Intra-Articular Administration of Recombinant Human Proteoglycan 4 (rhPRG4) as a Potential Therapy for Temporomandibular Joint Osteoarthritis: A Preclinical Histopathological Study

The proposed research aims to evaluate the histopathological effects of the intra-articular administration of recombinant human proteoglycan 4 (rhPRG4) on an experimental model of induced temporomandibular joint (TMJ) osteoarthritis (OA) in rabbits. An experimental study was conducted on rabbit TMJs. Twenty-four TMJs were included, distributed as follows: (1) TMJ-C, a control group consisting of four healthy TMJs; (2) TMJ-OA, a group consisting of five TMJs with OA; (3) TMJ-OA-WT, a group consisting of five untreated TMJ-OAs; (4) rhPRG4-30, a group consisting of five TMJ-OAs treated with rhPRG4 30 μg/mL; and (5) rhPRG4-100, a group consisting of five TMJ-OAs treated with rhPRG4 100 μg/mL. A histopathological analysis was performed, considering the mandibular condyle, articular disc, and mandibular fossa, comparing the groups. In addition, a quantitative comparative analysis was performed using the Osteoarthritis Research Society International (OARSI) scale. Kruskal-Wallis and Dunn's post hoc tests were used for statistical analysis, considering a statistical significance of <i>p</i> < 0.05. The histological analysis of TMJ tissue reveals key differences between healthy, osteoarthritic, and rhPRG4-treated joints. The intra-articular infiltration of rhPRG4 in TMJ-OA has a cartilage and articular disc repair effect, reducing the severity of osteoarthritis and promoting a more organized cartilage structure, with slightly better results at the 30 μg/mL concentration.