Overexpression of DMP1 accelerates mineralization and alters cortical bone biomechanical properties in vivo

Dentin matrix protein-1 (DMP1) is a key regulator of biomineralization. Here, we examine changes in structural, geometric, and material properties of cortical bone in a transgenic mouse model overexpressing DMP1. Micro-computed tomography and three-point bending were performed on 90 femora of wild type and transgenic mice at 1, 2, 4, and 6 months. Fourier transform infrared imaging was performed at 2 months. We found that the transgenic femurs were longer ( p < 0.01 ), more robust in cross-section ( p < 0.05 ), stronger ( p < 0.05 ), but had less post-yield strain and displacement ( p < 0.01 ), and higher tissue mineral density ( p < 0.01 ) than the wild type femurs at 1 and 2 months. At 2 months, the transgenic femurs also had a higher mineral-to-matrix ratio ( p < 0.05 ) and lower carbonate substitution ( p < 0.05 ) compared to wild type femurs. These findings indicate that increased mineralization caused by overexpressing DMP1 led to increased structural cortical bone properties associated with decreased ductility during the early post-natal period.