/data/photo/2022/04/14/6257c7fc23cd8.jpg "Eyes from a deceased donor have been successfully revived, how come? page all")
KOMPAS.com – Scientists at United States of America managed to revive the cells mata from deceased donors.
The study was carried out using donated eyes to better understand how nerve cells succumb to a lack of oxygen, by measuring activity in cells retina mice and humans as soon as possible after their death.
By adjusting some of the tissue environments, the study was able to revive the cells’ ability to communicate within hours of death.
When stimulated by light, the retina post-mortem emit a specific electrical signal known as a b-wave. These waves are also seen in the retinas of living people, meaning they represent communication between all the layers of macular cells that make it possible to see.
It was the first time that the eyes of a deceased human donor responded to light in this way, leading some experts to question the irreversible nature of death in humans. nervous system center.
“We were able to awaken photoreceptor cells in the human macula, which is part of the retina, responsible for central vision and the ability to see fine detail and color,” said biomedical scientist Fatima Abbas of the University of Utah. Science AlertThursday (12/5/2022).
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Mata obtained up to five hours after the donor’s death, cells respond to bright light, colored light, and even very faint flashes of light.
After death occurs, it is possible to save several organs in the human body for transplantation, including eye organs. But once circulation stops, the central nervous system as a whole stops responding too quickly to any form of long-term recovery.
But different regions and cell types have different survival mechanisms, making the overall problem of brain death much more complicated.
Studying how certain tissues in the nervous system cope with oxygen loss can provide information about restoring lost brain function.
Previous research conducted in 2018 by scientists at Yale University, scientists were able to keep pig brains alive for 36 hours after death.
Four hours post-mortemthe researcher is able to relive small responses even though there is no organized or overall response that can be measured by electroencephalogram (EEG).
Study eye cells reanimation after the donor dies is achieved by stopping the rapid degradation of mammalian neurons, using artificial blood, heaters, and pumps to restore circulating oxygen and nutrients.
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Apparently, a similar technique was performed on mice and human eyeswhich is the only extrusive part of the nervous system.
By restoring oxygenation and some nutrients to organ donor eyes, researchers at the University of Utah and Scripps Research were able to trigger synchronous activity among neurons after death.
“We were able to make retinal cells talk to each other, as they do in a living eye to mediate human vision,” said visual scientist Frans Vinberg of the University of Utah.
“Previous studies have restored very limited electrical activity in organ donor eyes, but this has never been achieved in the macula, and never as far as we now show.”
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Initially, experiments showed retinal cells continued to react to light for up to five hours after death, but important intercellular b-wave signals quickly disappeared, possibly due to loss of oxygen.
Even when retinal tissue was carefully protected from oxygen deprivation, the researchers were unable to completely recover the strong b-waves.
In addition, the temporary resurgence of retinal cells does not mean that the eyeball of a deceased donor can see.
The higher visual centers in the brain are needed to fully relive visual sensations and perceptions.
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eye illustration-
However, some definitions of brain death require a loss of synchronous activity between neurons.
If this definition is accepted, then the human retina in this study is not completely dead.
Because the retina is part of the central nervous system, the b-wave recovery in this study raises questions about brain death.
“As currently defined, it is completely irreversible,” the authors wrote.
If photoreceptors can be revived to some extent, it offers hope for future transplants that could help restore vision in people with eye disease.
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Furthermore, transplanted cells and donor retinal patches need to be seamlessly integrated into existing retinal circuits, a daunting challenge that scientists are already trying to overcome.
In the meantime, donor eyes and animal models should be performed, and b-wave testing can be a good way to determine whether a retinal graft can be done or not.
“The scientific community can now study human vision in a way that was not possible with laboratory animals,” said Vinberg.
“We hope this will motivate the organ donor community, organ donors, and eye banks by helping them understand the exciting new possibilities of this type of research.”
For information, research on reviving human eyes from deceased donors has been published in the journal Nature.
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