The Role Of The PDGF And The Study Of Its Correlative Mechanisms In The Earlier Period Of Fracture Repair In Vivo

Objective: To study the effect of platelet-derived growth factor (PDGF) in cartilage formation after fracture, and investigat its mechanisms on bone fracture healing, in order to find out the role of PDGF in bone remodeling. Methods: 30 male Wister rats were divided into 1, 2, 4 weeks groups (n=10). each rat was operated to cause a 3mm massive segmental bone defects in its both right and left radius. Radidal defects in the rats?right radius were treated with PDGF-AB(n30),left side were treated with 0.9% saline (n=3 0). The first, the neonate callus formation in bone defects areas were observed with skeletal X way and HE staining; the secondly, the bone mineral density in the regions of defects were quantitated by using DEXA; the last, the stimulation of PDGF in the earlier period of bone healing was assessed and its some mechanisms in the course of cartilage formation were analysised with immunohistochemical method and in situ hybridization technique. Results: 1. It was found that cartilage and bone decelopment in the PDGF groups were better than those in the saline groups by X-gram and HE staining. The bone mineral density of the neonate callus in PDGF groups were higher than that in saline groups (P<0.05-0.0l). These findings indicate that PDGF accelerated the new bone formation. 2. The expression of Proliferating Cell Nuclear Antigen (PCNA), C-FQS, and C-JUN were of concordance. In the PDGF groups, we demonstrated 4 strong and widespread expression of PCNA, C-FQS, C-JUN proteins and C-FQS gene in mesenchymal cells and chondrocytes; in the saline groups, the expression of these proteins and RNA in mesenchymal cells and chondrocytes were relatively low levels. Significant increase and elevation in the levels of staining for PCNA, C-FOS, C-JUN proteins expressed by mesenchymal cells and chondrocytes in PDGF groups were found compared to those in saline groups (P