[Repair of calvarial defect using a tissue-engineered bone with simvastatin-loaded β-tricalcium phosphate scaffold and adipose derived stem cells in rabbits].

Purpose: The osteogenic-angiogenic differentiation effects of simvastatin (Sim) were explored on adipose tissue-derived stem cells (ASCs). A tissue-engineered bone with simvastatin loaded β-tricalcium phosphate (β-TCP) scaffold and ASCs was constructed to repair the calvarial defect in rabbits.

Methods: ASCs were obtained from the groin of rabbits. After 14 days of osteogenic inducing culture, sufficient cells were expanded for the following experiments. Cell counting was conducted to ASCs in osteogenic inducing medium containing 0, 0.01, 0.1 and 1 μmol/L simvastatin. Concentrations of 0.05 and 0.1 μmol/L simvastatin were administrated to ASCs for real-time PCR of angiogenesis-osteogenesis related genes like RUNX2, OPN, OCN, and VEGF on day 1, 7. ALP staining was performed on day 7, Alizarin red staining for calcium deposits was carried out on day 14. Bilateral critical-sized defects were created on 12 New Zealand rabbits. Four groups of tissue-engineered bone were randomly allocated to them. Group A: β-tricalcium phosphate (β-TCP) (n=6); group B: β-TCP/Cell (n=6); group C: β-TCP/Sim (n=6); group D: β-TCP/Cell/Sim (n=6). Specimens were decalcified and stained by HE 8 weeks after operation. The data was statistically analyzed using SPSS 17.0 software package.

Results: The use of simvastatin with the concentration of 0.05 μmol/L enhanced the expression of angiogenic-osteogenic related genes like RUNX2, OPN, OCN, and VEGF. ALP activity and von Kossa were significantly stronger in osteogenic inducing medium containing 0.05 μmol/L simvastatin. The new bone formation area of β-TCP/Cell/Sim group at 8-week after implantation was significantly larger than the other groups.

Conclusions: 0.05 μmol/L simvastatin enhances the angiogenic-osteogenic differentiation of ASCs. Simvastatin loaded β-TCP scaffold and ASCs successfully repair the calvarial defect in rabbits. These results indicate a promising future in application of simvastatin for bone regeneration.