Astroglial injury in an ex vivo model: contributions to its analysis in enriched cell cultures.

In vitro cell culture models have been proposed to analyze some of the complex structural and functional characteristics involved in astroglial changes after neural injury in vivo. This report contributes to analyze the proposed hypothesis that an experimentally induced discontinuity of a confluent cellular culture could represent a useful model for the analysis of the processes involved in a neural lesion. For this purpose, it was decided to characterize astroglial proliferation and dye coupling state after a "scratch wound" applied to confluent, astrocyte-enriched cell cultures, obtained from several rat brain regions. Proliferation was assessed in terms of bromodeoxyuridine nuclear incorporation as a function of lesion width, serum deprivation, time after confluence, brain region origin, postlesional culture medium changes and agitation, and after application of a gap-junction uncoupling agent. The proliferative reaction after injury was neither cell type-specific nor brain region specific, nor was significantly affected by neither of the above-mentioned variables. Furthermore, injury failed to significantly affect the astroglial dye coupling state. Results suggest that the proliferative response observed under present conditions would depend on the disruption of contact inhibition rather than on astroglial mitogenic signals released from the wound and operating by either extracellular or cell coupling mechanisms. Present results question the validity of astrocyte-enriched cell cultures as an experimental model of neural tissue injury in vivo, as they do not appear to reproduce fundamental characteristics expressed in situ.