Scientists Have Revived a Glimmer of Activity in Human Eyes After Death

The cells in the human eye are dying.

A team of US researchers measured activity in mouse and human cells after they died in order to understand how nerve cells die.

They were able to revive the cells after tweaking the environment.

The postmortem retinas emit electrical signals when stimulated by light.

These waves can be seen in living retinas, and they indicate communication between the layers of cells that allow us to see.

It is the first time that dead human eyes have responded to light in this way, and it has some experts questioning the nature of death in the central nervous system.

Fatima Abbas from the University of Utah explains that they were able to wake up the cells in the human macula, which is the part of the retina responsible for our central vision and our ability to see fine detail and color.

The cells in eyes obtained after an organ donor's death responded to bright light, colored lights, and even dim flashes of light.

It is possible to save organs in the human body after death. The central nervous system stops responding quickly after circulation ceases.

Not all types of neuron fail at the same rate. The brain-death issue is more complicated because of the different regions and types of cell.

Learning how the nervous system copes with a loss of oxygen could teach us how to recover lost brain functions.

Researchers have had some success. Scientists at Yale University kept pig brains alive for as long as 36 hours after they died.

They were able to revive a small response after four hours, though there was no organized or global response.

The feats were accomplished by using artificial blood, heaters, and pumps to restore circulation of oxygen and nutrients.

The only part of the nervous system that can be extruded in mice and human eyes is the brain.

Researchers at the University of Utah and the Scripps Research were able to restore oxygenation to the eyes of organ donors.

Frans Vinberg, a visual scientist from the University of Utah, says that they were able to make the cells talk to each other.

Past studies have restored limited electrical activity in organ donor eyes, but this has never been achieved in the macula, and never to the extent we have now demonstrated.

After death, the cells continued to respond to light for up to five hours. The b-wave signals dropped off quickly because of the loss of oxygen.

The researchers were unable to completely restore robust b-waves even when the tissue was protected from oxygen deprivation.

The revival of the cells doesn't mean the donor eyeballs can see. Full visual sensation and perception can be revived by higher visual centers in the brain.

There are some definitions of brain death that require a loss of activity. The human retinas in the current study were not completely dead.

The question of whether brain death, as it is currently defined, is truly irreversible, is raised by the restoration of the b-wave in this study.

Hope for future transplantations that could help restore vision in those with eye disease is offered if specialized neurons can be revived to a certain extent.

It's still a long way off. Scientists are trying to find a way to integrate the cells and patches of a donor retina into existing circuits.

Donor eyes and animal models will have to be used, and testing for b-waves is a good way to determine if a Retinal Graft is viable or not.

Vinberg says that the scientific community can now study human vision in ways that are not possible with laboratory animals.

We hope this will motivate organ donor societies, organ donors, and eye banks by helping them understand the exciting new possibilities this type of research offers.

Nature published the study.