Dataset Information

Lentiviral gene transfer of RPE65 rescues survival and function of cones in a mouse model of Leber congenital amaurosis.

ABSTRACT:

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.

Methods and findings

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.

SUBMITTER: Bemelmans AP

PROVIDER: S-EPMC1592340 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeTo report an anatomic change following subretinal injection of voretigene neparvovec-rzyl (VN) for RPE65-mediated Leber congenital amaurosis.DesignMulticenter, retrospective chart review.ParticipantsPatients who underwent subretinal VN injection at each of 4 participating institutions.MethodsPatients were identified as having perifoveal chorioretinal atrophy if (1) the areas of atrophy were not directly related to the touch-down site of the subretinal cannula; and (2) the area of atrophy progressively enlarged over time. Demographic data, visual acuity, refractive error, fundus photographs, OCT, visual fields, and full-field stimulus threshold (FST) were analyzed.Main outcome measuresOutcome measures included change in visual acuity, FST, visual fields, and location of atrophy relative to subretinal bleb position.ResultsA total of 18 eyes of 10 patients who underwent subretinal injection of VN were identified as having developed perifoveal chorioretinal atrophy. Eight of 10 patients (80%) developed bilateral atrophy. The mean age was 11.6 years (range, 5-20 years), and 6 patients (60%) were male. Baseline mean logarithm of the minimum angle of resolution visual acuity and FST were 0.82 (standard deviation [SD], 0.51) and -1.3 log cd.s/m2 (SD, 0.44), respectively. The mean spherical equivalent was -5.7 diopters (D) (range, -11.50 to +1.75 D). Atrophy was identifiable at an average of 4.7 months (SD, 4.3) after surgery and progressively enlarged in all cases up to a mean follow-up period of 11.3 months (range, 4-18 months). Atrophy developed within and outside the area of the subretinal bleb in 10 eyes (55.5%), exclusively within the area of the bleb in 7 eyes (38.9%), and exclusively outside the bleb in 1 eye (5.5%). There was no significant change in visual acuity (P = 0.45). There was a consistent improvement in FST with a mean improvement of -3.21 log cd.s/m2 (P < 0.0001). Additionally, all 13 eyes with reliable Goldmann visual fields demonstrated improvement, but 3 eyes (23.1%) demonstrated paracentral scotomas related to the atrophy.ConclusionsA subset of patients undergoing subretinal VN injection developed progressive perifoveal chorioretinal atrophy after surgery. Further study is necessary to determine what ocular, surgical delivery, and vector-related factors predispose to this complication.