Background: Recent studies demonstrated that plasma exosomes from diabetic patients and animals lose their ability to maintain physiological properties of cardiomyocytes. Exosome inhibitor GW 4869 (GW) tended to improve heart function in diabetic mice with myocardial infarction. We tested the hypotheses that systemic blocking exosome synthesis/formation improves ischemic hindlimb repair in diabetes. Methods and Results: Unilateral hindlimb ischemia (HLI) surgery was conducted by ligation of left femoral artery in 12-week male db/db and db/+ mice which were administrated with either GW (2 mg/kg body weight, i.p) or vehicle for 4 weeks starting from one week before HLI. Blood perfusion in ischemic hindlimbs was examined by Laser Doppler at pre-HLI, and 0, 3, 7, 14 and 21 days post-HLI. Plasma exosomes were isolated by standard ultracentrifugation method and counted by NanoSight. GW increased blood concentration of CD31 + /Sca-1 + cell 3-day post-HLI and decreased necrosis and loss of toe/toenail; improved blood flow; enhanced capillary/arterial density determined by CD31 and SMA-α staining and decreased fibrosis in the muscles of ischemic hindlimbs in db/db mice 21-day post-HLI. Plasma exosomes from db/db mice significantly impaired human cardiac microvascular endothelial cells (HCMVECs) tube formation and migration. Mechanistically, hepatocyte growth factor (HGF) expression was decreased in bone marrow-derived endothelial progenitor cells (EPCs) from db/db mice and HCMVECs treated with diabetic plasma exosomes. Administration of GW increased HGF level in diabetic EPCs. Furthermore, diabetic plasma exosomes decreased H3K4me3 (active maker of transcription) whereas increased H3K27me3 (suppressive marker of transcription) at HGF promoter. Finally, treatment of HCMEVs with exogenous HGF rescued diabetic exosomes impaired tube formation of HCMVEC. Conclusions: Systemic inhibition of exosome synthesis/formation by GW increased ischemic limb repair in diabetic db/db mice, at least partially, via histone methylation mediated suppression of HGF. Our findings suggest that therapeutic targeting of systemic dysfunctional exosomes could represent a new avenue for therapeutics of ischemic tissue injury in patients with diabetes.