The RPE is located right next to the photoreceptors of the eye and provides them with nourishment and support. People with OCA lack the pigmented RPE and have underdeveloped fovea, an area in the retina that is important for central vision. The optic nerve carries visual signals to the brain.
People with OCA have misdirected optic nerve fibers. The scientists think that RPE plays a role in the formation of these structures and wanted to understand how the lack of pigment affects their development.
“The animals used to study albinism are less than ideal,” says Brian P. Brooks, MD, Ph.D., NEI clinical director and head of the Ophthalmic Genetics and Visual Function Branch. because they lack foveae. “A human stem cell model that mimics the disease is an important step forward in understanding albinism and testing potential therapies to treat the disease.”
To create this model, the researchers reprogrammed skin cells from people without OCA and those with the two most common types of OCA (OCA1A and OCA2) into pluripotent stem cells (iPSCs). . The iPSCs were then differentiated into RPE cells. RPE cells from OCA patients resembled RPE cells from unaffected individuals but showed significantly reduced pigmentation.
The researchers will use the model to study how the lack of pigment affects the function and physiology of RPE. In theory, if fovea growth is dependent on RPE pigment and pigmentation can be somehow ameliorated, vision defects associated with fovea abnormal growth can be as few as possible. partially resolved, according to Brooks.
“Treating albinism at a very young age, possibly even before surgery, when the eye’s structures are forming, will have the greatest chance of saving vision,” says Brooks. “For example, in adults, the benefits may be limited to improving light sensitivity, but children may see more dramatic effects.”
The team is now exploring how to use their model for high-throughput screening of potential OCA therapies.