Interaction between rhBMP‐2 and different types of bone grafts (922.18)

Abstract

This study evaluated the bone healing process in surgical defects on rat skulls using different bone grafts, associated or not with rhBMP ‐2 (5 µg).It was used 112 rats (♂, 250g) euthanized at 4 or 6 weeks, divided into 8 groups: G1. autologous bone graft; G2. homologous bone graft; G3. heterologous bone graft (lyophilized bovine bone); G4. autologous bone graft + rhBMP‐2; G5. homologous bone graft + rhBMP‐2 and G6. heterologous bone graft + rhBMP‐2; G7. rhBMP‐2; G8. surgical bone defect. The following methodologies were used for evaluation of the new bone formation: histological, radiographic, immunohistochemical, zymographic, and mineral quantity (Ca).After 4 weeks, the zymographic analyses revealed increased production of MMP‐2, the MMP‐9 levels remained consistently in both surgical times. The G1 group shows better results, followed by G2 and G3 respectively, however the addition of rhBMP‐2 on the graft (G4, G5, G6) does not appear to influence the MMP‐2 and MMP‐9 levels. The Ca dose revealed that G1 and G2 were the most mineralized, the other groups had lower Ca levels that decreasing after 6 weeks. The histological and radiographic analyses demonstrated that the bone grafts improve the bone repair specially when associated with rhBMP‐2, increasing the new bone formation after 4 and 6 weeks, without significant statistical differences between G4, G5 and G6. Immunohistochemistry for osteogenic and angiogenic growth factors showed positive identification for all groups, particularly for G4 , G5 and G6.