Degradation of proteoglycans affects astrocytes and neurite formation in organotypic tissue cultures

Abstract

Chondroitin sulfate proteoglycans (CSPGs) promote nerve growth during development, and inhibit axonal growth in the adult CNS after injury. Chondroitinase ABC (ChABC) and methyl-umbelliferyl-β-d-xyloside (β-xyloside), two compounds that degrade CSPGs, promote regeneration after injury, however, they demonstrate opposing results in tissue culture. To elucidate the effect of the two compounds, organotypic tissue cultures, treated with ChABC or β-xyloside, were employed to monitor nerve fiber outgrowth and astrocytic migration. Rat ventral mesencephalon (VM) and spinal cord (SC) from embryonic day (E) 14 and E18 were treated early, from the plating day for 14 days in vitro, or late where treatment was initiated after being cultured for 14 days. In the early treatment of E14 VM and SC cultures, astrocytic migration and nerve fiber outgrowth were hampered using both compounds. Early treatment of E18 cultures reduced the astrocytic migration, while nerve growth was promoted by β-xyloside, but not by ChABC. In the late treated cultures of both E14 and E18 cultures, no differences in distances that astrocytes migrated or nerve fiber growth were observed. However, in β-xyloside-treated cultures, the confluency of astrocytic monolayer was disrupted. In E18 cultures both early and late treatments, neuronal migration was present in control cultures, which was preserved using ChABC but not β-xyloside. In conclusion, ChABC and β-xyloside had similar effects and hampered nerve fiber growth and astrocytic migration in E14 cultures. In E18 cultures nerve fiber growth was stimulated and neuronal migration was hampered after β-xyloside treatment while ChABC treatment did not exert these effects.

Keywords: CSPGs; ChABC; Spinal cord; Ventral mesencephalon; β-xyloside.