Prevascularization of tissue-engineered bone grafts promotes repair of femoral bone defects in rats

Objective To investigate the effect of prevascularized tissue-engineered bone graft on regeneration of femoral bone defects in rats. Methods Models of femoral bone defect were created at the bilateral hind limbs of 20 healthy female 10 week-old rats which were divided into 2 even groups randomly (n=10). In group A, conventional tissue-engineered bone grafts were transplanted into the femoral bone defects; in group B, tissue-engineered bone grafts and vascular bundles were implanted into the femoral defects. At 1, 4 and 8 weeks after operation, 3 rats were sacrificed each time in each group to harvest samples. The remaining one in each group served as a spare animal. Regeneration of bone defects and degradation of scaffolds were assessed by radiologic modality and hematein eosin staining. Results At week 1, the new bone ratio (BV/TV) was 5.47%±1.90% in group A and 8.49%±1.26% in group B, showing no significant difference (P >0.05); at weeks 4 & 8, the BV/TV were 17.54%±2.04% and 39.73%±4.01% in group A, significantly lower than those in group B (25.32%±2.15% and 53.22%±2.94%) (P 0.05). At week 8, the scaffold degradation ratio in group A (65.46%±4.51%) was significantly higher than that in group B (50.19%±4.91%) (P< 0.05). At week 8, hematein eosin staining showed better integration of scaffolds with the femur, faster degradation of the interior scaffolds and greater osteogenetic activity in group B. Conclusion Prevascularization of tissue-engineered bone graft may increase new bone volume and scaffold degradation rate, promoting repair of femoral bone defects in rats. Key words: Femur; Bone defect; Model, animal; Tissue engineering bone; Prevascularization