Does integrin α10β1 enrichment improve cartilage regeneration? Insights from an in vitro and ex vivo human chondral defect repair model.

Integrin α10β1 is a collagen type II-specific receptor selectively expressed on chondrocytes and has demonstrated therapeutic relevance in mesenchymal stem cell (MSC)-based cartilage repair. However, its functional significance in terminally differentiated chondrocytes remains unclear. This study aimed to evaluate whether enrichment of α10β1⁺ (CD11c⁺CD29⁺) chondrocytes improves chondrogenic capacity and cartilage repair potential in-vitro and in an ex-vivo human osteochondral unit (OCU) model. Chondrocytes isolated from human osteoarthritic cartilage were subjected to FACS to enrich CD11c⁺CD29⁺ subpopulations. Sorted and unsorted chondrocytes were evaluated for chondrogenic marker expression (SOX9, ACAN, COL2A1), hypertrophic markers (COL10A1, RUNX2), and matrix production (GAG/DNA, type II collagen ELISA). Functional outcomes were further assessed in an ex-vivo PRP-embedded chondral defect repair model using histology, immunohistochemistry, and modified Wakitani scoring. Compared to unsorted cells, α10β1⁺ chondrocytes exhibited modest changes in surface marker expression but no consistent improvement in gene expression of chondrogenic or hypertrophic markers. Histological, biochemical, and immunohistochemical analyses of pellets and OCUs showed comparable outcomes between groups. Type II collagen deposition and repair scores were not significantly different, and matrix organization remained immature in all conditions. α10β1 enrichment did not confer a regenerative advantage in chondrocytes, likely due to their lineage commitment and limited phenotypic plasticity. Unlike in MSCs, integrin-based sorting alone may be insufficient in mature chondrocytes. Scaffold-based strategies or combinatorial markers may be required to enhance outcomes in cartilage repair applications.