Effect of static compressive force on in vitro cultured PDL fibroblasts: monitoring of viability and gene expression over 6 days.

ABSTRACT

OBJECTIVES: The aim was to investigate the impact of static compressive force (CF) application on human PDL-derived fibroblasts (HPDF) in vitro for up to 6 days on the expression of specific genes and to monitor cell growth and cell viability. MATERIALS AND METHODS: CF of 2 g/cm2 was applied on HPDFs for 1-6 days. On each day, gene expression (cFOS, HB-GAM, COX2, IL6, TNFα, RUNX2, and P2RX2) and secretion (TNFα, PGE2) were determined by RT-qPCR and ELISA, respectively. Cell growth and cell viability were monitored daily. RESULTS: In comparison with controls, significant upregulation of cFOS in compressed HPDFs was observed. HB-GAM showed no changes in expression, except on day 5 (P < 0.001). IL6 expression was significantly upregulated from day 2-5, reaching the maximum on day 3 (P < 0.001). TNFα expression was upregulated on all but day 2. COX2 showed upregulation, reaching the plateau from day 3 (P < 0.001) until day 4 (P < 0.001), and returning to the initial state till day 6. P2RX7 was downregulated on days 2 and 4 to 6 (P < 0.001). RUNX2 was downregulated on days 2 and 5 (both P < 0.001). Cells in both groups were proliferating, and no negative effect on cell viability was observed. CONCLUSION: Results suggest high molecular activity up to 6 days, therefore introducing further need for in vitro studies with a longer duration that would explain other genes and metabolites involved in orthodontic tooth movement (OTM). CLINICAL RELEVANCE Extension of an established in vitro force application system for prolonged force application (6 days) simulating the initial phase of OTM.