Expression of tissue inhibitor of metalloproteinase during early stages of bone graft healing.

The aim of this study was to investigate the temporal expression of TIMP-1 within endochondral and intramembranous bone grafts during the early stages of healing in thirty six adult New Zealand white rabbits. Total RNA was isolated from bone grafts extracted on days 0-11 and day 14 post-grafting, for RT-PCR analysis. In situ hybridization was carried out on days 1-9 and day 14. Results showed TIMP-1 expression coincides with osteogenesis, which indicates a role for TIMP in preserving the newly formed bone during the initial stages of graft healing. Bone grafts play an important role in influencing the healing process mediated by the host tissues. The temporal expression of TIMP-1 differs in endochondral and intramembranous bone grafts. The earlier expression of TIMP-1 by endochondral bone grafts, could be the reason for the delayed vascularization while the expression of TIMP-1 by the intramembranous bone grafts, at a later stage could allow for earlier vascularization.