BACKGROUND: Treatment of large bone defects is an important problem faced by orthopedic physicians. Allogeneic bone transplantation is a classic method, but it has many restrictions. The membrane guided bone regeneration technique has become an important method for the research nowadays.OBJECTIVE:To compare the effects of self-made high strength biodegradable nano-hydroxyapatite/multi(amino acid) copolymer (n-HA/MACP) guided bone regeneration membrane tube and allograft bone graft segment in the repair of large segmental bone defect in goats. METHODS: The model of 30 mm large segment bone defect in the middle section of the femur in 32 adult goats was established. Experimental group used self-made n-HA/MACP tube to bridge defects following bone plate fixation. The control group was treated with allograft bone graft bone segments combined with plate fixation. The animals were sacrificed at 4, 8, 12 and 16 weeks after operation, and the bone callus growth was observed in the specimens. The X-ray and histological observations were performed at the same time. Biomechanical measurement of plate fixation of allograft cortical bone segment was done at 12 and 16 weeks after operation. RESULTS AND CONCLUSION: (1) After 4 to 16 weeks, gross and pathological results showed fibrous callus growth inside and outside of the membrane tube, and the fibrous callus gradually hardened into a bony callus. Additionally, the callus was larger in the experimental group than in the control group. X-ray films showed significantly increased lateral callus density in the experimental group as compared with the control group. (2) Maximum bending strength was significantly higher in the experimental group than in the control group at 16 weeks (P < 0.05). Overall, the n-HA/MACP membrane tube used for bridging large segment bone defects in goats can obtain similar repair effects to the allograft cortical bone, and further achieve the better mechanical strength of the new bone segment than the allograft bone.

Objective:To study the differentiation capacity of the fibroblast-like cells isolated from human skin dermis into mesenchymal stem cells, and to explore the feasibility to use these cells as alternative cell source of autologus bone marrow mesenchymal stem cells (BMSCs ) for regeneration of tissue inj uries and defects. Methods:Full thickness skin samples were obtained from the abdomen of surgical patients, then digested with dispase and collagenase Ⅰ subsequently. Thereafter, the digested cells were collected and cultured, followed by suspension with serum free medium containing N2,B27,basic fibroblast growth factor (bFGF),and epidermal growth factor (EGF).The skin dermis derived spheroids (SDDSs)were collected and monolayer cultured in serum-containing medium.Finally,the cells were characterized by immunofluorescence staining and differentiation assays.Results:The dermis derived cells proliferated and formed SDDSs in the suspension of serum-free medium. After monolayer cultivation in serum-containing medium, the cells from spheroids were successfully expanded to large number. The cells expressed mesenchymal stem cells markers CD90, CD105 and vimentin. Under osteogenic,chondrogenic and adipogenic differentiation conditions,these cells were differentiated into the alizarin red,safranin O, and oil red O staining positive cells, displayed similar differentiation traits with BMSCs. However,safranin O staining was weaker in the dermis derived cells than BMSCs. Conclusion:A kind of fibroblast-like cells exist in human skin dermis, and have osteocytic, chondrogenic and adipogenic differentiation potentials,demonstrating that these cells will be utilized as a novel cell source for repairing the tissue injury and defect in clinic.