Next Generation Treatment of PAD - Peripheral artery disease (PAD) is a progressive condition marked by the narrowing and blockage of arteries supplying the legs, often leading to debilitating leg pain and significant walking impairment known as claudication. While standard therapies exist, their effectiveness is limited, and there remains a critical need for treatments that enhance limb perfusion and function while reducing reliance on costly interventions. Recent clinical trials have suggested that stem cell therapy may hold promise for PAD treatment, yet results have been mixed, with ongoing barriers regarding the optimal cell type, delivery method, and therapeutic targeting. In this proposal, we overcome these barriers by using an autologous cellular preparation (adipose stromal vascular fraction, or SVF), and by targeting the inflow collateral vessels and employing a novel access and delivery strategy to enhance perfusion. We have developed and validated a minimally-invasive porcine model of hindlimb ischemia (percutaneous catheter-based coil occlusion of the iliofemoral and popliteal arteries) which recapitulates key aspects of human PAD and can be a platform for PAD therapy development. We have demonstrated that transvenous periarterial administration (around the porcine aortic trifurcation) of SVF increases long-term arterial inflow to the ischemic hindlimb and improves treadmill performance with respect to sham-treated ischemic hindlimbs. The objective of our proposal is to compare regenerative, cell-based regimens for PAD treatment (including SVF and SVF-derived exosomes) in a clinically relevant animal model of hindlimb ischemia whose size, anatomy, physiology, and comorbidities closely mirror those of human PAD patients. Our central hypothesis is that: (i) delivery of SVF into the peri-arterial region of the aortic trifurcation, in our porcine hindlimb ischemia model, will increase arteriogenesis and improve hemodynamic and functional endpoints more effectively than either intra-arterial SVF delivery or sham treatment; and (ii) SVF vs. SVF-derived exosomes, delivered peri-arterially in the same model, will provide equivalent benefits on the same endpoints. We will test this central hypothesis in three Specific Aims: Aim 1 will compare the effect of transvenous/peri-arterial (aortic trifurcation region) SVF delivery vs. intra- arterial SVF delivery on arteriogenesis, hindlimb perfusion, treadmill performance, and histological endpoints in our porcine model of hindlimb ischemia; Aim 2 will compare the effect of transvenous/peri-arterial (aortic trifurcation region) delivery of SVF vs. exosomes derived from SVF on arteriogenesis, hindlimb perfusion, treadmill performance, and histological endpoints; and Aim 3 will investigate the mechanisms by which SVF or exosomes delivered to the retroperitoneum around the aortic trifurcation drive arteriogenesis. Successful performance of this research proposal should lead to development of arterial inflow-enhancing therapies which would be useful in PAD patients, particularly ones who are not fit, not appropriate, or not willing to undergo a major revascularization procedure.
