Moon Jellyfish Mucin and Collagen Attenuate Catabolic Activity in Chondrocytes but Show Limited Efficacy in an Osteoarthritis Rat Model

Cartilage regeneration has long been a major challenge in the treatment of osteoarthritis (OA). Aiming to develop a simple outpatient treatment for knee OA, we have demonstrated the potential of combining Nomura's jellyfish mucin (JM) and hyaluronic acid (HA) to contribute to cartilage repair and regeneration in chondrocytes. In this study, we examined the effects of moon jellyfish JM and jellyfish collagen (JC) on chondrocytes. Polydactyly-derived chondrocytes (PDs), obtained from polydactyly surgery, were used. PDs were cultured in media supplemented with JM or JC, harvested, and evaluated by RT-qPCR. The effects of simultaneous addition of the inflammatory cytokine IL-1β were also examined. Furthermore, the effects on rat articular cartilage were investigated. A mono-iodoacetate (MIA) model was created by intra-articular injection in 6-week-old rats, followed by four intra-articular injections. Evaluations were performed using macroscopic observation and histological assessment with the OARSI scoring system. In vitro, the addition of JM or JC significantly affected the expression of <i>ACAN</i>, <i>MMP3</i>, and <i>ADAMTS5</i>. However, in vivo, intra-articular injection of JM alone did not significantly suppress cartilage degeneration in MIA-induced OA model rats. Both JM and JC may contribute to the suppression of cartilage degeneration as well as to cartilage repair and regeneration, even in the absence of HA. However, further studies are needed to clarify the optimal conditions, such as dosage, timing, and delivery method, that are required to achieve these effects in articular cartilage.