Dual Preconditioning: A Novel Strategy to Withstand Mesenchymal Stem Cells against Harsh Microenvironments.

Purpose: Poor survival rate of mesenchymal stem cells (MSCs) following their transplantation is one of the major challenges in their therapeutic application. Therefore, it is necessary to augment the viability of the MSCs in order to improve their therapeutic efficacy. Several strategies have been used to overcome this problem. Preconditioning of MSCs with oxidative stresses has gained a lot of attention. Therefore, in the present study, we investigated the effects of simultaneous preconditioning of MSCs with hydrogen peroxide and serum deprivation stresses on their survival and resistance to stressful conditions. Methods: MSCs were isolated from human umbilical cord blood. To perform simultaneous preconditioning, the cells were cultured in DMEM medium containing 1, 2.5 and 5 percent FBS and different concentrations of H2 O2 (5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 80 and 100 µM) for 24 hrs. Then, the cells were cultured in recovery culture medium. Finally, one group of the cells was exposed to a lethal concentration of H2 O2 (300µM), and the other cells were cultivated in FBS free DMEM medium as the lethal situation. In addition, the percentage of apoptotic cells was analyzed using Caspase 3 assay kit. Results: Simultaneous preconditioning of the MSCs with 15µM H2 O2 plus serum deprivation, 2.5% FBS, significantly increased the resistance of the cells to the toxicity induced following their cultivation in FBS free DMEM medium. It exerted the protective effect on the cells after treating with the lethal dose of H2 O2 as well. Conclusion: Simultaneous preconditioning of MSCs with oxidative and serum deprivation stresses enhances their survival against harsh conditions, which might increase the viability and stability of the MSCs following their transplantation.