Genetic variations in bone density, histomorphometry, and strength in mice.

Area of Science:

• Comparative genomics
• Skeletal biology
• Biomedical research

Background:

• Bone mineral density (BMD) and content (BMC) vary across mouse strains.
• Understanding these differences is crucial for preclinical research and drug development.

Purpose of the Study:

• To investigate breed-related variations in bone histomorphometry, biomechanics, and serum biochemistry.
• To compare three mouse breeds (C3H/HeJ, C57BL/6J, DBA/2J) known to differ in BMD and BMC.

Main Methods:

• Collected femurs, tibiae, and sera from 16-week-old mice (n=12/breed).
• Assessed BMD, BMC, histomorphometry (cancellous and cortical bone), femoral biomechanical strength, and serum alkaline phosphatase (ALP).

Main Results:

• C3H mice exhibited higher BMD, BMC, cancellous bone volume, cortical bone area, periosteal bone formation rate, biomechanical strength, and serum ALP compared to BL6 and DBA mice.
• BL6 mice had the largest mid-diaphyseal femoral and tibial cross-sectional area and moment of inertia, indicating differences in bone shape and size.
• Cortical bone distribution suggests distinct adaptive responses to mechanical loads among breeds, with C3H bones showing greater resistance to bending.

Conclusions:

• Breed-specific genetic factors regulate bone size, shape, and BMD.
• C3H mice possess superior bone quality and adaptive capacity compared to BL6 and DBA mice, despite BL6 having larger bone dimensions.
• Differences in bone material properties or adaptive mechanisms contribute to observed variations in skeletal strength and efficiency.