title: Genetic variation in mouse femoral tissue-level mineral content underlies differences in whole bone mechanical properties.
abstract: A/J mice, as compared to C57BL/6J (B6) mice, have a significantly greater total femoral mineral (ash) content which correlates with an increased femoral stiffness (resistance to deformation), but also with an increased brittleness (catastrophic failure). To determine if this whole bone variation in mineral content is indicative of significant mineral and/or matrix variation at the tissue level, femora from 16-week-old female A/J and B6 mice were isolated, embedded in PMMA, sectioned and mounted on barium fluoride infrared windows for FTIRI analyses. In addition, preliminary studies of femora from C3H/HeJ (C3H) mice were conducted, since they have an ash content intermediate to A/J and B6. Mean values for mineral-to-matrix ratio were significantly different for A/J (8.4 +/- 0.8) and B6 (7.5 +/- 0.4), as were values for collagen cross-link maturity (1.8 +/- 0.05 and 3.2 +/- 0.1, respectively). C3H mice appeared to have a mineral-to-matrix ratio intermediate of A/J and B6, and cross-link maturity greater than both A/J and B6. B6 femora had similar carbonate-to-amide ratios, carbonate-to-mineral ratios and acid phosphate levels. Thus, whole bone differences in mineral content are concurrent with tissue-level variation in mineral content and collagen maturity in inbred mice. The greater stiffness and brittleness of A/J femora are likely due to differential biological control (osteoblast activity) of the amount of mineral.
authors.affiliation: Leni and Peter W. May Department of Orthopaedics, Mount Sinai School of Medicine, New York, NY 10029, USA.
authors.forename: Hayden-William
authors.initials: HW
authors.lastname: Courtland
authors.forename: Mila
authors.initials: M
authors.lastname: Spevak
authors.forename: Adele L
authors.initials: AL
authors.lastname: Boskey
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Jepsen
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density / Q000502:physiology*; D001857:Bone Matrix / Q000502:physiology; D005260:Female; D005269:Femur / Q000378:metabolism*; D014644:Genetic Variation; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D017550:Spectroscopy, Fourier Transform Infrared