Histological sections of cartilage repair tissue within the knee joint of a minipig model 6 months after treatment by microfracturing alone (MFX) or combined with overexpression of Chondromodulin-I (Chm-I) (MFX + AAVChm-I), which was performed by Adenovirus-Associated-Virus (AAV)- mediated gene transfer as described previously [27]. Repair cartilage induced by MFX was characterized by only weak immunostaining for Chm-I, but was typically associated with outgrowths of the subchondral bone plate. By contrast, efficient AAV-mediated overexpression of Chm-I was confirmed by strong immunostaining for Chm-I within the repair matrix treated by MFX + AAVChm-I, which stabilized the chondrocyte phenotype and inhibited the formation of intralesional osteophytes.

Figure 4: Stabilizing effect of Chondromodulin-I on the chondrocyte phenotype.