In vitro organization of human induced pluripotent stem cell-derived cardiovascular cells into vascularized cardiac tissue

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Cardiac tissue engineering strategies may provide new therapeutic options for the treatment of cardiovascular disease, with patient-specific stem-cell derived cardiovascular cells as an ideal cell source. For the in vitro generation of functional heart tissue, sufficient vascularization by endothelial cells and smooth muscle cells is a critical aspect in addition to the contractile force of cardiomyocytes and mechanical stabilization by fibroblasts. Recent findings offer the unique opportunity to generate all cell types of the heart from pluripotent stem cells. The overall objective of the proposed research is the investigation of mechanisms of stem cell-derived human vascularized bioartificial cardiac tissue formation and self-organization in vitro and its regenerative potential in vivo. We hypothesize that 1) cardiovascular cell types can be derived from a single cell source of human induced pluripotent stem cells (iPSCs); and 2) these cells are able to self-organize in vitro to form fully autologous vascularized myocardial tissue for therapeutic application; and 3) pericytes might play an important role to support the formation of functional vascular structures. Consequently, the specific objectives include:- Optimization of differentiation and/or selection strategies to generate from a single stem cell source (human pluripotent stem cells) five different cell types present in the native heart tissue (cardiomyocytes, endothelial cells, smooth muscle cells, pericytes, and fibroblasts). So far, no single differentiation protocol is available for the generation of all cardiovascular cell types of the heart in a simultaneous one pot reaction, yielding defined and appropriate proportions of the desired cell types. Therefore, the use of individual protocols for the directed differentiation of the respective cell types seems more promising. - Implementation of all cardiovascular cell types for the in vitro generation of functional myocardial tissue. Mechanisms of tissue formation, optimal cell type stoichiometry and spatial organization as well as the need for further in situ maturation will be investigated.- Investigation of the role of pericytes for vascularization in the in vitro model of bioartificial cardiac tissue formation, including analysis of pericyte-derived pro-angiogenic factor expression and activation of cell signaling pathways in other cardiovascular cell types. - Investigation of the regenerative potential of vascularized bioartificial cardiac tissue in vivo in a small animal model of myocardial infarction in guinea-pigs with a direct comparison to non-vascularized tissue.Together with progress concerning patient-specific iPSC generation and their clinical applicability, knowledge gained in this project would facilitate the generation of autologous bioartificial vascularized cardiac tissue from human iPSCs for future tissue replacement therapy of damaged and diseased myocardium.