Formation of collagen in osteogenesis induced by bone morphogenetic protein and the promoting effect of transforming growth factor β_1 in the event

Objective To explore the change rules of hydroxyproline(HP) and hydroxylysine(HL) in osteogenesis induced by bone morphogenetic protein (BMP) and the effect of transforming growth factor β 1 (TGF-β 1) in the collagen secretion for the mechanism of osteogenesis induced by BMP and the regulative mechanism of TGF-β 1 in bone reparation. Methods An experimental model of 12 mm defect in the left ulna of rabbits was adopted. The rabbits were divided into experimental group, control group and blank group at random. BMP/TGF-β 1/carrier(experimental group), BMP/carrier(control group) and carrier only(blank group) were implanted into bone defect respectively. Contents of HP and HL in the defect area were measured in the 1st, 2nd, 3rd, 4th and 5th week after implantation. VG staining for collagen, histological image analysis and electron microscopy observation were performed. Results Comparing with control group and blank group, more HP, shorter chondrogenesis time, more osteoblasts, earlier appearance of type Ⅰ collagen and obviously higher total osteogenic collagen contents were observed in experimental group. Conclusion TGF β 1 plays a role in improving bone formation in the courses of BMP inductive osteogenesis. It also shortens chondrogenesis time and stimulates bone healing through promoting osteoblast differentiation and proliferation, elevating type Ⅰ collagen secretion as well as inhibiting the synthesis of type Ⅱcollagen of chondrocytes. BMP and TGF-β 1 might have synergic effect in bone repair.