[Expression of vascular endothelial growth factor and microvessel density in rabbit radius defects repaired with...

To investigate the expression levels and significance of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in rabbit radius defects repaired with allogeneic and autogenic bone.

Forty adult New Zealand rabbits were chosen, and 10 mm bone defect model was created in the bilateral radii of 28 experimental rabbits. The other 12 rabbits provided allogeneic bone under the standard of American Association of Tissue Bank. In the left side, allogeneic bone were used to repair bone defect (experimental group), equal capacity autogenous iliac bone was used in the right side (control group). Animals were sacrificed at 2, 4, 8, and 12 weeks postoperatively. Immunohistochemical method was used to determine the expression of VEGF, CD34 protein and MVD counting. Bone histomorphometric parameters, including percent trabecular area (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular separation (Tb.Sp) were measured by von Kossa staining undecalcified slices. The relation was analyzed between VEGF and MVD, histomorphometric parameters.

The positive signals of VEGF protein were detected in cytoplasm of vascular endothelial cells, chondrocytes, osteoblasts, fibroblasts and osteoclasts. At 2 weeks, there was no significant difference in VEGF protein expression between experimental group and control group (P > 0.05); at 4 and 8 weeks, the expression of VEGF in control group was significantly higher than that in experimental group (P < 0.05); and at 12 weeks, there was no significant difference between two groups (P > 0.05). There was a positive correlation (P < 0.01) between VEGF expression and MVD value in two groups at 2, 4, 8, and 12 weeks postoperatively. There was no significant difference in bone histomorphometric parameters (BV/TV, Tb.Th, Tb.N, Tb.Sp) between two groups at 12 weeks postoperatively (P > 0.05), but there was a positive correlation between VEGF expression and parameters of BV/TV, Tb.Th, and Tb.N (P < 0.01); and a negative correlation between VEGF and Tb.Sp (P < 0.01).

VEGF can express diversity at different time and positions, and the different expressions indicated various biology significances in the process of the bone healing. It can coordinate growth of cartilage and bone and profit vascular reconstruction of allogeneic bone. VEGF may participate in promoting osteogenesis in the course of allogeneic bone transplantation.