The Effect Of Endothelial Progenitor Cells On Neovascularization During Nonvaseular Transport Distraction Osteogenesis

Object:To investigate the effect of local transplantation of EPCs on neovascularization during canine mandible nonvascular transport distraction osteogenesis(NTDO), and the role of VEGF and bFGF in this surgical model.Methods:Twelve healthy dogs were randomly divided into two groups with six dogs in each group:EPCs group(NTDO with EPCs transplantation); control group(NTDO alone). Mandibular nonvascular transport distraction osteogenesis was performed on all subjects. EPCs group injected with EPCs locally in distraction gap while control group injected with normal saline of equal volume. Three dogs in each groups were euthanized after 1 and 2-week consolidation. New soft tissue and bone formation and reconstruction measured by general view and X-ray; H&E dyeing and IHC of CD 105 were used to exam the structure of new blood vessels in distraction gap; expression of VEGF and bFGF were measured by immunohistochemistry, RT-PCR and Western Blot.Result:All the animals underwent the surgery of NTDO and distracting courses without halfway death, wound infection, distraction device or titanium nails falling off.General observation:After 1-week and 2-week consolidation, new soft tissues was observed in distraction region, while no bone formation was observed. New capillaries were found at the surface of the soft tissues.X-ray:After 1-week and 2-week consolidation, distraction region of each group showed low density image, no high density image was observed. The boundary between distraction gap and bone line or transport disc was clear.H&E dyeing:After one-week and two-week consolidation, granulation tissues were observed in both groups with mesenchymal-like cells. There were a great quantity of collagen fibers and blood capillaries without osteogenesis. Granulation tissues were more mature and collagen fibers thicker in EPCs group than in control group.Microvascular density:Result of microvascular density detected by IHC of CD 105 showed that the microvascular density in EPCs group were higher than that in control group no matter after one-week or two-week consolidation(P< 0.05), and in both groups microvascular density in one-week consolidation were higher than that in two-week consolidation(P<0.05).Expression of VEGF:The level of VEGF expression detected by immunohistochemistry, RT-PCR and Western Blot in EPCs groups was higher than that in control group(P<0.05), and the expression level in all groups after 1-week consolidation was higher than the level after 2-week consolidation(P< 0.05).Expression of bFGF:The level of bFGF expression detected by immunohistochemistry, RT-PCR and Western Blot in EPCs groups was higher than that in control group(P<0.05), and the expression level in all groups after 1-week consolidation was higher than the level after 2-week consolidation(P< 0.05).Conclusion:Our research prove that neovascularization during canine mandible nonvaseular transport distraction osteogenesis may be improved by local transplantation of EPCs, and VEGF and bFGF may play an important role during the procedure.