OR13

Modelling Stargardt disease using three-dimensional retinal organoids

C Morival(1,2) E Mortier(1,2) J Varin(1,2) S Renault(1,2) A Pereira(1,2) B Robert(1,2) B Fraysse(1,2) M Croyal(1,3) J B Dupont(1,2) T Cronin(1,2) O Adjali(1,2)

1:Université de Nantes; 2:UMR INSERM 1089; 3:Inserm UMR 1087; CNRS UMR 6291- Institut du thorax

Stargardt disease (STGD1) is an autosomal recessive genetic disorder caused by mutations in the ABCA4 gene, leading to a juvenile form of severe macular dystrophy. Accounting for nearly 7% of retinopathies, STGD1 currently has no treatment. To overcome the limitations of existing STGD1 models, the use of human induced pluripotent stem cells (hiPSCs) carrying disease-associated mutations represents a promising approach. Due to their differentiation potential, hiPSCs can generate multi-layered 3D structures resembling optic vesicles, known as retinal organoids (ROs), which recapitulate human retinal structure and physiology in vitro.

The objective of our project is to model the visual cycle—a critical process for vision that is dysregulated in STGD1—using hiPSCs and ROs derived from both patients and healthy donors. In our initial experiments, we successfully cultivated mature ROs that exhibited proper organization, discernible photoreceptors (PRs), and ABCA4 expression. Additionally, we obtained mature retinal pigment epithelium (RPE) cells with correct polarization, as evidenced by RPE65 expression and ZO-1 localization in confocal imaging. Differentiated RPE cells also participated in the visual cycle, as demonstrated by metabolite measurements using mass spectrometry. Finally, electron microscopy images of RPE cells revealed characteristic microvilli and melanosomes.

Comparative analysis between patient-derived and healthy control models will provide deeper insights into the cellular and molecular mechanisms underlying retinal degeneration in STGD1. Furthermore, our STGD1 models may serve as a platform for evaluating and optimizing gene therapy strategies in our lab.