Abstract 12626: Co-Injection of Induced Pluripotent Stem Cell-Derived Endothelial Cells With Shear Thinning Hydrogel Enhances Survival and Angiogenesis in a Murine Model of Peripheral Arterial Disease

Introduction: Human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) are a promising cell source for enhancing blood perfusion for treatment of peripheral arterial disease (PAD). However, poor cell survival is a critical bottleneck to the efficacy of stem cell therapy. Hypothesis: We hypothesize that encapsulation of cells within an injectable shear-thinning hydrogel with controllable properties will prolong cell survival under ischemic conditions and maintain cellular phenotype, in comparison to cell injection in saline. Methods: The protein hydrogel is comprised of two complementary engineered proteins that self-assemble upon simple mixing. The hydrogel network incorporates a polyethylene glycol physical crosslinker that modulates hydrogel stiffness and degradation. Bioluminescent iPSC-ECs were encapsulated within the hydrogel with controllable stiffness ( G’ ~10-800 Pa) under conditions of hypoxia (1% O 2 ). The cells within hydrogel were then subjected to an in vitro model of injection and assayed for cell survival, proliferation, and endothelial phenotype for up to 14 days. To verify these results in an experimental model of PAD, 10 6 cells were injected in saline or in 400 Pa hydrogel into the ischemic limb of SCID mice for assessment of cell viability and blood flow recovery. Results: Acutely after injection in vitro , cell survival in saline was 65%, in comparison to 94% in hydrogels with stiffnesses of 10-800 Pa. Bioluminescence imaging demonstrated the highest cell proliferation in the hydrogel with 400 Pa stiffness after 14 days. In the 400 Pa hydrogel, iPSC-ECs maintained elongated morphology with robust expression of endothelial phenotypic marker, CD31. In the ischemic hindlimb, iPSC-EC retention was markedly increased when encapsulated in the 400 Pa hydrogel, compared to saline delivery. Concomitantly, mean blood perfusion recovery in the ischemic limb after 14 days was 0.68 when treated with cells in hydrogel, in contrast to 0.61 when cells were injected in saline. Conclusions: These findings demonstrate that stem cell encapsulation within the 400 Pa protein hydrogel improves cell viability and blood perfusion, which may have therapeutic benefit for treatment of PAD.