Researchers based at the John A. Moran Eye Centre, University of Utah, Salt Lake City, USA, have reported a significant study on the viability of reviving human macular photoreceptors for transplantations from organ donors. This research, published in the journal Nature (May 11th, 2022, online ahead of print), indicates that key modifiable factors could extend the “time window for recovery of trans-synaptic neuronal transmission in the CNS, thereby raising questions about the irreversible nature of neuronal death”. While this study used the retina as a model for the central nervous
system (CNS), studying the kinetics of neuronal recovery may impact implications on both ophthalmology and brain sciences.
Researchers showed that certain modifiable factors and methods – reversal of acidification and restoral of oxygenation – could extend the time window for recovery the retina for up to 5 hours transplantation. According to the researchers, “the recovery of light-evoked macular photoreceptor responses from human eyes enucleated up to 5h post-mortem unlocks the potential for using these tissues to understand human photoreceptor physiology and supports the potential for future transplantation”. In addition, viable tissues could also be used to study the effects of drugs or devices on human rod and cone phototransduction, questions that have not been easy to study outside of nonhuman primate models. The researchers commented that “this research can be done without causing any harm to animals (including humans) and is more economical than nonhuman primate research. Consequently, this approach will be easier to explain to the general public and is expected to facilitate the generation of new knowledge about human neurons and neurodegenerative diseases, a major challenge in the aging society of developed countries”.
Independently, Dr. Cynthia Toth, Vice Chair of Clinical Research at the Duke Eye Center in Durham stated that “the results of this study open a new realm of human tissue-based research methodology using donor eyes. This has great potential for identifying relevant disease pathways, advancing therapeutic discovery and paving the way to retinal cell layer transplantation. Our patients regularly ask when an eye transplant could be performed. We now are one step closer to this goal, thanks to this team. As a retinal surgeon who treats both adult and pediatric retinal disease, I am personally excited that my answer to retinal/eye transplant can now be, ‘not yet, but eye researchers are pushing us closer to this goal’”.