Regeneration of Osteochondral Defects in the Knee

The application of autologous cells is a standard procedure for the treatment of chondral lesions of the knee. Here, the most frequently used cells are differentiated chondrocytes (autologous chondrocyte implantation, ACI; matrix-induced autologous chondrocyte implantation, MACI). The enzymatic digestion of cartilage tissue by collagenase and isolation of chondrocytes followed by in vitro cultivation are associated with cellular de- and transdifferentiation. To prevent these effects some authors recommend 3D-cultures and culture medium supplementation of defined growth factors and cytokines. Another aim is the reduction of donor site morbidity. Therefore, different progenitor cell types were tested towards their potential for osteochondral regeneration. In particular, MSC derived from bone marrow include several advantages for the treatment of osteochondral defects such as unproblematic sampling, cultivation techniques, and a relatively high degree of biological safety. This review summarises the basic cellular principles as well as clinical results of cell therapeutics for the regeneration of osteochondral defects in the knee.