Abstract 120: Reversal of Nox 4-Induced Oxidative Stress in Type 2 Diabetic Mesenchymal Stem Cells Restores Their Capacity to Augment Postischemic Neovascularization in db/db Mice

Abstract

Rationale: We have recently shown that experimental type 2 diabetes (db/db mouse) restricts mesenchymal stem cell’ (MSCs) differentiation capacity through a hyperinsulinemia-dependent induction of Nox 4 expression that promotes adipocytic and inhibits endothelial cell differentiation both in vitro and in vivo. We also showed that transplantation of type 2 diabetic MSCs into wild type (WT) recipients reduced post-ischemic neovascularization significantly below that of WT recipients receiving WT MSCs. Objective: This study tested the hypothesis that pretreatment of db/db MSCs with siRNA Nox4 prior to their transplantation and infusion 24 hrs after the induction of hindlimb ischemia restores their differentiation capacity in vivo and rescues their impaired capacity to promote neovascularization in wild type mice. Methods and Results: To reverse oxidative stress in db/db MSCs, we knockdown NOX 4 expression by a siRNA under in vitro conditions. In vitro inhibition of Nox 4 expression of db/db MSCs significantly increased their differentiation capacity towards endothelial cells and reduced their propensity to differentiate into adipocytes. Db/db MSCs also showed significantly increased tubular formation ability after Nox 4 knockdown. We transplanted NOX 4 siRNA transduced db/db MSCs into WT recipients 24 hours after induction of hindlimb ischemia. Blood flow recovery was measured at different time points by laser Doppler scanning. Reversal of oxidative stress in db/db MSCs by pretreatment with Nox4 siRNA prior to transplantation reversed their impaired capacity to augment post-ischemic neovascularization as evidenced by blood flow recovery that increased to that of WT mice. In addition, knockdown of NOX 4 expression in db/db MSCs also increased collateral artery diameter and capillary density by 50%. Conclusions: Pretreatment of db/db MSCs with siRNA against Nox 4 significantly increased their differentiation capacity towards endothelial cells rather than adipocytes and also their capacity to augment neovascularization after induction of hindlimb ischemia. Reversal of MSC oxidant stress induced by type 2 diabetes might permit greater leverage of the therapeutic potential of MSC transplantation to treat cardiovascular diseases.