Effects on Mineralisation Potential of Human Osteoblasts Induced by Simvastatin

Introduction: Simvastatin (SV) is a member of the statin family. As an HMG-CoA reductase inhibitor, it is a therapeutic agent for lowering blood cholesterol. Various pleiotropic effects have been reported for SV. Some of them are anti-inflammatory effects and SV stimulates angiogenesis. Proven by animal experiments, SV promotes osteoblast proliferation and differentiation; additionally, a suppression of osteoclastic action has been reported. Methods: This cell culture study analysed the effects of SV on 20 primary mandibular osteoblast cell lines. SV concentrations of 0.01 up to 1 µM were used. Control groups were untreated cells of the specific cell line. The commonly applied clinical dosage ranges from 5-40 mg/d, which matches a systemic SV concentration of 0.05 - 5.0 µM. Effects on cell proliferation (MTT), osteogenic activity (ALP), and the mineralisation rate (alizarin red S quantification) were analysed on day 9, 13, and 16. The sample size per concentration and cell line was 3 for ALP and alizarin red S. The sample size for MTT was 6 per concentration and cell line. Data were not distributed normally, and thus statistical analysis was performed using the Kruskal-Wallis Test at p0.05. Results: The determination of mineralisation relative to the proliferation on day 16 showed a significant increase of 1 µM SV compared to the control (p=0.00001), 0.05 µm SV (p=0.000002), 0.01 µM SV (p=0.000016) and 0.5 µM SV (p=0.06). Additionally, 0.5 µM SV caused a significant increase compared to 0.05 µM SV (p=0.040). On day 16 the SV concentration of 0.5 µM SV showed a significant decrease in the conversion of the alkaline phosphatase relative to the total protein compared to the control (p=0.044), 0.01 µM (p=0.028), and 0.05 (p=0.028). Conclusion: Although observed effects differ in strength between different primary osteoblast cell lines, SV enhanced the conversion of the alkaline phosphatase relative to the total protein, which shows an increased osteogenic activity and mineralisation potential. The stimulation occurred within common clinically applied dosages. The increased mineralisation potential which can be found in higher SV concentrations is limited by the conversion rate of alkaline phosphatase relative to the total protein. Concentrations between 0.05 µM SV and 0.1 µM SV seem to be beneficial for mineralisation. On the other hand, this stimulation may have negative effects elicited by a possible unintentional bone mineralisation. Keywords: mineralisation, osteoblasts, osteogenic effect, simvastatin