The first ever contracting human muscle in a lab has been created by researchers at Duke University. The dish-grown muscle responds to electrical and chemical signals, just like our own muscles, and may be used for testing new drugs and studying muscular diseases outside of a human body.
[caption id="attachment_184" align="alignright" width="400"] Lab-grown skeletal muscle showing cell nuclei (blue) and striated pattern from protein subunits (red). Image credit: Nenad Bursac, Duke University.[/caption]
Starting with human cells that were somewhere between “blank slate” stem cells and mature skeletal muscle cells, the team multiplied these muscle cell precursors and placed them into a 3D supportive scaffold structure. The scaffold was filled with a nutrient gel for the cells to feed on and allowed them to form long, linear muscle fibres (pictured) like those found in our bodies.
This seems straightforward, but according to Dr Lauran Madden, researcher on the project, it was no easy task to get right. Dr Madden says “We have a lot of experience making bioartifical muscles from animal cells in the laboratory, and it still took us a year of adjusting variables like cell and gel density and optimizing the culture matrix and media to make this work with human muscle cells.”
The artificial muscle fibres were then studied to see how similar they are to natural human muscles. In our bodies, skeletal muscles are voluntarily controlled, that is to say, they expand and contract to electrical signals from our nerves, allowing us to move. Madden subjected the artificial fibres to electrical signals and drugs, like statins, whose effects are well known in human muscle tissue.
The researchers found that the artificial muscle contracted in response to the electrical signal as a normal natural muscle does, a first for lab-grown muscle fibres. The artificial muscle response to drugs also corresponded with the known natural responses, suggesting that artificially created muscles could be used to accurately test and study muscle disease models in a dish, rather than in animals.
Associate professor Nenad Bursac commented “The beauty of this work is that it can serve as a test bed for clinical trials in a dish. One of our goals is to use this method to provide personalized medicine to patients."
This goal is not far off the horizon, and Bursac is working with other groups to develop the artificially grown muscle into a working model system for testing drugs and studying diseases like Duchenne Muscular Dystrophy. His lab is now working on creating the same contracting muscle from induced pluripotent stem cells – cells that have been tricked into becoming the “blank slate” once again.
Growing artificial muscle fibres from induced stem cells rather than from biopsied muscle tissue has major advantages according to Bursac, adding “If we could grow working, testable muscles from induced pluripotent stem cells, we could take one skin or blood sample and never have to bother the patient again.”