Mineral changes in a mouse model of osteogenesis imperfecta detected by Fourier transform infrared microscopy

Osteogenesis imperfecta (OI) is a heritable disease characterized by skeletal deformities and brittle bones. In the current study, the nature of the mineral in long bones of a mouse model of OI (oim/oim, a mutant which produces an alpha 1(I) collagen homotrimer) was examined by Fourier transform infrared microscopy. The mineral:matrix ratio of oim/oim cortical bone was greater than that of the heterozygous oim/+ and of the normal +/+ bones, probably as a result of reduced collagen content. The molecular environments of the apatitic phosphates differed among the oim/oim and the oim/+ and the +/+ bones. This was attributable to several factors, including dissimilar mineral-matrix interactions and differences in the chemical composition of the mineral. It was concluded from these data that the defective collagen matrix leads to abnormal mineral formation at the molecular level and thus results in tissues with reduced mechanical properties.