Aging May Slow When Certain Cells Are Killed

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Killing off certain aging cells in the body may lead to a longer life, suggests a new study done in genetically engineered mice.

Researchers used a drug to kill these "aging" cells in mice around the time the animals reached midlife. Those mice lived longer, on average, than mice in which the cells had not been removed, the study found.

The drug that the researchers administered to the mice only worked because the mice were transgenic, and researchers "can't make transgenic humans," noted Christin Burd, an assistant professor of molecular genetics at The Ohio State University, who was not involved in the new study. In other words, it not clear whether the finding would hold true in people.

Nonetheless, the new results do suggest that if researchers can one day find a way to get rid of these cells in humans, "it can have some really huge impacts on health care," she said.

The "aging," or senescent, cells that the researchers investigated in the study are dysfunctional cells that have stopped dividing, and whose presence has been linked to age-dependent diseases.

In the study, the researchers developed the genetically engineered mice. Then, when the mice were 12 months old (midlife for the rodents),the scientists started injecting the animals with a drug to kill off these cells. The researchers also included a group of control mice that were not injected with the drug, but were instead injected with a placebo solution.

The results showed that the mice whose senescent cells had been killed lived longer. Their median life spans were increased by 24 to 27 percent, compared with those of the mice in the control group, according to the study, published today (Feb. 3) in the journal Nature.

The researchers also found that the mice who were injected with the drug were slower to develop certain conditions related to aging, such as cataracts and deterioration of the kidneys and heart function, compared with those animals in the control group.

The results suggest that during a normal aging process, the presence of senescent cells shortens the life spans of mice and the period of life during which the animals are generally healthy, the researchers said.

These findings "demonstrate that the removal of senescent cells does indeed delay aging and increase healthy life span," Jesus Gil and Dominic Withers, both professors of clinical science at Imperial College London who were not involved in the study, wrote in a related editorial published in the journal.

But Gil and Withers also noted that senescent cells are involved in certain important processes such as wound healing. Although the new study suggests that the removal of these cells has limited side effects overall, "any future senescence-based therapies must take care to control for possible detrimental consequences," Gil and Withers wrote.

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