Immobilised Chondroitinase ABC Promotes Axonal Regrowth in Lesioned Spinal Cord

Abstract

Chondroitinase ABC (ChABC) has been utilised to digest restrictive chondroitin sulphate (CS) at scar tissue of injured nerves and therefore make way for axonal regrowth beyond the scar. Enzymic efficacy of the purified enzyme however decayed rapidly in physiological solution. Here we report cross-linking of recombinant ChABC to chitosan microspheres as an alternative means of delivery. Immobilized ChABC demonstrated CS-cleaving activity on both purified CS and that deposited by reactive astrocytes in culture. Cortical neurons seeded on ChABC-treated astrocyte cultures extended neurites that were significantly longer than those on the null-treated control cultures. We tested the efficacy in vivo by introducing the soluble versus immobilised ChABC to hemisected lesion made in the thoracic cord. Two weeks later, CS (probed by CS56 antibody) was barely detectable at the lesion site treated by either soluble enzyme or immobilised enzyme. Axons were observed in the lesion treated with immobilised enzyme but not in cases treated with soluble enzyme. To conclude, treatment with immobilised ChABC improves the injured environment for axonal regrowth. [This work is supported by Innovation and Technology Support Programme (ITS/100/10)].