Project description:Heart failure results from the inability of the human heart to replenish damaged tissue after myocardial infarction (MI), forming an unresolved scar which leads to functional impairment and tissue remodeling. Unlike humans, many animals, including certain fish and amphibians, are able to regenerate their hearts. Comparative analyses have been performed in many model systems including zebrafish (Danio rerio), with the goal to identify factors that could promote cardiac regeneration in humans. However, profound physiological differences between regenerative and non-regenerative models often make it difficult to extract informative data that are directly relevant to cardiac regeneration. Recently, medaka (Oryzias latipes), another fresh water teleost, has been reported to lack activation of neovascularization and cardiomyocyte (CM) proliferation post cardiac injury, and to display excessive fibrosis and an unresolved scar. This finding constitutes a unique opportunity to directly compare reparative responses to cardiac injury between regenerative (zebrafish) and non-regenerative (medaka) models with common physiological condition and anatomical structures, as well as phylogenetically close orthologous genes. Here we investigate potential triggers that promote heart regeneration using a comparative transcriptomic analysis between zebrafish and medaka. We generated a detailed dataset containing more than 15000 orthologous genes, covering multiple time points in the first week after cardiac injury. Analyses based on gene ontology revealed that differential responses in processes such as the immune response and angiogenesis exist between the two models. Pathway analyses further suggested potential candidates accounting for these differential responses including the Toll-like receptor agonist poly I:C. Altogether, these data provide further insight into the complex role of the immune response during regeneration, and serve as a platform to identify and test additional regulators of cardiac repair.

Project description:Ischemic cardiopathy is the leading cause of death in the world, for which efficient regenerative therapy is not currently available. In mammals, after a myocardial infarction episode, the damaged myocardium is replaced by scar tissue featuring collagen deposition and tissue remodelling with negligible cardiomyocyte proliferation. Zebrafish, in contrast, display an extensive regenerative capacity as they are able to restore completely lost cardiac tissue after partial ventricular amputation. Due to the lack of genetic lineage tracing evidence, it is not yet clear if new cardiomyocytes arise from existing contractile cells or from an uncharacterised set of progenitors cells. Nonetheless, several genes and molecules have been shown to participate in this process, some of them being cardiomyocyte mitogens in vitro. Though questions as what are the early signals that drive the regenerative response and what is the relative role of each cardiac cell in this process still need to be answered, the zebrafish is emerging as a very valuable tool to understand heart regeneration and devise strategies that may be of potential value to treat human cardiac disease. Here, we performed a genome-wide transcriptome profile analysis focusing on the early time points of zebrafish heart regeneration and compared our results with those of previously published data. Our analyses confirmed the differential expression of several transcripts, and identified additional genes the expression of which is differentially regulated during zebrafish heart regeneration. We validated the microarray data by conventional and/or quantitative RT-PCR. For a subset of these genes, their expression pattern was analyzed by in situ hybridization and shown to be upregulated in the regenerating area of the heart. The specific role of these new transcripts during zebrafish heart regeneration was further investigated ex vivo using primary cultures of zebrafish cardiomyocytes and/or epicardial cells. Our results offer new insights into the biology of heart regeneration in the zebrafish and, together with future experiments in mammals, may be of potential interest for clinical applications. In order to study zebrafish heart regeneration, a time course experiment was realized where amputated heart regenerating were compared to control heart. Samples in triplicate were extracted at 1, 3, 5 and 7 days post-amputation.

Project description:Ischemic cardiopathy is the leading cause of death in the world, for which efficient regenerative therapy is not currently available. In mammals, after a myocardial infarction episode, the damaged myocardium is replaced by scar tissue featuring collagen deposition and tissue remodelling with negligible cardiomyocyte proliferation. Zebrafish, in contrast, display an extensive regenerative capacity as they are able to restore completely lost cardiac tissue after partial ventricular amputation. Due to the lack of genetic lineage tracing evidence, it is not yet clear if new cardiomyocytes arise from existing contractile cells or from an uncharacterised set of progenitors cells. Nonetheless, several genes and molecules have been shown to participate in this process, some of them being cardiomyocyte mitogens in vitro. Though questions as what are the early signals that drive the regenerative response and what is the relative role of each cardiac cell in this process still need to be answered, the zebrafish is emerging as a very valuable tool to understand heart regeneration and devise strategies that may be of potential value to treat human cardiac disease. Here, we performed a genome-wide transcriptome profile analysis focusing on the early time points of zebrafish heart regeneration and compared our results with those of previously published data. Our analyses confirmed the differential expression of several transcripts, and identified additional genes the expression of which is differentially regulated during zebrafish heart regeneration. We validated the microarray data by conventional and/or quantitative RT-PCR. For a subset of these genes, their expression pattern was analyzed by in situ hybridization and shown to be upregulated in the regenerating area of the heart. The specific role of these new transcripts during zebrafish heart regeneration was further investigated ex vivo using primary cultures of zebrafish cardiomyocytes and/or epicardial cells. Our results offer new insights into the biology of heart regeneration in the zebrafish and, together with future experiments in mammals, may be of potential interest for clinical applications.

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MicroRNA expression profiling of zebrafish heart regeneration

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