Mice live only a few months in the wild, but can survive two to three years in the lab. Those in the last experiment were already 124 weeks old when they received the drug – almost at the end of their lives. Not only did the treated mice survive noticeably longer, according to Davidsohn, but they also scored better on measures of general health.
The observed amount of life extension is not unprecedented in itself. A US government program that tests drugs for their longevity effects has shown that several compounds, including the drug rapamycin, can extend the life of mice by 5 to 15%.
But the mice have to take those drugs for much of their lives, while reprogramming has immediate effects. “This is like being able to do nothing all your life and still get the benefit,” says Davidsohn.
What’s next?
Rejuvenate is currently developing gene therapy drugs for dogs and humans, including one designed to treat heart failure. But Davidsohn says he believes it will be possible to rejuvenate people in the long run. “I wouldn’t work on it if I didn’t believe that,” he says.
Much more information will be needed to learn exactly what changes the reprogramming genes cause in the mice, and researchers say other groups will need to repeat the experiment before they’re convinced. “I’d like to see a separate group do something similar and dig deeper into what’s really happening,” says Borch Jensen.
Sebastiano says the life-prolonging effect reported by Rejuvenate may be due to changes in a single organ or group of cells, rather than a general mouse-wide rejuvenation effect. Among other shortcomings in its research, Rejuvenate did not carefully document which and how many cells were altered by the genetic treatment.
Several companies are pushing ahead with drug reprogramming plans, but they’re opting for recognized medical conditions and limiting their efforts to specific organs.
For example, Turn Bio, a company co-founded by Sebastiano, hopes to inject reprogramming factors into people’s skin to fight wrinkles or restart hair growth. Another company, Life Biosciences, is preparing to test whether reprogramming cells in the eye can treat blindness.