[Repair of calvarial defect using a tissue-engineered bone with simvastatin-loaded ß-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 ß-tricalcium phosphate (ß-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: ß-tricalcium phosphate (ß-TCP) (n=6); group B: ß-TCP/Cell (n=6); group C: ß-TCP/Sim (n=6); group D: ß-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 ß-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 ß-TCP scaffold and ASCs successfully repair the calvarial defect in rabbits. These results indicate a promising future in application of simvastatin for bone regeneration.

Osteogenic potential of bone marrow stromal cells derived from streptozotocin-induced diabetic rats.

Type 1 diabetes mellitus (T1DM) is associated with a series of bone complications, which are still a great challenge in the clinic. Bone marrow stromal cells (BMSCs) are crucial to bone remodeling and are attractive candidates for tissue engineering. Hence, we aimed to investigate whether impaired functions of BMSCs play a role in the pathogenesis of bone complications associated with T1DM. BMSCs were isolated from normal and streptozotocin-induced diabetic rats, and their proliferation and osteogenic differentiation ability were analyzed. Diabetic BMSCs demonstrated reduced proliferation ability, osteoblast gene expression, alkaline phosphatase activity and mineralization. Nude mice transplanted with diabetic BMSCs in a calcium phosphate cement scaffold exhibited reduced new bone formation, as detected by hematoxylin and eosin staining and immunohistochemistry. These changes may be partially related to impaired insulin and insulin-like growth factor 1 (IGF-1) signaling. Weak gene expression of insulin receptor (IR), IGF-1, insulin-like growth factor 1 receptor (IGF-1R), and insulin receptor substrate-1 (IRS-1) was observed in the diabetic BMSCs compared with normal BMSCs, together with decreased protein level of IGF-1, IGF-1R, IRS-1 and phosphorylated extracellular signal-regulated kinase. Therefore, impaired proliferation and osteogenic potential of BMSCs may be responsible for bone complications related to T1DM, mediated partially by impaired insulin and IGF-1 signaling. These findings may provide a new target with which to devise strategies for therapy.