Osteogenic Differentiation Of Rat Bone Marrow Mesenchymal Stem Cells Cultured On Nano-hydroxyapatite/polyamide 66 Scaffold In Vitro

Objective: To investigate the effects of the three dimensional composite scaffold nano-hydroxyapatite/polyamide 66(n-HA/PA 66) structure on the proliferation and osteogenic differentiation of the rat bone marrow mesenchymal stem cells(BMSCs), as well as its ascendancy and limitations employed as bone tissue engineering scaffold, so as to provid theoretical support for further refining and clinical applications. Methods: The n-HA/PA 66 scaffolds were seeded with BMSCs and cultured in the osteogenic medium under static condition or in a dynamic perfusion bioreactor. Same amount of cells were seeded and statically cultured on plates as a control. The proliferation and differentiation of BMSCs in this study were examined by the MTT assay, alkaline phosphatase (ALP) activity and scanning electronic microscopy (SEM). Results: The MTT curves of both static and dynamic culture appear a steadily rising trend while a decline was found in control group after day 14. The ATP activity of the 3 groups reached their peak at day 7 and little difference was found between static and dynamic group. The OCN expression of dynamic culture was higher than that of the static's at day 14 and 21. Being quite identical from the cell blanket structure in static culture, the SEM image of the dynamic culture showed 3-D structure formed by BMSCs. Conclusions: The results indicated that the caffold could improve BMSCs proliferation at day 14 and 21 as compared with 2-D culture. At the early stage, the dynamic perfusion did not necessarily improve BMSCs proliferation on the scaffold structure compared with static culture, but contributed to the osteogenic differentiation and bone matrix formation of BMSCs.Based on these findigs, the newly developed composite scaffold nano-hydroxyapatite/ polyamide 66 with 3-D microstructures had excellent capacabilty of biocompatibility and osteoconduction, and that it can be employed as bone substitute scaffold material in the clinic. However, this pilot study in vitro needs futher investigation in future animal experiments.