WASHINGTON, July 9 (Xinhua) -- American scientists found that a combination of two existing drugs could clear the growing-old cells from tissues and restore physical function in mice model.
A study published on Monday in the journal Nature Medicine revealed that injecting even a small number of senescent cells into young, healthy mice causes damage that can result in physical dysfunction.
However, treatment with dasatinib and quercetin could prevent cell damage, delay physical dysfunction, and, when used in naturally aging mice, extend their life span, according to the study.
"This study provides compelling evidence that targeting a fundamental aging process, in this case, cell senescence in mice, can delay age-related conditions, resulting in better health and longer life," said Richard J. Hodes, director of National Institute on Aging under National Institutes of Health (NIH).
Cell senescence is a process in which cells lose function, including the ability to divide and replicate, but are resistant to cell death.
Senescent cells increase in many tissues with aging since they have been shown to affect neighboring ones because they secrete several pro-inflammatory and tissue remodeling molecules, according to researchers at Mayo Clinic in Minnesota.
The two drugs are known as senolytics, a class of drugs that selectively eliminate senescent cells. Dasatinib is used to treat some forms of leukemia while quercetin is a plant flavanol found in some fruits and vegetables.
The researchers first injected young (four-month-old) mice with senescent cells.
As early as two weeks after transplantation, the senescent mice showed impaired physical function as determined by maximum walking speed, muscle strength, physical endurance, daily activity, food intake, and body weight.
In addition, the researchers saw increased numbers of senescent cells, beyond what was injected, suggesting a propagation of the senescence effect into neighboring cells.
They treated senescent mice for three days with the compound mix, and found that it selectively killed senescent cells and slowed the deterioration in walking speed, endurance, and grip strength in the SEN mice.
In addition to young mice injected with senescent cells, the researchers also tested older (20-month-old), non-transplanted mice with two drugs intermittently for four months.
They found the treatment alleviated normal age-related physical dysfunction, resulting in higher walking speed, treadmill endurance, grip strength, and daily activity.
Finally, the researchers found that treating very old (24- to 27-month-old) mice with the combination biweekly led to a 36 percent higher average post-treatment life span and lower mortality hazard than control mice.
The researchers noted that current and future preclinical studies may show that senolytics could be used to enhance life span not only in older people, but also in cancer survivors treated with senescence-inducing radiation or chemotherapy and people with a range of senescence-associated chronic diseases.