Effect of orthodontic forces on the osteogenic differentiation of human periodontal ligament stem cells

The purpose of this study was to evaluate the effects of orthodontic forces (OF) on the proliferation and differentiation of human periodontal ligament stem cells (hPDLSCs). The experimental sample consisted of 6 premolars extracted from 2 patients. After application of OF for I month, the hPDLSCs were separated from the primary cultured PDL cells using magnetic-activated cell sorting. The cell proliferation rate was assessed using a 3-[45-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. The hPDLSCs were cultured in osteogenic medium, and the osteogenic differentiation was analyzed on day 7 and 14 using alkaline phosphatase staining and reverse transcription polymerase chain reaction analyses. The gene expression level of osteogenic markers and angiogenic markers were measured and normalized. The results showed that the application of OF increased the proliferation rates, the expression of osteogenic factors, and the expression of angiogenic factors of hPDLSCs. These findings suggest that OF can serve as a potent positive modulator of proliferation and osteogenic differentiation of hPDLSCs.