BOSTON (MA) -- Scientists at Joslin Diabetes Center, Harvard University, and the University of Cambridge have found that the age-related impairment of the body's ability to replace protective myelin sheaths, which normally surround nerve fibers and allow them to send signals properly, may be reversible, offering new hope that therapeutic strategies aimed at restoring efficient regeneration can be effective in the central nervous system throughout life.
In a proof-of-principle study published in the journal Cell Stem Cell, the researchers report that defects in the regeneration of the myelin sheaths surrounding nerves, which are lost in diseases such as multiple sclerosis may be at least partially corrected following exposure of an old animal to the circulatory system of a young animal. Myelin is a fatty substance that protects nerves and aids in the quick transmission of signals between nerve cells.
Using a surgical technique, the researchers introduced an experimental demyelinating injury in the spinal cord of an old mouse, creating small areas of myelin loss, and then exposed those areas to cells found the blood of a young mouse. By doing so, they found that the influx of certain immune cells, called macrophages, from the young mouse helped resident stem cells restore effective remyelination in the old mouse's spinal cord. This "rejuvenating" effect of young immune cells was mediated in part by the greater efficiency of the young cells in clearing away myelin debris created by the demyelinating injury. Prior studies have shown that this debris impedes the regeneration of myelin.
"Aging impairs regenerative potential in the central nervous system," says author Amy J. Wagers, PhD, an associate professor of stem cell and regenerative biology at Harvard University and Joslin, who co-led the study with Professor Robin Franklin, director of the MS Society's Cambridge Centre for Myelin Repair at the University of Cambridge. "Th
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Joslin Diabetes Center