Caution: old cages!
Stem cell transplantation from old mice worsened the condition of their peers
Polina Loseva, N+1
Transplanting old cells can be dangerous for the recipient, even if he is as old as the donor. This conclusion was reached by scientists after transplantation of stem cells to elderly mice from young and elderly relatives. Even a small number of aged cells in the transplant turned out to be enough for the recipients to decrease their physical activity. Probably, similar complications can wait for elderly people who decide to be treated with their own stem cells. The work was published in the journal Aging Cell (Wang et al., Transplanting cells from old but not young donors causes physical dysfunction in older recipients).
With age, cells accumulate in the animal's body, which, under the influence of external or internal stresses, have turned into old ones (although it is more correct to call them senescent). They not only cease to perform their former functions, but also acquire new ones – for example, they secrete pro-inflammatory proteins into the tissue. Under their influence, the surrounding cells can also turn into senescent – and at the cellular level, old age turns out to be contagious.
Thus, it has long been clear that transplanting cells from old animals to young ones, most likely, will not lead to anything good, but will only accelerate the aging of recipients. But what about transplanting cells from old animals to their peers? This question is much more relevant, because this is how modern medicine offers to treat many age-related diseases: to take stem cells from an elderly patient, multiply them in vitro and plant them back, for example, in a destroyed joint.
Scientists led by James Kirkland and Ming Xu from the Mayo Clinic in In Rochester, they checked what happens to stem cells if they are transplanted from one elderly mouse to another. To do this, they took a group of old mice (28-31 months) and young mice (6-7 months) as donors, took about a million adipose tissue stem cells from them (as is known from previous studies, this is enough to cause old age in tissue neighbors) and transplanted elderly mice (20 months).
After 4-6 weeks, the scientists measured the overall health of the animals (weight, food intake and daily activity), as well as their endurance (maximum running speed, grip strength and duration of running in the wheel). It turned out that in those who received a portion of young cells, the physiological parameters practically did not change. For those who got the old cells, several parameters of physical health sank at once: maximum speed, grip strength, hanging time on the wire and daily activity.
Nevertheless, even in old animals, not all cells in the tissue turn into senescent. To confirm that they affected the health of elderly recipients, the researchers isolated several thousand stem cells from the adipose tissue of young and elderly donors and compared the set of genes that work in them. It turned out that, judging by the standard markers of senescent cells, they make up about 3 percent of tissue stem cells in young donors, and 8.9 percent in old ones.
The experiment that the scientists set up, of course, differs from what older people may have to go through in clinics – at least in that the authors of the work transplanted cells between animals, and not from a donor to themselves. Nevertheless, the very fact that even a small number of senescent cells (not a million, as in previous studies, but 9 percent of a million, that is, a hundred thousand) can worsen the physical health of mice, suggests that people may have unforeseen consequences of therapy with their own stem cells.
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