New insights in osteocyte imaging by synchrotron radiation

Bone health depends on the bone mineral density and mechanical strength, characterised quantitatively and inferred through qualitative parameters such as the trabecular and cortical micro-architecture, and other parameters describing the bone cells. Among these cells, the osteocyte has been recognised as the orchestrator of bone remodelling, playing a key role in directing osteoblastic and osteoclastic activities. Conventional optical and electron microscopies have greatly improved our understanding of the cell physiology mechanisms involved in different osteoarticular pathophysiological contexts, especially osteoporosis. More recently, imaging methods exploiting synchrotron radiation, such as X-ray tomography, ptychography, and deep ultraviolet and Fourier transform infrared spectroscopies, have revealed new biochemical, chemical and 3D morphological information about the osteocyte lacuna, the surrounding matrix and the lacuna–canalicular network at spatial length scales spanning microns to tens of nanometres. Here, we review recent results in osteocyte lacuna and lacuna–canalicular network characterisation by synchrotron radiation imaging in human and animal models, contributing to new insights in different physiologic and pathophysiological situations.