Scientists from Duke University have grown an engineered muscle that is self-healing both in cell culture and when implanted into an animal, and is also over ten times stronger than any other previous lab grown muscle.
Scientists are keen to engineer functional skeletal muscle tissues not only because they can provide accurate models for the physiology of muscles, but they also have the potential to be used in the treatment of muscle disorders, or to rapidly repair severe muscle damage or loss which could be the result of injury. Although engineered skeletal muscle has been developed before, they have never retained the contractile strength of muscle found in the body. Not only is the muscle developed by Duke University scientists superior in terms of strength, it also quickly integrated when implanted into mice, and demonstrated self-healing abilities.
The success of this study was down to two key elements; a readily available pool of satellite cells, and well developed contractile muscle fibers. Satellite cells, or myosatellite cells, are progenitor cells present in mature muscle that are able to differentiate into skeletal muscle cells, assisting in muscle regeneration if it becomes damaged. But the scientists found that simply implanting these cells wasn't enough to get the results they needed. That's where the well developed muscle that they had made came in. This provided an environment for the satellite cells to reside in until they were needed for repair duties.
In lab tests the engineered muscle fared well, demonstrating good contractile strength when given small electric pulses. Next, they tested the ability of the satellite cells to become activated and repair muscle damage in response to snake venom, and they found that they could do this successfully. Check out the images below to see how the muscle healed itself after exposure to this snake venom.
Image credit: Duke University.
But what's really incredible is that the team developed a system where they could watch what happened to the muscle after implantation. Not only did they place their synthesized muscle into mice, but they did so using a glass chamber which meant that they could monitor the muscle's progress in real-time as the animal moved around. Mark Juhas, the lead author of the study said "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." If you'd like to take a look at the vasculature of the implanted muscle, check out the YouTube video below, where you can see blood pumping through it to sustain the new tissue.
The team are now moving onto studies hoping to demonstrate whether this engineered muscle can successfully vascularize and repair muscles that have been damaged.