ABSTRACT
Functional replacement of specific neuronal populations through transplantation of neural tissue represents an attractive therapeutic strategy for treating neurodegenerative disorders like Parkinson's disease (PD). Even though the brain is a partially immune privileged site, immunosuppression is still needed for the prevention of host immune response, and thus, xenograft rejection. Here, we investigated the fate of human ventral mesencephalon derived immortalized cell line ReNcell VM upon unilateral transplantation into the intact rat striatum with or without immunosuppression with cyclosporine A (CsA). The status of xenografted human ReNcell VM cells was analysed by immunohistochemistry/immunofluorescence 4 and 6weeks after transplantation. Four weeks after transplantation, ReNcell VM cells could be detected in both groups, although the number of survived cells was significantly higher in brains of immunosuppressed rats. In contrast, only 2 out of 6 brains grafted without immunosuppression revealed human ReNcell VM cells 6weeks post grafting, whereas a considerable number of human cells could still be found in all the brains of immunosuppressed rats. Immunohistochemical analysis of grafted cells showed almost no evidence of neuronal differentiation, but rather astroglial development. In summary, we have shown that the immunosuppression is needed for the survival of human VM derived progenitor cells in the rat striatum. CsA affected cell survival, but not differentiation capacity: in both groups, grafted either with or without immunosuppression, the ReNcell VM cells lacked neuronal phenotype and developed preferentially into astroglia.
Subject(s)
Brain/cytology , Immunosuppressive Agents/pharmacology , Neural Stem Cells/transplantation , Stem Cell Transplantation/methods , Animals , Antigens, Nuclear/metabolism , Blotting, Western , Brain/drug effects , Cell Count , Cell Differentiation/physiology , Cell Movement/physiology , Cell Proliferation , Cell Survival/physiology , Culture Media , Fluorescent Antibody Technique , Glial Fibrillary Acidic Protein/metabolism , Graft Survival/physiology , Immunohistochemistry , Intermediate Filament Proteins/genetics , Intermediate Filament Proteins/metabolism , Neostriatum/cytology , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Nestin , Proteome/genetics , RatsABSTRACT
Previous evidence suggests that guanine nucleotides can directly inhibit N-methyl-d-aspartate (NMDA) and AMPA/kainate receptors and antagonize a variety of cellular functions elicited by these glutamate receptor agonists. We investigated the possibility that the guanine nucleotides GTP, GDP, and GMP exert a neuroprotective effect on cultured rat hippocampal or neocortical neurons exposed to the excitotoxicants NMDA (30 microM) or kainate (300 microM). On co-application with NMDA all three nucleotides revealed a comparable rescue effect from 100 microM nucleotide concentrations onwards, with a higher inhibitory potential in hippocampal than in neocortical cultures. Similarly, kainate-induced neurotoxicity was inhibited by all three nucleotides but the inhibitory potential was lower than after application of NMDA. Guanosine had no effect on either culture system. GTP and GDP where hydrolyzed by hippocampal and cortical cultures with GMP accumulating in the medium, suggesting that hydrolysis of GTP had no effect on the effective nucleotide concentration. Our results show that GTP, GDP, and GMP inhibit NMDA- and kainate-mediated neurotoxicity in cultured hippocampal and neocortical neurons. They suggest that guanine nucleotides may be candidates for broadly antagonizing glutamate receptor-mediated neurotoxicity.
