A human meniscus explant model for studying early events in osteoarthritis development by proteomics

Abstract

Degenerative meniscus lesions have been associated with both osteoarthritis etiology and its progression. We, therefore, sought to establish a human meniscus ex vivo model to study the meniscal response to cytokine treatment using a proteomics approach. Lateral menisci were obtained from five knee‐healthy donors. The meniscal body was cut into vertical slices and further divided into an inner (avascular) and outer region. Explants were either left untreated (controls) or stimulated with cytokines. Medium changes were conducted every 3 days up to Day 21 and liquid chromatography–mass spectrometry was performed at all the time points for the identification and quantification of proteins. Mixed‐effect linear regression models were used for statistical analysis to estimate the effect of treatments versus control on protein abundance. Treatment by IL1ß increased release of cytokines such as interleukins, chemokines, and matrix metalloproteinases but a limited catabolic effect in healthy human menisci explants. Further, we observed an increased release of matrix proteins (collagens, integrins, prolargin, tenascin) in response to oncostatin M (OSM) + tumor necrosis factor (TNF) and TNF+interleukin‐6 (IL6) + sIL6R treatments, and analysis of semitryptic peptides provided additional evidence of increased catabolic effects in response to these treatments. The induced activation of catabolic processes may play a role in osteoarthritis development.

Degradation of Proteoglycans and Collagen in Equine Meniscal Tissues

“…This leads to sectioning artefacts and undesirable variability in the samples being studied. This challenge has also been documented by other researchers in the field [45]. Every possible measure was undertaken to obtain quality sections.…”

“…Regarding meniscal collagen network degradation, it has been theorized that it would occur in areas with significant proteoglycan loss [ 15 ] as aggrecan would shield the collagen network until a sufficient amount of aggrecan was released, allowing MMPs to access the collagen molecules to initiate collagenolysis [ 42 ]. A recent human meniscus degeneration ex vivo explant model found that though cytokine Il-1 induced glycosaminoglycan release, combinations of oncostatin M and TNF alpha induced a much stronger catabolic effect, and the authors propose that these molecules trigger meniscal ECM degradation [ 45 ].…”

“…It is acknowledged that this investigation has several limitations. A limited number of ROIs were available for study, as it proved challenging to have multiple, site-matched high-quality sections within the same ROIs to permit analysis across all the parameters Others have also reported the challenge of cutting menisci for intact sections [ 45 ]. Although the stifle joints of origin were examined to identify cartilage lesions, their exact clinical status was unknown, except for one specimen that had clinical OA and severe meniscal damage.…”

“…At the same time, this could be considered an advantage as most meniscal tears are of a degenerative type [ 3 ]. The association of aging and inflammatory processes like OA with meniscal degeneration and the contribution of each of these factors to degradation remains to be elucidated [ 45 ].…”