A research team in Canada, led by Michael A. Rudnicki, a Howard Hughes Medical Institute international research scholar at the Ottawa Health Research Institute and director of the Institute’s molecular medicine program and its Sprott Centre for Stem Cell Research, has made a startling, even shocking, discovery which could lead to future regenerative therapies for muscular diseases, including Muscular Dystrophy.
It is known that adult mouse and human muscle contain cells called satellite cells. The researchers initially believed that these cells were fully dedicated to the repair of muscle tissue—activated when a muscle is injured or stressed. What they learned was that 10% of these satellite cells were actually a novel population of stem cells—ones that did not express a gene called Myf5, which is turned on in mature muscle cells.
Rudnicki and his colleagues devised a way to view satellite cell divisions as they occurred in mice. The group’s findings indicated that when satellite stem cells divide, those that remain attached to the muscle fiber’s collagen sheath become new satellite stem cells. Those that lose contact with the sheath, however, turn on the Myf5 gene and become committed to developing into mature muscle cells.
Rudnicki’s group is continuing their work to develop a better understanding of the genes that are differentially expressed between these populations of satellite cells, so they can identify them in humans. Knowing this, drugs could be developed that target satellite stem cells to stimulate muscle regeneration. Research could also be pursued to isolate and expand the cells for use in transplantation studies.
Illustration: Howard Hughes Medical Institute.
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