Role of P2X7 receptor in osteogenic differentiation of periodontal ligament stem cells

Sun Ya-nan; Wei Jian-min; Sun Wei; Wu Jun-jie; Wu Li-an

doi:10.3969/j.issn.2095-4344

Abstract：BACKGROUND:Ion channels related to the osteogenic differentiation of periodontal ligament stem cels have been studied. OBJECTIVE:To preliminarily investigate the effect of P2X7 receptor on the osteogenic differentiation of human periodontal ligament stem cels. METHODS:Human periodontal ligament stem cels were isolated and divided into four groups, cultured in 100 nmol/L adenosine triphosphate+osteogenic medium, osteogenic medium, 100 nmol/L adenosine triphosphate, and normal culture medium (control group), respectively. After induction for 7 and 14 days, osteogenic effect was detected by alizarin red staining, and expressions of OCN, Runx2 and P2X7 receptor at mRNA and protein levels were analyzed by qRT-PCR and western blot assay, respectively. RESULTS AND CONCLUSION: Under alizarin red staining, the osteogenic effect of periodontal ligament stem cels was better in the group of adenosine triphosphate+osteogenic medium than the osteogenic medium group at <br> 7 days, but it was better in the osteogenic medium group than the group of adenosine triphosphate+osteogenic medium at 14 days (P < 0.05). Results from qRT-PCR showed that, in the group of adenosine triphosphate+osteogenic medium, the mRNA expression of Runx2 and OCN reached peak at 7 days, but decreased significantly at 14 days (P < 0.05). The expression of P2X7 receptor mRNA in the group of adenosine triphosphate+osteogenic medium was significantly higher than that in the adenosine triphosphate group at 7 days (P < 0.05), but significantly lower than that in the adenosine triphosphate group at 14 days (P < 0.05). There was no expression of P2X7 receptor mRNA in the osteogenic medium group and control group. Western blot assay showed that at 7 days, the expression of P2X7 receptor peaked in the adenosine triphosphate+osteogenic medium group at 7 days, which was significantly higher than that in the adenosine triphosphate group, and there was a low expression of P2X7 receptor in the osteogenic medium group and no expression in the control group; at 14 days, the expression of P2X7 receptor decreased significantly in the adenosine triphosphate+osteogenic medium group but increased in the adenosine triphosphate group. Experimental findings show that exogenous adenosine triphosphate could significantly improve the osteogenic differentiation of periodontal ligament stem cels at 7 days, but after that, inhibit the osteogenic differentiation; exogenous adenosine triphosphate could activate the expression of P2X7 receptor in periodontal ligament stem cels, and P2X7 receptor expression has positive correlation with the osteogenic differentiation of periodontal ligament stem cels.