Project description:Direct conversion of fibroblasts to induced cardiomyocytes (iCMs) has great potential for regenerative medicine. Recent publications have reported significant progress, but the evaluation of reprogramming has relied upon non-functional measures such as flow cytometry for cardiomyocyte markers or GFP expression driven by a cardiomyocyte-specific promoter. The issue is one of practicality: the most stringent measures - electrophysiology to detect cell excitation and the presence of spontaneously contracting myocytes - are not readily quantifiable in the large numbers of cells screened in reprogramming experiments. However, excitation and contraction are linked by a third functional characteristic of cardiomyocytes: the rhythmic oscillation of intracellular calcium levels. We set out to optimize direct conversion of fibroblasts to iCMs with a quantifiable calcium reporter to rapidly assess functional transdifferentiation. We constructed a reporter system in which the calcium indicator GCaMP is driven by the cardiomyocyte-specific Troponin T promoter. Using calcium activity as our primary outcome measure, we compared several published combinations of transcription factors along with novel combinations in mouse embryonic fibroblasts. The most effective combination consisted of Hand2, Nkx2.5, Gata4, Mef2c, and Tbx5 (HNGMT). This combination is >50-fold more efficient than GMT alone and produces iCMs with cardiomyocyte marker expression, robust calcium oscillation, and spontaneous beating that persists for weeks following inactivation of reprogramming factors. HNGMT is also significantly more effective than previously published factor combinations for the transdifferentiation of adult mouse cardiac fibroblasts to iCMs. Quantification of calcium function is a convenient and effective means for the identification and evaluation of cardiomyocytes generated by direct reprogramming. Using this stringent outcome measure, we conclude that HNGMT produces iCMs more efficiently than previously published methods. Mouse embryonic fibroblasts were treated with different combinations of transcription factors to drive transdifferentiation to induced cardiomyocytes (iCMs). Putative iCMs were enriched by zeocin selection. Zeocin resistance was conferred to iCMs via the TroponinT-GCaMP5-Zeo lentiviral reporter.
Project description:To gain insight into the molecular regulation of human heart development, a detailed comparison of the mRNA and miRNA transcriptomes across differentiating human-induced pluripotent stem cell (hiPSC)–derived cardiomyocytes and biopsies from fetal, adult, and hypertensive human hearts was performed. Gene ontology analysis of the mRNA expression levels of the hiPSCs differentiating into cardiomyocytes revealed 3 distinct groups of genes: pluripotent specific, transitional cardiac specification, and mature cardiomyocyte specific. Hierarchical clustering of the mRNA data revealed that the transcriptome of hiPSC cardiomyocytes largely stabilizes 20 days after initiation of differentiation. Nevertheless, analysis of cells continuously cultured for 120 days indicated that the cardiomyocytes continued to mature toward a more adult-like gene expression pattern. Analysis of cardiomyocyte-specific miRNAs (miR-1, miR-133a/b, and miR-208a/b) revealed a miRNA pattern indicative of stem cell to cardiomyocyte specification. A biostatistitical approach integrated the miRNA and mRNA expression profiles revealing a cardiomyocyte differentiation miRNA network and identified putative mRNAs targeted by multiple miRNAs. Together, these data reveal the miRNA network in human heart development and support the notion that overlapping miRNA networks re-enforce transcriptional control during developmental specification. Comparison of mRNA expression profiling of differentiating human-induced pluripotent stem cell (hiPSC)–derived cardiomyocytes, biopsies from fetal, adult and hypertensive human hearts and primary cardiomyocytes
Project description:To gain insight into the molecular regulation of human heart development, a detailed comparison of the mRNA and miRNA transcriptomes across differentiating human-induced pluripotent stem cell (hiPSC)–derived cardiomyocytes and biopsies from fetal, adult, and hypertensive human hearts was performed. Gene ontology analysis of the mRNA expression levels of the hiPSCs differentiating into cardiomyocytes revealed 3 distinct groups of genes: pluripotent specific, transitional cardiac specification, and mature cardiomyocyte specific. Hierarchical clustering of the mRNA data revealed that the transcriptome of hiPSC cardiomyocytes largely stabilizes 20 days after initiation of differentiation. Nevertheless, analysis of cells continuously cultured for 120 days indicated that the cardiomyocytes continued to mature toward a more adult-like gene expression pattern. Analysis of cardiomyocyte-specific miRNAs (miR-1, miR-133a/b, and miR-208a/b) revealed a miRNA pattern indicative of stem cell to cardiomyocyte specification. A biostatistitical approach integrated the miRNA and mRNA expression profiles revealing a cardiomyocyte differentiation miRNA network and identified putative mRNAs targeted by multiple miRNAs. Together, these data reveal the miRNA network in human heart development and support the notion that overlapping miRNA networks re-enforce transcriptional control during developmental specification. miRNA expression profiling of differentiating human-induced pluripotent stem cell (hiPSC)–derived cardiomyocytes (days 0-120)
Project description:Analysis of human iPS-derived cardiomyocytes exposed to glucose, endothelin-1 and cortisol in vitro. Treatment produces a surrogate diabetic cardiomyopathic phenotype. Results provide insight into the pathways regulated by the treatment in the cardiomyocyte. The RNA for each vehicle-control treated and glucose endothelin cortisol treated iPS derived cardiomyocytes from 4 replicate samples, were extracted and hybridized to 8 individual human HG-U133 Plus2.0 Affymetrix microarray gene chips, whereby each chip represented the expression profile for one cell culture at 2 days.
Project description:We report the application of a pericentriolar material 1 (PCM-1) based cardiomyocyte-specific nuclear isolation protocol on human cardiac tissue to specifically ask what transcriptional changes occur in cardiomyocytes of humans with atrial fibrillation. We performed RNA-sequencing on the cardiomyocyte-specific nuclear RNA and found that there are more differentially dysregulated (1343) than similarly regulated transcripts (99) in the right versus left atria. This study is the first of its kind aimed at understanding the transcriptional changes that occur specifically in the left and right atrial cardiomyocytes of humans with atrial fibrillation.
Project description:Cardiomyocytes exhibit differential growth patterns throughout development. In fetal life the increase in cardiac mass is associated with hyperplastic growth and cardiomyocyte proliferation. The majority of fetal cardiomyocytes are also mononucleated. During the early neonatal period in mice there is a switch from hyperplastic to hypertrophic growth of cardiomyocytes. This period is characterized by bi-nucleation and polyploidization of cardiomyocyte nuclei and a decreased capacity for cardiomyocytes to proliferate and complete cytokinesis. Increases in myocardial mass occur predominantly via hypertrophic growth. Adult mammalian cardiomyocytes are generally accepted to have little or no proliferative capacity and to be terminally withdrawn from the cell cycle. The vast majority of adult murine cardiomyocytes are bi-nucleated. The present study sought to accurately establish the growth pattern of cardiomyocytes throughout development in mice and identify genes associated with the switch from hyperplastic to hypertrophic growth. These cell cycle associated genes are crucial to the understanding of the mechanisms of bi-nucleation, polyploidization and hypertrophy in the neonatal period. Cardiomyocytes were FACS sorted from the hearts of ED11-12 embryos, neonatal day 3-4 and adult (10 week) eGFP ?-MHC mice whereby GFP expression is driven constitutively by the ?-MHC promoter. Gene analyses identified genes whose expression was predicted to be particular to day 3 -4 neonatal cardiomyocytes, compared to embryonic or adult cells. Cell cycle associated genes are crucial to the understanding of the mechanisms of bi-nucleation and hypertrophy in the neonatal period, and offer attractive candidates for manipulation. Total RNA obtained from isolated cardiomyocytes from ED11-12; Neonatal day 3-4 and adult timepoints compared with each other. Several hearts per sample, RNA was pooled within samples. FACS samples were prepared in the following manner: embryonic, neonatal and adult hearts were dissected and dissociated to single cell solution with Liberase Blendzyme 3 (0.1 mg/ml) (Roche Diagnostics), washed and spun down and resuspended in cardiomyocyte isolation buffer (130 mM NaCl; 5 mM KCl; 1.2 mM KH2PO4; 6 mM HEPES; 5 mM NaHCO3; 1 mM MgCl2; 5 mM Glucose).
Project description:To gain insight into the molecular regulation of human heart development, a detailed comparison of the mRNA and miRNA transcriptomes across differentiating human-induced pluripotent stem cell (hiPSC)–derived cardiomyocytes and biopsies from fetal, adult, and hypertensive human hearts was performed. Gene ontology analysis of the mRNA expression levels of the hiPSCs differentiating into cardiomyocytes revealed 3 distinct groups of genes: pluripotent specific, transitional cardiac specification, and mature cardiomyocyte specific. Hierarchical clustering of the mRNA data revealed that the transcriptome of hiPSC cardiomyocytes largely stabilizes 20 days after initiation of differentiation. Nevertheless, analysis of cells continuously cultured for 120 days indicated that the cardiomyocytes continued to mature toward a more adult-like gene expression pattern. Analysis of cardiomyocyte-specific miRNAs (miR-1, miR-133a/b, and miR-208a/b) revealed a miRNA pattern indicative of stem cell to cardiomyocyte specification. A biostatistitical approach integrated the miRNA and mRNA expression profiles revealing a cardiomyocyte differentiation miRNA network and identified putative mRNAs targeted by multiple miRNAs. Together, these data reveal the miRNA network in human heart development and support the notion that overlapping miRNA networks re-enforce transcriptional control during developmental specification.
Project description:Analysis of human iPS-derived cardiomyocytes exposed to glucose, endothelin-1 and cortisol in vitro. Treatment produces a surrogate diabetic cardiomyopathic phenotype. Results provide insight into the pathways regulated by the treatment in the cardiomyocyte.
Project description:Analysis of the effect of electrical field stimulation frequency at the gene expression level. Electrical stimulation has been shown to mature nascent cardiomyocytes and alter their beating properties. The purpose of the array was to identify potential mediators of these effects. Total RNA was isolated from cardiomyocytes subjected to 0.5 Hz, 1 Hz, or 2 Hz continuous electrical stimulation for 7 days, compared to an unstimulated control. Three samples from each group were analyzed