Scientists create artificial human muscles

By Dr. Ananya Mandal, MDJan 10 2018

Researchers have successfully created artificial human muscles in the laboratories that are tiny but fully functional. These small muscles actually respond to the nerve stimulations, says the latest study reporting this scientific breakthrough.

The muscles cells have been created from skin cells that have been stimulated to turn into muscles. This could be a great deal for several diseases and ailments the scientists add. These muscles could be used to understand and study muscular disorders and also test new drugs that could be used on these diseases. The research is published in an article this week in the journal Nature Communications.

It is not new to make one kind of cells from a different kind of cell such as skin cells by coaxing them to turn. However making muscle cells from skin cells is a novel finding that has never been tried before.

The team of researchers first took samples of skin from humans and turned them into “pluripotent stem cells” or cells that are capable of becoming any type of human cell. These stem cells then were turned into muscle stem cells by the researchers. These were termed “myogenic progenitors”.

Senior study author Nenad Bursac, a professor of biomedical engineering at Duke University in North Carolina explained that these induced pluripotent stem cells could be made into muscle stem cells by making them create a protein called “Pax7”. This protein is the key that signals the cells to become muscle cells he explained.

The whole reprogramming takes around three weeks he added. These muscle stem cells then multiply rapidly to create thousands of cells. Once there were enough cells to work with, the team successfully turned the Pax7 protein off and now used a 3D culture or scaffolding with nutrients and growth factors or nutrient gels that helped these cells to grow into organized muscle fibres.

Lingjun Rao, a postdoctoral researcher in Bursac's laboratory and first author of the study explained that this study has been the result of years of trial and errors. They succeeded because of the 3D matrix that was used instead of the 2D cell cultures that were earlier used he said.

Within the culture solution, in around three weeks a muscle tissue was grown that measured 2 centimeters (0.8 inches) long and 1 millimeter (0.004 inches) in diameter. Once this was successfully achieved, the muscle tissue was subjected to physiological tests to check for its viability. Bursac said these muscle cells that come originally from skin cells are weaker than the earlier version they had created using muscle cells as origin around three years ago. This was something that the team was working on – to strengthen these muscle cells that come from reprogrammed skin cells. Also the blood vessels that supply blood to the muscle tissues were small and so bigger samples could not be created. The size limit is another hurdle that needs to be overcome he added.

According to researchers worldwide, this is a major scientific breakthrough and provides hope for people with several genetic muscular diseases including Duchenne muscular dystrophy.

Until now to check for new drugs and the understanding of the molecular mechanisms of the disease, muscle samples were needed from these pediatric patients with Duchenne muscular dystrophy who already had weak muscles and a low reserve. Now that part could be addressed by using these artificially created muscles tissues said Bursac.

New treatments can also be tested on these samples he added and these would be more accurate in their results than trying the new agents on lab animals he explained.