Background. Critical limb ischemia (CLI), a devastating peripheral arterial disease, affects patients with type 2 diabetes (T2D) and obesity, and is prevalent in minorities. Half of cases require amputation, leading to up to 40% mortality and worse prognosis in minorities. There is no effective medical treatment. Several stem cells are promising in clinical trials, but there are three concerns: a) studies based mainly on their angiogenic capacity, but not on their efficacy in skeletal muscle regeneration or neural repair; b) stem cell autografts from the T2D patient may be severely impaired by long term exposure to the T2D milieu; and c) the ischemic/diabetic tissue impact on the implanted stem cells is not targeted. We have shown: a) at short periods muscle derived stem cells (MDSC) stimulate early myogenesis in the muscle of the db/db mouse with CLI, but this is accompanied by myostatin overexpression and fibrosis that interfere with myofiber formation; b) the T2D milieu damages MDSC and impairs their repair capacity by in another diabetic complication, imprinting their transcriptional signature; c) pioglitazone at low doses prevents inflammation and fibrosis independently from glycemic control, and myostatin inhibitors stimulate muscle mass and are antifibrotic and proangiogenic. Overall goal: to optimize in a T2D mouse model the stem cell therapy of CLI, comparing MDSC with a stem cell currently in clinical trials for CLI, adipose derived stem cells (ADSC). This is in order to: a) stimulate myogenesis and regenerate striated myofibers, in addition to neoangiogenesis; and b) define and counteract the impairment of stem cell repair capacity upon long exposure to the T2D milieu, by pharmacological modulation with pioglitazone, a PPAR? agonist, and/or shRNA against myostatin as inhibitor of this negative regulator of muscle mass and pro-lipofibrotic effector, and study their mechanism and impact on the stem cells transcriptional signatures.
Specific Aim 1. To determine in the T2D mouse model of CLI: 1) the repair efficacy of MDSC and ADSC on the ischemic/diabetic muscle, and the impact of their prior exposure to the T2D milieu on efficacy and underlying transcriptional signatures; and 2) whether pharmacological modulation with pioglitazone and/or a myostatin inhibitor stimulates stem cells repair and counteracts the T2D-induced damage.
Specific Aim 2. To characterize in vitro: a) the roles of hyperglycemia and/or dyslipidemia in the T2D-induced stem cell damage; b) a preliminary insight on the mechanism of pioglitazone and myostatin inhibition effects on survival and differentiation of stem cells, and on their transcriptional signatures affected by treatments. Impact/innovation: High translational impact of a very novel approach aiming to improve the efficacy of stem cells targeting myofiber repair, through concurrent pharmacological modulation with a new modality for a widely clinically used drug and a promising ancillary approach, to define if and how the T2DM milieu damages them, and to counteract this damage through the drug combinations.
Critical limb ischemia (CLI) is a devastating diabetes-associated disease leading to limb amputation and high mortality, that affects disproportionately minorities. This project aims to optimize the promising novel stem cell therapy of CLI, by studying preclinically in an animal model and cell culture the modulation of the muscle repair capacity of muscle derived stem cells, in comparison to stem cells from the adipose tissue, by a concurrent pharmacological therapy with clinically used drugs, and whether this treatment may counteract the damage exerted by diabetes on the stem cells themselves.
