Researchers have created a magnet-containing gel mat that simulates the mechanical forces exerted on muscle cells during exercise. The novel ‘workout mat’ might assist in testing treatments for people with muscle injuries and neuromuscular diseases or for growing artificial muscles for use in soft robots.
In the body, cells communicate through a combination of chemical, electrical and mechanical signals, especially during exercise. With lab-made cells, creating life-like mechanical cell-cell contact can be difficult because it can often cause the cells damage.
Researchers from MIT have created a non-damaging way of simulating the mechanical effects that skeletal muscle cells are exposed to during exercise. They want you to think of it as a workout mat for cells.
“Here, we wanted to decouple the two main elements of exercise – chemical and mechanical – to see how muscles respond purely to exercise’s mechanical forces,” said Ritu Raman, corresponding author of the study.
The researchers turned to magnets as a way of exposing muscle cells to regular and repeated mechanical forces without causing damage. Mixing commercially available magnetic nanoparticles with a rubbery silicone solution, the mixture was cured to form a slab and sliced into very thin bars. A prototype mat was created, consisting of four magnetic bars spaced slightly apart and sandwiched between two hydrogel layers.
Muscle cells were placed on the surface of the mat and the circular cells gradually elongated and fused with neighboring cells to form fibers. Beneath the gel mat, the researchers placed an external magnet on a track and programmed it to move back and forth. The gel-embedded magnets moved in response, wobbling the gel and generating forces similar to what cells would experience during real-world exercise. They ‘exercised’ the cells for 30 minutes a day for 10 days. A group of unexercised muscle cells acted as a control.
“Then, we zoomed out and took a picture of the gel and found that these mechanically stimulated cells looked very different from the control cells,” Raman said.
They found the exercised cells grew longer and into fibers that aligned in the same direction. In contrast, the control cells tended to remain circular and were aligned haphazardly.
Under normal circumstances, muscle cells would contract in response to a nerve’s electrical impulse but, under lab conditions, that might damage the cells. So, the researchers genetically engineered the cells to contract in response to blue light.
“When we shine light on the muscles, you can see the control cells are beating, but some fibers are beating this way, some that way, and overall producing very asynchronous twitch,” said Raman. “Whereas with the aligned fibers, they all pull and beat at the same time, in the same direction.”
The researchers say the new ‘workout gel’ can be used as a quick and non-invasive way of shaping muscle fibers and studying how they respond to exercise, which might identify therapies to help people recover from muscle injuries and neuromuscular disorders. They also plan to grow other cell types on the gel to research how they respond to 'exercise.'
“There’s evidence from biology to suggest that a lot of types of cells are responsive to mechanical stimulation,” Raman said. “And this is a new tool to study interaction.”
The study was published in the journal Device.
Source: MIT