(F1327) TRANSPLANTATION OF HYALINE-CARTILAGE-LIKE TISSUES INDUCED FROM HUMAN PLURIPOTENT STEM CELL-DERIVED LIMB BUD-MESENCHYMAL CELLS TO A MINI PIG MODEL WITH OSTEOCHONDORAL DEFECTS
Abstract: Cartilage tissue is known to have poor self-repair capacity and lacks effective treatments for damage. Although the advancement of regenerative medicine, challenges remain in the quality of repaired tissue and biological integration at the transplant site. We have successfully developed a technique for expandable limb-bud mesenchymal-like cells (ExpLBM) while maintaining their chondrogenic differentiation potential. Furthermore, we have confirmed the engraftment of cartilage-like tissues derived from ExpLBM into immunodeficient mice and rats. In this study, we aimed to evaluate the clinical applicability of this approach using an osteochondral defect Göttingen mini-pig model. We assessed the effects of immunosuppressive agents and produced various shapes of ExpLBM-derived hyaline cartilage-like tissue, followed by xenotransplantation into large animals. Tacrolimus was administered to eight mini-pigs, and blood concentrations were measured accordingly. ExpLBM cells were induced to undergo chondrogenic differentiation using a 96-well culture plate or a self-aggregation technique, producing spherical or sheet-like ExpLBM-derived hyaline cartilage-like tissues. These tissues were transplanted into 3 mm diameter osteochondral defect on the medial femoral condyles of both knees. Two weeks after transplantation, tissue sections were prepared for Safranin O staining and immunohistochemistry (human Vimentin / Aggrecan / COL2), followed by histological evaluation. The blood concentration of tacrolimus remained stable and consistently exceeded the minimum therapeutic concentration at trough levels. Additionally, engraftment of ExpLBM-derived hyaline cartilage-like tissues, exhibiting tissue morphology similar to normal cartilage, was confirmed at all transplantation sites. Given that successful engraftment was observed in the load-bearing site of the mini-pig knee joint cartilage. ExpLBM-derived hyaline cartilage-like tissues are considered to be potentially useful for transplantation therapy in knee joint cartilage defect site.
