EFFECTS OF ASTROCYTE IMPLANTATION INTO THE HEMISECTED ADULT-RAT SPINAL-CORD

Morphological and biochemical methods were applied to assess the effec ts of implanting cultured astrocytes into the hemisected adult rat spi nal cord. Astrocytes were purified from neonatal rat cortex and introd uced into the lesioned spinal cord either in suspension injection or c ultured on gelfoam first. The control groups were rats which had hemis ection with injection of culture media or with gelfoam grafted alone. At various time points after surgery (two weeks to two months), the sp inal cord was removed and processed for routine light microscopy, immu nofluorescence, gel electrophoresis and immunoblotting. As early as tw o weeks after surgery, a significantly smaller volume of scar tissue w as consistently found in the experimental groups. This reduced scarrin g was also confirmed by immunofluorescence staining and immunoblotting for glial fibrillary acidic protein in the specimens two months after hemisection. Compared to the control groups, the experimental groups also had more intense staining for neurofilaments, which was confirmed by immunoblotting. However, labelling of the astrocytes with Phaseolu s vulgaris leucoagglutinin conjugated with fluorescein showed that the astrocytes migrated at a rate of 0.6 mm/day from the original implant ed site. The results therefore suggested that the cultured astrocytes probably exerted their effects over a short time period (less than two weeks) around the lesion site. They could have altered the microenvir onment and as a result less scar tissue was formed. Hence, there was l ess barrier to the regrowth of nerve fibres.