Expression of TGF-beta in region of bone defect repaired by collagen/nano-beta-tricalcium phosphate composite artificial bone.

The distribution and function of transforming growth factor-beta (TGF-beta) in the region of bone defect repaired by collagen/nano-beta-tricalcium phosphate composite artificial bone (Co/N-TCP) and the ability of Co/N-TCP recruiting osteoblasts to precipitate the repair of bone defect were investigated. Twenty-four domestic rabbits were operated on bilateral cranial bone to create an experimental bone defect of 8.0 mm in diameter through the whole bone. On the left, Co/N-TCP was implanted as experimental group, but on the right, Co/TCP was implanted as control group. At 2nd, 4th, 8th, 12th week after operation, all animals were sacrificed and the implanted materials with surrounding bone were taken out. Immunohistochemical staining was performed for TGF-beta assay by avidin-biotin complex method (SABC). Simultaneously, TGF-beta was quantitatively analyzed by HPIAS-1000 imaging analysis system. The immunohistochemical staining for TGF-beta revealed that osteoblasts and immature osteocytes highly expressed TGF-beta. Diffused TGF-beta positive staining particles appeared in the mesenchymal and fibrous-tissue. There was no significant difference in the TGF-beta positive staining between two groups in the medial region to original osseous beds at different time points (P > 0.05). However, in distal original osseous bed of the defected region, the positive expression of TGF-beta in the Co/N-TCP group was significantly stronger than in the control group (P < 0.05 or 0.01). The Co/N-TCP has good bioactivities and ability of stimulating and conducting TGF-beta to aggregate and precipitate the healing of bone defect.