This study aims to evaluate the chondrogenic potential of a tri-coculture system incorporating human articular chondrocytes, fibronectin-adherent chondroprogenitors (FAA-CPs), and migratory chondroprogenitors (MCPs) derived from the same donor tissue. The hypothesis was that this tri-coculture model would demonstrate superior chondrogenic differentiation compared to monocultures, providing insights into advanced cartilage regeneration strategies. Human osteoarthritic cartilage samples were collected from donors undergoing total knee arthroplasty, and primary cells were isolated and expanded. Three culture conditions were established: individual monocultures of chondrocytes, FAA-CPs, and MCPs, and a tri-coculture of all three cell types. Chondrogenic potential was assessed through cellular phenotyping, gene expression analysis (SOX9, ACAN, COL2A1, COL1A1, COL10A1, RUNX2), and histological evaluation (Alcian Blue, Toluidine Blue, Safranin O).
The tri-coculture model demonstrated increased COL2A1 gene expression compared to the monoculture conditions, suggesting enhanced chondrogenic commitment. However, this increase in COL2A1 expression did not translate into significant improvements in matrix deposition or overall differentiation outcomes. Histological analyses showed similar patterns of matrix formation and cartilage-like differentiation across all culture conditions. While the tri-coculture model showed increased COL2A1 expression, it did not outperform individual monocultures in terms of matrix production and overall chondrogenic potential. These findings highlight the complexity of replicating the native cartilage microenvironment in vitro and suggest that the success of tri-coculture systems depends on optimizing spatial organization and paracrine signalling. Future research should focus on improving co-culture systems, using early-passage cells, and refining culture conditions to fully harness the therapeutic potential of such models for cartilage regeneration.
