DECREASED BONE MASS AND BONE ELASTICITY IN MICE LACKING THE TRANSFORMING GROWTH-FACTOR-BETA-1 GENE

Transforming growth factor-beta 1 (TGF-beta 1) knockout (TGF beta 1(-/ -)) mice were used to investigate the role of TGF-beta 1 in postnatal bone development, Volumetric bone mineral density (BMD and mineral con tent (BMC) in these mice and in their normal (TGF-beta 1(+/+)) and het erozygous (TGF-beta 1(+/-)) littermates were analyzed by quantitative computed tomography (pQCT, Analysis of the proximal tibial metaphysis showed a significant decrease in the BMC of the TGF-beta 1(-/-) mice c ompared to TGF-beta 1(+/+) or TGF-beta 1(+/-) mice; however, no signif icant difference was observed in BMD) between the groups of mice. pQCT analysis of the tibial midshaft diaphysis showed no difference in the BMD or BR IC of cortical bone between the groups. Histomorphometry re vealed no significant difference in trabecular connectivity or in trab ecular bone volume, number, or thickness. However, the width of the ti bial growth plate and the longitudinal growth rate were significantly decreased in the TGF-beta 1(-/-) mice, resulting in shorter tibia, Aco ustic velocity measurements showed significant differences between the groups of mice with an apparent dosage effect of TGF-beta 1 expressio n on the anisotropic properties of the bone. These data show that long itudinal growth and total mineral content are affected in mice lacking TGF-beta 1, as well as the elastic properties of the bone, consistent with an important role for TGF-beta 1 in bone modeling and bone quali ty. (Bone 23:87-93; 1998) (C) 1998 by Elsevier Science Inc. All rights reserved.