Trichostatin A enhances differentiation of human induced pluripotent stem cells to cardiogenic cells for cardiac tissue engineering.
ABSTRACT: Human induced pluripotent stem (iPS) cells are a promising source of autologous cardiomyocytes to repair and regenerate myocardium for treatment of heart disease. In this study, we have identified a novel strategy to enhance cardiac differentiation of human iPS cells by treating embryoid bodies (EBs) with a histone deacetylase inhibitor, trichostatin A (TSA), together with activin A and bone morphogenetic protein 4 (BMP4). Over a narrow window of concentrations, TSA (1 ng/ml) directed the differentiation of human iPS cells into a cardiomyocyte lineage. TSA also exerted an additive effect with activin A (100 ng/ml) and BMP4 (20 ng/ml). The resulting cardiomyocytes expressed several cardiac-specific transcription factors and contractile proteins at both gene and protein levels. Functionally, the contractile EBs displayed calcium cycling and were responsive to the chronotropic agents isoprenaline (0.1 ?M) and carbachol (1 ?M). Implanting microdissected beating areas of iPS cells into tissue engineering chambers in immunocompromised rats produced engineered constructs that supported their survival, and they maintained spontaneous contraction. Human cardiomyocytes were identified as compact patches of muscle tissue incorporated within a host fibrocellular stroma and were vascularized by host neovessels. In conclusion, human iPS cell-derived cardiomyocytes can be used to engineer functional cardiac muscle tissue for studying the pathophysiology of cardiac disease, for drug discovery test beds, and potentially for generation of cardiac grafts to surgically replace damaged myocardium.
Project description:Human embryonic and induced pluripotent stem cells (hESCs/iPSCs) are promising cell sources for cardiac regenerative medicine. To realize hESC/iPSC-based cardiac cell therapy, efficient induction, purification, and transplantation methods for cardiomyocytes should be required. Though marker gene transduction or fluorescent-based purification methods were reported, fast, efficient and scalable purification methods with no genetic modification are essential for clinical purposes but have not been established yet. In this study, we used microarrays to detail the global gene program during cardiac differentiation and to identify cardiac-specific cell surface markers. hiPSCs (201B6) were differentiated toward cardiomyocytes using a modified-directed differentiation protocol (high density culture in RPMI+B27-insulin, sequential administration of Activin A 100ng/mL 1 day, BMP4 10ng/mL+bFGF 10ng/mL 4 days, and Dkk1 100ng/mL 2 days). Beating clusters were first observed at day 8-9 and spread by day 11 after Activin A administration. Cardiac troponin-T (cTnT)-positive cells appeared at day 7-8 after induction and were observed in 30-70% of cells at day 11. qPCR and genome-wide analysis reflected differentiation processes from the undifferentiated state to cardiomyocytes. Rapid downregulation of pluripotent stem cell markers such as NANOG and POU5F1 was observed within 2 days of differentiation. Early and cardiac mesodermal genes (T, MESP1, KDR, ISL1) were expressed during day 2-5, and cardiac genes (NKX2-5, MYH6, MYH7, MYL2, and MYL7) were expressed after day 7. We identified VCAM1 as a cardiac-specific cell surface marker by microarray and flow cytometry. Human induced pluripotent stem cells (iPSCs; 201B6) were differentiated toward cardiomyocytes (RPMI+B27 medium supplemented d0-1 Activin A, d1-5 BMP4+bFGF, d5-7 Dkk1). RNA was extracted from cells at day 0, day 2, day 5, day 7, day 9, and day 11. Cardiomyocytes appeared after day 7 and reached about 50% of total cells at day 11.
Project description:Human induced pluripotent stem (iPS) cells hold great promise for cardiovascular research and therapeutic applications, but the ability of human iPS cells to differentiate into functional cardiomyocytes has not yet been demonstrated. The aim of this study was to characterize the cardiac differentiation potential of human iPS cells generated using OCT4, SOX2, NANOG, and LIN28 transgenes compared to human embryonic stem (ES) cells. The iPS and ES cells were differentiated using the embryoid body (EB) method. The time course of developing contracting EBs was comparable for the iPS and ES cell lines, although the absolute percentages of contracting EBs differed. RT-PCR analyses of iPS and ES cell-derived cardiomyocytes demonstrated similar cardiac gene expression patterns. The pluripotency genes OCT4 and NANOG were downregulated with cardiac differentiation, but the downregulation was blunted in the iPS cell lines because of residual transgene expression. Proliferation of iPS and ES cell-derived cardiomyocytes based on 5-bromodeoxyuridine labeling was similar, and immunocytochemistry of isolated cardiomyocytes revealed indistinguishable sarcomeric organizations. Electrophysiology studies indicated that iPS cells have a capacity like ES cells for differentiation into nodal-, atrial-, and ventricular-like phenotypes based on action potential characteristics. Both iPS and ES cell-derived cardiomyocytes exhibited responsiveness to beta-adrenergic stimulation manifest by an increase in spontaneous rate and a decrease in action potential duration. We conclude that human iPS cells can differentiate into functional cardiomyocytes, and thus iPS cells are a viable option as an autologous cell source for cardiac repair and a powerful tool for cardiovascular research.
Project description:We cultured hESC and hiPSC lines and compared the transcriptome of untreated cells with cells treated with Activin or BMP4 during 5 days Pluripotent cell lines cultured in feeder-free conditions were treated with 100 ng/ml of activin or 50 ng/ml BMP4 daily during 5 days and collected for analysis
Project description:This study aimed to examine gene expression in human ES cells (the RUNX1C GFP reporter line) differentiated towrads hameatopoietic mesoderm in a defined serum free medium. At day 7 of differentiation, the cells were sorted into fractions based on CD34 and CD41 expression and the four fractions analysed by microarray. The total number of samples analysed was 13. Undifferentiated hESC (RUNX1C GFP/w, based on the HES3 cell line) plus samples from d1 to d8 of differentiation comprised one experiment (9 samples) and four flow sorted fractions from d7 differentiated cells (CD34-CD41-, CD34lo CD41-, CD34hi CD41- and CD34lo CD41lo) comprised the second experiment. The parent cell line was maintained on mouse feeder cells in KOSR containing medium supplemented with 10 ng/ml FGF2. Differentiation was performed as spin EBs in APEL medium (Ng et al Nature Protocols 2008). For the first 4 days, medium was supplemented with BMP4, VEGF, SCF and Activin. Medium was changed at d4 to fresh APEL medium supplemented with BMP4, VEGF, SCF, FGF2 and IGF2.
Project description:The current protocols for generation of induced pluripotent stem (iPS) cells involve genome integrating viral vectors which may induce tumorgenesis. The aim of this study was to develop and optimize a non-viral method without genetic manipulation for reprogramming of skeletal myoblasts (SMs) using small molecules.SMs from young male Oct3/4-GFP(+) transgenic mouse were treated with DNA methyltransferase (DNMT) inhibitor, RG108. Two weeks later, GFP(+) colonies of SM derived iPS cells (SiPS) expressing GFP and with morphological similarity of mouse embryonic stem (ESCs) were formed and propagated in vitro. SiPS were positive for alkaline phosphatase activity, expressed SSEA1, displayed ES cell specific pluripotency markers and formed teratoma in nude mice. Optimization of culture conditions for embryoid body (EBs) formation yielded spontaneously contracting EBs having morphological, molecular, and ultra-structural similarities with cardiomyocytes and expressed early and late cardiac markers. miR profiling showed abrogation of let-7 family and upregulation of ESCs specific miR-290-295 cluster thus indicating that SiPS were similar to ESCs in miR profile. Four weeks after transplantation into the immunocompetent mice model of acute myocardial infarction (n?=?12 per group), extensive myogenesis was observed in SiPS transplanted hearts as compared to DMEM controls (n?=?6 per group). A significant reduction in fibrosis and improvement in global heart function in the hearts transplanted with SiPS derived cardiac progenitor cells were observed.Reprogramming of SMs by DNMT inhibitor is a simple, reproducible and efficient technique more likely to generate transgene integration-free iPS cells. Cardiac progenitors derived from iPS cells propagated extensively in the infarcted myocardium without tumorgenesis and improved cardiac function.
Project description:Wnt/beta-catenin signaling is an important regulator of differentiation and morphogenesis that can also control stem cell fates. Our group has developed an efficient protocol to generate cardiomyocytes from human embryonic stem (ES) cells via induction with activin A and BMP4.We tested the hypothesis that Wnt/beta-catenin signals control both early mesoderm induction and later cardiac differentiation in this system. Addition of exogenous Wnt3a at the time of induction enhanced cardiac differentiation, while early inhibition of endogenous Wnt/beta-catenin signaling with Dkk1 inhibited cardiac differentiation, as indicated by quantitative RT-PCR analysis for beta-myosin heavy chain (beta-MHC), cardiac troponin T (cTnT), Nkx2.5, and flow cytometry analysis for sarcomeric myosin heavy chain (sMHC). Conversely, late antagonism of endogenously produced Wnts enhanced cardiogenesis, indicating a biphasic role for the pathway in human cardiac differentiation. Using quantitative RT-PCR, we show that canonical Wnt ligand expression is induced by activin A/BMP4 treatment, and the extent of early Wnt ligand expression can predict the subsequent efficiency of cardiogenesis. Measurement of Brachyury expression showed that addition of Wnt3a enhances mesoderm induction, whereas blockade of endogenously produced Wnts markedly inhibits mesoderm formation. Finally, we show that Wnt/beta-catenin signaling is required for Smad1 activation by BMP4.Our data indicate that induction of mesoderm and subsequent cardiac differentiation from human ES cells requires fine-tuned cross talk between activin A/BMP4 and Wnt/beta-catenin pathways. Controlling these pathways permits efficient generation of cardiomyocytes for basic studies or cardiac repair applications.
Project description:<h4>Background</h4>Disturbances in oxygen levels have been found to impair cardiac organogenesis. It is known that stem cells and differentiating cells may respond variably to hypoxic conditions, whereby hypoxia may enhance stem cell pluripotency, while differentiation of multiple cell types can be restricted or enhanced under hypoxia. Here we examined whether HIF-1alpha modulated Wnt signaling affected differentiation of iPS cells into beating cardiomyocytes.<h4>Objective</h4>We investigated whether transient and sustained hypoxia affects differentiation of cardiomyocytes derived from murine induced pluripotent stem (iPS) cells, assessed the involvement of HIF-1alpha (hypoxia-inducible factor-1alpha) and the canonical Wnt pathway in this process.<h4>Methods</h4>Embryoid bodies (EBs) derived from iPS cells were differentiated into cardiomyocytes and were exposed either to 24 h normoxia or transient hypoxia followed by a further 13 days of normoxic culture.<h4>Results</h4>At 14 days of differentiation, 59 ± 2% of normoxic EBs were beating, whilst transient hypoxia abolished beating at 14 days and EBs appeared immature. Hypoxia induced a significant increase in Brachyury and islet-1 mRNA expression, together with reduced troponin C expression. Collectively, these data suggest that transient and sustained hypoxia inhibits maturation of differentiating cardiomyocytes. Compared to normoxia, hypoxia increased HIF-1alpha, Wnt target and ligand genes in EBs, as well as accumulation of HIF-1alpha and beta-catenin in nuclear protein extracts, suggesting involvement of the Wnt/beta-catenin pathway.<h4>Conclusion</h4>Hypoxia impairs cardiomyocyte differentiation and activates Wnt signaling in undifferentiated iPS cells. Taken together the study suggests that oxygenation levels play a critical role in cardiomyocyte differentiation and suggest that hypoxia may play a role in early cardiogenesis.
Project description:The generation of cardiomyocytes from human embryonic stem cells (hESC) enables a variety of potential therapeutic and diagnostic applications. However, progress is challenged by the low efficiency of cardiomyocyte differentiation. Recently, Kattman et al., 2011 showed that individual hESC lines required proper balance of the Activin A and BMP4 signaling for efficient cardiac differentiation, presenting their differentiation protocols for several human and mouse ESC lines. However, two of the most utilized hESC lines, H7 and H9, were not included. Therefore, we set out to verify the published methodology for highly efficient cardiac specification and investigate the cardiac differentiation in the H7 and H9 ESC lines. Our studies examined a range of time points for the initial culture of hESC as embryoid bodies (EB) prior to transfer to monolayer culture, as well as, concentrations of Activin A and BMP4 in the medium formulations. The results highlight an efficient protocol for reproducibly generating cultures with approximately 50% cardiomyocytes from H7 and H9 ESC lines.
Project description:Induced pluripotent stem (iPS) cells can efficiently differentiate into the three germ layers similar to those formed by differentiated embryonic stem (ES) cells. This provides a new source of cells in which to establish preclinical allogeneic transplantation models. Our iPS cells were generated from mouse embryonic fibroblasts (MEFs) transfected with the Yamanaka factors, the four transcription factors (Oct4, Sox2, Klf4 and c-Myc), without antibiotic selection or MEF feeders. After the formation of embryoid bodies (EBs), iPS cells spontaneously differentiated into Flk1-positive cardiac progenitors and cardiomyocytes expressing cardiac-specific markers such as alpha sarcomeric actinin (?-actinin), cardiac alpha myosin heavy chain (?-MHC), cardiac troponin T (cTnT), and connexin 43 (CX43), as well as cardiac transcription factors Nk2 homebox 5 (Nkx2.5) and gata binding protein 4 (gata4). The electrophysiological activity of iPS cell-derived cardiomyocytes (iPS-CMs) was detected in beating cell clusters with optical mapping and RH237 a voltage-sensitive dye, and in single contracting cells with patch-clamp technology. Incompletely differentiated iPS cells formed teratomas when transplanted into a severe combined immunodeficiency (SCID) mouse model of myocardial infarction. Our results show that somatic cells can be reprogrammed into pluripotent stem cells, which in turn spontaneously differentiate into electrophysiologically functional mature cardiomyocytes expressing cardiac-specific makers, and that these cells can potentially be used to repair myocardial infarction (MI) in the future.
Project description:The use of human pluripotent cell progeny for cardiac disease modeling, drug testing and therapeutics requires the ability to efficiently induce pluripotent cells into the cardiomyogenic lineage. Although direct activation of the Activin-A and/or Bmp pathways with growth factors yields context-dependent success, recent studies have shown that induction of Wnt signaling using low molecular weight molecules such as CHIR, which in turn induces the Activin-A and Bmp pathways, is widely effective. To further enhance the reproducibility of CHIR-induced cardiomyogenesis, and to ultimately promote myocyte maturation, we are using exogenous growth factors to optimize cardiomyogenic signaling downstream of CHIR induction. As indicated by RNA-seq, induction with CHIR during Day 1 (Days 0-1) was followed by immediate expression of Nodal ligands and receptors, followed later by Bmp ligands and receptors. Co-induction with CHIR and high levels of the Nodal mimetic Activin-A (50-100 ng/ml) during Day 0-1 efficiently induced definitive endoderm, whereas CHIR supplemented with Activin-A at low levels (10 ng/ml) consistently improved cardiomyogenic efficiency, even when CHIR alone was ineffective. Moreover, co-induction using CHIR and low levels of Activin-A apparently increased the rate of cardiomyogenesis, as indicated by the initial appearance of rhythmically beating cells by Day 6 instead of Day 8. By contrast, co-induction with CHIR plus low levels (3-10 ng/ml) of Bmp4 during Day 0-1 consistently and strongly inhibited cardiomyogenesis. These findings, which demonstrate that cardiomyogenic efficacy is improved by optimizing levels of CHIR-induced growth factors when applied in accord with their sequence of endogenous expression, are consistent with the idea that Nodal (Activin-A) levels toggle the entry of cells into the endodermal or mesodermal lineages, while Bmp levels regulate subsequent allocation into mesodermal cell types.