http://www.sciencemag.org/news/2020/12/researchers-restore-lost-sight-mice-offering-clues-reversing-aging

Researchers inserted genes into mouse eye cells to protect and restore the optic nerve (red fibers in microscope image of healthy mouse retina, above).

Do old and damaged cells remember what it was like to be young? That’s the suggestion of new study, in which scientists reprogrammed neurons in mouse eyes to make them more resistant to damage and able to regrow after injury—like the cells of younger mice. The study suggests that hallmarks of aging, and possibly the keys to reversing it, lie in the epigenome, the proteins and other compounds that decorate DNA and influence what genes are turned on or off.