This impaired mineralisation has been shown to alter the bone material quality and the functional biomechanics of the tissue at micro- [14] and nanoscale levels [15]. In this study, we have used an N-ethyl-N-nitrosourea (ENU) induced mouse mutant for X-linked hypophosphatemic rickets
(Hpr), arising from a Trp314Arg missense mutation in the Phex (phosphate-regulating gene with homologies to endopeptidases on the X-chromosome) gene [15], and focused our studies on the scapula for the following reasons. The scapula is a large triangular flat bone which has five thick bony ridges (glenoid, scapula spine, medial and lateral border BIBF 1120 molecular weight (LB) and caracoid process) and two hard flat bony structures, denoted as infraspinous fossa (IF) and supraspinous fossa [5]. The scapula is subject to a number of muscle, ligament and joint reaction forces during movement, and the location, magnitude and direction of these forces differ extensively between tissue regions within the same scapula. Indeed, the force variation at different muscle insertion points
can be very large, Fluorouracil nmr with a spatially variable stress distribution ranging from 0.05 MPa at IF versus 60 MPa at LB estimated using finite element modelling at the macroscale [5]. We therefore utilised the scapula from Hpr mice as a model system to investigate muscle force-mediated mineral particle orientation and its alteration
due to defective bone mineralisation, using synchrotron scanning X-ray nanoimaging methods. Advances in synchrotron X-ray sources generate X-ray beams of micrometre size (1–10 micrometres), Pregnenolone allowing scanning SAXS experiments to map spatial variations in the nanostructure with a high resolution [16]. This technology enables quantitative investigation of the nanocrystallite organisation in the tissue, with micron-scale resolution. An ENU induced mouse model for X-linked hypophosphatemic rickets (Hpr) arising from a missense Trp314Arg Phex mutation was used [15]. Wild-type and Hpr male mice aged 1, 4, 7 and 10 weeks were studied. Mice were kept in accordance with UK Home Office welfare guidelines and project licence regulations. Dissected scapulae from 1, 4, 7 and 10 week old mice were skinned, cleaned of muscle tissue, wrapped in gauze, soaked in phosphate buffered saline (PBS), and stored at − 20 °C until the scanning SAXS experiment was conducted (approximately 1 week). Just before the experiment, each scapula was mounted in a saline sample chamber with Ultralene® (SPEX SamplePrep, Metuchen, NJ, USA) foil windows, as shown in Fig. 1(A). For the scanning SAXS measurements of specimens, 3.4 mm2 (Fig. 1(B)) areas were selected.