Extracellular Matrix

The cartilage extracellular matrix is the structural framework that gives articular cartilage its load-bearing properties, and its progressive degradation is a hallmark of osteoarthritis [1]. It is built mainly from type II collagen and the proteoglycan aggrecan, whose dense fibril network and high-density negative charge together retain water and resist compression [3]. In osteoarthritis the balance tips toward breakdown, as chondrocytes and synoviocytes release matrix-degrading enzymes, chiefly the collagenase MMP-13 and the aggrecanases ADAMTS4 and ADAMTS5 [2]. As these enzymes cleave collagen and aggrecan they generate proteolytic fragments, or matrikines, that can themselves signal through diverse receptors and drive further catabolic responses [1].

Because loss of matrix integrity underlies the pain and disability of the disease, an ideal therapy would both halt degradation and help restore the matrix [2]. The same dense, negatively charged network that protects cartilage also forms a barrier that limits drug penetration, a practical obstacle that shapes emerging delivery strategies [3]. Mapping the matrikine landscape that accompanies, and even precedes, visible degeneration is therefore a promising route to biomarkers and druggable targets [1]. Understanding how matrix composition and its breakdown interact with chondrocyte behaviour is central to Jessica's interest in cartilage biology [2].