Despite current therapeutic strategies, human subjects with diabetes and peripheral artery disease (PAD), an atherosclerotic arterial occlusive disease that impairs blood flow to the lower extremities, suffer from an increased risk of critical limb ischemia (CLI), or impaired blood flow. CLI triggers chronic limb rest pain, impaired wound healing of the foot, and a higher risk of limb amputation. MicroRNAs are small non-coding RNAs that are key regulators of biological processes through the suppression of target gene expression. However, the role of microRNAs in diabetic CLI remains poorly understood. We performed a comprehensive analysis of plasma microRNA profiles from both human patients with PAD and mouse models to identify new microRNAs that may not only serve as biomarkers for CLI, but also play important roles in regulating diabetic ischemia. Among the differentially expressed microRNAs, miR-181 was capable of regulating angiogenesis in endothelial cells. By using different knockout mouse models we identified that depletion of miR-181 in bone marrow cells improve blood flow recovery after
ischemic injury. However, this effect was abrogated under diabetic conditions. Our work revealed the importance of miRNAs in the pathobiology of CLI and may open new therapeutic strategies for patients with CLI.
Human subjects with peripheral artery disease (PAD) and diabetes mellitus suffer from an increased risk of critical limb ischemia (CLI) and limb amputation. MicroRNAs are crucial regulators of gene expression whose role in diabetic CLI remains poorly understood. Through stratification of the miRNA sequencing screens across 2 different hindlimb ischemia models in diabetic mice and human cohorts with diabetic CLI, we identified miR-181 as a top differentially expressed miRNA capable of regulating angiogenesis in vitro. Surprisingly, systemic miR-181 knockout mice demonstrated better blood flow recovery (BFR, by ~3.7 fold) from limb ischemia. MiR-181 KO bone marrow (BM) transplantation also demonstrated increased BFR suggesting BM-derived cells are the prominent driver of the phenotype. In support of this, endothelial-specific miR-181 KO mice revealed no difference in BFR. Changes in immune cell population and mRNA expression in ischemic muscle suggested that a change in macrophages towards an M1-like pro- inflammatory response improves angiogenesis after limb ischemia. Paradoxically, the beneficial effects of miR-181b depletion change under diabetic conditions (on a high-fat sucrose containing diet), which shows poor BFR (~1.4 fold) after injury and increased limb necrotic events. Altogether, our findings reveal miR-181 as a key therapeutic target for promoting tissue perfusion in PAD and diabetes.