Functioning muscles from stem cells

Yulia Vorobyova, "The Attic"

Obtaining artificial donor muscles is an important task that will facilitate the treatment of many diseases, such as diabetes, muscular and skeletal dystrophy, Huntington's disease, not to mention the consequences of various injuries. However, synthesizing such muscles is not so easy.

Usually, scientists begin to grow muscles from stem cells or from so–called muscle myoblasts - cells that have already advanced beyond the stem stage, but have not yet become mature muscle fibers. This involves a number of difficulties: as a rule, such cells do not tolerate in-vitro experiment conditions, quickly losing their "stem" potential.

Until recently, no one has been able to generate enough muscle cells. In addition, such cells are difficult to obtain in elderly or seriously ill patients.

Nenad Bursak's group from Duke University in the USA has been working on the creation of artificial muscles for more than 15 years. However, last year, scientists made a real breakthrough: for the first time they managed to grow working muscles from pluripotent stem cells obtained from humans, which can differentiate into all types of cells, except cells of extra-embryonic organs. The peculiarity of the method is that scientists take cells from adult non-muscle tissues, such as skin or blood, and reprogram them in a special way to return them to their original pluripotent state.

Then, during the growth process, the resulting cells are treated with a special substance called Pax7, which signals to the cells that they should become muscular. Another invention of the Bursak group turned out to be an original three-dimensional matrix-a framework for the growth of fibers (before that, the authors used two-dimensional frameworks). As a result, for the first time, scientists managed to get fully functioning muscle fibers (growth takes from two to four weeks). The resulting muscles can be transplanted into mice and survive in their body for at least several weeks, gradually integrating into their native muscle tissue.

Now Bursak and his team are planning to improve their technique of obtaining artificial muscles in order to use it for the treatment of various diseases.

"The treatment of rare muscle diseases is of particular interest to us," says Bursak (in the press release How to grow functioning human muscles from stem cells – VM). - When a child suffers, for example, Duchenne muscular dystrophy, it is not so easy to get cells from him, sometimes it is also cruel. With our technique, we can simply take a small sample of skin or blood, return the cells to a pluripotent state and eventually get an unlimited supply of new working muscles."

The study is published in the journal Nature communications (Rao et al., Engineering human pluripotent stem cells into a functional skeletal muscle tissue).

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