Abstract 24: Hydrogen Sulfide Potentiates Bone Marrow-derived Angiogenic Progenitor Cell-mediated Ischemic Limb Angiogenesis in Diabetic Animals

Abstract

Rationale: Critical hindlimb ischemia (CLI) represents an outcome of peripheral artery disease with a high incidence in diabetic patients. Recently, insufficient hydrogen sulfide (H 2 S) production has been implicated in cardiovascular disease. Objective: Explore the role of H 2 S in diabetes-induced bone marrow-derived angiogenic progenitor cells (BMAPC) dysfunction and its therapeutic effects on ischemic hindlimb injury of diabetes. Methods and Results: Diabetic BMAPCs from db/db mice showed decreased intracellular H 2 S production and blunted cystathionine γ-lyase (CSE) expression-an enzyme required for H 2 S generation. High glucose (HG) inhibited H 2 S production, migration and increased apoptosis of BMPAC that was rescued by H 2 S donor diallyl trisulfide (DATS) or overexpression of CSE. Administration DATS or local injection of diabetic BMAPCs overexpressing CSE significantly potentiated BMAPC-mediated blood flow recovery, capillary and arteriole formation, skeletal muscle architecture preservation, cell survival and decrease of perivascular infiltration of monocytes (CD68 + ) cells in ischemic skeletal muscle. Moreover, overexpression of CSE increased diabetic BMAPCs homing and engraftment in ischemic hindlimb. HG-impaired human cardiac microvascular endothelial cells (HCMVECs) tube formation and migration were rescued by DATS or overexpression of CSE. Mechanistically, HG increased threonine-495 phosphorylation of eNOS (eNOS-pT495) and inhibited nitric oxide (NO) production in HCMVECs which were rescued by DATS or overexpression of CSE. Silencing CSE by siRNA impaired tube formation and increased eNOS-pT495 expression in HCMVECs. Finally, HG-treated BMAPCs impaired mouse microvascular endothelial cell tube formation that was rescued by DATS. Conclusions: Our data suggests that CSE downregulation-induced H 2 S insufficient plays a critical role in diabetes-mediated BMAPC dysfunction. Administration of DATS or overexpression of CSE improves diabetic BMAPC-mediated angiogenesis/neovascularization via, at least partially, eNOS inactivation/NO reduction pathways. Our data indicate that H 2 S and overexpression of CSE in diabetic BMAPCs may open novel avenues for cell-based therapeutics of CLI in diabetic patients.