Injured mice that were treated with stem cell therapy experienced muscle repair and enhancement, creating mighty mice with bulky muscles that stayed big and strong for the rest of their lives, U.S. researchers said this past week. These findings could lead to new treatments for human diseases that would help people resist the gradual erosion of muscle strength that comes with aging, Bradley Olwin, of the University of Colorado at Boulder, and colleagues reported in the journal Science Translational Medicine.
The experiment goals were to strengthen the muscles of the mice and to repair damage. The researchers transplanted between 10 and 50 stem cells along with attached myofibers – which are individual skeletal muscle cells – from the young donor mice into the host mice. Surprisingly, these cells not only repaired the injury, but they caused the treated muscle to increase in size by 170%! Olwin’s team had thought the changes would be temporary, but they lasted through the lifetime of the mice, which was about 2 years.
Olwin said: ‘We found the transplanted stem cells altered and reduced the aging of the transplanted muscle, maintaining muscle strength and mass. When the muscles were examined two years later, we found the procedure permanently changed the transplanted cells, making them resistant to the aging process in the muscle.”
The experiments also indicated different effects when cells were injected into a healthy leg, suggesting that there’s something important about injecting the cells into an injured muscle that triggers growth. “The environment that the stem cells are injected into is very important, because when it tells the cells there is an injury, they respond in a unique way,” he said.
This breakthrough paves the way for a possible treatment that would help humans to maintain the muscle strength of their youth, cutting the risk of falls and fractures in old age. Such a drug could also benefit the young who suffer with crippling muscle-wasting diseases such as muscular dystrophy.
The study was funded in part by the National Institutes of Health and the Muscular Dystrophy Association.