Mayo Study Discovers Tactic to Attack Deadbeat Cells, Delay Age-Related Disorders
Potential for fundamental change in way we provide treatment for chronic diseases in older people
Nov. 2, 2011 As we age, we accumulate cells that
Mayo Clinic researchers call
deadbeat cells. In a new study they show that by eliminating these worthless cells we can prevent or at least delay age-related disorders
and disabilities. At least in mice models, they say these cells contribute to aging.
The findings appear in the journal Nature,
along with an independent commentary on the discovery.
"By attacking these cells and what they produce, one day we may be able to break the link between aging mechanisms and
predisposition to diseases like heart disease, stroke, cancers and dementia," says co-author
James Kirkland,
M.D., Ph.D., head of Mayo's Robert and
Arlene Kogod
Center on Aging and the Noaber Foundation Professor of Aging Research.
Older patients with acute leukemia do not tolerate and benefit from standard, aggressive therapies as much as younger
patients, but it matters what kind of 70-year-old you are
"There is potential for a fundamental change in the way we provide treatment for chronic diseases in older people."
Five decades ago, scientists discovered that cells undergo a limited number of divisions before they stop dividing. At
that point the cells reach a state of limbo -- called cellular senescence -- where they neither die nor continue to multiply. They produce
factors that damage adjacent cells and cause tissue inflammation. This alternative cell fate is believed to be a mechanism to prevent runaway
cell growth and the spread of cancer. The immune system sweeps out these dysfunctional cells on a regular basis, but over time becomes less
effective at "keeping house."
As a result, senescent cells accumulate with age. Whether and how these cells cause age-related diseases and dysfunction
has been a major open question in the field of aging. One reason the question has been so difficult to answer is that the numbers of senescent
cells are quite limited and comprise at most only 10 to 15 percent of cells in an elderly individual.
"Our discovery demonstrates that in our body cells are accumulating that cause these age-related disorders and
discomforts," says senior author
Jan van Deursen,
Ph.D., a Mayo Clinic molecular biologist and the Vita Valley Professor of Cellular Senescence. "Therapeutic interventions to get rid of
senescent cells or block their effects may represent an avenue to make us feel more vital, healthier, and allow us to stay independent for a
much longer time."
"Through their novel methodology, the research team found that deletion of senescent cells in genetically engineered mice
led to improvement in at least some aspects of the physiology of these animals. So, with the caveat that the study involved a mouse model
displaying accelerated aging, this paper provides important insights on aging at the cellular level," says Felipe Sierra, Ph.D., Director of
the Division of Aging Biology, National Institute on Aging, National Institutes of Health.
How They Did It
Dr. van Deursen and colleagues genetically engineered mice so their senescent cells harbored a molecule called caspase 8
that was only turned on in the presence of a drug that has no effect on normal cells. When the transgenic mice were exposed to this drug,
caspase 8 was activated in the senescent cells, drilling holes in the cell membrane to specifically kill the senescent cells.
The researchers found that lifelong elimination of senescent cells delayed the onset of age-related disorders such as
cataracts and muscle loss and weakness. Perhaps even more importantly, they showed that removing these cells later in life could slow the
progression of already established age-related disorders.
The findings support a role of senescent cells in the aging process and indicate that chemicals secreted by these cells
contribute to age-related tissue dysfunction and disease.
Other co-authors of the article are: Darren Baker, Ph.D., Tamar Tchkonia, Ph.D., Nathan LeBrasseur, Ph.D. and Bennett
Childs, all of Mayo Clinic; and Tobias Wijshake and Bart van de Sluis, Ph.D., both of Groningen University, The Netherlands. The Ellison
Medical Foundation, the Noaber Foundation, the Robert and Arlene Kogod Center on Aging, and the National Institutes of Health funded the
study.
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Nov. 2, 2011 As we age, we accumulate cells that
