological analysis of hSBPs Bone explants were fixed in 4% formalin solution. The samples were dehydrated in an ascending alcohol series at room temperature and infiltrated and embedded in a resin specifically developed for mineralized tissues (Technovit 9100 Kulzer). Infiltrated explants were placed in specific molds filled with polymerization mixture. 4 m-sections were cut using Leica RM2255 sawing microtome and stretched on slides. For hematoxylin-eosin staining the sections were immersed into hematoxylin solution and washed with 1% eosin solution. For Masson's trichrome staining sections were immersed in hematoxylin solution containing picric acid. After washing, Fuchsin Ponceau staining was performed, and unspecific parts were washed with with 1% phosphomolybdic acide solution.

[0709] We have found that culturing hSBPs in 10% (v/v) SPRF supplemented medium for 5 days preserved bone marrow integrity as hematoxylin and eosin-stained sections (FIG. 23, A) and Masson's trichrome sections (B) show, in a surprisingly good state. However, 10% (v/v) FCS supplementation for 5 days appeared less effective and gave an inferior result in this regard. That means, SPRF revealed higher level of hMSC accumulation (C) compared to FCS (G), and preserved better the local vasculature (D,H).

[0710] Gene Expression Analysis of Human Subchondral Bone Chips

[0711] Culturing MSC on bone chips and rt-qPCR analysis were carried out as described above.

[0712] In FIG. 24A relative gene expression level on Y axis is shown compared to the values measured right after the bone chip explantation. As previously, three media were applied: serum-free medium: (), 10% (v/v) of FCS (), 10% (v/v) SPRF ().

[0713] It has been found that hMSC markers did not change in average (FIG. 24A1: ENG FIG. 24A2: ITGB1 FIG. 24A3: ANPEP FIG. 24A4: ALCAM). FIG. 24B indicates that the hematopoetic cells were not induced, however they could be present in bone chips. This indicates the selectivity of the MSC proliferation method (FIG. 24B1: CD34 FIG. 24B2: CD14 FIG. 24B3: PTPRC). Furthermore, FIG. 24C shows that adipocites were not induced in PSRF medium, thus, similarly to the MSC-cultures, adipocytes differentiation does not occur on explants either (FIG. 24C1: PPARg FIG. 24C2: FABP4 FIG. 24C3: ADPOQ).

[0714] However, surprisingly, while MSC character of the cell is maintained, an osteoblast direction differentiation can be observed on the 5.sup.th day of culturing (FIG. 24D). We monitored the expression of the following osteoblast marker genes: FIG. 24D1: COL1A1 FIG. 24D2: P4HA2 FIG. 24D3: ALPL FIG. 24D4: RUNX2, among which COL1A1 and to a lesser extent ALPL seem to be upregulated.

INDUSTRIAL APPLICABILITY

[0715] The present invention is applicable both in research and medicine among others to improve proliferation of cells or by maintaining their proliferation potential preferably for the purpose of bone regeneration or for using them in MSC cell therapy.