Long-term evaluation of retinal function in Prph2Rd2/Rd2 mice following AAV-mediated gene replacement therapy.
BACKGROUND
Prph2(Rd2/Rd2) mice have a retinal degeneration due to a null mutation for the Prph2 gene which encodes a photoreceptor-specific glycoprotein, peripherin2, essential for outer-segment formation. We have previously shown improvement of photoreceptor function at a single time point following AAV-mediated gene replacement therapy. Here we quantify the functional rescue over a 15-week time course and present a detailed analysis of the improvement in retinal function.


METHODS
An AAV2 vector, AAV.rho.rds, carrying a peripherin2 c-DNA, was in injected subretinally into 10-day-old Prph2(Rd2/Rd2) mice. One group was injected at a single time point while in a second group the injections were repeated after 5 days. The effect of treatment was analysed histologically using electron microscopy and electroretinography (ERG) was used to assess functional changes. Treated mice were recorded at regular intervals over 15 weeks. Untreated contralateral eyes served as internal control.


RESULTS
A significant increase in b-wave amplitude was first noted 3 weeks after treatment of 10-day-old Prph2(Rd2/Rd2) mice and persisted for up to 14 weeks. An increase in the area of retina exposed to vector resulted in a significant increase in both b-wave amplitude and persistence.


CONCLUSIONS
In this study AAV-mediated gene replacement in Prph2(Rd2/Rd2) mice resulted in a significant functional improvement over a period of 14 weeks. These results support the utility of gene therapy approaches as treatment for photoreceptor dystrophies.
Schlichtenbrede
Frank C
FC
Department of Molecular Genetics, Institute of Ophthalmology, University College London, UK.
da Cruz
Lyndon
L
Stephens
Clare
C
Smith
Alexander J
AJ
Georgiadis
Anastasios
A
Thrasher
Adrian J
AJ
Bainbridge
James W B
JW
Seeliger
Mathias W
MW
Ali
Robin R
RR
D000818:Animals; D000229:Dependovirus / Q000235:genetics*; D004195:Disease Models, Animal; D004596:Electroretinography; D015316:Genetic Therapy; D005822:Genetic Vectors; D007381:Intermediate Filament Proteins / Q000235:genetics*; D008562:Membrane Glycoproteins; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics*; D064531:Peripherins; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology / Q000648:ultrastructure; D012160:Retina / Q000166:cytology / Q000473:pathology / Q000503:physiopathology*; D012162:Retinal Degeneration / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D013997:Time Factors
D007381:Intermediate Filament Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D064531:Peripherins; C578996:Prph2 protein, mouse