ABSTRACT
BACKGROUND:The process of oxidative stress that impacts the curative effect exists in the region which accepts cel transplantation. However, there are few reports about the effects of oxidative stress on human dental pulp stem cels and relevant mechanism. OBJECTIVE:To understand the effect of hydrogen peroxide on the senescence of human dental pulp stem cels. METHODS:Human dental pulp stem cels were isolated and cultured in PBS, 100 and 200 μmol/L hydrogen peroxide for 2 hours, respectively. Cel morphology was observed under inverted microscope, degree of cel senescence monitored by β-galactosidase staining, cel proliferation ability detected by BrdU kit and cel counting method, cytoskeleton of dental pulp stem cels and expression of sirt1 tested using immunofluorescence method, and expression of sirt1 and p16 proteins measured by western blot assay. RESULTS AND CONCLUSION:Dental pulp stem cels exhibited a fibroblast-like morphology with spindle-shaped appearance. After stimulated by hydrogen peroxide, the cel volume was enlarged, theβ-galactosidase staining deepened and the proliferation of dental pulp stem cels reduced. The enhancement of senescence of dental pulp stem cels was accompanied with the increasing concentration of hydrogen peroxide, and in this process, the expression of p16 was raised while the expression of sirt1 was decreased. In conclusion, the senescence of human dental pulp stem cels can be promoted by the stimulation of hydrogen peroxide, and sirt1 and p16 are involved in this process. Our findings may provide a theoretical and experimental foundation for autologous transplantation of dental pulp stem cels.
ABSTRACT
BACKGROUND:During the healing of fractures, removal of sciatic nerve can result in insufficient mechanical rigidity of newborn woven bone. However, there are less reports concerning the denervation effects during distraction osteogenesis. OBJECTIVE:To observe the effect of removal of the sciatic nerve on bone regeneration and the expression of Runt-related transcription factor 2 (Runx2) protein during distraction osteogenesis in a rabbit model. METHODS:Twenty-four adult male New Zealand rabbits were selected and underwent left tibial osteodistraction to construct animal models of distraction osteogenesis. Before distraction, the animals were randomly divided into group R (resecting the left sciatic nerve) and group I (intact left sciatic nerve). Six weeks after completion of distraction, the animals were kil ed and the lengthened tibias were harvested for radiography, three-dimensional CT reconstruction, histological evaluation, connectivity density (Conn.D) evaluation. RESULTS AND CONCLUSION:New regenerated bone was present and Runx2 protein was expressed in the distraction gaps of al animals at the end of the study, as revealed by radiography, three-dimensional CT reconstruction, and histological observation. However, less new bone formation and a lower degree of mineralization and expression of Runx2 protein were observed in group R compared with group I. The results suggest that the denervation appears to have an inhibitory effect on bone formation and the expression of Runx2 protein during distraction osteogenesis.