San Diego scientists have seemingly turned back time for aging mice. Their new research, published Thursday in Cell, demonstrates that biological hallmarks of aging can be reversed in living animals through cellular reprogramming.
The research may not have direct applications in humans yet, but experts say it shows that aging could be a more malleable process than many people think.
"We are starting to learn that we can manipulate aging," said Alejandro Ocampo, first author of the new paper and research associate in Juan Carlos Izpisua Belmonte's lab at the Salk Institute. "We can, in this case, rejuvenate the animals.”
Ocampo and his colleagues reversed signs of aging in living mice by reprogramming their cells. This cellular reprogramming technique has already been use by many scientists to turn isolated cells — including human skin cells — back into stem cells capable of becoming any type of cell in the body.
But Ocampo said this new study takes the approach a step further by showing it can also revert cells in a living animal to a younger, healthier state. The mice in these experiments came away with less DNA damage, healthier organ tissue and improved muscle regeneration.
"One of the most striking things we saw is that the animals were able to live 30 percent longer," Ocampo said. "They were going from 18 weeks to 24 weeks."
Ocampo says the lifespan of the mice was extended because the cellular reprogramming process altered their epigenome — the chemical signs of wear and tear that accumulate on DNA over time.
Previous studies have shown that cellular reprogramming, when taken too far, can have negative effects on animals, giving rise to tumors. But the Salk researchers found that "partial" reprogramming was enough to bring about anti-aging benefits without causing cancerous complications.
Scientists not involved with the study said the research was "interesting" and "surprising." But they said the approach isn't ready to fight aging in humans.
Scripps Research Institute associate professor Kristin Baldwin, who recently co-authored a paper about the effects of aging on reprogrammed stem cells, wrote in an email to KPBS News, "While this exact approach is unlikely to be directly applicable for human therapy, the proof that some of the key effects of aging are reversible in an intact animal could lead to searches for alternative methods to accomplish the same thing without involving genetic modification of humans."
Stem cell scientist Jeanne Loring, also of the Scripps Research Institute, uses cellular reprogramming in her work on Parkinson's disease. She told KPBS News via email, "The information learned may help in understanding the causes of age-related diseases."
But, Loring wrote, "It is important to note that this is a study that can only be done in mice, because it involves generating animals that carry a transgene integrated into their genome."
Ocampo also doesn't think these mouse experiments could be carried out in humans. But he says this research does show that aging shouldn't be thought of as a one-way process, even in humans.
"As we get older, our epigenome is changing. And if we have the right tools and the right therapies to reverse those changes, then we can slow down how we age and even revert the process," he said.
