BACKGROUND:Nano-hydroxyapatite/collagen (NHAC) is an ideal substitute for tissue engineered stent. Vascular endothelial growth factor (VEGF) is a kind of growth factor that can promote vascularization and slowly release NHAC. This indicated a good bone tissue repair function. OBJECTIVE:To investigate the effect of NHAC combined with VEGF in repairing bone defects. DESIGN,TIME AND SETTING:The randomized controlled animal study was performed at the Animal Laboratory,Xiangya Medical College,Central South University from October 2008 to January 2009. MATERIALS:Nano-hydroxyapatite powder and collagen protein powder were mixed and prepared into NHAC artificial bone according to the ratio of 8:2. 2 ?g of VEGF and NHAC were mixed and prepared into NHAC/VEGF artificial bone according to the ratio of 1.8:1. Each artificial bone contained 0.5 g nano-hydroxyapatite powder,0.125 g collagen protein and 150 ng VEGF. METHODS:Thirty-six healthy rabbits whose left radiuses were cut off 1 cm were divided into three groups. The wounds of the rabbits in blank group were sewed up directly without any treatment of the bone. The bone defects of the rabbits in NHAC group were repaired with NHAC artificial bones and the NHAC/VEGF group with NHAC/VEGF artificial bones. MAIN OUTCOME MEASURES:After 2,4 and 8 weeks,4 rabbits in each group were killed to evaluate whether they have significant differences of bone healing according to general observation,radiograph,pathological section and bone density test. RESULTS:Radiograph showed that osteotylus growth and the repairing of bone defects in the NHAC/VEGF group were better than in the blank group and NHAC group. It was better in the NHAC group than in the blank group. The difference in bone density of two groups in the same time was significant (P