Abstract
Purpose :
Recent studies on VLC-PUFAs (C24-36) have revealed their specific presence and importance in retina. They are rarely consumed in diets and are specifically synthesized in vivo from long-chain PUFAs through the action of an enzyme known as ELOVL4. Genetic defects in ELOVL4 underlie the retinal pathology in Stargardt Type 3 (STGD3), a dominant, early-onset blinding disease with many symptoms that mirror dry age-related macular degeneration (dAMD). In a previous study, we chemically synthesized a VLC-PUFA (32:6 n-3) and measured its uptake in mouse retina and its beneficial effects on vision. In order to further study the role of VLC-PUFAs on photoreceptor development and maintenance, we supplemented 32:6 n-3 to ELOVL4 knockout retinal organoids.
Methods :
We knocked out ELOVL4 in normal human iPSCs using CRIPR/Cas9 technology and generated retinal organoids using standard techniques. When the organoids had completed the phase of photoreceptor birth (17 weeks), the ELOVL4-/- organoids were divided into two groups. One group was supplemented with 8 µM 32:6 n-3, while the control group received vehicle alone. Photoreceptor outer segment morphology and length were measured at 33 weeks of age.
Results :
By 33 weeks of age, the vehicle-treated ELOVL4-/- organoids had outer segments, but they appeared shorter and more disorganized than expected for normal human retinal organoids. The ELOVL4-/- organoids supplemented with 32:6 n-3 had significantly longer outer segments (P<0.001) with normal morphology.
Conclusions :
These results establish that ELOVL4-/- organoids can be used as a model to study the pathophysiology and treatment of diseases associated with ELOVL4 dysfunction and that a synthetic VLC-PUFA can rescue abnormalities associated with absence of ELOVL4 activity. We are currently studying the ultrastructure of the outer segments of our treated and control organoids and the efficacies of n-3 versus n-6 VLC-PUFAs.
This is a 2021 ARVO Annual Meeting abstract.