Deletion of the gelatinase MMP-2 affects the compositional and biomechanical properties of bone

While determinants independent of bone mass have been identified for bone strength and toughness, little is known about genetic regulation of these factors, referred to collectively as bone quality. In the present work, using a mouse model, we investigated whether the deletion of the gene coding for matrix metalloproteinase-2 (MMP-2) could affect the structural, compositional, and biomechanical properties of cortical bone. Analysis by micro-computed tomography of the femur of 8-week and 16-week old, male mice revealed that the loss of MMP-2 caused thinner cortices but had no effect on moment of inertia. Regardless of age, the MMP-2 null femurs had lower modulus and strength than the wild-type femurs. This effect was likely related to the decrease in bone mineral density and mineral-to-collagen ratio that was observed for the knock-out femurs. Enzymes important for the turnover of collagen may be important to bone quality.