Scientists have finally discovered how to reverse the effects of aging—in mice. Humans might be next.

Scientists at the Dana-Farber Cancer Institute in Boston developed an experimental treatment that regenerated old and weak organs of mice, erasing any previous signs of aging. They used a process called “telomere shortening.”

Telomeres are the protective caps at the end of each chromosome that shorten every time a cell divides. As cells continue to divide, telomeres eventually become so short that the cell dies or falls into a suspended state. The scientists bred a group of mice that lacked telomerase, so they aged prematurely. But then they gave all of the mice telomerase injections, which fixed all of the damaged organs and reversed any signs of aging.

Ronald DePinho, the study’s leader, said:

What we saw in these animals was not a slowing down or stabilization of the aging process. We saw a dramatic reversal—and that was unexpected. This could lead to strategies that enhance the regenerative potential of organs as individuals age and so increase their quality of life. Whether it serves to increase longevity is a question we are not yet in a position to answer. Don’t like ads? Become a supporter and enjoy The Good Men Project ad free

You knew there would be a catch.

In humans, there’s a good chance these telomerase injections could cause cancer.

Mice manufacture telomerase throughout their lives, but we don’t. Telomerase production shuts down as we get older, killing cells and bringing about aging, but also protecting us from cancer. Raising telomerase levels in older people might slow aging, but it might also multiply the risk of cancer.

While none of the mice developed cancer, DePinho isn’t sure whether the treatment will actually extend the lifespan of the mice, or just allow them to live more healthily into old age.

David Kipling, a professor at Cardiff Univeristy, isn’t so bright on the study’s prospects for humans:

The goal for human tissue “rejuvenation” would be to remove senescent cells, or else compensate for the deleterious effects they have on tissues and organs. Although this is a fascinating study, it must be remembered that mice are not little men, particularly with regard to their telomeres, and it remains unclear whether a similar telomerase reactivation in adult humans would lead to the removal of senescent cells.

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