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A British and American study in mice has found that the age-associated decline in the regeneration of the nerve’s myelin sheath, or remyelination, is reversible.
The proof of principle study demonstrated that when old mice are exposed to the inflammatory cells (called monocytes) from young mice, the aging remyelination process can be reversed.
As people age, the body’s ability to regenerate tissue decreases. This is not only true for our skin – this is evident in the wrinkles that develop as we age – but also true for other tissues in the body, including the regenerative processes in the brain.
For diseases that often span several decades and are affected by regenerative processes, such as multiple sclerosis, this can have massive implications.
In multiple sclerosis, the insulating layers that protect nerve fibers in the brain, known as myelin sheaths, become damaged. The loss of myelin in the brain prevents nerve fibers from sending signals properly and will eventually lead to the loss of the nerve fiber itself.
However, early in the disease, a regenerative process, or remyelination, occurs and the myelin sheaths are restored. Unfortunately, as people with MS age, remyelination decreases significantly, resulting in more nerve fibers being permanently lost.
MS affects approximately 100,000 people in the United Kingdom, 400,000 in the United States and several million worldwide. Symptoms of the disease can include the loss of physical skills, sensation, vision, bladder control, and intellectual abilities.
“What we have shown in our study, carried out in collaboration with Dr. Amy Wagers and colleagues at Harvard University, is that the age-associated decline in remyelination is reversible,” said Prof. Robin Franklin, director of the MS Society’s Cambridge Centre for Myelin Repair at the University of Cambridge. “We found that remyelination in old adult mice can be made to work as efficiently as it does in young adult mice. For individuals with MS, this means that in theory regenerative therapies will work throughout the duration of the disease. Specifically, it means that 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.”
“We’ve invested heavily in myelin repair research and are pleased to see key discoveries such as this being made as a result,” said Dr. Doug Brown, head of Biomedical Research at the MS Society said. “Prof. Franklin and his team have made significant breakthroughs in recent years and this provides more encouraging progress in their tireless effort to develop therapies that might stop or reverse the devastating effects of MS.”
Citation: “Rejuvenation of Regeneration in the Aging Central Nervous System;” Julia M. Ruckh, Robin J.M. Franklin et al.;Cell Stem Cell, Volume 10, Issue 1, 96-103, 6 January 2012, DOI: 10.1016/j.stem.2011.11.019
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