[Reconstruction of critical sized calvarial defects by porous nano-hydroxyapatite/polyamide 6 composite with bone marrow mesenchymal stem cells in rat].

Objective To evaluate the effects of the nano-hydroxyapatite/polyamide 6(n-HA/PA6) on the proliferation and osteoblastic differentiation of rat bone marrow mesenchymal stem cells(BMSCs),and the feasibility of using both for constructing tissue engineered bone in the calvarias of rats with critical sized defects.Methods The third passage of BMSCs were cultured in osteoblastic medium and seeded on the scaffolds of n-HA/PA6,the proliferation of the BMSCs was tested by MTT(3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazolium-bromide) on scheduled dates,and the osteoblastic differentiation of the BMSCs were measured by alkaline phosphatase(ALP) staining.Furthermore,the scaffolds with or without BMSCs in rat calvarial defects,after 4 weeks,8 weeks,and 16 weeks have been implanted.Histology and scanning electron microscope were used to test the bone healing in the different groups.Results The BMSCs seeded on the n-HA/PA6 grew well,the proliferation of cells was not affected by the scaffold,and the staining of ALP was also positive.At 4 week and 8 week after implantation,the n-HA/PA6 with BMSCs showed more new bone formation on the surface of scaffolds,with a better osseointegration of implant and host bone when compared with the group of n-HA/PA6 without BMSCs.However,there was no significant difference between these two groups at 16 week.Conclusion The porous n-HA/PA6 has no negative effects on the proliferation and osteoblastic differentiation of rat BMSCs,and using BMSCs as seed cells and n-HA/PA6 as scaffolds is a good choice for constructing tissue engineered bone due to the enhanced new bone formation and osseointegration.