Helper-dependent adenovirus-mediated gene transfer into the adult mouse cochlea.
BACKGROUND
Gene therapy may provide a way to restore cochlear function to deaf patients. The most successful techniques for cochlear gene therapy have been injection of early-generation adenoviral vectors into scala media in guinea pigs. However, it is important to be able to perform gene therapy research in mice because there is wide availability of transgenic strains with hereditary hearing loss.


OBJECTIVE
We demonstrate our technique for delivery of a third-generation adenoviral vector, helper-dependent adenovirus (HDAd), to the adult mouse cochlea.


METHODS
Mice were injected with an HDAd that contained a reporter gene for either beta-galactosidase or green fluorescent protein into scala media. After 4 days, the cochleae were harvested for analyses. Auditory brainstem response monitoring of cochlear function was performed before making a cochleostomy, after making a cochleostomy, and before killing the animal.


RESULTS
Beta-galactosidase was identified in the spiral ligament, the organ of Corti, and spiral ganglion cells by light microscopy. Green fluorescent protein epifluorescence was assessed in whole-mount organ of Corti preparations using confocal microscopy. This demonstrated transduction of inner hair cells, outer hair cells, and supporting cells. Paraffin-embedded cross sections similarly revealed gene transduction within the organ of Corti. Threshold shifts of 39.8 +/- 5.4 and 37.7 +/- 5.5 dB were observed in mice injected with HDAd or control buffer, respectively.


CONCLUSIONS
The technique of scala media HDAd injection reliably infects the adult mouse cochlea, including cells within the organ of Corti, although the procedure itself adversely affects hearing.
Bobby R. Alford Department of Otolaryngology-Head and Neck Surgery, Baylor College of Medicine, Houston, Texas 77030, USA.
Gentiana I
GI
Wenzel
Anping
A
Xia
Etai
E
Funk
M Bradley
MB
Evans
Donna J
DJ
Palmer
Philip
P
Ng
Fred A
FA
Pereira
John S
JS
Oghalai
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D003051:Cochlea / Q000033:anatomy & histology / Q000254:growth & development* / Q000502:physiology; D004566:Electrodes; D004848:Epithelium / Q000254:growth & development / Q000502:physiology; D016057:Evoked Potentials, Auditory, Brain Stem; D018014:Gene Transfer Techniques; D017930:Genes, Reporter / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D006378:Helper Viruses / Q000235:genetics*; D007763:Lac Operon / Q000235:genetics; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D020409:Molecular Motor Proteins / Q000235:genetics; D009925:Organ of Corti / Q000502:physiology; D001616:beta-Galactosidase / Q000235:genetics
D020409:Molecular Motor Proteins; C498720:Pres protein, mouse; D049452:Green Fluorescent Proteins; D001616:beta-Galactosidase