Preclinical Pluripotent Stem Cell Investigation for Vascular Therapeutics

About This Grant

Project Summary Patients with obstructive vascular diseases, such as atherosclerosis or peripheral arterial disease, or acute peripheral injuries require vascular grafts to restore blood flow to areas of the body. While the use of autologous vessels is considered the gold standard of treatment, many patients lack suitable vessels due to either vascular disease, previous usage, or have a size mismatch to the injured vessel. Therefore, clinicians turn towards synthetic grafts, such as expanded polytetrafluoroethylene (ePTFE) or Dacron, for large diameter vessel reconstruction. However, these synthetic materials fail when used in clinical small-diameter vascular applications, requiring the development of novel, hemocompatible vascular grafts for these clinical needs. Previous clinical trials have investigated acellular tissue-engineered vascular grafts (TEVGs) developed using human primary smooth muscle cells seeded on biodegradable scaffolds. After robust extracellular matrix (ECM) deposition, these TEVGs were subsequently decellularized and directly investigated for vascular treatment. While promising, the acellular TEVGs lacked an endothelium, and resulted in significant occlusion and suboptimal function within patients. Therefore, developing a novel TEVG with a functional endothelium that is immunocompatible to any recipient is of great clinical need. To address this issue, we propose using human induced pluripotent stem cells (hiPSCs) to fabricate a robust TEVG lined with an endothelium that is universally accepted by any patient, mitigating allogeneic immunorejection. In this proposal, hiPSCs will be differentiated into vascular smooth muscle cells (VSMCs) and subsequently used to generate a robust TEVG in our bioreactors that is then decellularized. Of novelty, we will then endothelialize the TEVGs with hypoimmunogenic, “universal” endothelial cells (ECs) that have been previously developed in our lab by modulating human leukocyte antigens (HLA) expression. To avoid xenograft immunorejection, this proposal will develop and characterize universal pig iPSCs (piPSCs) to endothelialize the TEVGs through downregulating expression of MHC I and II molecules and upregulating expression of CD47 via CRISPR-Cas9. The aims of this grant are to (1) characterize hypoimmunogenic universal piPSC lines for vascular graft engineering and (2) to generate universal iPSC- TEVGs and investigate their hemocompatibility in a preclinical porcine carotid bypass model in vivo. By investigating the universal iPSC technology in a preclinical porcine model, future studies will investigate human universal iPSCs for vascular tissue engineering purposes, furthering our goal towards developing a universal vascular conduit accepted by any patient.