Human Mesenchymal Stem Cells in Cardiomyocyte Co-Culture
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ABSTRACT: Evaluate the change in transcription factors that have a role in human mesenchymal stem cell (hMSC) commitment to a cardiomyocyte lineage when co-cultured for 4 days with rat neonatal cardiomyocytes and before acquiring a recognizable cardiac phenotype.
Project description:Evaluate the change in transcription factors that have a role in human mesenchymal stem cell (hMSC) commitment to a cardiomyocyte lineage when co-cultured for 4 days with rat neonatal cardiomyocytes and before acquiring a recognizable cardiac phenotype. A myocardial microenvironment was generated by dissociating neonatal rat hearts and establishing cardiomyocyte primary cultures. HumanMSCs constitutively labeled with dsRed localized to the cell's mitochondria were either grown separately (control) or added to the cardiomyocyte primary cultures and grown for 4 days. dsRed fluorescent hMSCs were harvested from co-cultures at 4 days using a FACscan flow cytometer. The RNA for the microarray analysis was prepared from three biologically separate samples of hMSCs co-cultured for 4 days and from hMSCs grown separately for 4 days (control).
Project description:Mammalian cardiomyocytes rapidly mature after birth, with hallmarks such as cell-cycle exit, binucleation, and metabolic switch to oxidative phosphorylation of lipids. The causes and transcriptional programs regulating cardiomyocyte maturation are not fully understood yet. Thus, we performed single cell RNA-seq of neonatal and postnatal day 7 rat hearts to identify the key factors for this process and found AP-1 as a key factor to regulate cardiomyocyte maturation. To find the mechanism of AP-1 during cardiomyocyte maturation, we performed RNA-seq analysis of neonatal rat ventricular cardiomyocytes and found Ap-1 promote cardiomyocyte maturation by regulating cardiomyocyte metabolism.
Project description:Some cell type-specific gene expression is maintained in the maturation of cardiomyocytes, where DNA hypomethylation of gene body regions of a set of specific genes. We used microarrays to detail the global gene expression program underlying the maintenance of cardiomyocyte function and maturation and compared it with DNA methylation status. Cardiomyocytes and cardiac fibroblasts were carefully isolated from neonatal and adult hearts and used fresh for the analysis.
Project description:Heart muscle cells, cardiomyocytes, are highly differentiated cells that usually do not proliferate . During the non-proliferative state, extracellular signals control cardiomyocyte contractile function. However, during development and regeneration, cardiomyocytes enter the cell cycle and divide. It is unknown how cardiomyocytes modify their intracellular signaling to direct the cell cycle program. Here, we show that the nuclear lamina protein Lamin B2 (Lmnb2) regulates cardiomyocyte cell cycle activity using a gatekeeper mechanism. We identified Lmnb2 as a candidate for regulating intracellular signaling with deep transcriptional profiling of single cardiomyocytes. Lmnb2 was sufficient and necessary for cardiomyocyte cycling in the presence of serum. Lmnb2 increased the nucleoporin NUP98 and permeability of the nuclear membrane for phosphorylated ERK1/2. In vivo, the Lmnb2 gene was required for cardiomyocyte cell cycle activity during development. Increasing the expression of Lmnb2 in neonatal mice promoted cardiomyocyte M-phase and cytokinesis. LmnB2 gene transfer in neonatal mice that received a myocardial injury increased cardiomyocyte division and myocardial function in the injury border zone, indicating that the regenerated cardiomyocytes were functionally integrated. We propose a gatekeeper function of Lmnb2 that can be targeted to increase cardiomyocyte regeneration without the administration of exogenous growth factors.
Project description:Cardiomyocyte poly(A) RNA was sequenced from purified bulk cardiomyocytes collected from one male and female murine heart at postnatal day 2 (P2). Neonatal cardiomyocytes were isolated and purified (96% cardiomyocytes at P2) by Langendorff retrograde perfusion and immunomagnetic cell separation, respectively. We found evidence of sexual dimorphism with 9 differentially expressed genes (FDR<0.05) encoded on XY chromosomes in this RNA-Seq dataset.
Project description:Cardiac maturation lays the foundation for postnatal heart development and disease, yet little is known about the contributions of the microenvironment to cardiomyocyte maturation. By integrating single-cell RNA-sequencing data of mouse hearts at multiple postnatal stages, we construct cellular interactomes and regulatory signaling networks. Here we report switching of fibroblast subtypes from a neonatal to adult state and this drives cardiomyocyte maturation. Molecular and functional maturation of neonatal mouse cardiomyocytes and human embryonic stem cell-derived cardiomyocytes are considerably enhanced upon coculture with corresponding adult cardiac fibroblasts. Further, single-cell analysis of in vivo and in vitro cardiomyocyte maturation trajectories identify highly conserved signaling pathways, pharmacological targeting of which substantially delays cardiomyocyte maturation in postnatal hearts, and markedly enhances cardiomyocyte proliferation and improves cardiac function in infarcted hearts. Together, we identify cardiac fibroblasts as a key constituent in the microenvironment promoting cardiomyocyte maturation, providing insights into how the manipulation of cardiomyocyte maturity may impact on disease development and regeneration.
Project description:Significance Heart disease accounts for 1 in 4 deaths in the United States annually, making it one of the leading causes of death and related morbidity resents a significant economic burden. Mammalian cardiomyocytes are terminally differentiated with low turnover rate, insufficient to repopulate myocardium after heart attack caused by myocardial infarction (MI). As such, there is an urgent need for the development of non-invasive, effective, and efficient therapeutic approaches for treating MI. One strategy is to promote proliferation in mature cardiomyocytes, inspired by the observation of a transient regenerative window in neonatal mouse cardiomyocytes. During postnatal development, it is believed that cardiomyocytes exit cell cycle in response to high oxygen environment and a metabolic shift to oxidative phosphorylation. Strategies to lower oxidative stress in neonatal mouse hearts to prolong regenerative time window have been reported. While many studies have focused on mitigating injury-related ROS, it is not clear whether the developmental ROS increase in neonatal cardiomyocytes plays a role during postnatal myocardial maturation and establishment of injury response. The following study details the crucial role of neonatal ROS as signaling molecules in cardiomyocyte injury response after MI.
Project description:Since the proliferative capacity of cardiomyocytes is extremely limited in the adult mammalian hearts, the irreversible loss of cardiomyocytes following cardiac injury markedly reduces cardiac function, leading to cardiac remodeling and heart failure. However, the early neonatal mice have a strong ability in cardiomyocyte proliferation and cardiac regeneration after heart damage such as apical resection. Besides of cardiomyocytes, non-myocytes in heart tissue also play important roles in the regeneration process. Previous studies showed that cardiac macrophages, regulatory T cells and CD4+ T cells are all involved in regulating the myocardial regeneration process. However, the roles of other cardiac immune cells in cardiac regeneration remains to be elucidated. B cells is a prominent immune cell in injured heart; here we discovered the indispensable function of cardiac B cells in improving cardiomyocyte proliferation and heart regeneration in neonatal mice.
Project description:Cardiomyocytes and cardiac fibroblasts undergo coordinated maturation after birth, and cardiac fibroblasts are required for postnatal cardiomyocyte maturation in mice. Here, we investigate the role of cardiac fibroblast-expressed Growth Differentiating Factor 10 (GDF10) in postnatal heart development. In neonatal mice, Gdf10 is expressed specifically in cardiac fibroblasts, with its highest expression coincident with onset of cardiomyocytes cell cycle arrest and transition to hypertrophic growth. In neonatal rat ventricular myocyte cultures, GDF10 treatment promotes cardiomyocyte maturation indicated by increased binucleation, downregulation of cell cycle progression genes and upregulation of cell cycle inhibitor genes. GDF10 treatment leads to an increase in cardiomyocyte cell size together with increased expression of mature sarcomeric protein isoforms and decreased expression of fetal cardiac genes. RNAsequencing of GDF10-treated NRVM shows an increase in gene expression related to myocardial maturation, including upregulation of sodium and potassium channel genes. In vivo, loss of Gdf10 leads to a delay in myocardial maturation indicated by a decrease in cardiomyocyte cell size and binucleation as well as increased mitotic activity at postnatal (P) day 7. Further, induction of mature sarcomeric protein isoform gene expression is delayed, and expression of cell cycle progression genes is prolonged. However, by P10 indicators of cardiomyocyte maturation and mitotic activity are normalized in Gdf10-null hearts relative to controls. Together, these results implicate Gdf10 as a novel crosstalk mediator between cardiomyocytes and cardiac fibroblasts, required for appropriate timing of cardiomyocyte maturation steps including binucleation, hypertrophy, mature sarcomeric isoform switch and cell cycle arrest in the postnatal period.
Project description:The acquisition of knowledge pertaining to the molecular mechanisms that govern cardiomyocyte (CM) proliferation would enable the creation of novel approaches to promote cardiac regeneration in adult individuals, a crucial therapeutic objective that has yet to be accomplished. The limited regenerative response observed in adult myocardium may be attributed, in part, to the relatively low proliferative capacity of cardiomyocytes. The comprehension of cardiomyocyte division is a complex undertaking, as cardiomyocytes are capable of entering the cell cycle but are unable to complete cell division. Our research revealed that the induction of cardiac cytoskeleton changes by Blebbistatin result in the entry of cardiomyocytes entry into the cell cycle but, followed by cell cycle arrest at the G2/M phase. Sirt1 is identified as a potential mediator of the binucleation process in neonatal rat cardiomyocytes, which is regulated by the cardiomyocyte cytoskeleton. Furthermore, the distribution of H3K9me3 in cardiomyocytes with varying nuclear numbers and treatments indicates a significant involvement in the formation of binucleated cardiomyocytes.