Exendin-4 Protects The Adipose-derived Mesenchymal Stem Cells Against Oxidative Stress Injury

Aim:Evidences from many researches have accumulated for the roles of ADMSCs’ grafts in the treatment of myocardial infarction (MI) due to heart replacement, cardioprotective, and cardiotrophic effects. Despite visible advances in the field of stem cells-based therapy, the reported functional improvements are generally modest partly due to the low cellular survival rate triggered by oxidative injury in vivo. Therefore, understanding its mechanisms by which oxidative injury cause donor cell death and protection of these cells from apoptosis, together with enhancing their ability to survival under oxidative stress conditions, would have an vital influence on promoting the use of ADMSCs-based therapy. Exendin-4, an antidiabetes drug, exerts cell-protective influences on several kinds of cells. This study mainly explored the mechanisms by which oxidative stress injury caused ADMSCs apoptosis, and investigated the detailed survival signals regarding the anti-apoptotic actions of Exendin-4 on ADMSCs.Methods:ADMSCs were acqiured from inguinal adipose tissue of Sprague-Dawley rats, and characterized by flow cytometry analysis and multilineage differentiation. The change of cell proliferative capacity and GLP-1 receptor expression under different doses of Exendin-4 were investigated. ADMSCs apoptosis induced by H2O2 in vitro. And the role of caspase9-related mitochondrial death pathways in ADMSCs apoptosis were detected. Besides, Exendin-4 was applied to protect the ADMSCs against apoptosis. Furthermore, the association between the PI3K/Akt-Sfrp2 pathways and anti-apoptotic effect of Exendin-4 was explored.Results:1. ADMSCs expressed mesenchymal stem cell marker but express little endothelial marker or hematopoietic lineage markers.2. When incubated under adipogenic or osteogenic culture, ADMSCs could differentiate into adipogenic and osteogenic cells.3. Exendin-4 increased the number of AMDSCs in a concentration- dependent manner.4. Hydrogen peroxide treatment improved the ratio of apoptotic cells. Under oxidative injury, the concentrations of ROS and MDA were increased but the contents of GSH and SOD were reduced. H2O2 led to lower mitochondrial transmembrane potential that caused the cyt-c release into the cytoplasm or nuclear. Higher apoptotic proteins expression (Bax、caspase9 and caspase3) and lower anti-apoptotic proteins expression (Bcl-2, c-IAP1 and c-IAP2) appeared in ADMSCs under oxidative injury.5. Exendin-4 could reduce the number of apoptotic ADMSCs, maintain the mitochondrial transmembrane potential and inhibit the leakage of cyt-c. Moreover, more GSH and SOD as well as less ROS and MDA emerged when ADMSCs pretreated with Exendin-4. Furthermore, Exendin-4 could up-regulate the anti-apoptotic proteins but down-regulate the apoptotic proteins.6. Exendin-4 was able to active the Sfrp2 via the PI3K/Akt pathway. However, blockade of PI3K/Akt pathways with LY294002 or knockdown of Sfrp2 with siRNA obviously abolished the protective effects of Exendin-4 on mitochondrial function and anti-apoptotic proteins, reversing the beneficial actions of Exnedin-4 on ADMSCs apoptosis under H2O2.Conclusions:1. Exendin-4 could increase the AMDSCs proliferation in a dose-dependent manner in vitro.2. H2O2 induced ADMSCs apoptosis through caspase-9-dependent mitochondrial death pathways.3. Exendin-4 could enhance antioxidant defense systems to indirectly remove ROS, and inhibit mitochondrial death pathways through recruitment of anti-apoptotic proteins by activation of the PI3K/Akt-Sfrp2 pathways, leading to the ADMSCs survival under oxidative stress injury.