Three-dimensional imaging of porcine joint tissues down to the subcellular level

TL;DR

This study develops a microtomography method to visualize porcine joint tissues at the cellular level by optimizing tissue preparation and imaging techniques, enabling detailed 3D imaging of joint structures.

Contribution

The paper introduces a combined tissue preparation and imaging approach for high-resolution 3D visualization of joint tissues at the subcellular level.

Findings

Successful visualization of individual cells in all joint tissue layers.

Ethanol fixation and paraffin embedding improve contrast in microtomography.

Effective imaging of laser-induced joint lesions.

Abstract

Joint tissues consist of trabecular and cortical bone as well as calcified and hyaline cartilage, which presents a challenge for hard X-ray-based visualization on the sub-cellular level due to the wide range of local X-ray absorption values. The density of the calcified tissues requires rather high photon energy, which often leads to insufficient contrast within the cartilage and impedes the visualization of individual biological cells. Decalcification of the tissues reduces the total and local X-ray absorption values and allows for selecting a lower photon energy. Further contrast enhancement can be achieved by ethanol fixation and paraffin tissue embedding. In this study, we (i) searched for an appropriate visualization method to investigate lesions generated by a laser osteotome and (ii) visualized a decalcified porcine joint after ethanol fixation and subsequent paraffin embedding using laboratory- and synchrotron radiation-based microtomography. The experiments at the ANATOMIX beamline of Synchrotron SOLEIL were performed in off-axis scan mode with a pixel size of 1.3 um. Individual cells in all layers of the joint could be made visible and the effect of ethanol fixation and paraffin embedding demonstrated.