Related Experiment Video
Updated: May 24, 2026
Limbal Approach-Subretinal Injection of Viral Vectors for Gene Therapy in Mice Retinal Pigment Epithelium
Published on: August 7, 2015
Tyrosine-mutant AAV8 delivery of human MERTK provides long-term retinal preservation in RCS rats
Wen-Tao Deng1, Astra Dinculescu, Qiuhong Li
1Department of Ophthalmology, College of Medicine, University of Florida, 1600 SW Archer Road, Gainesville, FL 32610, USA. wdeng@ufl.edu
Purpose:
The absence of Mertk in RCS rats results in defective RPE phagocytosis, accumulation of outer segment (OS) debris in the subretinal space, and subsequent death of photoreceptors. Previous research utilizing Mertk gene replacement therapy in RCS rats provided proof of concept for treatment of this form of recessive retinitis pigmentosa (RP); however, the beneficial effects on retinal function were transient. In the present study, we evaluated whether delivery of a MERTK transgene using a tyrosine-mutant AAV8 capsid could lead to more robust and longer-term therapeutic outcomes than previously reported.
Methods:
An AAV8 Y733F vector expressing a human MERTK cDNA driven by a RPE-selective promoter was administrated subretinally at postnatal day 2. Functional and morphological analyses were performed at 4 months and 8 months post-treatment. Retinal vasculature and Müller cell activation were analyzed by quantifying acellular capillaries and glial fibrillary acidic protein immunostaining, respectively.
Results:
Electroretinographic responses from treated eyes were more than one-third of wild-type levels and OS were well preserved in the injection area even at 8 months. Rescue of RPE phagocytosis, prevention of retinal vasculature degeneration, and inhibition of Müller cell activation were demonstrated in the treated eyes for at least 8 months.
Conclusions:
This research describes a longer and much more robust functional and morphological rescue than previous studies. We also demonstrate for the first time that an AAV8 mutant capsid serotype vector has a substantial therapeutic potential for RPE-specific gene delivery. These results suggest that tyrosine-mutant AAV8 vectors hold promise for the treatment of individuals with MERTK-associated RP.
Insights
A novel gene therapy using a modified AAV8 vector successfully restored retinal function and structure in rats with Mertk-deficient retinitis pigmentosa (RP). This approach offers a promising, long-term treatment for RP caused by MERTK mutations.
Area of Science:
- Ophthalmology
- Gene Therapy
- Retinal Degeneration
Background:
- Mertk deficiency in RCS rats causes retinal pigment epithelium (RPE) phagocytosis defects, leading to photoreceptor death and retinitis pigmentosa (RP).
- Previous Mertk gene replacement therapy showed transient benefits, highlighting the need for more durable treatment strategies.
Purpose of the Study:
- To evaluate the therapeutic potential of a tyrosine-mutant AAV8 (AAV8 Y733F) vector for delivering a MERTK transgene.
- To assess if this approach could achieve more robust and longer-term outcomes compared to previous therapies for Mertk-deficient RP.
Main Methods:
- Subretinal injection of an AAV8 Y733F vector carrying human MERTK cDNA into RCS rats at postnatal day 2.
- Functional (electroretinography) and morphological analyses were conducted at 4 and 8 months post-treatment.
- Evaluation of retinal vasculature and Müller cell activation (gliosis).
Main Results:
- Treated eyes showed over one-third of wild-type electroretinographic responses and preserved outer segments (OS) at 8 months.
- Restored RPE phagocytosis, prevented retinal vascular degeneration, and inhibited Müller cell activation for at least 8 months.
- Demonstrated significant functional and morphological rescue, exceeding previous study outcomes.
Conclusions:
- AAV8 Y733F vectors provide a robust and long-lasting therapeutic effect for MERTK-associated RP.
- This study demonstrates the significant potential of tyrosine-mutant AAV8 vectors for RPE-specific gene delivery.
- The findings suggest a promising therapeutic avenue for patients with MERTK-related inherited retinal diseases.
