University of Oulu

Karhula SS, Finnilä MA, Freedman JD, Kauppinen S, Valkealahti M, Lehenkari P, Pritzker KPH, Nieminen HJ, Snyder BD, Grinstaff MW and Saarakkala S (2017) Micro-Scale Distribution of CA4+in Ex vivo Human Articular Cartilage Detected with Contrast-Enhanced Micro-Computed Tomography Imaging. Front. Phys. 5:38. doi: 10.3389/fphy.2017.00038

Micro-scale distribution of CA4+ in ex vivo human articular cartilage detected with contrast-enhanced micro-computed tomography imaging

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Author: Karhula, Sakari S.1,2; Finnilä, Mikko A.1,3,4; Freedman, Jonathan D.5;
Organizations: 1Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu
2Infotech Doctoral Program, University of Oulu
3Department of Applied Physics, University of Eastern Finland, Kuopio
4Medical Research Center, University of Oulu
5Departments of Biomedical Engineering and Chemistry, Boston University
6Department of Surgery and Intensive Care, Oulu University Hospital
7Department of Anatomy and Cell Biology, University of Oulu
8Department of Laboratory Medicine and Pathobiology, University of Toronto
9Mount Sinai Hospital, Toronto
10Department of Physics, University of Helsinki
11Department of Neuroscience and Biomedical Engineering, Aalto University
12Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Harvard Medical School
13Department of Diagnostic Radiology, Oulu University Hospital
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
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Language: English
Published: Frontiers Media, 2017
Publish Date: 2017-11-08


Contrast-enhanced micro-computed tomography (CEμCT) with cationic and anionic contrast agents reveals glycosaminoglycan (GAG) content and distribution in articular cartilage (AC). The advantage of using cationic stains (e.g., CA4+) compared to anionic stains (e.g., Hexabrix®), is that it distributes proportionally with GAGs, while anionic stain distribution in AC is inversely proportional to the GAG content. To date, studies using cationic stains have been conducted with sufficient resolution to study its distributions on the macro-scale, but with insufficient resolution to study its distributions on the micro-scale. Therefore, it is not known whether the cationic contrast agents accumulate in extra/pericellular matrix and if they interact with chondrocytes. The insufficient resolution has also prevented to answer the question whether CA4+ accumulation in chondrons could lead to an erroneous quantification of GAG distribution with low-resolution μCT setups. In this study, we use high-resolution μCT to investigate whether CA4+ accumulates in chondrocytes, and further, to determine whether it affects the low-resolution ex vivo μCT studies of CA4+ stained human AC with varying degree of osteoarthritis. Human osteochondral samples were immersed in three different concentrations of CA4+ (3 mgI/ml, 6 mgI/ml, and 24 mgI/ml) and imaged with high-resolution μCT at several timepoints. Different uptake diffusion profiles of CA4+ were observed between the segmented chondrons and the rest of the tissue. While the X-ray -detected CA4+ concentration in chondrons was greater than in the rest of the AC, its contribution to the uptake into the whole tissue was negligible and in line with macro-scale GAG content detected from histology. The efficient uptake of CA4+ into chondrons and surrounding territorial matrix can be explained by the micro-scale distribution of GAG content. CA4+ uptake in chondrons occurred regardless of the progression stage of osteoarthritis in the samples and the relative difference between the interterritorial matrix and segmented chondron area was less than 4%. To conclude, our results suggest that GAG quantification with CEμCT is not affected by the chondron uptake of CA4+. This further confirms the use of CA4+ for macro-scale assessment of GAG throughout the AC, and highlight the capability of studying chondron properties in 3D at the micro scale.

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Series: Frontiers in physics
ISSN: 2296-424X
ISSN-E: 2296-424X
ISSN-L: 2296-424X
Volume: 5
Article number: 38
DOI: 10.3389/fphy.2017.00038
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
Funding: The financial support in part from the Academy of Finland (grants no. 268378, 273571, 253579); Sigrid Juselius Foundation; European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement no. 336267; the strategic funding of the University of Oulu; the National Institutes of Health (R01GM098361), and the T32 Pharmacology Training grant (5T32GM008541-14) are acknowledged.
EU Grant Number: (336267) 3D-OA-HISTO - Development of 3D Histopathological Grading of Osteoarthritis
Academy of Finland Grant Number: 268378
Detailed Information: 268378 (Academy of Finland Funding decision)
273571 (Academy of Finland Funding decision)
253579 (Academy of Finland Funding decision)
Dataset Reference: The supplementary material for this article can be found online at:
Copyright information: © 2017 Karhula, Finnilä, Freedman, Kauppinen, Valkealahti, Lehenkari, Pritzker, Nieminen, Snyder, Grinstaff and Saarakkala. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.