Effect of protease activated receptor type 1 (PAR1) activation on the osteogenic activity of periodontal ligament cells

Protease activated receptor 1 (PAR1) was the first cloned member of the G protein-coupled receptor family. Its activation has been associated to tissue repair and bone healing. The aim of the present study was to evaluate the effect of PAR1 activation on the osteogenic and cementogenic activities of human periodontal ligament stem cells (HPLSC). HPLSC obtained from 3 subjects and treated with a control medium or with an osteogenic medium for 2, 7 and 14 days. Calcium deposits, calcium concentration (supernatant), alkaline phosphatase activity (ALP), cell proliferation and gene (qPCR) and protein expression (ELISA assay) of osteogenic and cementogenic factors were assessed in the presence of thrombin, PAR1 specific agonist peptide or PAR1 antagonist peptide. The activation of PAR1 led to increased formation of calcium deposits (p<0.05), which was associated to increased calcium concentration (p<0.05), ALP activity (p<0.05) and cell proliferation (p<0.05). Further, qPCR and ELISA assay showed that activation of PAR1 may increase gene expression of Runx2, OPG and CEMP1 (p<0.05) and protein levels of Runx2 and OPG (p<0.05). In conclusion, our results demonstrate that PAR1 activation increases osteogenic and cementogenic activities of HPLSC. (AU)