X-Ray Phase Nanotomography Resolves the 3D Human Bone Ultrastructure

Max Langer,Heikki Suhonen,Alexandra Pacureanu,Françoise Peyrin,Peter Cloetens,Quentin Grimal,Xi-Nian Zuo

doi:10.1371/journal.pone.0035691

Abstract

Bone strength and failure are increasingly thought to be due to ultrastructural properties, such as the morphology of the lacuno-canalicular network, the collagen fiber orientation and the mineralization on the nanoscale. However, these properties have not been studied in 3D so far. Here we report the investigation of the human bone ultrastructure with X-ray phase nanotomography, which now provides the required sensitivity, spatial resolution and field of view. The 3D organization of the lacuno-canalicular network is studied in detail over several cells in osteonal and interstitial tissue. Nanoscale density variations are revealed and show that the cement line separating these tissues is hypermineralized. Finally, we show that the collagen fibers are organized as a twisted plywood structure in 3D.

Highlights

Bone is a hierarchically organized, multiscale natural nanocomposite that is stiff and tough while maintaining lightness
The osteocytes and their processes reside in the lacuno-canalicular system, which is the imprint made by the cells
Osteocyte canaliculi enclosing the cellular processes are visible as black spots and striations depending on their orientation relative to the virtual cutting plane (Fig. 2a–d)

Summary

Introduction

Bone is a hierarchically organized, multiscale natural nanocomposite that is stiff and tough while maintaining lightness. Bone fragility disease is generally associated with a disturbance of the bone remodeling process, disrupting the balance between tissue resorption and formation. Understanding the mechanisms controlling bone remodeling is fundamental for the understanding of bone failure and to advance treatment of bone disease. In mature human cortical bone, osteons, forming units of bone remodeling, are organized in concentric layered lamellae around canals containing vessel and nerve. The osteons are delimited by a layer of tissue called the cement line. The osteocytes and their processes reside in the lacuno-canalicular system, which is the imprint made by the cells. It is increasingly thought that failure is due to microscopic and ultrastructural properties, the need for quantitative 3D imaging at the nanoscale has arisen [3,4]

Methods

Results

Conclusion