Contrast-Enhanced Micro–Computed Tomography for 3D Visualization and Quantification of Glycosaminoglycans in Different Cartilage Types

Abstract

Objective To compare CA4+-enhanced micro–computed tomography (microCT) of bovine articular, meniscal, nasal, and auricular cartilage, each of which possesses a different extracellular matrix (ECM) composition and structure. Design The diffusion kinetics of CA4+ in different native cartilage types were assessed over 20 hours. The feasibility of CA4+-enhanced microCT to visualize and quantify glycosaminoglycans (GAGs) in these different tissues was tested using safranin-O staining and 1,9-dimethylmethylene blue assay. Results The diffusion kinetics of CA4+ in auricular cartilage are significantly slower compared with all other cartilage types. Total GAG content per volume correlates to microCT attenuation with an R2 value of 0.79 for all cartilage types. Three-dimensional contrast-enhanced microCT images of spatial GAG distribution reflect safranin-O staining and highlight the differences in ECM structure, with heterogeneous regions with higher GAG concentrations highlighted by the contrast agent. Conclusions CA4+-enhanced microCT enables assessment of 3-dimensiona distribution and GAG content in different types of cartilage and has promise as an ex vivo diagnostic technique to monitor matrix development in different tissues over time as well as tissue-engineered constructs.