MIT engineers design workout mat for cells to review exercise’s mechanical effects

There is no doubt that exercise does a body good, including strengthening and toning our muscles. But how exactly does exercise make this occur?

As we run and lift and stretch, our muscles experience chemical signals from surrounding cells, in addition to mechanical forces from jostling against tissues. Some physiologists wonder: Is it the body’s natural chemical stimulants or the physical forces of repeated motion -; or some mixture of the 2 -; that ultimately drive our muscles to grow? The reply could possibly be the important thing to identifying therapies to assist people get better from muscle injuries and neurodegenerative disorders.

Now, MIT engineers have designed a form of workout mat for cells that may help scientists zero in, on the microscopic level, on exercise’s purely mechanical effects.

The brand new design is just not so different from a yoga mat: Each are rubbery, with a little bit of stretch. Within the case of the MIT mat, it’s created from hydrogel -; a soft, Jell-O-like material that’s in regards to the size of 1 / 4 and is embedded with magnetic microparticles.

To activate the gel’s mechanical function, the researchers used an external magnet underneath the mat to maneuver the embedded particles forwards and backwards, wobbling the gel in turn like a vibrating mat. They controlled the frequency of the wobbling to mimic the forces that muscles would experience during actual exercise.

They next grew a carpet of muscle cells on the gel’s surface and activated the magnet’s motion. Then, they studied how the cells responded to being “exercised” as they were magnetically vibrated.

Up to now, the outcomes suggest that regular mechanical exercise may help muscle fibers grow in the identical direction. These aligned, “exercised” fibers may also work, or contract, in sync. The findings reveal that scientists can use the brand new workout gel to shape how muscle fibers grow. With their recent device, the team plans to pattern sheets of strong, functional muscles, potentially to be used in soft robots and for repairing diseased tissues.

We hope to make use of this recent platform to see whether mechanical stimulation could help guide muscle regrowth after injury or lessen the consequences of aging. Mechanical forces play a extremely vital role in our bodies and lived environment. And now we have now a tool to review that.”

Ritu Raman, the Brit and Alex d’Arbeloff Profession Development Professor in Engineering Design at MIT

She and her colleagues have published their leads to the journal Device.

All the way down to the mat

At MIT, Raman’s lab designs adaptive living materials to be used in medicine and robotics. The team is engineering functional, neuromuscular systems with an aim of restoring mobility in patients with motor disorders and powering soft and adaptable robots. To get a greater understanding of natural muscles and the forces that drive their function, her group is studying how the tissues respond, on the cellular level, to numerous forces equivalent to exercise.

“Here, we wanted a solution to decouple the 2 essential elements of exercise -; chemical and mechanical -; to see how muscles respond purely to exercise’s mechanical forces,” Raman says.

The team searched for a solution to expose muscle cells to regular and repeated mechanical forces, that at the identical time wouldn’t physically damage them in the method. They ultimately landed on magnets a secure and nondestructive solution to generate mechanical forces.

For his or her prototype, the researchers created small, micron-sized magnetic bars, by first mixing commercially available magnetic nanoparticles with a rubbery, silicone solution. They cured the mixture to form a slab, then sliced the slab into very thin bars. They sandwiched 4 magnetic bars, each spaced barely apart, between two layers of hydrogel -; a fabric that is often used to culture muscle cells. The resulting, magnet-embedded mat was in regards to the size of 1 / 4.

The team then grew a “cobblestone” of muscle cells across the surface of the mat. Each cell started off as a circular shape that progressively elongated and fused with other neighboring cells to form fibers over time.

Finally, the researchers placed an external magnet on a track beneath the gel mat and programmed the magnet to maneuver forwards and backwards. The embedded magnets moved in response, wobbling the gel and generating forces which might be just like what cells would experience during actual exercise. The team mechanically “exercised” the cells for half-hour a day, for 10 days. As a control, they grew cells on the identical mat, but left them to grow without exercising them.

“Then, we zoomed out and took an image of the gel, and located that these mechanically stimulated cells looked very different from the control cells,” Raman says.

Cells in sync

The team’s experiments revealed that muscle cells which might be commonly exposed to mechanical motion grew longer compared with cells that weren’t exercised, which tended to remain circular in shape. What’s more, the “exercised” cells grew into fibers that aligned in the identical direction, whereas nonmoving cells resembled a more haphazard haystack of misaligned fibers.

The muscle cells that the team utilized in this study were genetically engineered to contract in response to blue light. Typically, muscle cells within the body contract in response to a nerve’s electrical pulse. Electrically stimulating muscle cells within the lab, nonetheless, could potentially damage them, so the team selected to genetically manipulate the cells to contract in response to a noninvasive stimulus -; on this case, blue light.

“After we shine light on the muscles, you possibly can see the control cells are beating, but some fibers are beating this fashion, some that way, and overall producing very asynchronous twitch,” Raman explains. “Whereas with the aligned fibers, all of them pull and beat at the identical time, in the identical direction.”

Raman says the brand new workout gel, which she dubs MagMA, for Magnetic Matrix Actuation, can function a fast and noninvasive solution to shape muscle fibers and study how they reply to exercise. She also plans to grow other cell types on the gel so as to study how they reply to regular exercise.

“There’s evidence from biology to suggest that a whole lot of sorts of cells are conscious of mechanical stimulation,” Raman says “And it is a recent tool to review interaction.”

This study was supported partly by the U.S. National Science Foundation and the Department of Defense Army Research Office.