Extended periods of limb immobilization -- whether from long-term bed rest, casting, spaceflight, or other circumstances -- can reduce skeletal muscle mass and strength to the extent that recovery is delayed or never achieved. The biological basis for this lack of recovery, however, remains unclear. An animal study published in The FASEB Journal provides the first evidence that pericytes (cells integral to blood vessel formation) are important for regulating muscle mass, particularly in the context of recovery following disuse atrophy.
To conduct this study, researchers used two groups of mice, both of which were subjected to unilateral hind-limb immobilization for two weeks. One group received pericyte transplantation using donor cells, while the control group received a placebo injection. After a two-week recovery period following these respective treatments, the control group continued to exhibit deficits in muscle fiber size and capillary content, while the group that received pericyte transplantation demonstrated full recovery.
These findings demonstrated that while pericytes are significantly reduced in skeletal muscle following limb immobilization, replacement of pericytes with donor cells during the recovery period can facilitate full regrowth of muscle fibers.
"Our findings suggest that pericyte-based therapies may provide an effective approach toward rebuilding skeletal muscle mass and function after loss," said Marni D. Boppart, ScD, an associate professor of kinesiology and community health at the Beckman Institute for Advanced Science and Technology at the University of Illinois, Urbana-Champaign. "We hope that this study provides the first step toward preventing devastating disabilities that can occur in older adults following long periods of inactivity."
The study's findings also suggested that perivascular support cells are responsive to mechanical cues provided by contraction. As a result, researchers are examining a role for pericytes in mediating the benefits that occur with physical activity in healthy individuals, including enhanced muscle mass, blood flow, and strength.
"Mechanical signaling has emerged as a major axis of cellular regulation and differentiation, and this study adds a novel dimension," said Thoru Pederson, PhD, Editor-in-Chief of The FASEB Journal.
This research was supported by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases; the National Heart, Lung, and Blood Institute; and the University of Illinois, Urbana-Champaign.
The FASEB Journal is published by the Federation of the American Societies for Experimental Biology (FASEB). The world's most cited biology journal according to the Institute for Scientific Information, it has been recognized by the Special Libraries Association as one of the top 100 most influential biomedical journals of the past century.
FASEB is composed of 29 societies with more than 130,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB's mission is to advance health and well-being by promoting research and education in biological and biomedical sciences through collaborative advocacy and service to member societies and their members.