Chondroitinase ABC-I and -II crosslinked chitosan beads improve axonal regrowth in CSPG-enriched astrocyte culture

Abstract

After spinal cord injury, axonal regrowth is often restricted due to upregulation of chondroitin sulfate proteoglycans (CSPGs) at the lesion site. Chondroitinase ABC I and II (recombinant ChABC-I & II) cleave CS moieties of the PGs enhancing prospects of axonal regrowth through the lesion. To reduce decay of ChABC activity in vivo, we attempted to separately immobilize ChABC-I or -II on chitosan beads using glutaraldehyde as a crosslinker. Immobilized ChABC-I demonstrated CS-cleaving activity both in biochemical assay and in astrocyte cultures that had been activated by transforming growth factor beta(TGF-β) to secrete CSPGs. Neurite length was increased in co-cultures of TGF-β activated astrocytes and cortical neurons mixed with immobilized ChABC-I, immobilized ChABC-II or both. Given CSPG enrichment at astrocyte-Schwann cell (A/S) encounters, A/S confrontation co-culture was used in a further bioassay of immobilized enzyme activity. Preliminary data showed that neurite length was increased in ChABC-I treated A/S co-culture. In future, the effect of immobilized ChABC-I and -II on neurite length will be tested in A/S co-culture.