BIOMIMETIC LAMELLAR TISSUE SCAFFOLDS

Abstract

A biomimetic lamellar tissue scaffold for tissue regeneration comprises a plurality of lamellae formed of a polymer film and each having a first surface and a second surface. A patterned array of polymer nanofibers protrudes from the first surface of each lamella of the plurality. The lamellae form a plurality of interlamellar spaces between the first and second surfaces of adjacent lamellae. Protuberances formed on the first surface of each lamella maintain the interlamellar spaces. The arrays of polymer nanofibers on the first lamellar surface of each lamella protrude into the interlamellar spaces between adjacent lamellae and are configured to influence the propagation and differentiation of cells populated to or recruited to the scaffold.

Claims

1. A scaffold for tissue regeneration comprising: a plurality of lamellae formed of a polymer film and each having a first surface with a patterned array of polymer nanofibers protruding from said first surface, and a second surface; a plurality of interlamellar spaces formed between said first surfaces of said lamellae and said second surfaces of adjacent said lamellae; and a plurality of protuberances formed on said lamellae to maintain said interlamellar spaces; wherein said array of polymer nanofibers on said first lamellar surfaces protrude into said interlamellar spaces; and wherein said patterned array is configured to influence the propagation and differentiation of cells populated to or recruited to said scaffold.

2. The scaffold of claim 1 wherein said lamellae further comprise perforations between said first surface and said second surface.

3. The scaffold of claim 1 wherein said polymer film is bioabsorbable.

4. The scaffold of claim 1 wherein said polymer film is treated with another polymer such as poly-L-lysine or poly-D-lysine, or a biological substance such as proteoglycans (proteoglycan 4) or glycoproteins to improve surface wetting and cell attachment.

5. The scaffold of claim 1 wherein said lamellae are oriented perpendicular to the plane of said scaffold

6. The scaffold of claim 1 wherein said lamellae are oriented parallel to the plane of said scaffold.

7. The scaffold of claim 1 wherein said lamellae are arranged as parallel layers.

8. The scaffold of claim 1 wherein said lamellae form a coil.

9. The scaffold of claim 1 wherein said patterned array of nanofibers comprises rows of nanofibers.

10. The scaffold of claim 1 wherein said patterned array is uniform over said first surface of said lamella.

11. The scaffold of claim 1 wherein said first surface of said lamella has a first region with a first said patterned array, and a second region with a second said patterned array.

12. A method for treating a patient using a biomimetic scaffold comprising the steps of: providing a scaffold formed of one or more lamellae with a nanofiber array formed on a first surface of said one or more lamellae, said scaffold further comprising one or more interlamellar spaces wherein said nanofiber array protrudes into said interlamellar spaces; preparing a treatment site on said patient to receive said scaffold; and implanting said scaffold at said site.

13. The method of claim 12 further comprising the step of affixing said scaffold at said site.

14. The method of claim 12 wherein the fixation method comprises using a fibrin glue.

15. The method of claim 12 wherein the fixation method comprises using suture or mechanical fixation.

16. The method of claim 12 wherein said treatment site comprises an articular lesion.

17. The method of claim 16 wherein preparing said treatment site comprises performing a microfracture procedure.

18. The method of claim 12 wherein preparing said treatment site comprises the application of a bioactive material to the site prior to implanting the scaffold.

19. The method of claim 12 wherein said scaffold is immersed in a biologic fluid containing stem cells prior to implanting.

20. A method for creating a tissue structure for implantation in a patient comprising the steps of: providing a scaffold formed of one or more lamellae with a nanofiber array formed on a first surface of said one or more lamellae, said scaffold further comprising one or more interlamellar spaces wherein said nanofiber array protrudes into said interlamellar spaces, and said scaffold is configured to mimic a native tissue structure; submerging said scaffold in a biologic solution comprising stem cells; maintaining said scaffold and biologic solution in a suitable bioreactor until said scaffold is replaced by extracellular matrix and said tissue structure is complete; and removing said tissue structure from said bioreactor; wherein said nanofiber array is configured for optimal stem cell propagation and differentiation into a predetermined cell type.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Non-limiting and non-exhaustive embodiments are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various drawings unless otherwise specified. In the drawings, not all reference numbers are included in each drawing, for the sake of clarity.

[0056] FIG. 1 is a perspective view of a lamella for a scaffold of the present invention.

[0057] FIG. 2 is an expanded view of the lamella of FIG. 1 at location A.

[0058] FIG. 3 is a plan view of the objects of FIG. 1.

[0059] FIG. 4 is an expanded view of the objects of FIG. 3 at location B.

[0060] FIG. 5 is a side elevational view of the objects of FIG. 1.

[0061] FIG. 6 is an expanded view of the objects of FIG. 5 at location C.

[0062] FIG. 7 is a perspective view of a segment of a lamellar scaffold of the present invention.

[0063] FIG. 8 is a plan view of the objects of FIG. 7.

[0064] FIG. 9 is an expanded view of the objects of FIG. 8 at location A.

[0065] FIG. 10 is a plan view of a lamellar scaffold of the present invention with parallel planar lamellae.

[0066] FIG. 11 is a perspective view of the objects of FIG. 10.

[0067] FIG. 12 is a plan view of a lamellar scaffold of the present invention with lamellae arranged in a spiral fashion.

[0068] FIG. 13 is a perspective view of the objects of FIG. 12.

[0069] FIG. 14 is an expanded view of the objects of FIG. 13 at location A.

[0070] FIG. 15 is a perspective depiction of a lesion in a femoral condyle.

[0071] FIG. 16 is a side elevational view of the objects of FIG. 15.

[0072] FIG. 17 is a perspective depiction of the condyle of FIG. 15 with the lesion prepared for placement of a lamellar scaffold of the present invention.

[0073] FIG. 18 is a side elevational view of the objects of FIG. 17.

[0074] FIG. 19 is a plan view of the scaffold of FIG. 10 with the approximate outline of the prepared lesion of FIG. 17 marked thereon in preparation for shaping of the scaffold for placement in the lesion.

[0075] FIG. 20 is a plan view of the scaffold configured for placement in the lesion of FIG. 17.

[0076] FIG. 21 is a perspective view of the objects of FIG. 20

[0077] FIG. 22 is a perspective view of the condyle of FIG. 17 with the scaffold of FIG. 20 placed therein.

[0078] FIG. 23 is a side elevational view of the objects of FIG. 22.

[0079] FIG. 24 is a perspective view of the condyle and scaffold of FIG. 22 with the scaffold contoured to match the condyle surface.

[0080] FIG. 25 is a side elevational view of the objects of FIG. 24.

[0081] FIG. 26 is a perspective view of a femoral condyle with a lesion in the articular surface.

[0082] FIG. 27 is a side elevational view of the objects of FIG. 26.

[0083] FIG. 28 is a perspective view of the condyle of FIG. 26 with the lesion prepared for placement therein of a lamellar scaffold of the present invention.

[0084] FIG. 29 is a side elevational view of the objects of FIG. 28.

[0085] FIG. 30 is a perspective view of the condyle of FIG. 28 with the scaffold of FIG. 12 placed in the lesion.

[0086] FIG. 31 is a side elevational view of the objects of FIG. 30.

[0087] FIG. 32 is a perspective view of the condyle and scaffold of FIG. 32 with the scaffold contoured to match the condyle surface.

[0088] FIG. 33 is a side elevational view of the objects of FIG. 32.

[0089] FIG. 34 is a perspective view of a lamella for an alternate embodiment lamellar scaffold of the present invention.

[0090] FIG. 35 is an expanded view of the objects of FIG. 34 at location A.

[0091] FIG. 36 is a plan view of the objects of FIG. 34.

[0092] FIG. 37 is an expanded view of the objects of FIG. 36 at location B.

[0093] FIG. 38 is a side elevational view of the objects of FIG. 34.

[0094] FIG. 39 is an expanded view of the objects of FIG. 38 at location C.

[0095] FIG. 40 is a perspective view of a segment of an alternate embodiment lamellar scaffold of the present invention using the lamella of FIG. 34.

[0096] FIG. 41 is a side elevational view of the objects of FIG. 40.

[0097] FIG. 42 is a plan view of the objects of FIG. 40.

[0098] FIG. 43 is sectional view of the objects of FIG. 42 at location A-A.

[0099] FIG. 44 is an expanded view of the objects of FIG. 43 at location A depicting the propagation of stem cells through the scaffold of FIG. 40.

[0100] FIG. 45A is a perspective view of an alternate embodiment scaffold of the present invention.

[0101] FIG. 45B is an expanded view of the objects of FIG. 45A at location A.

[0102] FIG. 46 is a diagrammatic sectional view of a prior art fibrous scaffold placed in a defect in an articular surface.

[0103] FIG. 47 depicts the objects of FIG. 46 with the scaffold subjected to a compressive load.

[0104] FIG. 48 depicts the objects of FIG. 46 with after the compressive load of FIG. 47 is removed.

[0105] FIG. 49 is a diagrammatic sectional view of a lamellar scaffold of the present invention placed in a defect in an articular surface.

[0106] FIG. 50 depicts the objects of FIG. 49 with the scaffold subjected to a compressive load.

[0107] FIG. 51 depicts the objects of FIG. 50 after the compressive load of FIG. 50 is removed.

[0108] FIG. 52 is a diagrammatic perspective view of a lamellar scaffold of the present invention applied for tissue augmentation in a rotator cuff repair.

[0109] FIG. 53 is an exploded view of an alternate embodiment of the present invention wherein a scaffold of the present invention supplements a prior art scaffold.

[0110] FIG. 54 is an expanded view of the objects of FIG. 53 at location A.

[0111] FIG. 55 is a perspective view of the objects of FIG. 53 assembled for use.

[0112] FIG. 56 is a side elevational view of the objects of FIG. 55.

[0113] FIG. 57 is a perspective view of an alternate embodiment lamellar scaffold of the present invention comprising a structural element for enhanced strength and ease of fixation.

[0114] FIG. 58 is an expanded view of the objects of FIG. 57 at location A.

[0115] FIG. 59 depicts a lamellar scaffold of the present invention affixed to a soft tissue structure for augmentation thereof.

[0116] FIG. 60 is a perspective view of a lamella for an alternate embodiment lamellar scaffold of the present invention.

[0117] FIG. 61 is an expanded view of the objects of FIG. 60 at location B.

[0118] FIG. 62 is a plan view of the objects of FIG. 60.

[0119] FIG. 63 is an expanded view of the objects of FIG. 62 at location A.

[0120] FIG. 64 is a perspective view of a lamella for an alternate embodiment lamellar scaffold of the present invention.

[0121] FIG. 65 is an expanded view of the objects of FIG. 64 at location A.

[0122] FIG. 66 is a plan view of the objects of FIG. 64.

[0123] FIG. 67 is an expanded view of the objects of FIG. 66 at location B.

[0124] FIG. 68 is a perspective view of a lamella for an alternate embodiment scaffold of the present invention for forming elongate tissue structures.

[0125] FIG. 69 is an expanded view of the objects of FIG. 68 at location A.

[0126] FIG. 70 is a plan view of the objects of FIG. 68.

[0127] FIG. 71 is an expanded view of the objects of FIG. 70 at location B.

[0128] FIG. 72 is an alternate embodiment scaffold formed of lamellae depicted in FIG. 68.

[0129] FIG. 73 is an expanded view of the objects of FIG. 72 at location A.

[0130] FIG. 74 is a side elevational view of the objects of FIG. 72.

[0131] FIG. 75 is an expanded view of the objects of FIG. 74 at location B.

[0132] FIG. 76 is a plan view of a lamella for an alternate embodiment scaffold of the present invention for ex vivo growing of an elongate tissue structure.

[0133] FIG. 77 is a perspective view of the objects of FIG. 76.

[0134] FIG. 78 is a perspective view of an alternate embodiment scaffold of the present invention assembled to means for subjecting the scaffold to a tensile force.

[0135] FIG. 79 is a side elevational view of the objects of FIG. 78.

[0136] FIG. 80 is a plan view of a lamella for an alternate embodiment scaffold of the present invention configured to produce an ACL graft with an eyelet formed on one end of the graft for fixation.

[0137] FIG. 81 is a perspective view of the objects of FIG. 80.

[0138] FIG. 82 is a perspective view of a lamella for an alternate embodiment scaffold of the present invention.

[0139] FIG. 83 is an expanded view of the lamella of FIG. 82 at location B.

[0140] FIG. 84 is a side elevational view of the lamella of FIG. 82.

[0141] FIG. 85 is an expanded view of the lamella of FIG. 84 at location A.

[0142] FIG. 86 is a perspective view of a portion of an alternate embodiment scaffold of the present invention formed from lamellas of FIG. 82.

[0143] FIG. 87 is a side elevational view of the scaffold portion of FIG. 86.

DETAILED DESCRIPTION

[0144] While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that are embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.

[0145] To facilitate the understanding of the embodiments described herein, a number of terms are defined below. The terms defined herein have meanings as commonly understood by a person of ordinary skill in the portions relevant to the present invention. Terms such as a, an, and the are not intended to refer to only a singular entity, but rather include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as set forth in the claims.

[0146] The details of one or more embodiments of the presently disclosed subject matter are set forth in this document. Modifications to embodiments described in this document, and other embodiments, will be evident to those of ordinary skill in the art after a study of the information provided herein. The information provided in this document, and particularly the specific details of the described exemplary embodiments, is provided primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom. In case of conflict, the specification of this document, including definitions, will control.

[0147] While the terms used herein are believed to be well understood by one of ordinary skill in the art, definitions are set forth herein to facilitate explanation of the subject matter disclosed herein.

[0148] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the subject matter disclosed herein belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

[0149] The terms a, an, and the refer to one or more when used in this application, including the claims. Thus, for example, reference to a cell includes a plurality of such cells, and so forth. The use of the word a or an when used in conjunction with the term comprising in the claims and/or the specification may mean one, but it is also consistent with the meaning of one or more, at least one, and one or more than one.

[0150] All references to singular characteristics or limitations of the present disclosure shall include the corresponding plural characteristic(s) or limitation(s) and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made.

[0151] All combinations of method or process steps as used herein can be performed in any order, unless otherwise specified or clearly implied to the contrary by the context in which the referenced combination is made.

[0152] The methods and devices of the present disclosure, including components thereof, can comprise, consist of, or consist essentially of the essential elements and limitations of the embodiments described herein, as well as any additional or optional components or limitations described herein or otherwise useful.

[0153] Unless otherwise indicated, all numbers expressing physical dimensions, quantities of ingredients, properties such as reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term about. Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0154] As used herein, the term about, when referring to a value or to an amount of mass, weight, time, volume, concentration, percentage or a physical dimension such as length, width, or diameter, is meant to encompass variations of in some embodiments 20%, in some embodiments 10%, in some embodiments 5%, in some embodiments 1%, in some embodiments 0.5%, and in some embodiments 0.1% from the specified value or amount, as such variations are appropriate to perform the disclosed methods.

[0155] As used herein, ranges can be expressed as from about one particular value, and/or to about another particular value. It is also understood that there are a number of values disclosed herein, and that each value is also herein disclosed as about that particular value in addition to the value itself. For example, if the value 10 is disclosed, then about 10 is also disclosed. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0156] The present disclosure relates to the inventor's demonstration that the patterned matrices of polymer nanofibers disclosed herein promote stemness and cell-cell interaction of stem cells. Accordingly, in some embodiments, the disclosure is directed to a novel scaffold, that is, a temporary structure that provides an environment suitable for the regeneration of tissues and organs. Embodiments of a scaffold for promoting tissue growth can include lamellae formed of a polymer film and a patterned matrix of polymer nanofibers protruding from a surface thereof.

[0157] By the term lamella (plural lamellae) it is generally meant a thin plate-like structure. When describing biological tissue, a lamella may be a thin plate, membrane or layer, as in the basal lamella of an extracellular matrix. When used in reference to mimetic scaffolds of the present invention, lamella refers to a polymer film on which an ordered array of nanofibers has been formed integral to the film. Also, in reference to scaffolds of the present invention, lamellar structure is a construct formed of a plurality of lamellae arranged in a parallel fashion. A lamellar scaffold is a lamellar structure that temporarily mimics the extracellular matrix during tissue regeneration. Interlamellar space refers to a void formed between adjacent lamellae forming tissue scaffolds of the present invention for the purpose of cellular propagation therethrough.

[0158] As used herein, lamina is synonymous with lamella, laminae or laminas is synonymous with lamellae, and laminar is synonymous with lamellar, the terms being interchangeable throughout.

[0159] The polymer film can be any bioabsorbable thermoplastic polymer. Examples of suitable bioabsorbable thermoplastic polymers include epsilon-polycaprolactone (PCL), polyglycolic acid (PGA), polylactic acid (PLA), polydioxanone (PDS), and copolymers of PGA and PLA, among others.

[0160] By the term patterned it is generally meant that the polymer nanofibers disclosed herein are arranged or ordered into a user-defined pattern or array. In some embodiments, the term patterned can refer to the spacing of polymer nanofibers on a lamella. On a substantially flat lamella, such as a polymer film, the nanofibers disclosed herein can be spaced along an X-axis and a Y-axis at the same or different intervals along either axis. In some embodiments, nanofibers can be spaced about 50 microns, 40 microns, 30 microns, 20 microns, 10 microns, 9 microns, 8 microns, 7 microns, 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 microns apart on an X-axis and about 50 microns, 40 microns, 30 microns, 20 microns, 10 microns, 9 microns, 8 microns, 7 microns, 6 microns, 5 microns, 4 microns, 3 microns, 2 microns, or 1 micron apart on a Y-axis

[0161] The term matrix as used herein refers generally to a structure or environment in which living cells can be cultured and patterned matrix refers to a matrix with engineered order. For example, a patterned matrix of polymer nanofibers can include a plurality of standing polymer nanofibers with user-defined physical dimensions arranged according to user-defined spatial parameters. User-tunable parameters include fiber spacing, diameter (also sometimes referred to herein as width), height (also sometimes referred to herein as length), and number of fibers per unit of surface area (also referred to herein as fiber surface area density).

[0162] In some embodiments, a patterned matrix of polymer nanofibers can include nanofibers having an average length of at least 10.00 microns. In certain embodiments, the nanofibers can have a length of from about 10.00 microns to about 60.00 microns. In an exemplar embodiment, the nanofibers can have an average length of from about 15.00 microns to about 35.00 microns. In specific embodiments, the nanofibers can have a length of about 10.00 microns, 11.00 microns, 12.00 microns, 13.00 microns, 14.00 microns, 15.00 microns, 16.00 microns, 17.00 microns, 18.00 microns, 19.00 microns, 20.00 microns, 21.00 microns, 22.00 microns, 23.00 microns, 24.00 microns, 25.00 microns, 26.00 microns, 27.00 microns, 28.00 microns, 29.00 microns, 30.00 microns, 31.00 microns, 32.00 microns, 33.00 microns, 34.00 microns, 35.00 microns, 36.00 microns, 37.00 microns, 38.00 microns, 39.00 microns, 40.00 microns, 41.00 microns, 42.00 microns, 43.00 microns, 44.00 microns, 45.00 microns, 46.00 microns, 47.00 microns, 48.00 microns, 49.00 microns, 50.00 microns, 51.00 microns, 52.00 microns, 53.00 microns, 54.00 microns, 55.00 microns, 56.00 microns, 57.00 microns, 58.00 microns, 59.00 microns, or 60.00 microns.

[0163] In some embodiments, a patterned matrix of polymer nanofibers can include nanofibers having an average diameter of from about 0.10 microns to about 1.20 microns. In an exemplar embodiment, the nanofibers can have an average diameter of 0.24 microns to 0.34 microns. In certain embodiments, the nanofibers can have an average diameter of about 0.10 microns, 0.15 microns, 0.20 microns, 0.25 microns, 0.26 microns, 0.27 microns, 0.28 microns, 0.29 microns, 0.30 microns, 0.31 microns, 0.32 microns, 0.33 microns, 0.34 microns, 0.35 microns, 0.40 microns, 0.45 microns, 0.50 microns, 0.55 microns, 0.60 microns, 0.65 microns, 0.70 microns, 0.75 microns, 0.80 microns, 0.85 microns, 0.90 microns, 0.95 microns, 1.00 microns, 1.05 microns, 1.10 microns, 1.15 microns, or 1.20 microns.

[0164] The nanofiber lamella surface area density can range from about 1 to about 30 nanofibers per 100 microns.sup.2. In some embodiments, the nanofiber surface area density can range from about 6 to about 25 nanofibers per 100 microns.sup.2. In specific embodiments, the nanofiber surface density is about 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 nanofibers per 100 microns.sup.2. In an exemplar embodiment, the nanofiber surface area density is about 16.7 nanofibers per 100 micron.sup.2.

[0165] In certain embodiments, a matrix of polymer nanofibers is configured to modulate gene expression in stem cells cultured on or recruited to the scaffold relative to control cells cultured in the absence of the matrix. As used herein, modulate gene expression refers to increasing or decreasing the expression of one or more genes encoding a polypeptide involved in cell self-renewal or cell-cell interaction, alone or in combination with other transcription and/or translational regulatory factors or nucleic acids encoding such a polypeptide. As used herein, the term stem cell can be any type of undifferentiated cell of a multicellular organism that is capable of giving rise to more cells of the same type, and from which certain other kinds of cell arise by differentiation. Stem cells can be either embryonic or adult stem cells. In an exemplar embodiment, the stem cells are human mesenchymal stem cells. The terms culture and cultured as used herein refer to the cultivation or maintenance of cells under conditions suitable for growth. The term control cells refers to cells of the same type cultured under the same conditions as cells cultured on the matrix, except that the control cells are cultured on Tissue culture polystyrene (TCPS) or flat PCL in the absence of the matrix.

[0166] In specific embodiments, the patterned nanofiber matrix is configured to increase expression in cells cultured on or recruited to the matrix of a nucleic acid encoding a self-renewal transcription factor polypeptide or a cell-cell interaction marker polypeptide relative to control cells cultured in the absence of the matrix.

[0167] The terms polypeptide refers to a polymer of amino acids, or amino acid analogs, regardless of its size or function. Exemplary polypeptides include gene products, naturally occurring proteins, homologs, orthologs, paralogs, fragments and other equivalents, variants, and analogs of the foregoing.

[0168] Scaffolds of the present invention have a lamellar construction. In some embodiments the lamellae of the scaffold are perpendicular to the plane of the scaffold. In others they are parallel to the base. Nanofiber arrays optimally tuned for the propagation of a desired cell type are formed on a surface of each lamella. Pedestals formed on the surface maintain proper spacing between the lamellae so as to create interlamellar spaces through which cells may propagate and through which nutrients may be transported to the developing cells.

[0169] Referring now to FIGS. 1 through 6 diagrammatically depicting a lamella for forming scaffolds of the present invention, lamella 100 has an elongate flexible planar portion 102 with a first surface 120 and a second surface 122. First surface 120 has formed on it an array of nanofibers 104 and pedestals 106 integral with planar portion 102. Nanofibers 104 of basal diameter 105 are spaced distance 110 apart parallel to an elongate edge of planar portion 102, and distance 108 apart perpendicular to an elongate edge, distance 110 being greater than distance 108. Nanofibers 104 have a nominal height 112 with some variations in height occurring due to variations in the depth of nanoholes in the patterned substrate used to form the lamella, and possible stretching during removal of nanofibers 104 from the patterned substrate. Pedestals 106 have a height 114, height 114 being greater than nominal height 112. Distances 108 and 110, and heights 112 and 114 together are optimized to form a biomimetic cell culture substrate. Pedestals 106 are depicted as truncated cones. In other embodiments pedestals 106 may have elliptical, oval, or other cross-sections optimized for specific applications. In some embodiments planar portion 102 has formed therein holes 116. Holes 116 may be round, elliptical, slots, or have curvilinear shapes. The configuration, size, number and placement of holes 116 may be optimized to meet specific requirements.

[0170] As best seen in FIG. 6, nanofibers 104 have a non-uniform cross-section. Specifically, nanofibers 104 are tapered so as to provide a reduced flexural rigidity in portions of fibers 104 more remote from first surface 120 of lamella 100. This rigidity profile is beneficial for the attachment of stem cells thereto and for the transfer of shear stresses to the cell with its associated previously described benefits.

[0171] Lamella 100 forms a biomimetic cell culture substrate as described in co-pending application US 2016/0222345. Lamella 100 mimics the extracellular matrix (ECM), a primary environmental constituent that heavily influences cell behavior. Tuned arrays of nanofibers 104 provide a form of outside in signaling that, along with other factors, determines cell behavior. Specifically, the tuned arrays of lamella 100 are optimized for stem cells and human mesenchymal stem cells (hMSCs) to influence their decision to either maintain their stem cell phenotype or differentiate towards a specified cell lineage, for instance, to differentiate into chondrocytes for hyaline-like cartilage regeneration and/or osteocytes for subchondral bone formation. Nanofibers 104 are patterned on the micron scale over expanses of lamellar surfaces. The attachment of fibers 104 at the surface of planar portion 102 of substrate 100 mimics the basement membrane where fibrils of collagen forming an ECM are in contact with a highly cross-linked collagen IV layer. When used to culture hMSCs, biomimetic substrates typified by lamella 100 were found to significantly increase expression of critical regulators of self-renewal, as well as markers indicative of increased cell-cell interaction that are paramount in stem cell homeostasis.

[0172] Accordingly, nanofibers 104 may have a basal diameter preferably between 0.1 micron and 2.0 microns, and more preferably between 0.2 and 0.8 microns. Distances 108 and 110 between nanofibers 104 are preferably between 1 and 50 microns, and more preferably between 2 and 20 microns. Distances 108 and 110 may be equal or may differ. In some embodiments distances 108 and 110 may remain constant for the entirety of lamella 100. In other embodiments a first portion of the array of nanofibers 104 on lamella 100 may have first distances 108 and 110, and a second portion of the array in which distance 108 or distance 110 or both 108 and 110 differ from the values in the first portion. Indeed, distances 108 and 110 may have a range of values for the array of nanofibers 104 on a lamella 100, the range of values selected to achieve a specific outcome with relation to the propagation of hMSCs. The array of nanofibers 104 depicted on lamina 100 is formed of linear arrangements. In other embodiments arrays of nanofibers 104 may be formed of curvilinear or circuitous patterns of nanofibers 104.

[0173] Similarly, nominal height 112 of nanofibers 104 may be optimized to achieve specific outcomes. Height 112 of nanofibers 104 is preferably between 10 and 100 microns, and more preferably between 20 and 60 microns. In some embodiments the nominal height 112 of nanofibers 104 is constant. In other embodiments nominal height 112 of nanofibers 104 may have a first value for a first portion of the array of nanofibers 104 and a second value in a second portion of the array. As with the spacings 108 and 110 of nanofibers 104, nominal height 112 may have a range of values for the array of nanofibers 104 on a lamella 100, the range of values selected to achieve a specific outcome with relation to the propagation of hMSCs.

[0174] Lamella 100 is formed of a suitable bioabsorbable polymeric material. Among others, these materials include PCL (epsilon-polycaprolactone), PLLA (poly 1-lactic acid), PGA (polyglycolic acid), and PLGA (poly 1-lactic acid co-glycolic acid).

[0175] Nanofibers 104 may be formed on planar portion 102 by a variety of methods, planar portion 102 being a flexible polymeric film. In a preferred embodiment, nanofibers 104 are formed by hot pressing of the polymer film on a substrate in which arrays of nanoholes have been formed, the pattern of nanohole arrays being complementary to the pattern of nanofibers to be formed on the film. Prior to pressing, the film is heated sufficiently to allow the polymer to flow into the nanoholes when pressure is applied to the film. The film is cooled prior to removal from the substrate so as to allow the polymer to set sufficiently to allow removal of the nanofibers from the nanoholes in which they were formed. This hot-pressing method of nanofiber formation is described in detail in co-pending application US 2016/0223345. The arrays of nanofibers 104 may also be formed by solution casting. Like hot pressing, the solution casting process uses a substrate in which arrays of nanoholes have been formed, the pattern of nanohole arrays being complementary to the pattern of nanofibers to be formed on the film. A polymer/solvent solution is applied to a substrate in sufficient quantity to form a film on the surface of the substrate with the solution flowing into the nanoholes formed in the substrate. The solvent is then allowed to evaporate. When evaporation is complete, the film with nanofibers formed on its surface is peeled off of the substrate. A solution casting process for forming films with arrays of nanofibers is described in detail in co-pending application US 2015/0093550. The hot pressing and solution casting methods for forming a polymeric film with ordered nanofiber arrays on its surface are offered as examples of suitable manufacturing methods only. Any manufacturing method that allows the formation of ordered nanofiber arrays on the surface of a polymeric film suitable for forming lamellar scaffolds of the present invention may be used. Regardless of the manufacturing method, all lamella with ordered arrays of nanofibers formed integral with the film that forms the lamella fall within the scope of this invention.

[0176] A portion of a lamellar scaffold of the present invention having lamellae oriented perpendicular to a basal plane 5 of the scaffold is diagrammatically depicted in FIGS. 7 through 9. Scaffold portion 200 is formed of a plurality of lamellae 100 positioned with pedestals 106 contacting second surface 122 of adjacent lamellae so as to maintain spacing between the lamellae. In the interlamellar space so created, rows of nanofibers 104 form virtually columnar pipes for the propagation of cultured cells.

[0177] Lamellar scaffolds of the present invention may be formed with the lamellae in a parallel planar arrangement like scaffold blank 300 depicted in FIGS. 10 and 11. Scaffold blank 300 of length 302, width 304 and thickness 305 may be cut, etched, abraded, trimmed or shaped by some other method to configure it to meet the spatial requirements of a specific application.

[0178] Scaffolds of the present invention may also be formed with lamella 100 oriented perpendicular to a basal plane 5 of the scaffold and wrapped in a spiral manner as in scaffold 400 depicted in FIGS. 12 and 13. Scaffold 400 has an oval shape with width 402, length 404 and thickness 405. In other embodiments scaffold 400 is round. Scaffold 400 may be supplied to the surgeon in a variety of standard sizes and configurations. In use, the surgeon selects a scaffold 400 with the size and shape most suitable for a given requirement, and the treatment site is sized and configured to accept the scaffold 400 without modification to scaffold 400.

[0179] Parallel planar and spiral arrangements of lamella 100 are depicted herein for example only. Any configuration in which lamella 100 are assembled in a lamellar manner with structural elements maintaining spacing so as to create interlamellar spaces between adjacent lamella or adjacent lamella portions falls within the scope of this invention.

[0180] Hereafter, the use of lamellar scaffolds of the present invention will be described with reference to treating an articular lesion on a femoral condyle in a method of the present invention. FIGS. 15 and 16 depict a portion of a femoral condyle 10 with a lesion 12 with recessed surface 14 composed of calcified cartilage and bone. The surgeon preps lesion 12 by removing loose cartilage portions at the perimeter of the defect until the side walls are formed of healthy cartilage and are perpendicular to surface 14. The surgeon removes calcified cartilage from surface 14 to expose underlying bone. Thereafter, the site is as depicted in FIGS. 17 and 18. The size, shape and depth 18 of defect 12 are determined and the outline scribed on scaffold blank 300 (see FIG. 19) with suitable length 302 width 304 and thickness 305. Blank 300 is then shaped to form scaffold 500 shown in FIGS. 20 and 21. Thickness 505 of scaffold 500 may be reduced from 305 of blank 300, so long as it is still greater than depth 18 of defect 12. Thereafter, scaffold 500 is placed in lesion 12 as depicted in FIGS. 22 and 23. If required, scaffold 500 may be secured to the healthy cartilage forming the perimeter of lesion 12 using fibrin glue. After the glue has set, the outer surface of scaffold 500 is contoured to match the shape of the surrounding articular surface as shown in FIGS. 24 and 25.

[0181] As described previously, the surgeon removes calcified cartilage from surface 14 of defect 12 to expose healthy underlying bone prior to placing scaffold 500. Mesenchymal stem cells and growth factors flow from the underlying bone into scaffold 500 so as to populate scaffold 500. Viscous fluids enter the scaffold from the exposed surface bringing nutrients to the developing cells. The propagation and differentiation of stem cells within scaffold 500 is modulated by scaffold 500 so as to create hyaline cartilage or hyaline-like cartilage completely filling the defect.

[0182] In an alternate embodiment treatment method of the present invention, scaffold 500 is soaked in concentrated stem cells and growth factors prior to placement in lesion 12. This alternate method is identical in all aspects of form and function to the method previously described except as specifically subsequently described. In a preferred embodiment, autologous materials are used. In other embodiments, cells from another source are used. When using autologous cells, the surgeon first aspirates bone marrow from a suitable location, the bone marrow subsequently undergoing centrifuging to concentrate the stem cells and growth factors. When centrifuging is complete, scaffold 500 is soaked in the concentrated stem cells and growth factors from the centrifuge until scaffold 500 is saturated. Thereafter, scaffold 500 containing the stem cells with which it is infused are placed in lesion 12 as depicted in FIGS. 22 and 23. The repair is then completed in the same manner as the method previously described. Optionally, a coating of fibrin glue is applied to the surface to ensure that stem cells and growth factors remain in place at least temporarily.

[0183] In another alternate embodiment treatment method of the present invention a microfracture procedure is performed prior to placing scaffold 500 as previously described to enhance the supply of stem cells and growth factors to scaffold 500. The increased flow may increase the rate of population of stem cells in scaffold 500 yielding an associated increase in the rate of cell proliferation and differentiation. In all other aspects the method of this embodiment is identical to that previously herein described.

[0184] In yet another embodiment treatment method of the present invention, a bioactive substance is applied to surface 14 of prepared lesion 12 prior to the placement of scaffold 500 for the purpose of stimulating the growth of subchondral bone. In preferred embodiments the bioactive substance is calcium hydroxyapatite. In other embodiments the substance is silicon nitride or magnesium, these substances also having antimicrobial properties. In yet other embodiments, bioactive substances are provided in the scaffold, more specifically, in selected portions of the scaffold to enhance certain cell behaviors in these regions.

[0185] In the articular cartilage defect treatment method of the present invention previously described, scaffold 500 was configured to match the shape of lesion 12. In an alternate repair method of the present invention the defect site is configured to match the shape of the scaffold used in the repair. Referring now to FIGS. 26 and 27, condyle 30 has formed thereon lesion 32 with recessed surface 34. The surgeon measures the size and depth of the lesion and selects a scaffold 400 (FIGS. 12 to 14) somewhat larger than the lesion. The surgeon removes calcified cartilage from surface 34 to expose underlying bone. Defect 32 is enlarged and configured as depicted in FIGS. 28 and 29, width 42 being slightly larger than width 402 of scaffold 400 (FIG. 12), and length 44 being slightly larger than length 404 of scaffold 400. Thickness 405 of scaffold 400 is greater than depth 38 of prepared lesion 34. Scaffold 400 is then positioned in defect 32 as depicted in FIGS. 30 and 31. Optionally, fibrin glue may be applied between the perimeter of scaffold 400 and the cartilage side walls of lesion 32. After the glue has set, scaffold 400 is contoured to match the shape of the articular surface of condyle 30.

[0186] Optionally, as with the previously described alternate method of treatment, the surgeon may aspirate bone marrow from a suitable location, with the bone marrow subsequently undergoing centrifuging to concentrate the stem cells and growth factors. Scaffold 400 is saturated with stem cells in the manner previously described, before being positioned in defect 32 as depicted in FIGS. 30 and 31. Also, as previously described, the surgeon may perform a microfracture procedure prior to the placement of scaffold 400 in the manner previously described.

[0187] Lamellar scaffolds of the present invention previously herein described are formed of lamellae that are perpendicular to the basal plane 5 of the scaffold. In other embodiments the lamellae are parallel to the basal plane 5 of the scaffold. A lamella 600 for a lamellar scaffold of the present invention in which the lamella are parallel to the basal plane 5 of the scaffold is depicted in FIGS. 34 through 39. Lamella 600 has an elongate flexible planar portion 602 with a first surface 620 and a second surface 622. First surface 620 has formed on it an array of nanofibers 604 and pedestals 606. Nanofibers 604 of basal diameter 605 are spaced distance 610 apart in a first direction, and distance 608 apart in a direction perpendicular to the first direction, distance 610 being greater than distance 608. Nanofibers 604 have a height 612 and pedestals 606 have a height 614, height 614 being greater than height 612. Distances 608 and 610, and heights 612 and 614 and the diametric profile of nanofibers 604 together are optimized to form a biomimetic cell culture substrate for the propagation of stem cells, or for the differentiation of stem cells into a desired cell type. Pedestals 606 are depicted as truncated cones. In other embodiments pedestals 606 may have elliptical, oval, or other cross-sections optimized for specific applications. Planar portion 602 has formed therein holes 616. Holes 616 may be round, elliptical, slots, or have curvilinear shapes. The configuration, size, number and placement of holes 616 may be optimized to favor a particular desired cell behavior.

[0188] A lamellar scaffold 650 of the present invention with the lamellae parallel to the base 5 of the scaffold is diagrammatically depicted in FIGS. 40 through 43. Adjacent lamellae 600 have formed between them interlamellar spaces 651. Rows of nanofibers 604 in interlamellar spaces 651 form channels for the propagation of stem cells. As best seen in FIG. 44, these channels together with perforations 616 in lamellae 600 form a labyrinth through which cellular propagation, indicated by arrows 648, may occur. As in previously described lamellar scaffolds of the present invention, the geometry of nanofibers 604, and the geometry of the arrays formed of nanofibers 604 may be optimized for maintaining the stemness of stem cells populating scaffold 650, or may induce their differentiation into desired cell types. Scaffold 650 is formed of a plurality of lamellae 600 all of which have a single matrix geometry and that have nanofibers 604 of a single constant configuration throughout. In other embodiments of the present invention a scaffold may be formed wherein a first portion of the lamella stack forming the scaffold is formed of lamellae having a first array pattern and first nanofiber configuration optimized for the propagation of a first cell type, and a second portion of the stack formed of lamellae having a second array pattern and second nanofiber configuration optimized for the propagation of a second cell type. Such a scaffold of the present invention is depicted in FIGS. 45A and 45B. Scaffold 750 has a first portion 752 formed of lamellae 600, and a second portion 754 formed of lamellae 700. As best seen in FIG. 45B, nanofibers 604 of lamellae 600 differ in configuration from fibers 704 of lamellae 700. Also, the spacing of nanofibers 604 within the array of lamellae 600 differs from the spacing of nanofibers 704 within the array of lamellae 700. Lamellae 600 may have nanofibers 604 and the arrays of which they are formed optimized for the differentiation of stem cells populating region 752 of scaffold 750 into a first cell type, such as, for instance osteocytes. Lamellae 700 of region 754 of scaffold 750 may be optimized for the differentiation of stem cells populating region 754 of 750 into a second cell type, such as, for instance, chondrocytes. Indeed, by creating scaffolds with regions that favor the propagation of selected cell types scaffolds of the present invention may regenerate stratified tissue structures like hyaline cartilage.

[0189] Unlike prior art fibrous scaffolds, those of the present invention are able to support a compressive load without permanent deformation. Prior art fibrous scaffolds like those described by Arinzeh in US 2016/0354515 permanently deform when subjected to a load, resulting in incomplete filling of a defect, or flattening of the exposed surface contour. In contrast, lamellar scaffolds of the present invention are load bearing. They maintain their size and shape under load thereby allowing complete filling of a defect and the maintaining of contours of the exposed surface. Additionally, lamellar scaffolds of the present invention are resilient, that is, they elastically deform when subjected to a load and spring back when the load is removed or lessened.

[0190] Referring now to FIGS. 46 through 48 that depict a prior art fibrous scaffold 50 placed in defect 42 in condyle 40, initially, as depicted in FIG. 46, the profile of exposed surface 51 of scaffold 50 matches the profile of surface 44 of condyle 40. FIG. 47 depicts condyle 40 and scaffold 50 when scaffold 50 is subjected to a compressive load, shown as arrow 60. Scaffold 50 is compressed by the load such that surface 51 of scaffold 50 is flattened and displaced from surface 44 of condyle 40. FIG. 48 depicts scaffold 50 and condyle 40 after the compressive load is removed. Surface 51 of scaffold 50 remains flattened and displaced from the profile 44 of the surface of condyle 40. This will result in incomplete filling of lesion 42 as scaffold 50 is replaced by fibro cartilage. Importantly, with scaffold 50 compressed as shown, cells developing within scaffold 50 are not subjected to the shear stresses that enhance cell development. Specifically, because scaffold 50 is not subjected to repetitive compressive loading, cells developing within scaffold 50 will not experience the shear stresses required to optimally develop a tissue structure in which the cells are configured and aligned to resist a compressive load.

[0191] In contrast, highly ordered, lamellar scaffolds of the present invention are resilient, and capable of supporting a compressive load without appreciable permanent deformation. Referring now to FIGS. 49 through 51 depicting lamellar scaffold 300 of the present invention positioned in defect 42 in condyle 40, in FIG. 49 the contour of surface 301 of scaffold 300 matches the contour of surface 44 of condyle 40. Applying a compressive load, shown as arrow 60 depicted in FIG. 50, causes slight deformation of scaffold 300 such that the contour of surface 301 of scaffold 300 is slightly displaced from the contour of surface 44 of condyle 40. When compressive load 60 is removed (see FIG. 51) scaffold 300 returns to its original size and shape with surface 301 of scaffold 300 matching the contour of surface 44 of condyle 40. Repetitive cyclic loading of scaffold 300 subjects developing cells within it to shear stresses that enhance cell development and that create aligned cellular structures that are optimal for compressive strength in the regenerated tissue.

[0192] While the use of lamellar biomimetic scaffolds of the present invention has been described with reference to defects in condylar articular cartilage, this is for example only and is not limiting of the scope of this invention. Lamellar scaffolds of the present invention may be used for the regeneration or augmentation of virtually any bone or soft tissue.

[0193] Tissue augmentation is well known in the art. Products such as the Regeneten BioInductive Implant by Smith and Nephew, Inc. (Andover, Mass.), Allopatch HD by Conmed, Inc. (Utica, N.Y.), and the DX Reinforcement Matrix by Arthrex, Inc. (Naples, Fla.) are used to treat deficiencies in soft tissue. Among other uses, the products are frequently used to treat rotator cuff disease including partial thickness tears. The products are furnished in flexible sheet-like form and are applied as a patch to the soft tissue at the site of the pathology. The patch provides mechanical bracing to the site, and serves as a scaffold for the growth of tendon-like tissue as it is absorbed.

[0194] Biomimetic lamellar scaffolds of the present invention may be used in this manner for tissue augmentation. For instance, FIG. 52 depicts a scaffold 700 used for augmentation of rotator cuff 62 in the repair of a tear of cuff 62. A tear occurs when the lateral attachment of cuff 62 is separated from humerus 64. Cuff 62 is reattached to humerus 64 using suture 68 and suture anchors 66. The reattachment technique depicted is referred to as a double-row repair since sutures 68 are passed over cuff 62 from a medial row of anchors placed under cuff 62 to a second row 66 of anchors lateral to the edge of cuff 62. Sutures 68 compress the lateral portion of cuff 62 against a prepared portion of humerus 64. The lateral portion of cuff 62 reattaches itself to the humerus. If the lateral portion of the cuff is damaged by detachment from humerus 64, augmentation of cuff 62 is desirable to ensure success of the procedure. As depicted in FIG. 52, lamellar scaffold 700 is compressed against cuff 62 by sutures 68. While cuff 62 is reattaching to humerus 64, stem cells from cuff 62 propagate into scaffold 700 creating a supplemental layer of ligamentous tissue as scaffold 700 is absorbed. This results in a more secure reattachment with a decreased likelihood of re-injury.

[0195] Commercially available regenerative tissue scaffold patches for tissue augmentation may be formed with an acellular collagen scaffold and preserved vascular channels that enable repopulation and revascularization by host tissue. Typical of a matrix of this type is the GraftJacket from Wright Medical (Memphis, Tenn.). The GraftJacket is a human dermal collagen matrix that may be readily incorporated into the body. The material is essentially acellular and is treated with a proprietary process to preserve the intact matrix including vascular channels. The scaffold may be used to reinforce primary soft-tissue repairs throughout the body. After preparing a site for augmentation using the matrix, the scaffold is secured in place using sutures, staples, or fibrin glue, among other methods. The performance of scaffolds of this type may be enhanced by the addition of a biomimetic scaffold of the present invention. Specifically, one or more lamella with nanofiber matrices optimized for the propagation of stem cells may be positioned between the prepared site and the dermal collagen matrix to enhance the flow of stem cells into the matrix. FIGS. 53 through 56 diagrammatically depict a portion of a biomimetic scaffold formed of lamellae 800 positioned adjacent to collagen matrix 70, lamellae 800 being parallel to the plane of matrix 70. Lamellae 800 are alike in construction to lamella 600 (FIGS. 34 through 39) in all aspects of form and function having a planar portion 802, ordered arrays of nanofibers 804, pedestals 806 and perforations 816. Perforations 816 may comprise a larger portion of the surface area of planar portion 802 than perforations 816 of lamella 800 so as to increase the ease of flow of stem cells into and through the biomimetic scaffold formed of lamellae 800. External signaling provided by biomimetic arrays of nanofibers 804 to stem cells entering the scaffold portion formed by lamellae 800 may increase the differentiation of those cells into the types desired to populate matrix 70.

[0196] In another embodiment lamellar scaffold intended primarily for repairing or augmenting soft tissue structures, a porous layer of bioabsorbable material is added to the top surface of the scaffold to increase the strength of the scaffold and to aid in fixation of the scaffold at the treatment site. Referring now to FIGS. 57 and 58, scaffold 900 is formed of a plurality of lamellae 700 with bioabsorbable element 902 positioned adjacent to the top-most lamella 700. Element 902 has a plurality of perforations 904 that allow communication between the interlamellar spaces of scaffold 900 and the surrounding environment. As depicted in FIGS. 57 and 58 element 902 ends at the margins of lamellae 700. In other embodiments element 902 extends beyond the margins so that scaffold 900 can be affixed at the treatment site using sutures or bioabsorbable staples without perforating the body of the scaffold. As depicted scaffold 900 has lamellae 700 oriented parallel to the basal plane of the scaffold. In other embodiments comprising element 902 the lamellae are perpendicular to the basal plane of the scaffold. Element 902 may be formed of any bioabsorbable material having suitable strength and absorption properties.

[0197] FIG. 59 depicts a scaffold construct 1000 attached at a soft tissue treatment site for the purpose of regenerating or augmenting tissue. Scaffold construct 1000 has spiral wound scaffold 400 (see FIGS. 12 through 14) positioned at the site and secured by bioabsorbable woven element 1002. As depicted, woven element 1002 is affixed at the site by bioabsorbable tissue staples 1004, though any suitable fixation method may be used including suturing. Woven element 1002 prevents movement of scaffold 400 during healing without restricting communication between the biomimetic interlamellar spaces of scaffold 400 and the surrounding environment.

[0198] Lamellae previously described for scaffolds of the present invention have formed on them arrays formed of rows of nanofibers with a regular spacing of nanofibers within a row, and with uniform spacing of rows over the first surface of the lamellae. In other scaffold embodiments of the present invention the arrays of nanofibers may have discrete zones in which the array within in each zone is optimized for, for instance, maintaining the stemness of stem cells, or for differentiating stem cells into cells of a preferred type. An illustrative example of a lamella 1100 with an array having two zones is depicted in FIGS. 60 through 63. Lamella 1100 is like lamella 100 (FIGS. 1 through 6) in all aspects of form and function except as specifically hereafter described. Like lamella 100, lamella 1100 is configured to be positioned in a scaffold with the lamellae perpendicular to the base plane of the scaffold. Lamella 1100 has a first array portion with a first spacing between rows 1110, and a second array portion with spacing between rows 1111. Spacing 1110 may be optimized, for instance, for the differentiation of stem cells into osteocytes, while spacing 1111 may be optimized, for instance, for the differentiation of stem cells into chondrocytes. The number and characteristics of the arrays on a lamella may be optimized to create a desired stratified tissue structure.

[0199] FIGS. 64 through 67 depicted a lamella 1200 that like lamella 100 is configured for use in a scaffold of the present invention in which lamellae 1200 are perpendicular to the basal plane of the scaffold. Lamella 1200 is identical to lamella 100 in all aspects of form and function except as specifically subsequently described. Lamella 1200 has rows of hedges formed of nanofibers spaced distance 1211 apart, the hedges being distance 1210 apart. Distance 1210 is greater than distance 1211. Lamella 1200 has hedges formed of two rows of nanofibers. In other embodiments the hedges may be formed of three or more rows. In some embodiments the spacing of nanofiber rows in a hedge are uniform. In others they are non-uniform, the spacing of the rows in a hedge, and the spacing between hedges being optimized to achieve specific cell behaviors.

[0200] In embodiments of mimetic lamellar scaffolds of the present invention previously herein described, the scaffold is implanted in the body of a patient and tissue regeneration occurs within the patient. Scaffolds of the present invention may also be used for the regeneration of tissue external to the patient to create structures for subsequent implantation in the patient. Scaffolds of the present invention have the ability to provide a temporary structure that mimics the extracellular matrix so as to provide a support means and also to affect stem cell behavior to create specific tissue types through the use of biomimetic nanofiber arrays that mimic collagen tendrils.

[0201] FIGS. 68 through 71 depict an elongate lamella 1300 for a scaffold for the in vitro growing of an elongate soft tissue structure like a ligament. As depicted, lamella 1300 has a length 1370 and width 1372 suitable for a scaffold of the present invention for creating an ACL for use with aperture fixation, that is, for fixation in the femoral tunnel using an interference screw. Length 1370 is preferably between 120 and 180 millimeters. Width is preferably between six and ten millimeters. Nanofibers positioned distance 1310 apart from rows parallel to the axis of the lamella, the rows being spaced distance 1308 apart. Distances 1308 and 1310 are optimized to cause the growth of ligamentous tissue with cells that favor an axial orientation.

[0202] A scaffold 1400 for in vitro growing elongate soft tissue structures is depicted in FIGS. 72 through 75. Scaffold 1400, formed of lamellae 1300 has a height 1474 that is preferably between six and ten millimeters.

[0203] In use, scaffold 1400 is placed in a culture vessel containing a culture medium with pluripotent stem cells, preferably bone marrow stromal cells, so that the medium saturates scaffold 1400. Characteristics of the nanofiber arrays of lamellae 1300 cause the preferential differentiation into ligament tissue aligned with the axis of scaffold 1400.

[0204] The differentiation of stem cells into ligament tissue in vitro is strongly affected by loading of the scaffold and developing tissue. Specifically, cyclic tensional or torsional loading like that undergone by a native ACL favors the forming of ligament tissue. FIGS. 76 and 77 depict a lamella 1500 for a lamellar scaffold of the present invention incorporating means for applying a tensile or torsional load to the scaffold. Lamella 1500 is identical in all aspects of form and function to lamella 1300 except as specifically subsequently described. Lamella 1500 has formed at each end an eyelet 1580 through which a tensile force may be applied to lamella 1500. FIGS. 78 and 79 depict scaffold 1600 configured for growing an ACL or similar elongate structure. Lamellae 1500 are stacked and aligned such that links 1682 may be attached to scaffold 1600 using pins 1684 that engage eyelets 1580 of lamellae 1500. The culture vessel into which scaffold 1600 is placed has a means for applying cyclic tensile forces 1690 of predetermined length, force and frequency to scaffold 1600 at suitable times throughout the growth of ligament tissue in scaffold 1600. When formation of the tissue is complete and scaffold 1600 is completely absorbed, the eyelet portions of lamellae 1500 are detached. A soft tissue graft formed using scaffolds 1400 or 1600 will have a square cross-section. Other scaffolds of the present invention for creating elongate soft tissue grafts have a cylindrical form created by coiling lamellae 1300 or similar. An ACL formed using scaffolds 1400 or 1600 is attached in the usual manner using interference screws or a similar aperture fixation method.

[0205] Suspensory fixation of an ACL using an implant commonly referred to as a button (for example, the GFS Ultimate by Parcus Medical (Sarasota, Fla.) or similar) requires a longer graft with smaller cross-section. The graft is folded to create a loop through which sutures for engaging the button are passed for femoral fixation. The dimensions of scaffold 1600 may be modified to create this longer thinner ligament. Alternatively, an ACL may be formed with features that enable easy secure fixation at implantation. A lamella 1700 for a lamellar scaffold of the present invention is configured for growing an improved ACL configured for increased ease of suspensory femoral fixation. Lamella 1700 is identical to lamella 1500 in all aspects of form and function except as specifically hereafter described. The nanofiber array, pedestals and perforations of lamella 1500 are extended to so as to cover the surface surrounding eyelet 1780 at a first end of lamella 1700. An ACL grown using a lamellar matrix formed of lamellae 1700 will have an eyelet portion configured like the eyelet portion of lamellae 1500 and 1700 when viewed in a plan view. Suture may be threaded through the loop for suspensory fixation. Alternatively, a larger diameter tunnel may be formed with the graft extending through the tunnel so that the eyelet may be secured to the anterior surface of the femur using a washer and screw, staple or another mechanical fixation.

[0206] The ability of scaffolds of the present invention to affect the differentiation of stem cells through the configuration of nanofiber arrays formed on lamellae that make up the scaffold enable the forming of ACL and other elongate tissue structures with advanced features. For instance, a commonly used ACL graft type is a bone-tendon-bone (BTB) patellar tendon graft. The BTB graft has a bone portion attached to each end of the graft so that fixation during graft placement is achieved by affixing the bone blocks to the femur and tibia. A BTB may grown in vitro using scaffolds of the present invention made of lamellae like 1600, but with the nanofiber array having three zones, a first central zone wherein the nanofiber array characteristics are optimized for the growth of ligament tissue, and two end zones wherein the nanofiber array characteristics are optimized for the growth of bone. Additionally, the developing graft may be subjected to appropriate compressive, torsional and tensile stresses to encourage development of the desired tissue types.

[0207] In embodiments previously herein described lamellae forming scaffolds of the present invention have nanofiber arrays formed on a first surface of a lamella only. In other embodiments of the present invention, nanofiber arrays may be formed on both first and second opposed surfaces of the lamella with the nanofibers from both surfaces extending into the interlamellar spaces. FIGS. 82 through 85 depict a representative lamella 1800 for a scaffold of the present invention identical in all aspects of form and function to lamella 100 (FIGS. 1 to 6) except as specifically hereafter described. Lamella 1800 has arrays of nanofibers 1804 formed on both first surface 1820 and second surface 1822 of planar portion 1802. Referring now to FIGS. 86 and 87, scaffold portion 1900 formed of lamellas 1800 has formed therein interlamellar spaces in which nanofibers 1804 formed on the first and second surfaces 1820 and 1822 of adjacent lamellas 1800 both protrude into the interlamellar space. In all other aspects scaffold portion 1900 is alike in form and function to scaffolds previously herein described.

[0208] This description and appended claims include the words below, above, side, top, bottom, upper, lower, when, upright, etc. to provide an orientation of embodiments of the invention to allow for proper description of example embodiments. The foregoing positional terms refer to the apparatus when in the orientation shown in FIG. 1. A person of skill in the art will recognize that the apparatus can assume different orientations when in use. It is also contemplated that embodiments of the invention may be in orientations other than upright without departing from the spirit and scope of the invention as set forth in the appended claims. Further, it is contemplated that above means having an elevation greater than, and below means having an elevation less than such that one part need not be directly over or directly under another part to be within the scope of above or below as used herein.

[0209] The phrase in one embodiment, as used herein does not necessarily refer to the same embodiment, although it may. Conditional language used herein, such as, among others, can, might, may, e.g., and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states.

[0210] Although embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications can be made therein without departing from the spirit and scope of the invention as set forth in the appended claims.

[0211] This written description uses examples to disclose the invention and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

[0212] It will be understood that the particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention may be employed in various embodiments without departing from the scope of the invention. Those of ordinary skill in the art will recognize numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.

[0213] All of the compositions and/or methods disclosed and claimed herein may be made and/or executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of the embodiments included herein, it will be apparent to those of ordinary skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the invention as defined by the appended claims.

[0214] Thus, although there have been described particular embodiments of the present invention, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.