Extracellular matrix dysfunction in Sorsby patient-derived retinal pigment epithelium

Area of Science:

• Ophthalmology
• Genetics
• Cell Biology

Background:

• Sorsby Fundus Dystrophy (SFD) is a rare macular degeneration with sub-retinal pigment epithelium (RPE) deposits.
• Previous studies on SFD patient-induced pluripotent stem cell (iPSC)-derived RPE have yielded conflicting results regarding recapitulation of key pathological features.
• A hallmark of SFD is extracellular deposits beneath the RPE, clinically similar to age-related macular degeneration (AMD).

Purpose of the Study:

• To determine if SFD patient-derived iPSC-RPE form basal deposits comparable to SFD globes.
• To investigate whether SFD iPSC-RPE exhibit increased oxidative stress.
• To assess the impact of CRISPR-Cas9 gene correction of the S204C TIMP3 mutation on SFD RPE phenotype.

Main Methods:

• Comparison of iPSC-RPE from SFD patients and controls, alongside post-mortem SFD globes.
• Analysis of SFD iPSC-RPE after CRISPR-Cas9 gene correction of the S204C TIMP3 mutation.
• Targeted metabolomics and stable isotope-labeled metabolite analysis to assess oxidative stress and ECM turnover.

Main Results:

• SFD iPSC-RPE formed significantly more sub-RPE deposits than control RPE, mirroring those in SFD globes.
• CRISPR-Cas9 gene correction reduced basal laminar and sub-RPE calcium deposits in SFD iPSC-RPE.
• SFD RPE showed increased TIMP3 accumulation, elevated intracellular 4-hydroxyproline, decreased reduced glutathione, and heightened vulnerability to oxidative stress.

Conclusions:

• SFD pathology, including sub-RPE deposits and oxidative stress, can be recapitulated in iPSC-RPE cultures.
• These findings provide a valuable in vitro model for studying SFD mechanisms.
• Gene correction offers a potential therapeutic avenue by mitigating key pathological features.