Evaluation of AAV-mediated expression of Chop2-GFP in the marmoset retina.
OBJECTIVE
Converting inner retinal neurons to photosensitive cells by expressing channelrhodopsin-2 (ChR2) offers a novel approach for treating blindness caused by retinal degenerative diseases. In the present study, the recombinant adeno-associated virus serotype 2 (rAAV2)-mediated expression and function of a fusion construct of channelopsin-2 (Chop2) and green fluorescent protein (GFP) (Chop2-GFP) were evaluated in the inner retinal neurons in the common marmoset Callithrix jacchus.


METHODS
rAAV2 vectors carrying ubiquitous promoters were injected into the vitreous chamber. Expression of Chop2-GFP and functional properties of ChR2 were examined by immunocytochemical and electrophysiological methods 3 months after injection.


RESULTS
The percentage of Chop2-GFP-expressing cells in the ganglion cell layer was found to be retinal region- and animal age-dependent. The highest percentage was observed in the far-peripheral region. Chop2-GFP expression was also found in the foveal and parafoveal region. In the peripheral retina in young animals with high viral concentrations, the expression of Chop2-GFP was observed in all major classes of retinal neurons, including all major types of ganglion cells. The morphologic properties of Chop2-GFP-positive cells were normal for at least 3 months, and ChR2-mediated light responses were demonstrated by electrophysiological recordings.


CONCLUSIONS
The rAAV2-mediated expression of ChR2 was observed in the inner retinal neurons in the marmoset retina through intravitreal delivery. The marmoset could be a valuable nonhuman primate model for developing ChR2-based gene therapy for treating blinding retinal degenerative diseases.
Ivanova
Elena
E
Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, Michigan, USA. eivanova@med.wayne.edu
Hwang
Grace-Soon
GS
Pan
Zhuo-Hua
ZH
Troilo
David
D
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002144:Callithrix; D002352:Carrier Proteins / Q000235:genetics*; D000229:Dependovirus / Q000235:genetics*; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000502:physiology*; D019084:Fluorescent Antibody Technique, Indirect; D005786:Gene Expression Regulation / Q000502:physiology*; D015316:Genetic Therapy; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D012165:Retinal Ganglion Cells / Q000378:metabolism*; D014162:Transfection
D015415:Biomarkers; D002352:Carrier Proteins; D011993:Recombinant Fusion Proteins; C523009:channelopsin-2, Chlamydomonas reinhardtii; D049452:Green Fluorescent Proteins