Vitrified articular cartilage reveals novel ultra-structural features respecting extracellular matrix architecture

Abstract

The quality of cryosections prepared from high pressure frozen bovine articular cartilage has been recently evaluated by systematic electron diffraction analysis, and vitrification found to be zone-dependent. The lower radial layer was optimally frozen throughout the entire section thickness (150 microns), whereas in the upper radial, transitional and superficial layers this was achieved down to a depth of only approximately 5-50 microns. These differences were found to correlate proportionally with proteoglycan concentration and inversely with water content. In the current investigation, extracellular matrix ultrastructure was examined in high pressure frozen material (derived from the lower radial zone of young adult bovine articular cartilage), by both cryoelectron microscopy of cryosections and by conventional transmission electron microscopy of freeze-substituted and embedded samples. Several novel features were revealed, in particular, the existence of a fine filamentous network; this consisted of elements 10-15 nm in diameter and with a regular cross-banded structure similar to that characterising collagen fibrils. These filaments were encountered throughout the entire extracellular space, even within the pericellular region, which is generally believed to be free of filamentous or fibrillar components. The proteoglycan-rich interfibrillar/filamentous space manifested a fine granular appearance, there being no evidence of the reticular network previously seen in suboptimally frozen material.

Effect of bipolar radiofrequency energy on human articular cartilage

“…Future work could investigate microstructural changes using alternative techniques such as high-pressure cryopreservation for evaluation of cartilage architecture. 13,[24][25][26] CLM and LM were used in this study to analyze the bRFE-treated osteochondral sections and to compare these techniques for determining cell viability. In the histologic slides, normal chondrocyte morphology was clearly identifiable and nuclei were visible in the bRFE-treated regions; however, cartilage matrix staining was reduced with clear demarcation of reduced staining within the treated regions.…”

Ultrastructural Insights into the World of Cartilage: Electron Microscopy of Articular Cartilage

“…However, high pressure freezing (HPF), followed by freeze substitution (FS), preserves the tissue in a state closely resembling the natural situation, since molecules are exposed to chemicals in an already physically arrested stage [49]. Also for the ECM, HPF is the method of choice to keep the fine structural elements which are destroyed with conventional treatment methods [2,50].…”

Tensile and Compressive Properties of the Medial Rabbit Meniscus

“…collagen fibres and bundles were then quantified Unfortunately, all the above studies have been perusing these scanning electron microscopy (SEM) formed in larger animal models. Little characterizimages [33,34]. ation has occurred in small animal models, such as the rabbit, which are an ideal animal model for pre-…”