Insulin-like growth factor 1 gene delivery to the ependymal cell layer effectively increases transgenic peptide levels in cerebrospinal fluid: implication for gene therapy

HEREÑU CB; SONNTAG WE; MOREL GR; PORTIANSKY EL; GOYA RG

Washington DC

Congreso; 37th Annual Meeting of the Society for Neuroscience; 2008

Society for Neuroscience

Intracerebroventricular administration of insulin-like growth factor I (IGF-I) has been shown  to be an effective neuroprotective strategy in the brain of different animal models, a major advantage being the achievement of high concentrations of IGF-I in the brain without altering the circulating levels of the peptide. Intracerebroventricular IGF-I gene therapy has not been documented. We used recombinant adenoviral (RAd) vectors expressing their transgene under the control of the potent mouse cytomegalovirus immediate early (mCMV) promoter, to transduce brain ependymal cells with high efficiency and to achieve effective release of transgenic IGF-I into the cerebrospinal fluid (CSF). We constructed RAd vectors expressing either the chimeric protein (GFP/TK)fus (green fluorescent protein fused to HSV1 thymidine kinase) or the cDNA encoding rat IGF-I, both driven by the mCMV promoter. The vectors were injected into the lateral ventricles of young rats and chimeric GFP expression in brain sections was detected by fluorescence microscopy. The ependymal cell marker vimentin was detected by immunofluorescence and nuclei were labeled with the DNA dye DAPI. Blood and CSF samples  were drawn at different times post vector injection. In all cerebral ventricles, vimentin immunoreactive cells of the ependyma were predominantly transduced by RAd-(GFP/TK)fus , showing a strong nuclear  expression of the transgene, except for tanycytes where cytoplamic (GFP/TK)fus expression was also evident. Intracerebroventricular injection of RAd-IGF-I induced high levels of IGF-I in the CSF but not in serum. We conclude that the ependymal route constitutes an effective approach for implementing experimental IGF-I gene therapy in the brain