Project description:The discovery of mammalian cardiac progenitor cells has suggested that the heart consists of not only terminally differentiated beating cardiomyocytes, but also a population of self-renewing stem cells with the potential to generate new cardiomyocytes (Anderson, Self et al. 2007; Bearzi, Rota et al. 2007; Wu, Chien et al. 2008). A consequence of longevity is continual exposure to environmental and xenobiotic stresses, and recent literature suggests that hematopoietic stem cell pools tightly control cell health through upregulation of the integrated stress response and consequent cellular mechanisms such as apoptosis. However, whether or not this biological response is conserved in progenitor cells for later lineages of tissue specific stem cells is not well understood. Using human induced pluripotent stem cells (iPSC) of both cardiac progenitor and mature cardiomyocyte lineages, we found that the integrated stress response was upregulated in the iPSC cardiac progenitors leading to an increased sensitivity for apoptosis relative to the mature cardiomyocytes. Of interest, C/EBP homologous protein (CHOP) signaling plays a mechanistic role in the cell death phenotype observed in iPSC progenitors, by which depletion of CHOP prevents cell death following cellular stress by thapsigargin exposure. Our studies suggest that the integrated stress response plays a unique role in maintaining iPSC cardiac progenitor cellular integrity by removing unhealthy cells via apoptosis following environmental and xenobiotic stresses, thus preventing differentiation and self-renewal of damaged cells.
Project description:We explored the role of mammalian ETS1/2 and Mesp homologues of cardiogenic transcription factors of Ciona intestinalis, to convert primary human dermal fibroblasts into cardiac progenitors. ETS1/2 and Mesp homologues of cardiogenic transcription factors of Ciona intestinalis, to convert primary human dermal fibroblasts into cardiac progenitors. Here we show murine Ets2 has an obligatory role for directing cardiac progenitors during cardiopoesis in embryonic stem cells. ETS2 converted fibroblasts into KDR/Flk1+ replicative cells but, like the purported cardiac master regulatory gene Mesp1, could not by itself generate cardiac progenitors de novo from fibroblasts. Co-expression of both Ets2 and Mesp1, however, successfully reprogrammed differentiated fibroblasts into cardiac progenitors, as shown by the de novo appearance of core cardiac transcription factors, gap junction proteins, sarcomeric proteins, electrical activity and contractility. ETS2 and Mesp1 sit at the pinnacle of the cardiopoesis regulatory hierarchy and are well suited for treating human heart disease. Co-expression of both Ets2 and Mesp1, reprogrammed differentiated fibroblasts into cardiac progenitors All sample were done in triplicates, controls were NHDF and ETS2 only infected cells. NHDF were first infected with Doxycyline redulated (Doxy-) ETS2 lentivirus and supplemented with doxycycline for 1 week, sequentially cells were infected with Doxy-Mesp1 and treated for 1 more week. Cells were then aggegated to form EB and hangdrop for 1 week, at the end of that period cells were plated and samples were taken every 24 hrs
Project description:Background and Objective: Currently, the cells for transplantation were derived from either autologous or allogeneic tissue. The former has a drawback that the quality of donor cells could depend on the patient’s condition, and the quantity could also be limited. To solve these problems, we investigated the potential of allogeneic cardiac mesenchymal progenitors (CMPs) derived from postmortem heart, which might be an immunological privileged like bone marrow-derived mesenchymal progenitors. Materials and Methods: We examined whether viable CMPs could be isolated from murine postmortem cardiac tissue that was harvested 24 hours postmortem. After two to three weeks propagation with high dose of basic fibroblast growth factor, we performed the cellular characteristics analyses, which included proliferation and differentiation property flow cytometric analyses, and microarray analyses. Results: Postmortem CMPs had longer lag phase after seeding than CMPs from living tissues, but they demonstrated the similar characteristics in all above examinations. In addition, global gene expression analysis by microarray indicated the similar characteristics between the cell derived from postmortem and living tissue. Conclusion: These results indicate allogeneic postmortem CMPs could have promising potential for cell transplantation as clinical applications, because of circumventing the issue of brain death. The samples were collected fom living or postmortem cardiac tissue (24 hr at 4C). We generated cardiac mesenchymal progenitors (CMPs) from these cardiac tissue, and compared global gene expression by AgilentMouse GE 8x60k Microarray. Adult, or fetal mouse heart RNAs were used as positive control. Adult mouse total heart RNAs were purchased from Clontech. Fetal mouse heart was extracted from fetus which is embryonic day 16.5 C57BL/6 strain. Tg means Transgenic mouse (C57BL/6-Tg(Myh6-EGFP)MG2).
Project description:The accumulation of reactive oxygen species (ROS) is linked to several cardiovascular pathologies; it is also associated with cell cycle exit by nenonatal cardiomyocytes, a key limiting factor in the regenerative capacity of the adult mammalian heart. BMI1 is a component of the polycomb complex 1, which is linked to adult multipotent progenitors, and is also an important partner in DNA repair and redox regulation. Here we show that high BMI1 expression is associated with a cardiac Sca1+ progenitor subpopulation with low ROS levels. In homeostasis, BMI1 represses cell-fate genes, including a cardiogenic differentiation program. Persistent oxidative damage nonetheless modified BMI1 activity in vivo, by derepressing canonical target genes in favor of their antioxidant and anticlastogenic functions. This derepression induced cardiac progenitor proliferation and differentiation, and thus increased its contribution to mature cardiac progeny. This redox-mediated mechanism is not restricted to damage situations, and we report ROS-associated differentiation of cardiac progenitors in steady state. These findings demonstrate how redox status influences the adult cardiac progenitor response, and identifies a redox-mediated BMI1 function with potential implications in adult cardiac turnover.
Project description:The short-lived turquoise killifish Nothobranchius furzeri (Nfu) is a valid model for aging studies. Here, we investigated its age-associated cardiac function. We observed oxidative stress accumulation and an engagement of microRNAs (miRNAs) in the aging heart. MiRNA-sequencing of 5 week (young), 12-21 week (adult) and 28-40 week (old) Nfu hearts revealed 23 up-regulated and 18 down-regulated miRNAs with age. MiR-29 family turned out as one of the most up-regulated miRNAs during aging. MiR-29 family increase induces a decrease of known targets like collagens and DNA methyl transferases (DNMTs) paralleled by 5´methyl-cytosine (5mC) level decrease. To further investigate miR-29 family role in the fish heart we generated a transgenic zebrafish model where miR-29 was knocked-down. In this model we found significant morphological and functional cardiac alterations and an impairment of oxygen dependent pathways by transcriptome analysis leading to hypoxic marker up-regulation. To get insights the possible hypoxic regulation of miR-29 family, we exposed human cardiac fibroblasts to 1% O2 levels. In hypoxic condition we found miR-29 down-modulation responsible for the accumulation of collagens and 5mC. Overall, our data suggest that miR-29 family up-regulation might represent an endogenous mechanism aimed at ameliorating the age-dependent cardiac damage leading to hypertrophy and fibrosis.
Project description:We explored the role of mammalian ETS1/2 and Mesp homologues of cardiogenic transcription factors of Ciona intestinalis, to convert primary human dermal fibroblasts into cardiac progenitors. ETS1/2 and Mesp homologues of cardiogenic transcription factors of Ciona intestinalis, to convert primary human dermal fibroblasts into cardiac progenitors. Here we show murine Ets2 has an obligatory role for directing cardiac progenitors during cardiopoesis in embryonic stem cells. ETS2 converted fibroblasts into KDR/Flk1+ replicative cells but, like the purported cardiac master regulatory gene Mesp1, could not by itself generate cardiac progenitors de novo from fibroblasts. Co-expression of both Ets2 and Mesp1, however, successfully reprogrammed differentiated fibroblasts into cardiac progenitors, as shown by the de novo appearance of core cardiac transcription factors, gap junction proteins, sarcomeric proteins, electrical activity and contractility. ETS2 and Mesp1 sit at the pinnacle of the cardiopoesis regulatory hierarchy and are well suited for treating human heart disease. Co-expression of both Ets2 and Mesp1, reprogrammed differentiated fibroblasts into cardiac progenitors
Project description:Directed differentiation of human induced pluripotent stem cells creates billions of patient-specific cells. However, the differentiated derivatives of hiPS cells are immature relative to adult counterparts. Proliferative progenitor cells in these protocols are also therapeutically promising, but progenitors with enhanced potential for maturation have not been discovered. We hypothesized that brief epigenetic and innate immune modulation with polyinosinc cytidilic acid (pIC) could create cardiac progenitors with enhanced later maturation. Progenitor transcriptomic analysis revealed increases in cardiac crescent-like proliferative notch signaling by Jagged1, and activated progenitors spontaneously gave rise to cardiomyocytes with enhanced maturity and conductive microtissue with arrhythmogenic resistance. Furthermore, activated cardiac progenitors improved survival in animals after myocardial infarction compared to untreated progenitors. Our data suggest that future organization and maturation of cardiomyocytes are impacted by earlier pre-cardiomyocyte developmental signaling, and that progenitors modifying these pathways have translational promise. The forward epigenetic and immune modulation approach here utilized may be applicable to other cell lineages as well.
Project description:Mamamlian cardiogenesis occurs through the development of discreate populations of first and second heart field progenitors. We have used a dual transgenic color reproter system to isolate purified populations of these progenitors. We used microarrays to detail the global programme of gene expression underlying cardiac development in mouse; All four populations of cells are derived from embryonic stem cells differentiating in vitro (day 6 of in vitro differentaition). The stem cell line has two transgenic reporters as follows:; 1. The second heart field (SHF) specific reporter of the Mef2C gene (E. Dodou, S. M. Xu, B. L. Black, Mech Dev 120, 1021 (Sep, 2003)) driving the expression of dsRed; 2. The cardiac specific enhancer ( C. L. Lien et al., Development 126, 75 (Jan, 1999)) driving the expression of eGFP. Thus, the red cells are SHF specific, the green cells are cardiac specific, and the red/green are SHF and cardiac specific. These cells are compared to the double negative cells which serve as a control. Experiment Overall Design: Embryonic stem cell derived progenitors were isolated into four distinct populations by FACS purifying these progenitors based on a two color reporter system. Four populations were then compared to each other by transcriptional profiling.