Ellipsoidal mesoscale mineralization pattern in human cortical bone revealed in 3D by plasma focused ion beam serial sectioning

September 11, 2020

Dakota M. Binkley (1,4), Joseph Deering (2), Hui Yuan (3), Aurélien Gourrier(4,5), Kathryn Grandfield (1,2)
Journal of Structural Biology, 212, Issue 2, September 2020. DOI: 10.1016/j.jsb.2020.107615


Biomineralization, Cortical bone, Ultrastructure, Lacuno-canalicular network (LCN), FIB-SEM, PFIB, Serial sectioning


Visualizing bone mineralization and collagen fibril organization at intermediate scales between the nanometer and the hundreds of microns range, is still an important challenge. Similarly, visualizing cellular components which locally affect the tissue structure requires a precision of a few tens of nanometers at maximum while spanning several tens of micrometers. In the last decade, gallium focused ion beam (FIB) equipped with a scanning electron microscope (SEM) proved to be an extremely valuable structural tool to meet those ends. In this study, we assess the capability of a recent plasma FIB-SEM technology which provides a potential increase in measurement speed over gallium FIB-SEM, thus paving the way to larger volume analysis. Nanometer-scale layers of demineralized and mineralized unstained human femoral lamellar bone were sequentially sectioned over volumes of 6–16,000 μm3. Analysis of mineralized tissue revealed prolate ellipsoidal mineral clustersmeasuring approximately 1.1 μm in length by 700 nm at their maximum diameter. Those features, suggested by others in high resolution studies, appear here as a ubiquitous motif in mineralized lamellar bone over thousands of microns cubed, suggesting a heterogeneous and yet regular pattern of mineral deposition past the single collagen fibril level. This large scale view retained sufficient resolution to visualize the collagen fibrils while also partly visualizing the lacuno-canalicular network in three-dimensions. These findings are strong evidence for suitability of PFIB as a bone analysis tool and the need to revisit bone mineralization over multi-length scales with mineralized tissue.

How Our Software Was Used

Dragonfly was used to process tomographic datasets. Plus, our software's image processing toolbox was used to remove curtain artifacts.

Author Affiliation

(1) School of Biomedical Engineering, McMaster University, Hamilton, Canada.
(2) Department of Materials Science and Engineering, McMaster University, Hamilton, Canada.
(3) Canadian Centre for Electron Microscopy, McMaster University, Hamilton, Canada.
(4) Univ. Grenoble Alpes, LIPHY, F-38000 Grenoble, France.
(5) CNRS, LIPHY, F-38000 Grenoble, France.