Riparazione dei difetti a tutto spes-sore della cartilagine articolare con cellule condroprogenitrici

Articular cartilage is a unique tissue since it is avascular, aneural and has a limited capacity to repair. The repair of cartilage depends upon access to progenitor cells present in the underlying bone marrow. The studies presented here emphasize cell- based methods of repair of articular cartilage defects using these cells. Chondroprogenitor cells were used in combination with either Type I collagen gels or a polymer of benzyl-derivatized hyaluronic acid as a cell carrier. The repair of 3 mm full thickness articular cartilage defects in the medial femoral condyle of young adult New Zealand rabbits was studied. Chondroprogenitor cells were isolated from autologous bone marrow, purified and culture expanded and then loaded either into Type I collagen gels or the polymer of hyaluronic acid. Animals were killed four and twelve weeks after surgery and the repair of the defect histologically evaluated. Both cell carrier implants resulted in significant repair of the defect by twelve weeks after surgery. The repair tissue resembled hyalin cartilage with significant production of toluidine blue positive extracellular matrix. Subchondral bone remodelled and the tidemark was reconstituted in most defects. However, incomplete integration of the repair tissue to the host consistently was seen. The surface was roughened and irregular twelve weeks after implantation. These studies suggest that tissue engineered implants utilizing chondroprogenitor cells and biological carriers can effectively repair full thickness defects of articular surfaces.