Self-healing bioengineered muscles grown in lab

Scientists at Duke University have developed a new kind of bioengineered muscle tissue that is not only stronger than any previously engineered muscle, but can also heal itself, both in the lab and inside mice.

One of the goals of bioengineering is to create artificially-grown muscle tissues, for use in disease research and for replacing damaged muscles in accident and injury victims. In order to be useful for these purposes, the artificial muscles have to satisfy two requirements - they need to be strong enough to match natural muscle fibres, and they need to be able to regenerate like natural muscle fibres do. Researchers at Duke University have been working on this problem for years now, and their latest efforts are showing a lot of potential.

"The muscle we have made represents an important advance for the field," said Nenad Bursac, the Duke University biomedical engineer that led the research team, according to a press release. "It's the first time engineered muscle has been created that contracts as strongly as native neonatal skeletal muscle."

In the lab, they tested the muscle fibres with electrical impulses to see how strong they were, and found that they were 10 times stronger than any other engineered muscles produced so far. They also exposed them to snake venom to test their regenerative ability, and found it only took 10 days for them to return to their pre-injury state.

Muscles repair themselves using a type of stem cell known as satellite cells. In natural muscles, these cells hang out in 'niches' in the fibres, and are therefore on hand when any damage occurs and can immediately activate to repair that damage. For these engineered muscles to regenerate the same, the researchers needed to create similar microenvironments for them.

"Simply implanting satellite cells or less-developed muscle doesn't work as well," Mark Juhas, one of Bursac's graduate students, said in the statement. "The well-developed muscle we made provides niches for satellite cells to live in, and, when needed, to restore the robust musculature and its function."

Moving to the next stage in testing, the researchers modified the muscle fibres so that they'd light up whenever they contracted, and then implanted them into special glass-covered chambers on the backs of lab mice so they could watch them develop. As the muscle fibres grew and developed, the flashes of light they produced grew brighter, showing that they were actually getting stronger.

Also, a particularly important key for these fibres becoming useful in transplants for injuries is that the muscles can vascularize— that is, they can grow blood vessels that can connect with the rest of the body's circulatory system or the body's circulatory system can expand into the tissues, and this video from the researchers reveals this in action:

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It's still likely going to take years for this to reach the stage where these new muscle fibres can be used in human trials, and then go on to help us find new cures for muscular diseases and repair injuries, but this is still very promising news.

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