A single dose of healthy immune cells sped the recovery of muscle function in older mice following two weeks of physical inactivity, 犹他大学的健康科学家说. They say the finding could eventually lead to the development of treatments that accelerate muscle repair and help older people recover from falls and other injuries as quickly as younger individuals.
“很多人可能没有意识到这一点, but the immune system plays a vital role in muscle repair and restoration,” 弥迦书德拉蒙德博士.D., a professor of physical therapy and athletic training at U of U Health and corresponding author of the study, 它出现在 应用生理学杂志.
"然而, as we age, immune cells often become less responsive to muscle tissue injury. 大发娱乐相信, if we could find a way to reinvigorate the immune system in aging muscle, then we might be able to help older people retain or restore their ability to get out of chairs, 爬楼梯, 过上更好的生活."
年老，肌肉衰弱会导致跌倒和受伤
随着年龄的增长, 肌肉变得越来越小，越来越弱, making a person more susceptible to injury from falls and other accidents. 事实上, 每五次跌倒中就有一次造成伤害, 比如骨折, 至少有300人,000名老年人 髋部骨折住院 annually, according to the Centers for Disease Control and Prevention.
"When we gave the old immune cells to the older animals, 大发娱乐认为这可能会让情况更糟. 但令大发娱乐惊讶的是，他们实际上进步了."
“每年, 太多的老年人失去了行动能力, 立场。, 然后开始他们的日常生活,德拉蒙德说. "We want to prevent that from happening and get their muscles back to performing the way they should."
正常情况下, 当脚踝扭伤等受伤发生时, muscle in the affected area sends out signals to the immune system that attract white blood cells to the damaged tissue. 其中一些白细胞, 被称为巨噬细胞, cause swelling but also remove debris from the injury site and prompt stem cells to coordinate regrowth of muscle tissue.
然而, 当大发娱乐变老, the immune cells involved in this process can’t stimulate muscle repair as effectively as they did when we were younger, 据德拉蒙德说.
使年老的肌肉恢复年轻
To determine if some of this repair activity could be restored, Drummond and his colleagues from U of U Health and Miami University in Oxford, 俄亥俄州, 在实验室老鼠身上做了一系列的实验.
在他们的第一个实验中, the researchers weakened muscles in young and old laboratory mice by restricting the movement of their hind legs for 14 days. These mice were then given a dose of macrophages taken from a set of young and old mice that were allowed to move freely around. Another set of mice with restricted movement were given saline treatment as a control.
The researchers found the experimental young mice that received immune cells from other young mice showed no difference in their muscle recovery compared to the control group. 然而, 老年实验小鼠, 注射年轻老鼠的免疫细胞, had improved muscle strength recovery to virtually the same levels as older mice that remained physically active.
与此形成鲜明对比的是, when younger experimental mice received immune cells from older mice, 他们的肌肉变弱了, suggesting that the old immune cells were somewhat dysfunctional, 德拉蒙德说.
有趣的是, 给年老的老鼠注射年老的供体免疫细胞, their muscle strength dramatically improved during recovery, 他说.
"When we gave the old immune cells to the older animals, 大发娱乐认为这可能会让情况更糟,德拉蒙德说. “但令大发娱乐惊讶的是，他们实际上有所改善."
Drummond theorizes that even though the old immune cells are a bit less effective than young immune cells, 他们仍然有潜力做出改变, particularly if enough of them are introduced to the muscle.
“它们可能不是100%有效, 但如果你把它们集中在一块肌肉里, 他们可能还能做他们的工作,德拉蒙德说. "Whereas in a younger animal not as many are needed because their immune cells are in their prime and very efficient."
Better cell communication accelerates muscle rejuvenation, too
The researchers note that immune cell dysfunction is only one of several factors that contribute to poor muscle recovery in older muscles. 在某些情况下, it’s possible that muscle cells aren’t sending out enough of the right signals to the immune system, 德拉蒙德说. As a result, fewer macrophages are available to help restore muscle.
为了验证这个概念, the researchers gave some of 老年实验小鼠 a growth factor called macrophage colony stimulating factor (MCSF) that normally alerts the immune system to begin repairing damaged muscle. 整体, the aged mice given MCSF had more macrophage immune cell production and had greater muscle strength than control animals.
尽管这项研究显示了希望, Drummond emphasizes that much more work is needed before it can be used in humans.
"We’re looking at many factors that may rejuvenate immune cells and allow them to more effectively restore muscle function,他说. “但大发娱乐还有更多的实验要做."
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In addition to 弥迦书德拉蒙德, University of Utah Health researchers E.余先生，J.J. 帕特塞利、维.K. 修复,C.T. 豪泽,N.M.M.P. 德·哈特.S. Mahmassani和R.M. 奥康奈尔也参与了这项研究. P. T. Reidy of Miami University in Oxford, 俄亥俄州, also participated in this research.
这项研究, "Macrophage immunomodulation accelerates skeletal muscle functional recovery in aged mice following disuse atrophy,出现在 应用生理学杂志. The research was supported by the National Institute on 老化 (NIA) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).