Up to a point, that is. As the decades pass, our bodies lose the ability to regenerate themselves. The results are obvious: wrinkled skin, weak muscles, and forgetful brains.
All the more tragic for those among us with diseases that attack the very processes of regeneration. Multiple sclerosis (MS), for example, keeps the body from restoring the insulating layers that protect nerve fibers. The insulation—“myelin”—breaks down naturally. In most human brains, “remyelination” is a constant process, rebuilding the myelin that protects the brain cells and allows them to do their work. For people with MS, remyelination is under attack.
Working with mice, researchers seem to have found a way to reinstate the remyelination process. In a report in the January 6 issue of Cell Stem Cell, researchers at Harvard and Cambridge Universities show that the capacity for remyelination can be restored in aging mice.
The cells that are responsible for remyelination are still present in the aging mouse. It’s just that they have been switched off. By exposing these cells to switching signals present in a much younger mouse, researchers were able to reverse the effects of aging on the cells that do the work of remyelination.
How did they do this? They literally joined the old and the young mouse together surgically. This allows their blood to circulate together. In the young blood, apparently, were various chemical signals that reset the switches in the cells of the brains of the aging mice. The result: spontaneous remyelination.
According to Robin Franklin, one of the researchers, the study shows that “age-associated decline in remyelination is reversible. We found that remyelination in old adult mice can be made to work as efficiently as it does in young adult mice.” Franklin, who is Director of the MS Society's Cambridge Centre for Myelin Repair at the University of Cambridge, made her comments in a press release issued by her university.
What’s perhaps most interesting about this report is that it is a kind of stem cell research that doesn’t implant stem cells. It works on the principle that stem cells already exist in the patient’s body but that they’ve been silenced by age or disease. They need to be switched back on or rejuvenated. According to Franklin, “remyelination therapies do not need to be based on stem cell transplantation since the stem cells already present in the brain and spinal cord can be made to regenerate myelin - regardless of the patient's age."
As interesting as this is, it is important to stress that this is a “proof of concept” study. The techniques here are simply not applicable to human beings. They are encouraging because they suggest that perhaps some day, researchers will discover just what it is in the young body that keeps it young. What are the specific factors that keep the body’s own stem cells switched on? And if it circulates in the blood as this study shows, perhaps these factors could simply be injected.
Of course, if researchers discover how to do this, it’s not just people with diseases like MS who will be interested. One of the interesting social features about this work is that it is funded in part by the UK MS Society and the American MS Society. In other words, the funding is motivated by the search for a cure for a very specific disease. But the mice is the study were aging, not ill. That suggests to me, at least, that the larger portion of the “beneficiaries” of this work will be aging humans, not those with MS. If so, then this study is one more step in the quest of human enhancement, suggesting that it may be possible to reverse aging in the one part of the body where it is most feared—the human brain.
The journal report ends with this comment: “Moreover, this work demonstrates that the CNS maintains its responsiveness to age-regulated circulatory factors, such that age-dependent deficiencies in repair of these tissues can, in part, be reversed by circulating factors.”
The paper, “Rejuvenation of regeneration in the aging central nervous system,”' is published in the January 6 issue of Cell Stem Cell.