Attenuating Hypoxia-Induced Apoptosis and Autophagy of Mesenchymal Stem Cells: the Potential of Sitagliptin in Stem Cell-Based Therapy.

Dipeptidyl peptidase-4 (DPP-4) inhibitors have pleiotropic effects on cardiovascular protection beyond the antidiabetic property. However, it remains unknown that the impact of one DPP-4 inhibitor sitagliptin on the survival of mesenchymal stem cells (MSCs) in hypoxia and serum deprivation (H/SD) environment. The apoptosis and autophagy of MSCs were analyzed in different concentrations of sitagliptin under H/SD condition. For later studies, we tested the relationship between anti-apoptotic and anti-autophagic effects of sitagliptin. The level of cell apoptosis was analyzed by Annexin V-FITC/PI staining, western blot of Bcl-2 and Bax proteins. Autophagy flux was assessed by multiple autophagy related proteins and substrates. Cell autophagy was identified by acridine orange staining, western blot of Beclin 1 and light chain 3 protein, and transmission electron microscopy. We demonstrated that sitagliptin attenuated hypoxia-induced apoptosis and autophagy of MSCs. Furthermore, sitagliptin regulated cell autophagy by Bcl-2/ Beclin 1 pathway in H/SD condition. This study provides insight into the utility of the DPP-4 inhibitor sitagliptin for MSCs transplantation in the ischemic microenvironment that extends its antidiabetic property.