Scientists Grow Mouse Leg Muscle in a Dish

An international team of scientists has successfully grown leg muscle in a lab dish, leading the way to possible treatments for a large number of muscle disorders, according to a new study.

The results were published in the journal EMBO Molecular Medicine.

Normally, creating skeletal muscle in challenging, and until now attempts to re-create a functional muscle either outside or directly inside the body have been unsuccessful. In vitro-generated artificial muscles typically don't survive the transfer in vivo because the host does not create the necessary nerves and blood vessels that would support the muscle's oxygen needs.

In this latest case, researchers from Italy, Israel and the United Kingdom used muscle precursor cells - called mesoangioblasts - grown in the presence of a hydrogel (support matrix) in a tissue culture dish. The cells were genetically modified to produce a growth factor that stimulates blood vessel and nerve growth from the host, which in this case was a mouse.

The cells, engineered to mimic the leg muscle Tibialis anterior, were then cultured in a dish to produce a graft. The subsequent graft was implanted close to a normal, contracting skeletal muscle where the new muscle was nurtured and grown.

Newly formed muscle fibers were able to form within a matter of just a few weeks, thanks to the way the researchers engineered the cells. Their novel method allowed the skeletal cells to express a protein growth factor that attracts other essential cells that give rise to the blood vessels and nerves of the host.

"The morphology and the structural organisation of the artificial organ are extremely similar to if not indistinguishable from a natural skeletal muscle," Cesare Gargioli of the University of Rome, one of the study's lead authors, said in a statement.

Researchers hope that their results may lead to treatments for various types of diseases such as Duchenne muscular dystrophy, in which there is irreversible damage to muscle tissue. However, the team is quick to point out that this idea is a long way off.

"While we are encouraged by the success of our work in growing a complete intact and functional mouse leg muscle we emphasize that a mouse muscle is very small and scaling up the process for patients may require significant additional work," noted EMBO Member Giulio Cossu, one of the authors of the study.

The researchers next plan to test their technique on larger animal models before conducting clinical studies.

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