New technology reveals cellular changes in the neural-epithelial-vascular complex in choroideremia

By combining traditional eye imaging techniques with adaptive optics – a technology that improves imaging resolution – researchers from the National Eye Institute (NEI) have shown for the first time how cells from different tissue layers of the eye eye are affected in people with choroideremia, a rare genetic disease that leads to blindness. Their study, which was funded by the NEI Intramural Research Program, is published in Communications Biology. NEI is part of the National Institutes of Health.

Johnny Tam, Ph.D., head of the NEI Clinical and Translational Imaging Unit combined adaptive optics with indocyanine green dye to visualize live retinal cells, including light-sensitive photoreceptors , retinal pigment epithelium (RPE), and choroidal blood vessels. His team was able to see in detail the extent to which choroideremia disrupts these tissues, providing information that could help design effective treatments for this disease and others. The RPE of the retina is a layer of pigmented cells essential for the nourishment and survival of photoreceptors.

Choroideremia affects men more than women because the gene responsible for the disease is located on the X chromosome. Since men have only one copy of the X chromosome, a mutation in the gene causes more severe symptoms in men, while women – who have two copies of the X chromosome – usually have milder symptoms, having a working copy of the gene on the other X chromosome.

One of the main findings of our study is that RPE cells are significantly enlarged in both men and women with choroideremia. We were surprised to see many cells enlarged up to five times.”


Johnny Tam, Ph.D., Head, NEI Clinical and Translational Imaging Unit

Study participants showed a mixture of enlarged and healthier-looking RPE cells. This may explain why women with choroideremia have milder symptoms, according to Tam. Photoreceptor and blood vessel layers were less affected in both male and female study participants, suggesting that RPE disruption plays an important role in choroideremia.

Tam’s adaptive optics is not part of routine diagnostic tests in eye clinics. Surprisingly, his team found that enlarged RPE cells can be detected even using only a commercially available laser scanning ophthalmoscope with indocyanine green dye.

“It’s not obvious at first, but using an existing tool in the clinic, we can monitor and track the cellular state of the RPE layer. This could prove useful in identifying patients who would benefit most from interventions. therapies,” Tam said.

Source:

Journal reference:

Aguilera, N. et al. (2022) Widespread subclinical cellular changes revealed in a neural-epithelial vascular complex in choroideremia using adaptive optics. Communications biology. doi.org/10.1038/s42003-022-03842-7.

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