Differences in RUNX2 and P2RX7 gene expression between mono- and coculture of human periodontal ligament cells and human osteoblasts under compressive force application

Objectives Objectives were (a) to establish an in vitro coculture model of human PDL-derived fibroblasts (HPDFs) and human alveolar bone-derived osteoblasts (HABOs), and (b) to measure RUNX2 and P2RX7 gene expression at multiple time points after compressive force (CF) stimulation for different durations. Setting/Sample population Human PDL-derived fibroblasts and HABOs from two individuals isolated from extracted teeth of healthy donors due to orthodontic reasons at LMU's Dental School were used. Materials and methods Mono- and cocultured cells were subjected to CF by centrifugation (47.4 g/cm(2)) for 1, 2 and 4 hours at 30 degrees C. Total RNA was isolated before and 2, 4, 8, 16 minutes after CF application. Expression of RUNX2 and P2RX7 was determined using quantitative real-time polymerase chain reaction. Results In monocultured cells, an upregulation of RUNX2 and P2RX7 expression was found after all CF durations: RUNX2 twofold in HPDFs after 4 hours (P = 0.002) and 1.7-fold in HABOs after 1 hour (P = 0.009) or 2 hours (P = 0.002) of CF. P2RX7 was significantly upregulated following 1 hour (P = 0.004) and 2 hours (P = 0.002) of CF application in HPDFS. In HABOs, a transient regulation was observed. In cocultured cells, a significant alleviation in gene expression was found for both loci after CF application. In both cell types, RUNX2 expression was significantly reduced in cocultured cells compared to cells in monoculture. P2RX7 expression showed significant attenuation in HPDFs only. Conclusions Cocultivation attenuated the CF induced increase of RUNX2 and P2RX7 gene expression in comparison to monoculture in both cell types. This suggests that intercellular communication may exist between HPDFs and HABOs.