Eyeworld

I SEPTEMBER 2020 | EYEWORLD | 39 response of the retina, and histology after the animal was euthanized. Dr. Bharti said they saw an electrical response in the area of the retina that had an RPE patch transplanted after laser ablation damage vs. an empty scaffold in a laser ablated area that did not see a response. "That gave us more confidence that it's not only preserving photoreceptors that we see by OCT or histology, it's preserving the synaptic connections of the photoreceptors to the retinal neurons and the visual processing is happening," Dr. Bharti said, adding that the re- search team has been refining its techniques and recently obtained an instrument that can look at a single cone photoreceptor at a time, assessing whether it's being preserved over the transplant. In the first-in-human clinical trial, Dr. Bharti said the RPE patch is being transplanted in the transition zone, between the area of the lesion and where there is still healthy retina in the hope of preventing additional photorecep- tors from dying. "Once we demonstrate the safety of this procedure, we hope we can transplant at an earlier stage with most of the photoreceptors still viable," he said. continued on page 40 About the sources Kapil Bharti, PhD Senior investigator Ocular and Stem Cell Translational Research Section National Eye Institute Bethesda, Maryland David Gamm, MD, PhD RRF Emmett A. Humble Distinguished Director McPherson Eye Research Institute University of Wisconsin Madison, Wisconsin Ula Jurkunas, MD Associate professor Department of Ophthalmology Harvard Medical School Boston, Massachusetts Elliott Sohn, MD Associate professor of ophthalmology and visual sciences University of Iowa Iowa City, Iowa Even further in the future, Dr. Bharti said they hope to test similar stem cell therapy for situations where the photoreceptor cells are no longer viable, such as in advanced retinitis pigmentosa or cases of eye injuries. Elliott Sohn, MD, is on a team working toward a stem cell therapy that could restore vision after cell loss. While gene therapy is useful, in general, for earlier stages of disease, in advanced stages where photoreceptors and potentially surrounding cells are degenerated and/or dysfunctional, stem cell therapies will be a primary way to restore vision, he said. "The stem cell work that we're doing is focused on trying to recreate a patient's own photoreceptors made from their skin cells to restore vision, after we genetically correct the cells of their mutation before they get them," Dr. Sohn said. "To achieve this we take a skin sample from the patient, bring it to the lab, turn them into induced pluripotent stem cells (IPS), correct the genetic mutation in these cells, then, because they're stem cells, we would turn them into the patient's photoreceptor cells; they could then be put into a scaffold that is inserted under Researchers will take a patient's own blood cells and in a lab, convert them into iPS cells capable of becoming almost any type of cell in the body. In this case, the iPS cells are then programmed to become retinal pigment epithelial cells, the type of cell that dies early in the geographic atrophy form of AMD. Source: National Eye Institute

• Blank Page
• Blank Page (1)