An Animal‐Free Patient‐Derived Tissue‐Mimetic Biochip Model of the Human Synovial Membrane for Human‐Relevant Osteoarthritis Research

Current synovial models fail to capture human-relevant OA traits. This study develops a fully humanized, animal-free synovial membrane model, mimicking OA synovial structure and molecular profile. Protocols for rheumatoid synovial micromasses are adapted for 3D biochip cultures of OA synoviocytes using TISSEEL fibrin and ELAREM lysate. Cell activity, mRNA expression, and structural changes are evaluated under varying hydrogel stiffness and cytokine exposure, with results compared to human OA and animal (equine and murine) synovial tissues. The animal-free biochip protocols replicate synovial architecture successfully. Improved gene expression of reticular collagen III (COL3A1) is achieved with 50 mg mL^-1 fibrinogen and 1% hPL. A 50 pg mL^-1 TNF-α and IL-1β stimulus induced a pro-fibrotic phenotype (COL1A1, COL3A1) distinct from the inflammatory response triggered by ng/mL dosages (IL6, MMP1, MMP3, and MMP13, vs the pg/mL model). The clinical relevance of the patient-relevant OA synovial model is underscored by significant Yap1 overexpression, reflecting synovial hyperplasia from cell activation and inflammation. Yap1 distribution, as a biomarker (ctrl vs kOA tissue), is best replicated in the low-dose pg/ml-treated model. The tissue-mimetic biochips provide a human-relevant OA study platform offering patient-relevant molecular insights into the structure-function relationships of osteoarthritic synovial tissues while eliminating animal-derived materials.