Effect of endothelial progenitor cells mobilization on the healing of calvarial defect in diabetic mice

Abstract

To evaluate the effect of endothelial progenitor cells (EPCs) mobilization on the healing of calvarial defect in diabetic mice. 55 type II adult male diabetic mice were included in this study. They were randomly divided into three groups: the non-operative group (n = 5), the experimental group (n = 25) and the control group (n = 25). Two circular bony defects, 3 mm in diameter, were created on the parietal bones of the diabetic mice. Intraperitoneal AMD3100 (10 mg/kg; n = 25) or sterile saline (control group) was administered daily beginning at post-operative day 3 and continuing for 15 days. 5 mice were sacrificed in each group at non-operation, post-operative week 1,2,4, 8,12. Circulation EPC level was measured at pre-operation, post-operative day 7 and day 14. Bony regeneration was assessed with micro-CT at post-operative week 4, 8 and 12. HE staining was performed on all the decalcified bone samples. Immunofluorescent CD31 and osteocalcin staining was performed on calvarial defects at weeks 1, 2, and 4 to assess the vascularity and osteoblast density, respectively. The mobilization of EPC in diabetic mice almost disappeared one week after trauma, while AMD3100 could dramatically increase the circulation EPC level for a long time after trauma. Compared to control group, the healing percentage of bony defect in the diabetic mice treated with AMD3100 was obviously increased at post-operative week 8 (50.5% vs. 34.8%) and week 12 (50.9% vs. 40.2%). Calvarial defects of AMD3100-treated mice harvested at 1, 2, and 4 weeks demonstrated increased vascularity and osteoblast density, compared to the controls. The difference was most marked in postoperative week 2 (vascularity: 6.11% vs. 2.47%; osteoblast density 2.81% vs. 1.22%, P < 0.01). AMD3100 can improve the healing of calvarial defect in diabetic mice by increasing the vascularity and osteoblast density at the regeneration area.