Human adipose-derived stem cells and simvastatin-functionalized biomimetic calcium phosphate to construct a novel tissue-engineered bone

To repair bone defects, we evaluate the in-vitro and in-vivo osteogenic activities of a novel tissue-engineered bone (TEB) by elaborately combining biomimetic calcium phosphate (BioCaP) granules with internally-incorporated simvastatin (SIM) and human adipose-derived stem cells (hASCs). First, we constructed BioCaP with SIM internally incorporated (SIM-BioCaP). Then we characterized the morphology and chemical composition of SIM-BioCaP. The release kinetics of SIM was monitored in vitro spectroscopically. Thereafter, we explored the in-vitro cellular responses of hASCs to SIM-BioCaP by performing scanning electron microscopy observation, proliferation assay, alkaline phosphatase (ALP) activity assay, alizarin red staining and real-time PCR. Finally, we investigated the in-vivo osteogenic activities of the novel TEB in a subcutaneous bone induction model in nude mice. We found that SIM was successfully incorporated internally in BioCaP and showed a slow release manner without significantly affecting the attachment and proliferation of hASCs. The released SIM from BioCaP could significantly enhance the proliferation, ALP activities, mineralized nodules formation and osteogenic genes of hASCs. The in-vivo tests showed this TEB could induce new bone formation while the other groups could not. Taken together, the present data show that this novel TEB represented a very promising construct to treat critical-volume bone defects.