Anyone who's been laid up for an extended period due to illness or injury will know how difficult it can be to get moving again. Long-term immobility can see a loss of muscle mass that can be hard to regain, especially for the elderly. In research on mice, a team at the University of Illinois at Urbana-Champaign have found that the injection of a type of cells known to promote blood vessel growth helps accelerate to restoration of muscle mass lost due to inactivity.

The cells in question are called pericytes and, in addition to promoting blood vessel growth, also play a role in dilating tissues throughout the body. When these cells were injected into muscles in one of the hind legs of mice that had been prevented from contracting for a period of two weeks, the researchers saw a much greater improvement in muscle mass restoration compared to mice that didn't receive an injection. After two weeks, mice that had received the cell injection had fully recovered, while those that hadn't still exhibited a significant loss of muscle mass.

"Just as the mice were becoming mobile again, we transplanted the pericytes and we found that there was full recovery of both muscle mass and the vasculature, too," says University of Illinois kinesiology and community health professor Marni Boppart, who led the research.

The research also revealed that there was a significant reduction in the amount of pericytes in affected muscle tissues as a result of muscle immobility, which Boppart says hadn't been documented previously.

The work was carried out in an attempt to better understand the factors that contribute to a loss of muscle mass, particularly losses resulting from immobility, with the hopes of finding ways to uncover clinical interventions that could be used to reverse the process.

"To my knowledge, no one has demonstrated that anything has been effective in improving the recovery process," Boppart says. "We're excited by the new findings because we hope to one day use these cells or biomaterials derived from these cells to help restore lost muscle mass."

Boppart adds that such an approach would be of particular benefit to older adults, who face extra difficulty when trying to regain muscle mass after extended periods of inactivity.

"They can't recover, they become disabled, and there's this downward spiral," she says. "They may become institutionalized and experience early mortality."

In future, the team hopes to identify the extracellular vesicles secreted by pericytes as a result of muscle contraction, and explore the potential for using those as a form of therapy to restore lost muscle mass.

The team's paper appears in The FASEB Journal, and Boppart discusses the research in the video below.