Local delivery of reporter gene to the cochlea does not spread to brain tissue in an animal model

Abstract

Conclusion. The results suggest that local injection of 1 µl of lentiviral-green fluorescent protein (LV-GFP) into rat scala tympani as a lentiviral (LV) vector in the cochlea does not disseminate into the surrounding brain tissue. Objective. To investigate whether the LV vector will spread into the cerebrospinal fluid (CSF) and affect brain tissue after local cochlear injection in an animal model. Materials and methods. Sixteen animals were sacrificed after cochleostomy and injection of 1 µl LV-GFP vectors with different promoters such as CAG (consisting of the cytomegalovirus immediate early enhancer and the chicken β-actin promoter), EF-1α (human elongation factor 1alpha), PGK (human phosphoglycerate kinase 1) and CPPT (central polypurine tract). Eleven brain tissues were fixed in 4% paraformaldehyde at 4°C, processed for cryosectioning and examined under fluorescence microscope. Results. The patterns of the fluorescent signals with red and green filters were compared to identify the GFP signals in the brain tissue. GFP reporter gene expression was not detected in any examined brain region in any of the animals.