Chondroitinase ABC promotes corticospinal axon growth in organotypic cocultures

Abstract

Organotypic coculture model using brain cortex and spinal cord of neonatal rats was used to test the effect of chondroitinase ABC (ChABC) on corticospinal axon growth. Chondroitin sulfate proteoglycan (CSPG) is neurite outgrowth inhibitory factor that combines with reactive astrocyte at the lesion site to form a dense scar that acts as a barrier to regenerating axons. ChABC is a bacteria enzyme that digests the glycosaminoglycan side chain of CSPG. We investigated the effect of ChABC on corticospinal axon growth quantitatively using the organotypic cocultures of brain cortex and spinal cord. Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University. We used organotypic cocultures with neonatal brain cortex and spinal cord as an in vitro assay system for assessing axon growth. After administering ChABC, we counted the number of axons passing through a reference line running parallel to the junction between the brain cortex and spinal cord 500 and 1000 microm from the junction. The immunoreactivity of CSPG was assessed. The average number of axons after ChABC administration was significantly greater than in the control group. Administration of ChABC decreased CSPG expression in this coculture system. ChABC induces axonal regeneration by degrading CSPG after central nerve system injury. ChABC has great potential for future therapeutic use in spinal cord-injured patients.