Selective Chemonucleolysis With Condoliase in Cynomolgus Monkeys.

Selective chemonucleolytic effects of condoliase, a glycosaminoglycan degrading enzyme, was investigated histopathologically in cynomolgus monkeys. Condoliase was administered once into the lumber intervertebral disc (IVD), and as a comparative control, chymopapain, a proteolytic enzyme, was administered in a similar manner. Histopathological changes of the IVD and the adjacent vertebral body (VB) were examined at 1 to 26 weeks after administration. Major changes induced by condoliase in the IVD were degenerative and necrotic changes in the nucleus pulposus, annulus fibrosus, cartilaginous endplate (CEP), and epiphyseal growth plate (EGP); focal disappearance of the EGP; and neovascularization and ossification of the CEP. Decreased/necrosis of bone marrow cells with new bone formation was observed in the VB. Cellular regeneration in the IVD was observed as a recovery changes on and after week 4. The changes in the IVD and VB subsided at week 26. Chymopapain induced qualitatively similar but more widely extended changes. The degrees of the changes in the IVD and VB were more severe than those of condoliase, and the changes were exacerbated even at week 26. These results indicated that histopathological changes caused by condoliase were less severe and more selective than those by chymopapain.