China's 'Myograft' Delivers Exercise-Like Benefits to Mice Without Any Movement

Scientists in China have created a self-exercising muscle graft, dubbed a "myograft," that might let bedridden people gain some benefits of working out without any physical exertion, according to a study published in the peer-reviewed journal Nature Ageing. With just an injection of muscle cells under the skin, the cells self-assembled into muscle grafts that improved whole-body muscle mass in mice, along with bone density, endurance, liver function and cognitive health.

"In a sense, we're distilling the best part of exercise out … and avoiding all the negative effects of exercise, whether it's the stress on the heart or the stress on your joints," said study author Ng Shyh-Chang, a professor and principal investigator at the Chinese Academy of Sciences' Institute of Zoology. The myografts, the team said, could offer the health benefits of exercise to patients with age-related conditions such as Alzheimer's and osteoporosis who have the most trouble moving. "It turns out that the people who need exercise the most are also the folks who cannot exercise the most," Ng said.

The team initially tried transplanting lab-grown muscle organoids into mice, but the three-dimensional structures were too large for nutrients to diffuse into, and the cells died. "Then my students decided, why don't we just go back to the basics. Why don't we just put the cells under the skin and let them form the organoid slowly under the skin," Ng said. Using myocytes derived from mouse muscle stem cells, transplanted with a supportive gel scaffold, the cells self-organised into mature myografts capable of long-term spontaneous contractions without any physical or neural input.

"We found that subcutaneous myograft transplantation ameliorates many problems associated with ageing, including muscle atrophy, osteoporosis, chronic inflammation, liver damage and metabolic dysfunction," the team wrote in the paper, which was published Wednesday. Because the grafts contract non-stop, Ng said, they persistently secrete beneficial factors into the bloodstream — "the sheer amount of good factors it's secreting exceeds what you can get from acute exercise for just one hour." The team also found the myografts could act as a living biofactory to produce therapeutic proteins in the body, including GLP-1, used to manage diabetes and for weight loss.

"While the complete safety and [pharmacological] profile of autologous myografts remains to be established in human trials, our mouse preclinical studies constitute a noteworthy first step in this direction," the team said in the paper. Ng said the team had not seen signs of toxicity so far and was considering trials with intensive care unit patients before testing the myografts in broader patient populations, once safety and efficacy are confirmed.