Readily Available Stem Cell-Based Vascular Grafts for Emergent Surgical Care

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Project Summary Tissue engineered vascular grafts (TEVGs) for traumatic vascular injury repair in small diameter (2- 4mm) vessels can be made from human induced pluripotent stem cell derived vascular smooth muscle cells (hiPSC-VSMC) seeded onto a polyglycolic acid (PGA) scaffold. Furthermore, these TEVGs can be subsequently decellularized and stored long term for use in acute care for traumatic injury. For larger diameter vessel repair, it is adequate to implant an acellular scaffold and allow host cells to migrate from anastomotic edges to line the implanted vessel lumen. However, this model is not effective for smaller diameter vessels that are more prone to thrombosis. Researchers have attempted to solve this problem by coating the lumen of implanted vessels with endothelial cells (ECs) prior to implantation. However, data from implanted grafts suggests there is a short turnover time for implanted EC populations within these grafts. In the case of elderly or diseased patients, they may not retain quality EC function. Therefore, this patient population may display poor integration of host cells into the implanted tissue, which may lead to an increased risk of thrombotic and stenotic events. The purpose of this project is to generate a stable hiPSC line with controllable expression of the pro-survival factor Bcl-2 to generate hiPSC derived endothelial cells (hiPSC-ECs) as a readily available cell source to line the lumen of decellularized TEVGs prior to implantation. A stable hiPSC line with doxycycline inducible expression of the pro-survival factor Bcl-2 will be generated via transcription activator-like effector nucleases (TALEN) gene editing. Additionally, a robust “safety switch” system using ectopically expressed thymidine kinase (TK) will be employed to ensure cells may be removed post implantation should unwanted effects occur. Decellularized TEVGs will have their lumen coated with hiPSC-ECs made from this gene edited Bcl-2+TK+ cell line. These endothelialized TEVGs will undergo fluid shear stress training to enhance hiPSC-EC function prior to implantation into an immunocompromised rat model as an aortic interposition graft to test the efficacy of this doxycycline inducible Bcl-2 system. This platform will allow for a readily available cell line to be used to produce a long lasting hiPSC-EC lumen that can maintain patency of the graft as it fully integrates with patients who may have subpar EC function.