Experimental Chemonucleolysis With Chondroitinase ABC in Monkeys

STUDY DESIGN: Experimental chemonucleolysis with chondroitinase ABC as compared with chymopapain was investigated in monkeys. The effects of these two enzymes were analyzed morphologically and biochemically. OBJECTIVES: The results of the present study facilitate the clinical application of chondroitinase ABC. SUMMARY OF BACKGROUND DATA: Many experimental studies on chemonucleolysis with chondroitinase ABC have been reported mostly in rabbits. Further examination in animals that are more similar to humans is necessary for its clinical application. METHODS: Ten mature rhesus monkeys were used. Lumbar intervertebral discs from six monkeys were injected with either chondroitinase ABC, chymopapain, or physiologic saline. The animals were killed not more than 6 weeks after injection, and their discs were examined morphologically and biochemically. The remaining four monkeys were used for a longer follow-up study to determine the changes in chondroitinase ABC-injected discs. RESULTS: Degenerative changes of discs were more severe with the injection of chymopapain, although the content of hyaluronic acid, chondroitin sulfate, and dermatan sulfate decreased more with the injection of chondroitinase ABC. In a longer follow-up study, chondroitinase ABC-injected discs recovered somewhat morphologically and biochemically. CONCLUSIONS: The results confirm that selective degradation is achieved with chondroitinase ABC in vivo in monkeys and that chondroitinase ABC is less toxic to discs than chymopapain is. From these considerations, chondroitinase ABC is believed to have a high potential for clinical application.