CULTURE MEDIUM COMPOSITION FOR MATURATING CARDIOMYOCYTES DERIVED FROM PLURIPOTENT MAMMALIAN STEM CELLS

Abstract

The current disclosure relates to a culture medium, different methods to generate adult-like cardiomyocytes from pluripotent embryonic stem cells (ESC) and/or (induced) pluripotent stem cells (iPSC) using the medium, in particular from stem cells that differentiated into (foetal) cardiomyocytes, and to kits comprising the medium, or the medium together with differentiated (foetal) cardiomyocytes derived from pluripotent embryonic stem cells (ESC) and/or (induced) pluripotent stem cells (iPSC).

Claims

1. An aqueous culture medium composition, wherein said culture medium composition is serum-free and comprises: a thyroid hormone-like compound; a lipid mixture; and a carnitine compound.

2. The composition according to claim 1, wherein the thyroid hormone-like compound is triiodothyronine (T3) and/or 3,5-diodothyropropionic acid (DITPA).

3. The composition according to claim 1, wherein the composition comprises about 25 ng/ml to about 150 ng/ml of T3 and/or about 1 microM to about 2 microM of DITPA.

4. The composition according to claim 1, wherein the lipid mixture comprises cholesterol and one or more lipids selected from linolenic acid, linoleic acid and palmitic acid.

5. The composition to claim 1, wherein the composition comprises about 1 microgram/ml to about 4 microgram/ml of cholesterol.

6. The composition according to claim 1, wherein the composition comprises about 0.5 mM to about 3.5 mM of carnitine.

7. The composition according to claim 1, wherein the composition comprises a creatine compound and a taurine compound.

8. The composition according to claim 1, wherein the composition comprises about 3.0 mM to about 7.0 mM of creatine.

9. The composition according to claim 1, wherein the composition comprises about 2 mM to about 7 mM of taurine.

10. The composition according to claim 1, wherein the composition comprises about 5 mg/L to about 15 mg/L of insulin, about 3 mg/L to about 8 mg/L of transferrin, and about 0.005 mg/L to about 0.0075 mg/L of selenium.

11. The composition according to claim 1, wherein said composition comprises about 2 mg/ml to about 7 mg/ml of polyvinyl alcohol (PVA).

12. A method to generate adult-like cardiomyocytes from foetal-like cardiomyocytes differentiated from pluripotent embryonic stem cells (PESC) and/or induced pluripotent stem cells (iPSC), comprising the steps of: (a) providing one or more fetal-like cardiomyocyte(s); (b) contacting said one or more fetal-like cardiomyocytes with the culture medium composition according to claim 1 so as to allow maturation of said one or more fetal-like cardiomyocytes into adult-like cardiomyocytes.

13. The method according to claim 12, wherein the one or more fetal-like cardiomyocytes are in contact with the culture medium composition for about 3 days up to about 15 days.

14. The method according to claim 12, wherein the one or more fetal-like cardiomyocytes are contacted with the culture medium composition, which lacks a thyroid hormone-like compound for about two days prior to contact with the culture medium composition comprising at least one thyroid hormone-like compound.

15. A kit suitable for generating adult-like cardiomyocytes cells in in vitro culture, comprising the culture medium composition according to claim 1.

16. The kit according to claim 15, wherein the culture medium composition lacks at least one thyroid hormone-like compound.

17. The kit according to claim 15, wherein culture medium composition is in a liquid form.

18. The kit according to claim 15, wherein the culture medium composition is in a solid form, preferably a powder form.

19. The kit according to claim 15, further comprising fetal-like cardiomyocytes.

20. The kit according to claim 15, comprising undifferentiated PESC and/or iPSC.

Description

BRIEF DESCRIPTION OF THE FIGURES RELATED TO THE INVENTION

[0204] FIG. 1 displays the effects of T3 on the maturation of foetal-like (immature) cardiomyocytes derived from human pluripotent embryonic stem cells (PESCs) in in vitro culture. The maturity of PESC-derived foetal-like (Immature) cardiomyocytes was revealed by their morphological features, which were assessed by immunohistochemistry (immunofluorescence) techniques using an antibody directed against alpha-actinin. Panels A and B show the morphological features of PESC-derived foetal-like (Immature) cardiomyocytes cultured in a basic differentiation medium as taught herein but which lacks T3 (control situation 1). Panels C and D show the morphological features of PESC-derived foetal-like (immature) cardiomyocytes cultured in the culture medium composition (or maturation medium composition) as taught herein but which lacks T3 (control situation 2). Panels E and F show the morphological features of PESC-derived foetal-like (Immature) cardiomyocytes cultured in the culture medium composition of the invention but which comprises 100 ng/ml of T3. Panels B, D, and F represent magnifications of panels A, C, and E, respectively. The results show that compared to the control situations 1 and 2 (see panels A-D), PESC-derived foetal-like (immature) cardiomyocytes cultured in the culture medium composition of the invention comprising T3 (see panels E, and F) displayed morphological features that were the most reminiscent or the closest to an adult cardiomyocyte phenotype, including polarization of cells, improved sarcomeric organization, and elongated shape. Note that in comparison to control 1 (see panels A and B), cardiomyocytes cultured in the culture medium composition as taught herein but lacking T3 (control 2, see panels C and D) also displayed morphological features that were reminiscent of an adult cardiomyocyte phenotype but to a lower extend (less efficient, less robust) than what was observed in the presence of T3 (see panels E and F).

[0205] FIG. 2 depicts the effects of T3 on the maturation of foetal-like (immature) cardiomyocytes derived from human pluripotent embryonic stem cells (PESCs) In vitro culture. The maturity of the PESC-derived foetal-like (immature) cardiomyocytes was revealed by their electrophysiological properties, which were assessed by patch clamp techniques. PESC-derived foetal-like (immature) cardiomyocytes were cultured for 12 days either in the culture medium as taught herein which lacks T3 (control situation, see black bar on graphs) or in the culture medium as taught herein which comprises 100 ng/ml of T3 (see white bar on graph). Panel A shows the effects of T3 on the maximal upstroke velocity. Panel B shows the effects of T3 on the resting membrane potential. Panel C shows the effects of T3 on the amplitude of an action potential. The results show that, compared to the control situation, PESC-derived foetal-like (Immature) cardiomyocytes treated with T3 display improvement in several electrophysiological parameters including greater maximal upstroke velocity (see panel A), lower resting membrane potential (see panel B), and greater amplitude of the action potential (see panel C). Data presented as mean+/SEM.

[0206] FIG. 3 displays the effects of T3 on the maturation of foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture. The maturity of the PESC-derived foetal-like (Immature) cardiomyocytes was revealed by their metabolic properties, which were assessed using a TMRM assay, which utilizes the potentiometric red fluorescent dye tetramethylrhodamine methyl ester, commonly known as TMRM. Treatment with TMRM results in mitochondrial membrane potential-driven accumulation of TMRM within the inner membrane region of healthy functioning mitochondria. PESC-derived foetal-like (immature) cardiomyocytes were cultured for 17 days in either a culture medium composition (CM) as taught herein, which lacks T3 (control situation) or a culture medium composition (CM) as taught herein (also referred to as maturation medium (MM), which comprises 100 ng/ml of T3. Both treatment groups were subjected to a TMRM assay. The results show that, in comparison to the control situation, PESC-derived foetal-like (immature) cardiomyocytes treated with T3 display greater increased in TMRM-associated orange fluorescence indicating a enhanced mitochondrial activity.

EXAMPLES

[0207] The present invention is further illustrated, but not limited, by the following Examples. From the above discussion and these Examples, one skilled in the art can ascertain the essential characteristics of the present invention, and without departing from the teaching and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, various modifications of the invention in addition to those shown and described herein will be apparent to those skilled in the art from the foregoing description. Such modifications are also intended to fall within the scope of the appended claims.

Example 1. Differentiation in Spin Embryonic Bodies (EBs)

[0208] The human PESC (hPESC) or human iPSC (hiPSC) were cultured in stem cell medium on mitotically inactivated mouse fibroblasts and passaged using TrypLE Select (Invitrogen). Stem cell medium contains DMEM/F12 (Gibco, cat. no. 11320-033), 20% (v/v) knockout serum replacement (Gibco, cat. no. 10828-028), 10 mM non-essential aminoacids (Gibco, cat. no. 11140-050), 2 mM L-glutamine (Gibco, cat. no. 25030-081) 2b-mercaptoethanol (Gibco, cat. no. 21985-023), 10 ng/ml human bFGF.

[0209] One day before differentiation, cells were passaged onto matrigel coated 6-well plates at a density of 1 million cells/well in stem cell medium.

[0210] Cells were differentiated in embryoid bodies (EB). At day 0, cells were collected and re-suspended at 6104 cells ml-1 In basic differentiation medium (serum-free) as taught herein comprising a lipid mixture (2.2 microgram/ml cholesterol, 0.1 microgram/ml of linoleic acid, 0.1 microgram/ml of linolenic acid, and 0.1 microgram/ml of palmitic acid), insulin (1 mg/L), transferrin (0.55 mg/L), selenium (0.00067 mg/L), trace element mix B as described herein (0.01%), Trace element mix C as described herein (0.1%), 20 ng ml-1 of BMP4 (R&D Systems) and 30 ng ml-1 activin A (R&D Systems), 30 ng ml-1 VEGF (R&D systems), 40 ng ml-1 SCF (R&D systems) and 1.5 M Chir99021 (Axon medchem). An amount of 50 l of this mix was placed into each well of a 96-well round-bottom non-adherent plate yielding EBs composed of 3,000 cells. On day 3, 7, 10, 14 and 17, the medium was replaced with differentiation medium without growth factors.

[0211] The foetal-like (immature) cardiomyocytes produced by this method are suitable for use in the method of the invention as taught herein, i.e. said foetal-like (Immature) cardiomyocytes may be matured into adult-like (mature) cardiomyocytes using the culture medium composition as well as the methods to generate adult-like (mature) cardiomyocytes as taught herein.

Example 2. Differentiation in Monolayer

[0212] The human PESC or human iPSC were cultured in monolayer according to the method described in Dambrot et al (2014), Exp. Cell. Res. (in press) (http://dx.doi.org/10.1016/j.yexcr.2014.05.001). In short, the cells were cultured on Matrigel (BD Biosciences)-coated tissue culture dishes in mTeSR1 according to the manufacturer's protocol (Stem Cell Technologies). To initiate differentiation to cardiomyocytes, the cells were dissociated into small clusters of cells and seeded onto a Matrigel-coated cell culture dish in mTeSR1. Three days later (differentiation day(d) 0), the medium was replaced with low insulin (1 mg/I), (LI)-BPEL medium and supplemented with BMP4 (day 0-day 3), Activin A (day 0-day 3), CHIR99021 (day 0-day 3) and XAV939 (day 3-day 6). From day 6 onward BMP4, Activin A, CHIR99021 and XAV939 were absent from the medium.

[0213] The foetal-like (immature) cardiomyocytes produced by this method are suitable for use in the method of the invention as taught herein, i.e. said foetal-like (immature) cardiomyocytes may be matured into adult-like (mature) cardiomyocytes using the culture medium composition as well as the methods to generate adult-like (mature) cardiomyocytes as taught herein.

Example 3. Generation of Adult-Like (Mature) Cardiomyocyte from Foetal-Like (Immature) Cardiomyocytes in In Vitro Culture

[0214] Tissue culture plastic was coated using Matrigel (Corning) at a concentration of 1/100 in DMEM, for 45 min at room temperature. A single cell suspension coming from dissociated embryoid bodies, dissociated monolayers or (commercially obtained) frozen foetal-like (immature) cardiomyocytes, all derived from PESC and/or iPSC in in vitro culture, were seeded at an appropriate density on matrigel coated tissue culture plastic (e.g. In 20-40k cells per well of a 96-well plate, e.g. 20-200k per well of a 12 well plate). On day 1 following plating, the foetal-like (immature) cardiomyocytes were exposed to a culture medium composition of the invention, which consists of a serum-free culture medium composition comprising 50 ng/ml of T3 (Sigma T6397), 2 mM of carnitine, 5 mM of creatine, 5 mM of taurine, 2.2 microgram/ml of cholesterol, 0.1 microgram/ml of linoleic acid, 0.1 microgram/ml of linolenic acid, 0.1 microgram/ml of palmitic acid (lipids, for example, from Gibco 11905), 10 mg/ml of insulin, 5.5 mg/ml of transferrin, 0.0067 mg/ml of selenium (Insulin, transferrin and selenium from e.g. Gibco 51500), 0.01% of trace element mix B (as described herein; Cellgro 99-175-CL), 0.1% of trace element mix C (as described herein; Cellgro 99-176-CL), 0.5 w/w % of antibiotics (penicillin-streptomycin mixture commercially available Gibco (Gibco 12070; 5000 U/ML), 0.05 mg/ml ascorbic acid, 2 mM of Glutamax supplement (i.e. L-alanyl-L-glutamine dipeptide in 0.85% NaCl, commercially available at Gibco, e.g. Gibco 35050), 0.125 w/w % polyvinylalcohol (PVA), 450 nM of alpha monothiolglycerol (MTG) (commercially available), 025 w/w % BSA (Bovostar BSAS1.0) in 46.5% (w/w) IMDM (Gibco 21056) and 46.5% (w/w) HAM F-12 with glutamax (Gibco 31765). All concentrations are expressed as final concentration in the culture medium composition.

[0215] The next day the culture medium composition as taught herein was refreshed. This step was repeated every 2-3 days until day 15.

[0216] Alternatively, treatment with the culture medium composition as just described above comprising 50 ng/ml of T3 may be started at either at day 3 or day 7 after plating the foetal-like cardiomyocytes, and continued for the remainder of the experiment, i.e. day 15. In this case, the cells are maintained in the culture medium composition as taught herein but devoid of T3 until the treatment with the culture medium composition as described above comprising 50 ng/ml of T3 is started. Various other media within the context of the media disclosed herein, but with varying concentration of individual components may also be used. Best results were obtained were using media comprised of components in concentrations as specifically disclosed herein.

Example 4. Assessment of the Effects of T3 on Morphological Features

[0217] Foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture were divided in two experimental groups. The first group was exposed to a culture medium composition as taught herein but which lacked T3 (control situation). The second group was exposed to a culture medium composition as taught herein but which comprised T3 (100 ng/ml). Both groups were incubated in their respective culture medium composition for 5 days. At the term of the treatment, cardiomyocytes from both experimental groups were fixed in 4% paraformaldehyde, permeabilised with phosphate buffer saline (PBS)/0.1% Triton X-100 (Sigma-Aldrich), and blocked with phosphate buffer saline (PBS)/0.1% Triton X-100 (Sigma-Aldrich) 1% BSA. Samples were incubated 1-hour at room temperature with a primary antibodies specific for the following: alpha-actinin (Eptomics Ab 68167) (at a concentration of 1/400). The primary antibody was detected with either Cy3- or Alexa-Fluor 647-conjugated secondary antibodies (at a concentration of 1/250). Images were captured using either a Leica SP5-STED or a Leica SP5 confocal laser-scanning microscope (Leica Microsystems).

[0218] The results are presented in FIG. 1. Specifically, the results show that foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture, which were exposed to the culture medium composition as taught herein comprising T3 (see Panels E and F in FIG. 1), matured more efficiently and more robustly into adult-like cardiomyocytes as evidenced by changes in their morphological features, which were reminiscent of an adult (or adult-like) stage such as polarization of cells, improved sarcomeric organization, and elongated shape. Such changes in morphological features were less clearly observed in foetal-like (immature) cardiomyocytes not exposed to T3 during the maturation process in in vitro culture (see Panels A-D in FIG. 1), showing the importance of T3, in particular T3 in the culture medium composition as detailed herein, in the maturation process in vitro. Example 5. Assessment of the effects of T3 on the electrophysiological properties Foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture were divided in two experimental groups. The first group was exposed to a culture medium composition as taught herein but which lacked T3 (control situation). The second group was exposed to a culture medium composition as taught herein but which comprised T3 (100 ng/ml). Both groups were incubated in their respective culture medium composition for 12 days. At the term of the treatment, foetal-like (immature) cardiomyocytes from both experimental groups were subjected to a patch clamp procedure.

[0219] Patch clamp electrophysiology was performed as described by Bellin, M. et al. EMBO J 32, 3161-3175 (2013)), using minor modifications. Action potentials from small groups of cells (5-10 cells) were measured with the perforated patch clamp technique using an Axopatch 200b amplifier (Molecular Devices) and low resistance patch pipettes (1.5-2.5 M). Data acquisition and analyses of action potentials were performed with pClamp 10 (axon instruments) and custom made software. Action Potentials were corrected for the calculated liquid Junction potential (15 mV).

[0220] Action potentials from spontaneous beating cells were measured at 370.20 C using a modified Tyrode's solution containing (in mM): 140 NaCl, 5.4 KCl, 1.8 CaCl2), 1.0 MgCl2, 5.5 glucose, 5.0 HEPES; pH7.2 (NaOH). The pipette solution contained (in mM): 125 K-gluconate, 20 KCl, 5 NaCl, 0.22 amphotericin-B, 10 HEPES; pH 7.2 (KOH). The resting membrane potential (RMP), maximal upstroke velocity (dV/dt max), AP amplitude in mV (APA), and AP duration in milli-seconds (APD) at 20, 50 and 90% repolarization (APD50, and APD90, respectively) were analyzed. Upstroke velocity was calculated from the first derivative of the change in voltage as a function of time. Thus the maximum upstroke velocity (dV/dt max) is equal to the maximum positive value of the first derivative of the action potential. Data from 10 consecutive action potentials were averaged.

[0221] The results are shown in FIG. 2. Specifically, the results show that foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture that were exposed to the culture medium composition comprising T3, matured more efficiently and more robustly into adult-like cardiomyocytes as evidenced by changes in their electrophysiological features which were reminiscent of an adult (or adult-like) stage such as increased maximum upstroke velocity (see panel A of FIG. 2), lower resting membrane potential (see panel B of FIG. 2) and increased amplitude of the action potential (see panel C of FIG. 2) in comparison to the data obtained for the foetal-like (immature) cardiomyocytes, which were not exposed to T3 during the maturation process in in vitro culture (see black bars in panels A, B, and C of FIG. 2).

Example 6. Assessment of the Effects of T3 on the Metabolic Profile

[0222] Foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture were divided in two experimental groups. The first group was exposed to a culture medium composition as taught herein but which lacked T3 (control situation). The second group was exposed to a culture medium composition as taught herein but which comprised T3 (100 ng/ml). Both groups were incubated in their respective culture medium composition for 17 days. An amount of 5 nM TMRM (Invitrogen) was added in the respective media the day before measurement. Cells were dissociated using 5 Tryple, but with TMRM included in all solutions and also present during measurement. Measurements were performed on a Miltenyi MACSquant VYB flow cytometer.

[0223] The results are shown in FIG. 3. Specifically, the results show that foetal-like (immature) cardiomyocytes derived from PESC in in vitro culture that were exposed to the culture medium composition as taught herein comprising T3, matured more efficiently and more robustly into adult-like cardiomyocytes as evidenced by changes in their metabolic profile, which were reminiscent of an adult (or adult-like) stage such as increased mitochondrial activity, and in comparison to foetal-like (Immature) cardiomyocytes that were not exposed to T3 during the maturation process in in vitro culture.