Design and In Vitro Evaluation of Simvastatin-Hydroxyapatite Coatings by an Electrochemical Process on Titanium Surfaces

The aim of this study was to deposit simvastatin-hydroxyapatite (sim-HA) coatings on titanium surfaces by an electrochemical process and evaluate osteoprogenitor cell responses to sim-HA-coated surfaces. Simvastatin was prepared onto titanium surfaces with varying concentration (10^–7, 10^–6, 10^–5 and 10^–4 mol/L). Surface characteristics were per- formed by FSEM, XRD and FTIR. LC-MS/MS method was used for simvastatin quantification in Sim-HA-coated surfaces. Murine calvaria-derived pre-osteoblastic cell (MC3T3-E1) proliferation, alkaline phosphatase activity (ALP) and osteocalcin release were used to measure osteoblastic activities. FSEM observation showed rod-like HA crystals covered on all sur- faces. As drug concentration increased, the crystal diameter decreased. XRD and FTIR observations showed all coatings consisted of HA. LC-MS/MS test showed the simvastatin concentration in 10^–6 mol/L group was 2.77 × 10^–7 mol/L/cm², while in 10^–7 mol/L group was 1.89 × 10^–7 mol/L/cm². MC3T3-E1 cells grown on 10^–7 mol/L and 10^–6 mol/L Sim-HA surfaces showed increased ALP activity as compared to HA-coated surfaces on day 7 (P < 0.05) while at 10 day, all Sim-HA groups were significantly increased than HA group (P < 0.05). Two Sim-HA groups showed significant increases in osteocalcin production on 7 10 and 14 day (P < 0.05). It showed that incubation with 10^–7 mol/L simvastatin enhanced the cell proliferation to a statistically significant extent (P < 0.05) compared with the HA group at day 7. It was concluded that simvastatin was successfully deposited into HA coatings using the electrochemical process and the sim-HA coatings enhanced differentiation of osteoprogenitor cells.