Smooth muscle cells.
Biomedical engineers have managed to create a lab-grown skeletal muscle that behaves like the genuine tissue. It is capable of contraction, can be integrated naturally into mice, and demonstrates the power to heal itself. (1)
“The muscle we have made represents an important advance for the field. It’s the first time engineered muscle has been created that contracts as strongly as native neonatal skeletal muscle,” reported Nenad Bursac, associate professor of biomedical engineering at Duke University. (1)
The Duke University researchers attribute their success to creating conditions perfect for muscle growth: well-developed contractible fibers and ample immature stem cells (also called satellite cells). (2) This newly engineered muscle demonstrated the ability to regenerate when the researchers exposed it to snake venom toxins. (2)
Every muscle has satellite cells on reserve, waiting for an injury to activate and begin regenerating the muscle. The team at Duke succeeded by creating small environments – called niches – where pools of these satellite cells could wait in reserve. (3)
The conducted research was subjected to a battery of tests to show its superiority over all previously engineered muscles. They subjected the muscle to electrical pulses to measure its contractile strength, demonstrating it was 10 times stronger than anything before it. As mentioned above, they damaged the muscle with snake venom and showed that the satellite cells could activate and successfully regenerate the muscle fibers. The Duke team monitored the integration of the muscle inside a mouse by literally watching it through a small window in the mouse’s back. (3)
The muscles implanted into the mice were treated to produce fluorescent flashes during calcium spikes (which is a natural trigger for muscles to contract), so the researches could watch the flashes become brighter as the muscle grew stronger. (1, 3)
“We could see and measure in real time how blood vessels grew into the implanted muscle fibers, maturing towards equaling the strength of its native counterpart,” said graduate student Mark Juhas, who was part of the research team at Duke. (1)
The bioengineers are now beginning to see if their biomimetic muscle can be used to repair muscle injuries and disease. (3)
References:
1 Self-healing engineered muscle grown in the laboratory. Available at: http://www.sciencedaily.com/releases/2014/03/140331153606.htm (10 April, 2014).
2 Self-healing muscle grown in the lab. Available at http://www.bbc.com/news/health-26821080 (10 April, 2014).
3 Ken Kingery, Self-Healing Engineered Muscle Grown in the Laboratory. Available at http://www.pratt.duke.edu/news/self-healing-engineered-muscle-grown-laboratory (10 April, 2014).