Simvastatin induces apoptosis and disruption of the actin cytoskeleton in human dental pulp cells and periodontal ligament fibroblasts

ObjectiveSimvastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, and widely used as cholesterol-lowering agent, has been suggested for its beneficial effects on alveolar bone formation, regeneration of dental pulp tissue and periodontal ligament. High doses of simvastatin appear to induce apoptosis in several cell types, but little is known about its possible effect on tooth-associated cells. Therefore, the effects of simvastatin were studied on apoptosis and cell morphology of human dental pulp cells (HDPCs) and periodontal ligament fibroblasts (HPLFs).MethodsHDPCs/HPLFs obtained from 4 patients were cultured with or without various concentrations of simvastatin (0.1, 1, and 10 μM) for 24, 48, and 72 h. The 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was performed to evaluate cell viability. The levels of apoptosis of HDPCs and HPLFs were measured by flow cytometry after Annexin V/propidium iodide double staining. Phalloidin-FITC and 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining was used to examine differences in the actin cytoskeleton and nuclear morphology, respectively.ResultsThe viability of HDPCs and HPLFs was significantly reduced after simvastatin treatment in a dose- and time-dependent manner (p < 0.05). The apoptosis of HDPCs and HPLFs was significantly increased in 10 μM simvastatin-treated cells (p < 0.05). The effect on apoptosis was comparable for HDPCs and HPLFs. Nuclear staining showed typical apoptotic nuclear condensation and fragmentation in simvastatin-treated HDPCs/HPLFs. A dose- and time-dependent simvastatin-induced disruption of the actin cytoskeleton was observed in both cell types.ConclusionOur data demonstrated that simvastatin decreases the viability of HDPCs and HPLFs, probably by inducing apoptosis.