Abstract 23: Exosome Inhibition Improved Blood Perfusion in Ischemic Hindlimb of db/db Diabetic Mice

Abstract

Background: Critical limb ischemia (CLI), a life-threatening condition characterized by pain at rest and tissue loss with ulcer and gangrene, imposes a major public healthy burden, resulting in high mortality and disability. The occurrence of CLI in patients with diabetes mellitus is very frequent. However, the effective therapy for CLI in diabetic patients is absent. Recent studies demonstrated that exosome from diabetic animals/cells has detrimental effects on the post-injury cardiovascular repair. Here, we tested the hypotheses that exosome inhibition in vivo improves blood flow recovery and protects skeletal muscle in ischemic hindlimbs of diabetic db/db mice following surgical ischemia. Methods and Results: Exosomes were isolated from bone-marrow derived progenitor cells or plasma in non-diabetic db/+ and diabetic db/db mice by ultracentrifugation. Diabetic exosome (5 ug/ml) inhibited tube formation of human cardiac microvascular endothelial cells. Unilateral hindlimb ischemia surgery was conducted by ligation of left femoral artery in 12-week old, male db/+ and db/db mice. Exosome inhibitor GW4869 (2 μg/g body weight) was given by intraperitoneal injection every other day for 4 weeks starting from one week before the HLI surgery. HLI mice injected with vehicle served as controls. Mice were divided into four groups: 1) db/+ + vehicle; 2) db/db+ vehicle; 3) db/+ GW4869; 4) db/db + GW4869. GW4869 decreased necrosis and loss of toe/toenail, improved blood flow, enhanced capillary/arterial density, skeletal muscle architecture and cell survival in ischemic hindlimb of diabetic db/db mice 21 days post-ligation. Conclusions: Although preliminary, our experiments suggest that therapeutic targeting of dysfunctional exosome secretion could represent a new avenue for the prevention and treatment of ischemic injury in diabetic patients.