Boston biotech company Life Biosciences is set to begin the first human trial of a treatment designed to reverse cellular aging later this year. The experimental process, “partial reprogramming” involves injecting three genes into one eye using a modified virus, then injecting them into the eye with an antibiotic that acts like a switch. The treatment could help damaged retinal nerve cells regrow, potentially restoring vision lost due to age. However, many researchers warn that the science remains far from proven. The excitement surrounding the research has revived an older question: If science could offer something close to immortality, many people would not wish it.