A novel study of the eye’s neuron-packed membrane is beginning to overturn the belief that upon death, neurons die with the individual.
Death is defined as the irreversible cessation of circulatory, respiratory or cerebral activity. Photo: Shutterstock
Death is defined as the irreversible cessation of circulatory, respiratory or cerebral activity.
Many peripheral human organs can be transplanted from deceased donors using protocols to optimize viability. However, central nervous system tissues rapidly lose viability after circulation ceases, thereby impeding their potential for transplantation.
The time course and mechanisms causing neuronal death and reactivation potential remain poorly defined.
In one study, the retina was used as a model of the central nervous system and the kinetics of neuronal death and reactivation were systematically examined.
The rapid decline of neuronal signaling was demonstrated and the conditions for reviving synchronous transsynaptic transmission in vivo were identified in post-mortem mouse and human retina.
Light-evoked responses in human macular photoreceptors in removed eyes were measured up to 5 h after death and modifiable factors that drive reversible and irreversible loss of light signaling after death were identified.
Finally, the rate-limiting deactivation reaction of phototransduction, a model G-protein signaling cascade, was quantified in the human retina and peripheral and macular macaques.
In short, the researchers restored the electrical activity of human retinas, from donors who died shortly before. This achievement, reported in Nature, will improve the study of eye diseases, such as age-related macular degeneration, a major cause of vision impairment and blindness. It could also lay the groundwork for reviving other nerve tissue and, perhaps one day, make retinal transplants possible.
Such research has broad applications and impact by enabling transformative studies in the human central nervous system, raising questions about the irreversibility of neuronal cell death, and providing new avenues for visual rehabilitation.
Sources consulted: National Library of Medicine y Nature Magazine