Cartilage regeneration by bone marrow cells-seeded scaffolds

Different approaches exist for the treatment of small articular cartilage defects. Several studies show comparable results for autologous chondrocyte implantation (ACI) and microfracture. Unfortunately, the fibrocartilage resulting from microfracture has neither the structure nor the mechanical properties of hyaline cartilage, even though the adult mesenchymal stem cells, which immigrate into the defect, are supposed to differentiate into chondrocytes. This study was performed to examine the capacity of a resorbable implant made from polylactide-co-glycolide acid (PGLA)-fleece combined with autologous bone marrow cells fixed with a fibrin/thrombin-clot in the weight-bearing area of the femoral condyle of mature sheep. For this study, six defects were treated with either the PGLA-implant alone or with a combination of the implant with added fibrin glue or were left untreated to serve as controls. The animals were sacrificed after 12 weeks; the operated knees were removed and examined by measuring the covering of the defect with cartilaginous tissue and according to the score of O'Driscoll. Additional criteria such as immunolabeling for collagen II and aggrecan were included. Results showed that no improvement of the tissue quantity or quality could be achieved by increasing the cell load of the implant with cells fixed by fibrin glue.