Aging and its associated aches and pains are typically considered a rite of passage— unavoidable despite how well we care for ourselves. However, a new report published this month in Nature Communications challenges this thought.
Drs. Niedernhofer and Haurd believe aging represents a loss of cells to regenerate in responds to stress. For example, at younger ages, a fall might cause a few days of tenderness, but the same stress in your 70’s may result in more long term damage. They argue this happens because the body is no longer able to regenerate the damaged tissue.
In the current study, the authors isolated a pool of stem cells from muscle tissue, noting that as the cells aged they lost their ability to proliferate, differentiate and regenerate.
Interestingly, by using mice with accelerated aging, they were able to show that transplantation of young muscle stem cells could rescue the aging mouse and increase its lifespan. Typically, these mice lived for an average of 21 days, but when the researchers transplanted young muscle stem cells into their bodies, their lifespan more than doubled.
Interestingly, further experimentation revealed the beneficial effect was not due to the cells themselves reconstituting the aging tissue, but rather due to a compound secreted by the young stem cells that actually induced changes in the old stem cells. The old cells, when cultured with the young cells, began to act young again, with increased proliferation and differentiation.
The ability to divide and self-renew, as well as differentiate into a broad type of specialized cells, defines a stem cell. Two main types of stem cells exist: embryonic and adult. Embryonic stem cells have the capacity to develop into any of the hundreds of tissue types that comprise the human body. Given their capacity for self-renewal and plasticity, scientists have long proposed their use for regenerative medicine and tissue replacement.
Although promising, much controversy revolves around the scientific use of embryonic stem cells and thus has driven the research of adult stem cells. Adult stem cells are capable of renewal, similar to embryonic cells.