Lentiviral gene transfer of RPE65 rescues survival and function of cones in a mouse model of Leber congenital amaurosis.
BACKGROUND
RPE65 is specifically expressed in the retinal pigment epithelium and is essential for the recycling of 11-cis-retinal, the chromophore of rod and cone opsins. In humans, mutations in RPE65 lead to Leber congenital amaurosis or early-onset retinal dystrophy, a severe form of retinitis pigmentosa. The proof of feasibility of gene therapy for RPE65 deficiency has already been established in a dog model of Leber congenital amaurosis, but rescue of the cone function, although crucial for human high-acuity vision, has never been strictly proven. In Rpe65 knockout mice, photoreceptors show a drastically reduced light sensitivity and are subject to degeneration, the cone photoreceptors being lost at early stages of the disease. In the present study, we address the question of whether application of a lentiviral vector expressing the Rpe65 mouse cDNA prevents cone degeneration and restores cone function in Rpe65 knockout mice.


RESULTS
Subretinal injection of the vector in Rpe65-deficient mice led to sustained expression of Rpe65 in the retinal pigment epithelium. Electroretinogram recordings showed that Rpe65 gene transfer restored retinal function to a near-normal pattern. We performed histological analyses using cone-specific markers and demonstrated that Rpe65 gene transfer completely prevented cone degeneration until at least four months, an age at which almost all cones have degenerated in the untreated Rpe65-deficient mouse. We established an algorithm that allows prediction of the cone-rescue area as a function of transgene expression, which should be a useful tool for future clinical trials. Finally, in mice deficient for both RPE65 and rod transducin, Rpe65 gene transfer restored cone function when applied at an early stage of the disease.


CONCLUSIONS
By demonstrating that lentivirus-mediated Rpe65 gene transfer protects and restores the function of cones in the Rpe65(-/-) mouse, this study reinforces the therapeutic value of gene therapy for RPE65 deficiencies, suggests a cone-preserving treatment for the retina, and evaluates a potentially effective viral vector for this purpose.
Bemelmans
Alexis-Pierre
AP
Unit of Gene Therapy and Stem Cell Biology, Jules Gonin Eye Hospital, Lausanne, Switzerland.
Kostic
Corinne
C
Crippa
Sylvain V
SV
Hauswirth
William W
WW
Lem
Janis
J
Munier
Francis L
FL
Seeliger
Mathias W
MW
Wenzel
Andreas
A
Arsenijevic
Yvan
Y
D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D004195:Disease Models, Animal; D004596:Electroretinography; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D044385:GTP-Binding Protein alpha Subunits; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D020962:Heterotrimeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D016086:Lentivirus / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D012160:Retina / Q000378:metabolism / Q000503:physiopathology; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism / Q000473:pathology*; D012174:Retinitis Pigmentosa / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D017299:Rod Opsins / Q000378:metabolism; D013997:Time Factors; D015293:Transducin; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase
D002352:Carrier Proteins; D005136:Eye Proteins; D044385:GTP-Binding Protein alpha Subunits; D020962:Heterotrimeric GTP-Binding Proteins; D017299:Rod Opsins; D015293:Transducin; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase; C488949:Gnat1 protein, mouse; C515337:Gnat2 protein, mouse