Abstract 12040: Direct Reprogramming of Fibroblasts into Functional Endothelial Cells Capable of Enhancing Angiogenesis in Infarcted Tissues and Re-Endotheliulization in Vessel Grafts
Background - The generation of induced pluripotent stem (iPS) cells is a fascinated tool for regenerative medicine including cardiovascular tissues. However, the main restriction for iPS cell application is the risk of tumour development.
Methods and Results - In this study we adapted a new method to generate partial-iPS (PiPS) cells by transferring four reprogramming factors (OCT4, SOX2, KLF4 and c-MYC) to human fibroblasts for short periods of time. PiPS cells did not form tumours in vivo, and have the potential to specifically differentiate into different cell lineages, such as neurons, adipocytes, osteocytes, chondrocytes as well as endothelial cells. The PiPS-derived endothelial cells expressed a panel of endothelial markers at gene and protein levels and they formed vascular tubes in vitro and in vivo Matrigel plaque assays. Data from a series of experiments indicate a novel gene SETSIP was crucial in endothelial cell differentiation. SETSIP was expressed in parallel with endothelial cell markers, and its overexpression induced endothelial marker expression, while its downregulation by shRNA resulted in suppression of these genes. Interesting, SETSIP was translocated to the cell nucleus during endothelial differentiation. Furthermore, ChIP assays showed that SETSIP bound direct to VE-cadherin promoter and induced endothelial differentiation via OCT4-SETSIP and VEGF signal pathways. Functionally, PiPS-derived endothelial cells displayed clearly endothelial properties in two animal models. When they seeded on decellularised vessels in a special constructed bioreactor and implanted in SCID mice, the cells displayed good attachment, stabilisation, patency and typical vascular structure. Moreover, PiPS-derived endothelial cells improved neovascularization and blood flow recovery in hind limb when they were injected into the infarcted tissues in an ischemia model.
Conclusion - We developed a new method to generate PiPS cells from human fibroblasts that can differentiate into a variety of cell types without tumour risk, in which endothelial cells can be produced via OCT4-SETSIP and VEGF pathways useful for regenerating damaged tissue and vessels in vivo.
- © 2011 by American Heart Association, Inc.