Preconditioning of human dental pulp stem cells by H2O2 promotes functional recovery in a rat spinal cord contusion injury model.

Cell therapy is a potential therapeutic choice to treatment spinal cord injury (SCI). Studies proved that hypoxic precondition has protective effects on damaged cells. It sounds that a sub-lethal hypoxic exposure is likely enhance survival rates of transplanted cells. The aim of this study is the effect a novel strategy of preconditioning of human dental pulp stem cells (hDPSCs) via hydrogen peroxide (H2O2) on treatment rat SCI model. The hDPSCs were isolated from human third molar. The cells were cultured in various concentrations of H2O2 (0-400 μM) at different time points (2-48 hours). Then, the cell viability was estimated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. In rat SCI model, 0.5×106 hDPSCs with and without H2O2 preconditioning were locally transplanted in contusion site. Behavioral assessment was rendered within 7 weeks after injection. Besides, the brain-derived neurotrophic factor (BDNF) was evaluated. The results of MTT showed that the cell viability rates were significantly lower at the higher concentrations of H2O2 at various times. However, the cell viability declined, followed by exposure to 50 μM H2O2 for a period of 2-12 hours compared with untreated cells. Basso, Beattie, and Bresnahan (BBB) findings revealed transplantation of the preconditioned hDPSCs increased BBB score significantly compared to the SCI group. Also, BDNF as a neurotrophic factor, dramatically increased in treated group. These finding suggest transplantation of sub-lethal concentration of H2O2 preconditioned hDPSCs would have protective roles through paracrine signals by enhancing survival capability transplanted cells which can cause motor neuron recovery in SCI.