Avaliação histométrica do reparo de defeito ósseo em calvária de rato após implante de rhMMP-2 ligada à monoleína

Abstract

Matrix metalloproteinases (MMPs) are zinc-dependent proteolytic enzymes that degrade extracellular matrix components, facilitating cell migration and tissue remodeling. MMPs secreted by osteclasts are important in the physiological bone resorption as in pathological bone degradation. However, the essentially bone absorbing hole of MMPs, particularly of the MMP-2, has been questioned in recent years by studies that show its importance in osteoblastic cells differentiation and in vitro bone formation. Therefore, the MMP-2 may have also an important hole in reparational bone formation. The purpose of the present study was to investigate the pretense osteostimulatory effect of the rhMMP-2 linked to monoolein (used as a carrier) implanted into rat calvarial defects. Bone defects of 4mm in diameter were created unilaterally in rats calvaria and filled with natural blood clot (control), monoolein or rhMMP-2 linked to monoolein. The animals were killed 2 and 4 weeks postoperatively and the rate of new bone formation was estimated in histological sections by a histometric differential point-counting method. The rate of reparational bone formation was similar in the animals from control and monoolein groups and was significantly greater in the MMP-2 group, in both periods. From the results it may be concluded that monoolein did not interfere with the reparacional process and seemed effective as a rhMMP-2 carrier. In addition, the results add evidence to the importance of MMP-2 activity for bone formation, in an in vivo bone healing experimental model.