Expression Of Cardiac Marker Genes Research Articles

Cardiac differentiation of chimpanzee induced pluripotent stem cell lines with different subspecies backgrounds.

The comparative analysis between humans and non-human primates is an instrumental approach for elucidating the evolutional traits and disease propensity of humans. However, in primates, cross-species analyses of their developmental events have encountered constraints because of the ethical and technical limitations in available sample collection, sequential monitoring, and manipulations. In an endeavor to surmount these challenges, in recent years, induced pluripotent stem cells (iPSCs) have garnered escalating interest as an in vitro tool for cross-species analyses between humans and non-human primates. Meanwhile, compared to humans, there is less information on in vitro differentiation of non-human primate iPSCs, and their genetic diversity including subspecies may cause different eligibility to in vitro differentiation methods. Therefore, antecedent to embarking on a comparative analysis to humans, it is a prerequisite to develop the efficacious methodologies for in vitro differentiation regardless of the intraspecies genetic background in non-human primates. In this study, we executed the in vitro differentiation of cardiomyocytes from four chimpanzee iPSC lines with different subspecies and individual backgrounds. To induce cardiomyocytes from chimpanzee iPSCs, we evaluated our methodology for in vitro cardiac differentiation of human iPSCs. Eventually, with minor alterations, our cardiac differentiation method was applicable to all chimpanzee iPSC lines tested as assessed by the expression of cardiac marker genes and the beating ability. Hence, our in vitro differentiation method will advance iPSC-based research of chimpanzee cardiac development and also hold possible utility to cross-species analyses among primate species.

Embryonic Ethanol but Not Cannabinoid Exposure Affects Zebrafish Cardiac Development via Agrin and Sonic Hedgehog Interaction.

Recent studies demonstrate the adverse effects of cannabinoids on development, including via pathways shared with ethanol exposure. Our laboratory has shown that both the nervous system and cardiac development are dependent on agrin modulation of sonic hedgehog (shh) and fibroblast growth factor (Fgf) signaling pathways. As both ethanol and cannabinoids impact these signaling molecules, we examined their role on zebrafish heart development. Zebrafish embryos were exposed to a range of ethanol and/or cannabinoid receptor 1 and 2 agonist concentrations in the absence or presence of morpholino oligonucleotides that disrupt agrin or shh expression. In situ hybridization was employed to analyze cardiac marker gene expression. Exposure to cannabinoid receptor agonists disrupted midbrain-hindbrain boundary development, but had no effect on heart development, as assessed by the presence of cardiac edema or the altered expression of cardiac marker genes. In contrast, exposure to 1.5% ethanol induced cardiac edema and the altered expression of cardiac marker genes. Combined exposure to agrin or shh morpholino and 0.5% ethanol disrupted the cmlc2 gene expression pattern, with the restoration of the normal expression following shh mRNA overexpression. These studies provide evidence that signaling pathways critical to heart development are sensitive to ethanol exposure, but not cannabinoids, during early zebrafish embryogenesis.

Differentiation of Amniotic Membrane Mesenchymal Stem Cells to Cardiomyocytes and the Expression of Nkx2.5 and C-TNT genes

Cardiovascular disease (CVDs) continues to account for more deaths globally than any other single disease. Currently, significant advances have been made in the field of cardiac diseases, and stem cell transplantation-based therapies have emerged as a hopeful therapeutic tool for improving cardiac regeneration and function. Mesenchymal stem cells (MSCs) represent a promising source to be used by regenerative medicine. MSCs have potential to self-renew and discriminate into several cell types. In this study, MSCs were isolated from the amniotic membrane, and their surface markers were identified using flow cytometry. The cells were differentiated to osteoblasts, adipocytes and cardiomyocytes using differentiation medium. RealTime-PCR, and immunochemistry assays were used to assess the expression of cardiac marker genes (Nkx2.5 and C-TNT) and protein. The results confirmed the differentiation of MCSs to cardiomyocytes. NKX2.5 and C-TNT expression level strikingly increased in cardiomyocyte cells compared to hAM-dMSCs. The results of the present study suggested that differentiated human amniotic MSC possessed some characteristics of cardiomyocytes.

Enhanced differentiation of human pluripotent stem cells into cardiomyocytes by bacteria-mediated transcription factors delivery.

Virus-mediated expression of defined transcription factor (TF) genes can effectively induce cellular reprogramming. However, sustained expression of the TFs often hinders pluripotent stem cell (PSC) differentiation into specific cell types, as each TF exerts its effect on PSCs for a defined period of time during differentiation. Here, we applied a bacterial type III secretion system (T3SS)-based protein delivery tool to directly translocate TFs in the form of protein into human PSCs. This transient protein delivery technique showed high delivery efficiency for hPSCs, and it avoids potential genetic alterations caused by the introduction of transgenes. In an established cardiomyocyte de novo differentiation procedure, five transcriptional factors, namely GATA4, MEF2C, TBX5, ESRRG and MESP1 (abbreviated as GMTEM), were translocated at various time points. By detecting the expression of cardiac marker genes (Nkx2.5 and cTnT), we found that GMTEM proteins delivered on mesoderm stage of the cardiomyocytes lineage differentiation significantly enhanced both the human ESC and iPSC differentiation into cardiomyocytes, while earlier or later delivery diminished the enhancing effect. Furthermore, all of the five factors were required to enhance the cardiac differentiation. This work provides a virus-free strategy of transient transcription factors delivery for directing human stem cell fate without jeopardizing genome integrity, thus safe for biomedical applications.

Effect of stem cell niche elasticity/ECM protein on the self-beating cardiomyocyte differentiation of induced pluripotent stem (iPS) cells at different stages

The transplantation of beating cardiomyocytes (BCMs) is expected to be made more effective for serious heart diseases. The identification of the appropriate engineering processes and suitable culture substrates for inducing stem cell differentiation into BCMs is thus indispensable. The differentiation can be divided into three major processes, the cardiac differentiation step, the beating-induction step and the beating-duration step. A protocol with the higher efficiency in all of the steps must be useful. In this study, we separately evaluated the effect of culture substrates at each three step. We clarified that the biological and the physical properties of the culture substrates required at these steps were different. We found useful criteria for effective cardiac cell niche systems design.

The CapZ interacting protein Rcsd1 is required for cardiogenesis downstream of Wnt11a in Xenopus laevis

Wnt proteins are critical for embryonic cardiogenesis and cardiomyogenesis by regulating different intracellular signalling pathways. Whereas canonical Wnt/β-catenin signalling is required for mesoderm induction and proliferation of cardiac progenitor cells, β-catenin independent, non-canonical Wnt signalling regulates cardiac specification and terminal differentiation. Although the diverse cardiac malformations associated with the loss of non-canonical Wnt11 in mice such as outflow tract (OFT) defects, reduced ventricular trabeculation, myofibrillar disorganization and reduced cardiac marker gene expression are well described, the underlying molecular mechanisms are still not completely understood. Here we aimed to further characterize Wnt11 mediated signal transduction during vertebrate cardiogenesis. Using Xenopus as a model system, we show by loss of function and corresponding rescue experiments that the non-canonical Wnt signalling mediator Rcsd1 is required downstream of Wnt11 for ventricular trabeculation, terminal differentiation of cardiomyocytes and cardiac morphogenesis. We here place Rcsd1 downstream of Wnt11 during cardiac development thereby providing a novel mechanism for how non-canonical Wnt signalling regulates vertebrate cardiogenesis.

Individual evaluation of cardiac marker expression and self-beating during cardiac differentiation of P19CL6 cells on different culture substrates.

Cell-based therapies using self-beating cardiomyocytes have been attracting great attention for use in cardiac regeneration, although an effective procedure to improve cardiac differentiation and self-beating induction is required. The purpose of this study is to clarify the effect of the culture substrate on cardiac maturation by separately evaluating the cardiac differentiation step and the beating induction step in vitro. To this end, the well-studied cardiomyocyte-like progenitor cell line P19CL6 and neonatal cardiomyocytes (NCMs) were selected and cultured on substrates coated with collagen type I (Col-I), gelatin (Gel), fibronectin (FN), or poly-l-lysine (PLL). It was found that the cardiac differentiation step, which was assessed using cardiac marker gene expression (GATA-binding protein 4 (GATA4), myocyte-specific enhancer factor 2D (MEF2D), and hyperpolarization-activated cyclic nucleotide-gated potassium channel 4 (HCN4)) in the P19CL6 embryonal carcinoma cells, was greatly enhanced on Col-I, Gel, and PLL. In contrast, the spontaneous beating step, which was directly assessed by counting the beating colonies and measuring contractile protein gene expression (α-myosin heavy chain (α-MHC), troponin C type 1 (TnC1), and troponin T type 2 (TnT2)) in the rat NCMs, was enhanced on the FN and PLL surfaces. In the present study, for the first time, it was found that PLL enhances both the cardiac differentiation and the beating induction steps of cardiac maturation, which can aid in preparing beating cardiomyocytes for regenerative medicine. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 1166-1174, 2017.

Effects of prenatal bisphenol-A exposure and postnatal overfeeding on cardiovascular function in female sheep.

Bisphenol-A (BPA) is a widely used endocrine-disrupting chemical. Prenatal exposure to BPA is known to affect birth weight, but its impact on the cardiovascular system has not been studied in detail. In this study, we investigated the effects of prenatal BPA treatment and its interaction with postnatal overfeeding on the cardiovascular system. Pregnant sheep were given daily subcutaneous injections of corn oil (control) or BPA (0.5 mg/kg/day in corn oil) from day 30 to day 90 of gestation. A subset of female offspring of these dams were overfed to increase body weight to ~30% over that of normal fed controls. Cardiovascular function was assessed using non-invasive echocardiography and cuff blood pressure (BP) monitoring at 21 months of age. Ventricular tissue was analyzed for gene expression of cardiac markers of hypertrophy and collagen at the end of the observation period. Prenatal BPA exposure had no significant effect on BP or morphometric measures. However, it increased atrial natriuretic peptide gene expression in the ventricles and reduced collagen expression in the right ventricle. Overfeeding produced a marked increase in body weight and BP. There were compensatory increases in left ventricular area and internal diameter. Prenatal BPA treatment produced a significant increase in interventricular septal thickness when animals were overfed. However, it appeared to block the increase in BP and left ventricular area caused by overfeeding. Taken together, these results suggest that prenatal BPA produces intrinsic changes in the heart that are capable of modulating morphological and functional parameters when animals become obese in later life.

The role of nuclear factor of activated T cells during phorbol myristate acetate-induced cardiac differentiation of mesenchymal stem cells.

BackgroundWe previously reported that phorbol 12-myristate 13-acetate (PMA) treatment can induce the cardiac differentiation of mesenchymal stem cells (MSCs). In the present study, we investigated how PMA induces cardiac differentiation of MSCs, focusing on its effect on the transcription factors responsible for increased cardiac marker gene expression.MethodsHuman MSCs (hMSCs) were treated with 1 μM PMA for 9 days. The expression of MSC markers and cardiac markers in the PMA-treated hMSC, as well as the nuclear translocation of transcription factors, nuclear factor of activated T cells (NFAT), and myogenic differentiation 1 (MyoD), was examined. Transcriptional activity of NFAT was examined by utilizing a green fluorescent protein (GFP) vector containing NFAT motif of human interleukin-2 promoter. The effect of PMA on the expression of key cell cycle regulators was examined.ResultsPMA induces the transcriptional activity of NFAT and MyoD, which have been associated with increased expression of cardiac troponin T (cTnT) and myosin heavy chain (MHC), respectively. Our data suggested that protein kinase C (PKC) mediates the effect of PMA on NFAT activation. Furthermore, PMA treatment increased cell-cycle regulator p27kip1 expression, suggesting that PMA triggers the cardiac differentiation program in MSCs by regulating key transcription factors and cell cycle regulators.ConclusionsThe results of this study demonstrate the importance of NFAT activation during PMA-induced MSC differentiation and help us to better understand the underlying mechanisms of small molecule-mediated MSC differentiation so that we can develop a strategy for synthesizing novel and improved differentiation-inducing small molecules.Electronic supplementary materialThe online version of this article (doi:10.1186/s13287-016-0348-6) contains supplementary material, which is available to authorized users.

Effective bioengineered niche for cardiac differentiation and/or beating induction of iPS and P19CL6 cells

Event Abstract Back to Event Effective bioengineered niche for cardiac differentiation and/or beating induction of iPS and P19CL6 cells Tetsuji Yamaoka1, Takaaki Dan1 and Mitsuhi Hirata1 1 National Cerebral and Cardiovascular Center Research Institute, Department of Biomedical Engineering, Japan Introduction: Various cues for cardiac differentiation of stem cells have been attracting great attentions. We are focusing on the cell culture substrates as biomechanical cues. In general, the differentiation profiles have been evaluated with cardiac gene expression, but they do not necessarily relate to the self-beating function. The purpose of this study is to study the suitable culture substrates for each step of the differentiation cascade (cardiac differentiation, beating induction, and beating duration) separately. To this end, in addition to iPS cells and P19CL6 cell, beating behaviors of neonatal cardiomyocytes (NCMs) were also analyzed (Figure 1). Materials and Methods: The iPS cells (iPS-MEF-Ng-178B-5)[1] were provided by the RIKEN Bioresource Center.[Y1] Neonatal cardiomyocytes (NCMs)[y2] were isolation from neonatal SD rat hearts. P19CL6 cells were purchased from Riken Bio Resource Center. Soft hydrogel substrates were prepared based on the previous report. These elastic moduli measured by AFM were 9, 20, and 180kPa. ECM proteins (collagen type I (Col-I), gelatin (Gel), and fibronectin (FN)) and other proteins were immobilized via N-sulfosuccinimidyl-6-(4-azido-2-nitrophenyl-amino) onto the gels and onto the tissue culture poly styrene (stiff surface). The cells were seeded on these substrates and treated with the conventional cardiac differentiation medium. The cardiac marker genes (GATA4, MEF2D, and HCN4) and the cell contractile proteins (a-MHC, b-MHC, TnC1, and TnT2) were quantified by qRT-PCR to evaluated cardiac differentiation and beating inductions. In addition, beating cells were visualized with calcium indicator dye Rhod-4 and counted under Eclipse TE-300 fluorescence microscope. Results and Discussion: It was found that each step of the cardiac differentiation was greatly improved by different substrates with the combination of modulus and protein. For example, Col-I- and Gel-coated TCPS was very efficient to induce the cardiac marker gene expression but did not induce the beating well. In contrast, FN coated surface showed the opposite tendency. The duration period of the beating behavior of differentiated iPS was greatly elongated on the soft substrates irrespective of the coated materials. We also found a couple of matrices that are effective both in the cardiac differentiation and beating induction steps. Conclusions: By studying the cardiac differentiation of iPS cells and P19CL6 cells in a step-by-step manner, very effective processes for cardiac differentiation were established. This work was supported by Grant-in-Aid for Challenging Exploratory Research, JSPS KAKENHI Grant Number 26560251.

Abstract 012: Directed Differentiation of c-kit+ Human Cardiac Stem Cells in vitro

Although transplantation of c-kit+ cardiac stem cells (CSCs) significantly alleviates post-myocardial infarction (MI) left ventricular dysfunction, the exogenous CSCs in the recipient heart do not generate cardiomyocytes robustly. Controlling the fate of transplanted CSCs and inducing their robust differentiation would be important in further improving the efficacy of cardiac stem cell therapies. We assessed the hypothesis that differentiation of human c-kit+ CSCs can be enhanced by programming them with cardiac transcription factors, including GATA4, MEF2C, Nkx2.5 and Tbx5. Transcription factors were introduced into CSCs in culture via lentivirus either individually or in combination. The transduced cells were then cultured for 1 or 2 weeks and analyzed for expression of 36 different markers of differentiated cardiac cell types by quantitative RT-PCR. Introduction of GATA4 led to marked increases in both early and late markers of cardiomyocyte differentiation, such as BNP and troponin T. By 2 weeks, GATA4 also significantly induced some of the smooth muscle cell markers, including calponin-1 and smooth muscle myosin heavy chain, as well as fibroblast markers. Interestingly, these gene expression changes induced by GATA4 were accompanied by dramatic morphological changes in CSCs. Overexpression of Tbx5 in CSCs resulted in induction of some of the cardiomyocyte markers specifically, although the number of genes differentially expressed was significantly less than those by GATA4. Interestingly, introduction of multiple transcription factors in combinations did not further increase the expression of cardiac marker genes. In conclusion, these findings suggest that cardiac gene programs can be activated in CSCs via introduction of defined transcription factors and that the pattern of expression of differentiated cardiac markers is unique to each transcription factor. However, none of the transcription factors alone was sufficient to induce differentiation of CSCs into mature cardiomyocyte-like cells, indicating that multiple and additional factors as well as temporal changes in their expression may be required for full differentiation and maturation of CSCs.

Spheroid Formation and Enhanced Cardiomyogenic Potential of Adipose-Derived Stem Cells Grown on Chitosan

Mesenchymal stem cells may differentiate into cardiomyocytes and participate in local tissue repair after heart injury. In the current study, rat adipose-derived adult stem cells (ASCs) grown on chitosan membranes were observed to form cell spheroids after 3 days. The cell seeding density and surface modification of chitosan with Arg-Gly-Asp–containing peptide had an influence on the sizes of ASC spheroids. In the absence of induction, these spheroids showed an increased level of cardiac marker gene expression (Gata4, Nkx2-5, Myh6, and Tnnt2) more than 20-fold versus cells on the tissue culture polystyrene (TCPS) dish. Induction by 5-azacytidine or p38 MAP kinase inhibitor (SB202190) did not further increase the cardiac marker gene expression of these spheroids. Moreover, the enhanced cardiomyogenic potential of the spheroids was highly associated with the chitosan substrates. When ASC spheroids were plated onto TCPS with either basal or cardiac induction medium for 9 days, the spheroids spread into a monolayer and the positive effect on cardiomyogenic marker gene expression disappeared. The possible role of calcium ion and the up-regulation of adhesion molecule P-selectin and chemokine receptor Cxcr4 were demonstrated in ASC spheroids. Applying these spheroids to the chronic myocardial infarction animal model showed better functional recovery versus single cells after 12 weeks. Taken together, this study suggested that the ASC spheroids on chitosan may form as a result of calcium ion signaling, and the transplantation of these spheroids may offer a simple method to enhance the efficiency of stem cell–based therapy in myocardial infarction.

MicroRNA 16 enhances differentiation of human bone marrow mesenchymal stem cells in a cardiac niche toward myogenic phenotypes in vitro

AimUpregulation of microRNA 16 (miR-16) contributed to the differentiation of human bone marrow mesenchymal stem cells (hMSCs) toward myogenic phenotypes in a cardiac niche, the present study aimed to determine the role of miR-16 in this process. Main methodshMSCs and neonatal rat ventricular myocytes were co-cultured indirectly in two chambers to set up a cardiac microenvironment (niche). miRNA expression profile in cardiac-niche‐induced hMSCs was detected by miRNA microarray. Cardiac marker expression and cell cycle analysis were determined in different treatment hMSCs. Quantitative real-time PCR and Western blot were used to identify the expression of mRNA, mature miRNA and protein of interest. Key findingsmiRNA dysregulation was shown in hMSCs after cardiac niche induction. miR-16 was upregulated in cardiac-niche‐induced hMSCs. Overexpression of miR-16 significantly increased G1-phase arrest of the cell cycle in hMSCs and enhanced the expression of cardiac marker genes, including GATA4, NK2-5, MEF2C and TNNI3. Differentiation-inducing factor 3 (DIF-3), a G0/G1 cell cycle arrest compound, was used to induce G1 phase arrest in cardiac-niche‐induced hMSCs, and the expression of cardiac marker genes was up-regulated in DIF-3-treated hMSCs. The expression of CCND1, CCND2 and CDK6 was suppressed by miR-16 in hMSCs. CDK6, CCND1 or CCND2 knockdown resulted in G1 phase arrest in hMSCs and upregulation of cardiac marker gene expression in hMSCs in a cardiac niche. SignificancemiR-16 enhances G1 phase arrest in hMSCs, contributing to the differentiation of hMSCs toward myogenic phenotypes when in a cardiac niche. This mechanism provides a novel strategy for pre-modification of hMSCs before hMSC-based transplantation therapy for severe heart diseases.

Focal adhesion kinase is essential for cardiac looping and multichamber heart formation.

Focal adhesion kinase (FAK) is a critical mediator of matrix- and growth factor-induced signaling during development. Myocyte-restricted FAK deletion in mid-gestation mice results in impaired ventricular septation and cardiac compaction. However, whether FAK regulates early cardiogenic steps remains unknown. To explore a role for FAK in multi-chambered heart formation, we utilized anti-sense morpholinos to deplete FAK in Xenopus laevis. Xenopus FAK morphants exhibited impaired cardiogenesis, pronounced pericardial edema, and lethality by tadpole stages. Spatial-temporal assessment of cardiac marker gene expression revealed that FAK was not necessary for midline migration, differentiation, fusion of cardiac precursors, or linear heart tube formation. However, myocyte proliferation was significantly reduced in FAK morphant heart tubes and these tubes failed to undergo proper looping morphogenesis. Collectively our data imply that FAK plays an essential role in chamber outgrowth and looping morphogenesis likely stimulated by fibroblast growth factors (and possibly other) cardiotrophic factors.

Comparative gene expression analysis and fate mapping studies suggest an early segregation of cardiogenic lineages in Xenopus laevis

Retrospective clonal analysis in mice suggested that the vertebrate heart develops from two sources of cells called first and second lineages, respectively. Cells of the first lineage enter the linear heart tube and initiate terminal differentiation earlier than cells of the second lineage. It is thought that both heart lineages arise from a common progenitor cell population prior to the cardiac crescent stage (E7.5 of mouse development). The timing of segregation of different lineages as well as the molecular mechanisms underlying this process is not yet known. Furthermore, gene expression data for those lineages are very limited. Here we provide the first comparative study of cardiac marker gene expression during Xenopus laevis embryogenesis complemented by single cell RT-PCR analysis. In addition we provide fate mapping data of cardiac progenitor cells at different stages of development. Our analysis indicates an early segregation of cardiac lineages and a fairly complex heterogeneity of gene expression in the cardiac progenitor cells. Furthermore, this study sets a reference for all further studies analyzing cardiac development in X. laevis.

Recombinant mouse SPARC promotes parietal endoderm differentiation and cardiomyogenesis in embryoid bodies

In the absence of leukemia inhibitory factor, murine embryonic stem cells cultured in vitro spontaneously aggregate to from three-dimensional embryoid bodies that differentiate to produce hematopoietic, endothelial, muscle, and neuronal cell lineages in a manner recapitulating the events of early embryogenesis. Cardiomyogenesis in embryoid bodies was recently demonstrated to be promoted by PYS-2-derived native SPARC (secreted protein, acidic and rich in cysteine), whose expression is upregulated in parietal endoderm at the onset of the epithelial to mesenchymal transition. Here, we confirm the stimulatory effects of mouse SPARC on cardiomyogenesis using a recombinant baculovirus-produced protein (rmSPARC). Embryoid bodies cultured in the presence of glycosylated rmSPARC, or an unglycosylated peptide spanning the C-terminal EF-hand domain, developed greater numbers of beating cardiomyocytes than did time-matched controls, with enhanced expression of cardiac marker genes including Nkx2.5, Troponin, BMP-2, and MHCalpha. Histochemical analysis revealed an expansion of the peripheral endoderm, with thicker layers of extracellular matrix (ECM) material observed atop underlying cells. Embryoid bodies treated with SPARC also displayed increased adherence to polystyrene culture dishes, with enhanced expression of ECM mRNAs including collagen IValpha3, collagen IValpha5, and laminin alpha1. These results indicate that, in addition to the promotion of cardiomyogenesis, SPARC may also help regulate the molecular composition and organization of ECM secreted by the mesenchymal parietal endoderm.

DM-GRASP/ALCAM/CD166 is required for cardiac morphogenesis and maintenance of cardiac identity in first heart field derived cells

Vertebrate heart development requires specification of cardiac precursor cells, migration of cardiac progenitors as well as coordinated cell movements during looping and septation. DM-GRASP/ALCAM/CD166 is a member of the neuronal immunoglobulin domain superfamily of cell adhesion molecules and was recently suggested to be a target gene of non-canonical Wnt signalling. Loss of DM-GRASP function did not affect specification of cardiac progenitor cells. Later during development, expression of cardiac marker genes in the first heart field of Xenopus laevis such as Tbx20 and TnIc was reduced, whereas expression of the second heart field marker genes Isl-1 and BMP-4 was unaffected. Furthermore, loss of DM-GRASP function resulted in defective cell adhesion and cardiac morphogenesis. Additionally, expression of DM-GRASP can rescue the phenotype that results from the loss of non-canonical Wnt11-R signalling suggesting that DM-GRASP and non-canonical Wnt signalling are functionally coupled during cardiac development.

Notch Signaling Contributes to the Expression of Cardiac Markers in Human Circulating Progenitor Cells

It has been demonstrated that adult human circulating endothelial progenitor cells (EPCs) can differentiate to a cardiomyogenic phenotype. Notch signaling promotes epithelial-to-mesenchymal transformation and plays a role in heart and vessel development. Here, we investigated the role of Notch activation for cardiac differentiation of EPCs in a coculture system with neonatal cardiomyocyte. After coculture, Notch activation was transiently detected in EPCs, as determined by immunohistochemical detection of NICD (the intracellular cleavage fragment of Notch-1) and expression of human Notch target genes. Inhibition of gamma-secretase blocked Notch cleavage and NICD translocation. Furthermore, the expression of the cardiac marker protein alpha-sarcomeric actinin and troponin T was significantly suppressed by gamma-secretase inhibition or addition of soluble recombinant Jagged-1, indicating that Notch activation facilitates cardiac marker gene expression. Because noncanonical Wnts have previously been shown to promote cardiac differentiation, we additionally determined the influence of Notch activation on the expression of Wnt5a and Wnt11. Wnt5a and Wnt11 expression in the human cells was induced by the coculture and was blocked by gamma-secretase inhibition. Likewise, stimulation of Notch signaling by immobilized Jagged-1 promoted Wnt5a expression in EPCs. These data suggest that Notch is activated upon coculture of EPCs with neonatal rat cardiac myocytes. Gamma-secretase-dependent Notch activation is required for cardiac gene expression in human cells and induces the expression of noncanonical Wnt proteins, which may act in a paracrine manner to further amplify cardiac differentiation.

Abstract 855: Circulating Mesoangioblasts Differentiate Into Cardiac Myocytes And Improve Function After Acute Myocardial Infarction

Mesoangioblasts (MAB) are vessel-associated cells identified during embryonic development. In contrast to hemangioblasts, MAB express mesenchymal (CD73) and endothelial marker, but lack the hematopoietic marker CD45. We recently identified circulating MAB in children. Children-derived MAB showed vigorous proliferation capacity and high telomerase activity. However, the potential of cardiac differentiation in these cells was not elucidated. Therefore, we tested the capacity of children-derived MAB to aquire a cardiomyogenic phenotype. MAB expressed several cardiac transcription factors such as Nkx2.5, GATA4 and MEF2C and the stem cell markers c-kit and islet-1. In order to assess cardiac differentiation capacity, we performed co-culture assays with neonatal rat cardiomyocytes (CM). Immunochemical analysis revealed that MAB expressed cardiac α-sarcomeric actinin 6 days after co-culture. Moreover, human troponin T (TnT) was expressed as demonstrated by human specific RT-PCR. To confirm these data, we examined TnT expression in MAB isolated of a 2 years old patient with a known mutation of TnT. Sequences of the cloned RT-PCR products were identical to human TnT except for the known mutation providing genetic proof of concept for cardiac differentiation. In order to exclude fusion between MAB and CM as a mechanism, we used paraformaldehyde-fixed CM as scaffold. In this assay, human TnT also was detected, indicating that differentiation is sufficient to induce cardiac marker gene expression. Next, we tested the effect of MAB to improve cardiac function. MAB were injected intramuscularly in nude mice after myocardial infarction. Functional analysis using Millar catheter 2 weeks after infarction demonstrated that cell therapy lowered filling pressure and preserved diastolic function when compared to the PBS injected group (LVEDP: −20.3%, tau: −20.6%, vs PBS injected heart). Furthermore, left ventricular volume was also decreased (LVEDV/weight −27.3%). In summary, children-derived MAB express cardiac-specific genes after co-culture with CM and improved cardiac function in vivo. Given that MAB can be easily isolated and expanded from peripheral blood, these cells might be suitable to augment cardiac repair in children with heart failure.

Abstract 689: Notch Signaling Stimulates Expression Of Wnts And Contributes To Cardiac Markers Gene Expression In Human Progenitor Cell

It has been demonstrated that adult human circulating endothelial progenitor cells (EPC) can differentiate to a cardiomyogenic phenotype. Notch signaling promotes epithelial-to-mesenchymal transformation and plays a prominent role in heart and vessel development. Here, we investigated the role of Notch activation for cardiac differentiation of EPC in a co-culture system with neonatal rat cardiomyocyte (CM). EPC expressed the receptors Notch-1 and Notch-2, whereas CM expressed high level of Notch ligand Jagged-1. Therefore, we hypothesized that CM may activate Notch signaling within EPC. Indeed, after co-culture, Notch activation was detected in EPC by immunohistochemical detection of the intracellular cleavage fragment of Notch-1 (NICD), whereas NICD was only rarely detected in EPC before co-culture. Western blot analysis confirmed Notch cleavage after co-culture. RT-PCR directed against the human specific sequences of the Notch target genes Hey2 and Hes1 demonstrated a transient activation of the transcriptional activity of Notch in human EPC after co-culture with CM. Inhibition of γ-secretase significantly blocked Notch cleavages and NICD translocations. Furthermore, the expression of the cardiac marker protein γ-sarcomeric actinin and troponin T was significantly suppressed by γ-secretase inhibition (55.8 ± 8.1% and 54.0 ± 10.5% of control, respectively) or addition of soluble recombinant Jagged-1, indicating that Notch activation facilitates cardiac marker gene expression. Because non-canonical Wnts have previously been shown to promote cardiac differentiation, we additionally determined the influence of Notch activation on the expression of Wnt5a and. Wnt5a and Wnt11 expressions in the human cells was induced by the co-culture and was blocked by γ-secretase inhibitor. Likewise, stimulation of Notch signaling by immobilized Jagged-1 promoted NICD cleavage and Wnt5a expression in EPC. These data suggested that Notch is transiently activated upon co-culture of EPC with neonatal rat CM. γ-Secretase-dependent Notch activation is required for cardiac gene expression in human cells and induces the expression of non-canonical Wnt proteins, which may act in an paracrine manner to further amplify cardiac differentiation.