Self-healing engineered muscle grown in the laboratory

March 31, 2014
Long, colorful strands of engineered muscle fiber have been stained to observe growth after implantation into a mouse. Credit: Duke University

Biomedical engineers have grown living skeletal muscle that looks a lot like the real thing. It contracts powerfully and rapidly, integrates into mice quickly, and for the first time, demonstrates the ability to heal itself both inside the laboratory and inside an animal.

The study conducted at Duke University tested the bioengineered by literally watching it through a window on the back of living mouse. The novel technique allowed for real-time monitoring of the muscle's integration and maturation inside a living, walking animal.

Both the lab-grown muscle and experimental techniques are important steps toward growing viable muscle for studying diseases and treating injuries, said Nenad Bursac, associate professor of biomedical engineering at Duke.

The results appear the week of March 25 in the Proceedings of the National Academy of Sciences Early Edition.

"The muscle we have made represents an important advance for the field," Bursac said. "It's the first time engineered muscle has been created that contracts as strongly as native neonatal ."

Through years of perfecting their techniques, a team led by Bursac and graduate student Mark Juhas discovered that preparing better muscle requires two things—well-developed contractile and a pool of , known as satellite cells.

The video will load shortly
After veins grow into the implanted engineered muscle fibers, blood cells can be seen traveling through them, sustaining and nourishing the new tissue. Credit: Duke University

Every muscle has satellite cells on reserve, ready to activate upon injury and begin the regeneration process. The key to the team's success was successfully creating the microenvironments—called niches—where these stem cells await their call to duty.

"Simply implanting satellite cells or less-developed muscle doesn't work as well," said Juhas. "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."

To put their muscle to the test, the engineers ran it through a gauntlet of trials in the laboratory. By stimulating it with electric pulses, they measured its contractile strength, showing that it was more than 10 times stronger than any previous engineered muscles. They damaged it with a toxin found in snake venom to prove that the could activate, multiply and successfully heal the injured muscle fibers.

Then they moved it out of a dish and into a mouse.

This series of images shows the destruction and subsequent recovery of engineered muscle fibers that had been exposed to a toxin found in snake venom. This marks the first time engineered muscle has been shown to repair itself after implantation into a living animal. Credit: Duke University

With the help of Greg Palmer, an assistant professor of radiation oncology in the Duke University School of Medicine, the team inserted their lab-grown muscle into a small chamber placed on the backs of live mice. The chamber was then covered by a glass panel. Every two days for two weeks, Juhas imaged the implanted muscles through the window to check on their progress.

By genetically modifying the muscle fibers to produce fluorescent flashes during calcium spikes—which cause muscle to contract—the researchers could watch the flashes become brighter as the muscle grew stronger.

"We could see and measure in real time how blood vessels grew into the implanted muscle fibers, maturing toward equaling the strength of its native counterpart," said Juhas.

The engineers are now beginning work to see if their biomimetic muscle can be used to repair actual muscle injuries and disease.

"Can it vascularize, innervate and repair the damaged muscle's function?" asked Bursac. "That is what we will be working on for the next several years."

Explore further: At the right place at the right time—new insights into muscle stem cells

More information: "Biomimetic engineered muscle with capacity for vascular integration and functional maturation in vivo." Juhas, M., Engelmayr, Jr., G.C., Fontanella, A.N., Palmer, G.M., Bursac, N. PNAS Early Edition, March, 2014. DOI: 10.1073/pnas.1402723111

Related Stories

At the right place at the right time—new insights into muscle stem cells

September 17, 2012
Muscles have a pool of stem cells which provides a source for muscle growth and for regeneration of injured muscles. The stem cells must reside in special niches of the muscle for efficient growth and repair.

A new way to make muscle cells from human stem cells

March 21, 2014
As stem cells continue their gradual transition from the lab to the clinic, a research group at the University of Wisconsin-Madison has discovered a new way to make large concentrations of skeletal muscle cells and muscle ...

A step closer to muscle regeneration

December 10, 2013
(Medical Xpress)—Muscle cell therapy to treat some degenerative diseases, including Muscular Dystrophy, could be a more realistic clinical possibility, now that scientists have found a way to isolate muscle cells from embryonic ...

Discovery of a 'conductor' in muscle development

February 25, 2014
A team led by Jean-François Côté, researcher at the IRCM, identified a ''conductor'' in the development of muscle tissue. The discovery, published online yesterday by the scientific journal Proceedings of the National ...

Cancer wasting due in part to tumor factors that block muscle repair, study shows

October 23, 2013
A new study reveals that tumors release factors into the bloodstream that inhibit the repair of damaged muscle fibers, and that this contributes to muscle loss during cancer wasting. The condition, also called cancer cachexia, ...

Promoting muscle regeneration in a mouse model of muscular dystrophy

April 1, 2013
Duchenne muscular dystrophy (DMD) is a degenerative skeletal muscle disease caused by mutations in the protein dystrophin. Dystrophin functions to protect muscle cells from injury and loss of functional dystrophin results ...

Recommended for you

Post-stroke patients reach terra firma with new exosuit technology

July 26, 2017
Upright walking on two legs is a defining trait in humans, enabling them to move very efficiently throughout their environment. This can all change in the blink of an eye when a stroke occurs. In about 80% of patients post-stroke, ...

Molecular hitchhiker on human protein signals tumors to self-destruct

July 24, 2017
Powerful molecules can hitch rides on a plentiful human protein and signal tumors to self-destruct, a team of Vanderbilt University engineers found.

Researchers develop new method to generate human antibodies

July 24, 2017
An international team of scientists has developed a method to rapidly produce specific human antibodies in the laboratory. The technique, which will be described in a paper to be published July 24 in The Journal of Experimental ...

New vaccine production could improve flu shot accuracy

July 24, 2017
A new way of producing the seasonal flu vaccine could speed up the process and provide better protection against infection.

A sodium surprise: Engineers find unexpected result during cardiac research

July 20, 2017
Irregular heartbeat—or arrhythmia—can have sudden and often fatal consequences. A biomedical engineering team at Washington University in St. Louis examining molecular behavior in cardiac tissue recently made a surprising ...

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.