NIH Researchers Develop First Albinism Stem Cell Model to Study Related Eye Conditions
Tuesday, January 11, 2022
The use of stem cells derived from patients will allow high throughput drug screening for potential therapies.
Researchers at the National Eye Institute (NEI) have developed the first patient-derived stem cell model to study eye conditions associated with oculocutaneous albinism (OCA). The development of the model is described in the January issue of the journal Stem Cell Reports. NEI is part of the National Institutes of Health.
“This ‘disease in a dish’ system will help us understand how the lack of pigment in albinism leads to abnormal development of the retina, optic nerve fibers and other eye structures crucial for central vision,” said Aman George, Ph .D., scientific staff member of the NEI’s Ophthalmic Genetics and Visual Function Branch, and lead author of the report.
OCA is a set of genetic conditions that affect the pigmentation of the eyes, skin, and hair due to a mutation in genes essential for the production of melanin pigment. In the eye, the pigment is present in the retinal pigment epithelium (RPE) and aids vision by preventing the scattering of light. The RPE is located right next to the photosensitive photoreceptors in the eye and provides them with nourishment and support. People with OCA do not have pigmented RPE and have an underdeveloped fovea, an area of the retina crucial for central vision. The optic nerve carries visual signals to the brain.
People with OCA have improperly routed optic nerve fibers. Scientists believe that RPE plays a role in the formation of these structures and want to understand how the lack of pigment affects their development.
“The animals used to study albinism are less than ideal because they lack fovea,” said Brian P. Brooks, MD, Ph.D., clinical director of NEI and head of the Ophthalmic Genetics and Visual Function branch. . “A human stem cell model that mimics disease is an important step forward in understanding albinism and testing potential therapies to treat it.”
To create the model, the researchers reprogrammed skin cells from individuals without AOC and from people with the two most common types of OCA (OCA1A and OCA2) into pluripotent stem cells (iPSC). The iPSCs were then differentiated into RPE cells. RPE cells from OCA patients were identical to RPE cells from unaffected individuals but showed significantly reduced pigmentation.
The researchers will use the model to study how the lack of pigmentation affects the physiology and function of the RPE. In theory, if the development of the fovea depends on RPE pigmentation and the pigmentation can be improved in some way, the vision defects associated with abnormal development of the fovea could be at least partially resolved, according to Brooks.
“Treating albinism at a very young age, maybe even before birth, when structures in the eye are forming, would have the best chance of saving vision,” Brooks said. “In adults, the benefits may be limited to improvements in photosensitivity, for example, 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.
NEI leads federal government research on the visual system and eye disease. NEI supports basic and clinical science programs to develop vision-saving treatments and meet the special needs of people with vision loss. For more information visit https://www.nei.nih.gov.
About the National Institutes of Health (NIH):The NIH, the national agency for medical research, comprises 27 institutes and centers and is part of the US Department of Health and Human Services. The NIH is the principal federal agency that conducts and supports basic, clinical, and translational medical research, and studies the causes, treatments, and cures for common and rare diseases. For more information about the NIH and its programs, visit www.nih.gov.
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Aman George, Ruchi Sharma, Tyler Pfister, Mones Abu-Asab, Nathan Hotaling, Devika Bose, Charles DeYoung, Justin Chang, David R. Adams, Tiziana Cogliati, Kapil Bharti, Brian P. Brooks. In vitro modeling of oculocutaneous albinism type I and II disease using retinal pigment epithelium derived from human pluripotent stem cells (2022). doi: 10.1016 / j.stemcr.2021.11.01. https://www.cell.com/stem-cell-reports/fulltext/S2213-6711(21)00597-X.