Visual scientists revive light-sensing cells in donor’s eyes
As part of a series of discoveries that help transform the brain and study vision, scientists have revived neurons that sense light in the eyes of organ donors and restore communication between them.
Billions of neurons in the central nervous system transmit sensory information in the form of electrical signals; In the eye, specialized neurons called light receptor cells perceive light.
Published today (May 11, 2022) in the journal Nature, a team of researchers from the John A. Moran Eye Center at the University of Utah and collaborators of the Scripps Study describe how they used the retina as a model of the central nervous system to investigate. How neurons die — and new methods to revive them.
Scientist Fatima Abbas of the Moran Eye Center, Fatima Abbas, lead author of the published study. “In the eyes obtained within five hours of the donor’s death, these cells respond to glare, colored lights, and even very dim rays of light.”
While early experiments revived the light receptors, the cells appeared to have lost the ability to communicate with other cells in the retina. The researchers identified hypoxia as an important factor in this loss of communication.
To overcome the ordeal, Professor Anne Hanneken, MD, Associate Professor of Scripps Research, shopped the organ donor’s eyes in less than 20 minutes of her death, while scientist Frans Vinberg, PhD of the Moran Eye Centre, designed a special transport unit to restore oxygen and other nutrients to the eye of organ donors.
Vinberg also built a device to stimulate the retina and measure the electrical activity of its cells. With this approach, the team was able to restore a specific electrical signal seen in the human eye, “wave b”. This is the first b wave recording made from the central retina of the human eye after death.
“We were able to make retinal cells talk to each other, in the way they work in the living eye to control human vision,” Vinberg said. Previous studies have restored very limited electrical activity in the eyes of organ donors, but this has never been achieved at a golden point and has never been to the point where we have proven it.”
The process demonstrated by the team could be used to study other nerve cell tissues in the central nervous system.
This is a transformative technical advance that could help researchers better understand neurodegenerative diseases, including blinding retinopathy such as age-related macular degeneration.
The Nature study, “The Resurgence of Light Signals in Mice and The Human Retina After Death,” has now provided data from more than 40 donor eyes — including the first description of the mechanism that is thought to limit the speed of central human vision.
Vinberg points out this approach could reduce research costs compared to non-human primate research, and that reliance on animal models produces results that don’t always apply to humans. Although rats are often used in vision studies, they do not have a macula. The researchers could also test potential new therapies on active human eye cells, speeding up drug development.
“The scientific community can now study human vision in ways that laboratory animals cannot,” Vinberg said. We hope this will motivate organ donor associations, organ donors and eye banks by helping them understand the exciting new possibilities that this type of research brings.”
Hanneken, who is also a longtime retinal surgeon affiliated with Scripps Memorial La Jolla Hospital, said the ability to create patches of human retinal tissue could lead to new therapies for blindness.
“Until now, it has not been possible to get cells in all different layers of the central retina to communicate with each other the way they normally do in the living retina,” Hanneken said. “In the future, we will be able to use this approach to develop treatments aimed at improving vision and light signaling in the eyes with macular disease, such as age-related macular degeneration.”
The Nature study involved a scientific team that raises questions about the irreversible nature of death, in part determined by the irreversible inactivity of neurons. Yale University researchers made headlines when they revived the bizarre brains of pigs four hours after death, but they failed to restore global neuronal activity.
The study’s authors are Fatima Abbas, Silke Becker, Bryan W. Jones, and Frans Vinberg of the University of Utah, Ludovic S. Mure and Satchidananda Panda of the Salk Institute for Biological Research, and Anne Hanneken of scripps Research.
The eyes of donors for the study were obtained in collaboration with the Utah Lion Eye Bank, The San Diego Eye Bank, and organ donation organization LifeSharing. The team is deeply grateful to those who donated their eyes and their legal representatives, who supported the surgical team’s efforts to acquire the eyes.
Reference: “The Resurgence of Light Signals in Mice and Human Retinas After Death” by Fatima Abbas, Silke Becker, Bryan W. Jones, Ludovic S. Mure, Satchidananda Panda, Anne Hanneken and Frans Vinberg, May 11, 2022, Nature.
DOI: 10.1038 / s41586-022-04709-x
The study was supported by the National Institutes of Health and Unrestricted Funding from the Blind Prevention Study, New York, NY, for the Department of Ophthalmology & Visual Sciences, University of Utah.