Novel technique to help create new muscles

Scientists have developed a novel technique to promote tissue repair in damaged muscles, an advance that may help treating millions of people suffering from muscle diseases.
The technique developed by researchers at Sanford-Burnham Medical Research Institute (Sanford-Burnham) in US also creates a sustainable pool of muscle stem cells needed to support multiple rounds of muscle repair.
The study provides promise for a new therapeutic approach to treating the millions of people suffering from muscle diseases, including those with muscular dystrophies and muscle wasting associated with cancer and ageing, researchers said.
There are two important processes that need to happen to maintain skeletal-muscle health. First, when muscle is damaged by injury or degenerative disease such as muscular dystrophy, muscle stem cells - or satellite cells - need to differentiate into mature muscle cells to repair injured muscles.

Second, the pool of satellite cells needs to be replenished so there is a supply to repair muscle in case of future injuries.
In the case of muscular dystrophy, the chronic cycles of muscle regeneration and degeneration that involve satellite-cell activation exhaust the muscle stem-cell pool to the point of no return.

"Our study found that by introducing an inhibitor of the STAT3 protein in repeated cycles, we could alternately replenish the pool of satellite cells and promote their differentiation into muscle fibres," said Alessandra Sacco, assistant professor in the Development, Ageing, and Regeneration Programme at Sanford-Burnham.
"Our results are important because the process works in mice and in human muscle cells," said Sacco.

"A treatment approach consisting of cyclic bursts of STAT3 inhibitors could potentially restore muscle mass and function in patients, and this would be a very significant breakthrough," said Vittorio Sartorelli, chief of the Laboratory of Muscle Stem Cells and Gene Regulation and deputy scientific director at the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS).
STAT3 (signal transducer and activator of transcription 3) is a protein that activates the transcription of genes in response to IL-6, a signalling protein released by cells in response to injury and inflammation.
The research team first used normally aged mice and mice models of a form of muscular dystrophy that resembles the human disease to see what would happen if they were given a drug to inhibit STAT3.

They found that the inhibitor initially promoted satellite-cell replication, followed by differentiation of the satellite cells into muscle fibres.
The study was published in the journal Nature Medicine.