In a groundbreaking advancement, American scientists have revived a portion of life in the eyes of a deceased organ donor who had been dead for five hours.
By placing retinal cells into a special culture medium, these cells responded to light and sent signals known as b-waves, “similar to the signals recorded from living subjects.“
This is the first time that b-waves have been reactivated from eye cells that had been dead for an extended period. Since the retina is also part of the central nervous system (CNS), scientists are now questioning whether other cells, such as those in the brain and spinal cord, can be revived in a similar manner.
This could challenge the definition of death, particularly the concept of brain death due to lack of oxygen, which is believed to be irreversible.
The retina is also part of the central nervous system (CNS)
The research was conducted by scientists from the University of Utah and the Scripps Research Institute. They found that after our bodies die, some organs can still maintain life. This could be beneficial for patients awaiting organ transplants.
However, from the moment circulation stops—when oxygen-carrying blood is no longer pumped to nerve cells—these cells begin to die within minutes. This makes efforts to restore them to a living state frequently unsuccessful.
In 2019, a team of scientists at Yale University made a breakthrough by restoring cellular signals in 32 pig brains that had been dead for four hours. They achieved this through a blood-pumping system that warmed and infused the pig brains with a solution.
The result was that the circulatory system and some cells were revived. However, no electroencephalogram signals were recorded from this “revival” response, indicating that the pig brain cells were not truly communicating with each other and the pig’s consciousness did not return.
The circulatory system revived pig brains four hours after death at Yale University.
Now, by restoring the flow of oxygen and creating a circulatory environment, Utah scientists report that they have taken a further step in reviving retinal cells from a dead state.
“We were able to awaken the light-sensitive cells in the fovea of humans, which is the part of the retina responsible for our central vision and the ability to see fine details and colors,” explained biomedical scientist Fatima Abbas.
“In the eyes obtained five hours after the organ donor’s death, these cells still reacted to bright light, colored lights, and even very dim rays.”
“The difference is that we were able to make the retinal cells communicate with each other, in the way they do in the eyes of living people to control human vision,” added Frans Vinberg, another vision scientist from the University of Utah.
Specifically, the revived cells communicated with each other using b-waves. B-waves are electrical signals generated when light hits the retina of a living person. Previously, scientists found that right after death, b-wave signals in the eyes would also disappear, even if a flashlight was directly shone into the eyes of the deceased.
“Previous studies have restored very limited electrical activity in the eyes of organ donors, but this has never been achieved in the fovea and has never reached the level we have demonstrated.” Vinberg said.
Research authors, Dr. Frans Vinberg and Dr. Fatima Abbas at the John A. Moran Eye Center, University of Utah.
It is important to note that the revival of b-wave signals in the eyes of deceased individuals does not mean they can see again. Visual activity also requires the involvement of brain regions and higher-level neuronal activity.
However, research on how retinal cells cope with oxygen deprivation may initially open up hopes for restoring lost brain functions.
“Since the retina is part of the central nervous system, our ability to restore b-waves in this study raises the question: Is brain death—as currently defined—truly an irreversible state?” the scientists wrote.
Currently, some definitions of ‘brain death‘ require a loss of synchronized activity among neurons. If that definition is accepted, then the retina of the person in this new study may not be completely dead.
The new study challenges the definition of brain death.
Moreover, if specialized neurons, known as photoreceptor cells, can be revived to a certain extent, it would bring hope for future transplants that could help restore vision in those with eye diseases.
“We hope this will encourage organ donation associations, organ donors, and eye banks by helping them understand the exciting new possibilities that this type of research presents.” the scientists stated.
Their new research has been published in the journal Nature.
