High-Resolution X-Ray Tomography: A 3D Exploration Into the Skeletal Architecture in Mouse Models Submitted to Microgravity Constraints

Abstract

Bone remodeling process consists in a slow building phase and in faster resorption with the objective to maintain a functional skeleton locomotion to counteract the Earth gravity. Thus, during spaceflights, the skeleton does not act against gravity, with a rapid decrease of bone mass and density, favoring bone fracture. Several studies approached the problem by imaging the bone architecture and density of cosmonauts returned by the different spaceflights. However, the weaknesses of the previously reported studies was two-fold: on the one hand the research suffered the small statistical sample size of almost all human spaceflight studies, on the other the results were not fully reliable, mainly due to the fact that the observed bone structures were small compared with the spatial resolution of the available imaging devices. The recent advances in high-resolution X-ray tomography have stimulated the study of weight-bearing skeletal sites by novel approaches, mainly based on the use of the mouse and its various strains as an animal model, and sometimes taking advantage of the synchrotron radiation support to approach studies of 3D bone architecture and mineralization degree mapping at different hierarchical levels. Here we report the first, to our knowledge, systematic review of the recent advances in studying the skeletal bone architecture by high-resolution X-ray tomography after submission of mice models to microgravity constrains.

Keywords: animal model; bone microarchitecture; high-resolution tomography; mice; microgravity; synchrotron radiation.

Figure 1

MDS spaceflight mission. Femurs of mice housed for 3 months in the International Space Station (ISS). (A–C) Wt2 (A), PTN-Tg1 (B), PTN-Tg2 (C) color map of trabecular thickness distribution of vivarium (representative sample), ground and flight mice. (D,E) Quantification of cortical thickness distribution in Wt (D) and PTN-Tg (E) vivarium control (average on 3 mice), ground and flight mice. (F,G) Cortical thickness color maps of representative 3D reconstructions in Wt2 vivarium, ground and flight (F) and in PTN-Tg2 vivarium, ground, and flight (G). (A–C) were originally published in Figure 1 of (Tavella et al., 2012). (D–G) were originally published in Figure 3 of (Tavella et al., 2012).