Mesenchymal stem cells (MSCs) survival decreased following in vivo injection and its application has been limited in stem cell therapy. Preconditioning was established as a strategy to increase the cells' efficiency, but more studies are necessary to determine its safety and mechanisms. Objectives: The aim of this study was to evaluate the effect of preconditioning mesenchymal stem cells with low serum and H2O2 on in vitro cell survival. Methods: Mesenchymal stem cells were cultured and

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... tioned with low serum and H2O2 for 6, 12, 24 and 48 hours in six groups. Control, group I with 5 µM H2O2, group II with 10 µM H2O2, group III with 0.5% fetal bovine serum (FBS), group IV: 5 µM H2O2 + 0.5% FBS and V: 10 µM H2O2 + 0.5% FBS. Cell proliferation was evaluated with the MTT assay. Results: Cell proliferation in groups IV and V increased significantly compared to the other groups after 6, 12 and 24 hours of treatment (P < 0.05). Also, after 48 hours, cell treatment with 5 µM H2O2+ 0.5% FBS led to a significant increase in cell proliferation (P < 0.05). Conclusions: Our data suggest that preconditioning with 5 µM H2O2 + 0.5% FBS and 10 µM H2O2 + 5% FBS improved cell proliferation and viability. However, the mechanisms related to protective properties of preconditioning and using this strategy in stem cell therapy requires more research.