In Vitro Evaluation of the Nano-Hydroxyapatite/Hydrogel Compound and Its Combination with BMP7 Transfected Bone Marrow Mesenchymal Stem Cells

Objective: To evaluate the validity of a type of nano-hydroxyapatite/hydrogel compound named FlexBone for bone formation in vitro. Methods: The nano hydroxyapatite (HA) was combined with Poly(2-hydroxyethyl methacrylate) or pHEMA to construct the FlexBone. Then the BMP7 gene-modified BMSCs were used as seed cells and cultured on the scaffold. The effects of BMP7 on osteogenic differentiation of BMSCs on the material were evaluated in vitro. In addition, the duration of the BMP7 release and biomechanical properties of the FlexBone were also evaluated. Results: The results of MTT and Fluorescence microscopy showed good proliferation and growth of BMP7 gene-modified BMSCs on the scaffold. The ALP activity and RT-PCR tests demonstrated that the BMP7 can significantly facilitate osteogenic differentiation of BMSCs cultured on the FlexBone composites. The western blot analysis indicated that BMP7-BMSCs/FlexBone composites can provide a sustained release of BMP7 for at least 3 weeks. The compression test found that the FlexBone composites can bear high compressive loads and strains without brittle fractures. Conclusion: The FlexBone composite could be used as a promising bone tissue engineering scaffold and BMP7 gene-modified BMSCs as seed cells can provide a sustained delivery of the bioactive factor to significantly expedite bone regeneration.