In zero gravity, scientists can print muscle tissue in seconds

Spending time in space comes with serious challenges. One of the biggest is that astronauts’ bodies start to break down. Muscles shrink, bones weaken, and over time, the lack of gravity takes a heavy toll.

Even with hours of exercise each day, astronauts lose muscle mass and strength much faster than they would on Earth.

To figure out how to stop this from happening, scientists need a better way to study what’s going on. And that means finding ways to test human tissue in conditions that actually mimic space.

Printing muscle works better in space

The team has been experimenting with 3D printing muscle in zero gravity. Normally, building tissue on Earth is tough.

Even tiny structures like muscle fibers can collapse under their own weight before they harden. Gravity pulls the living cells inside the printing material downward, disrupting the structure.

In space – or in microgravity, to be specific – that problem disappears. Without gravity dragging things down, scientists can create much more accurate models of real human muscle.

System prints muscle tissue in seconds

To make this happen, researchers from ETH Zurich created a new system they call G-FLight, short for Gravity-independent Filamented Light.

The team tested the system by taking short flights that mimic weightlessness. These are called parabolic flights, and during each one, gravity disappears for about 20 seconds.

Using this system, the scientists printed muscle tissue during the weightless phases of 30 parabolic cycles.

The results showed that tissue printed in microgravity had comparable cell viability and a similar number of muscle fibers to tissue printed under normal gravity.

It worked fast. The system could create usable muscle tissue in just seconds. And the team made sure the materials could be stored for long periods, which makes future space use more practical.

Why zero gravity makes better models

To print tissue, scientists use something called bio-ink. It’s a mix of living cells and a soft gel-like substance.

On Earth, the cells inside this ink tend to sink or shift unevenly. That creates messy, unrealistic structures.

In microgravity, everything stays in place. The bio-ink holds its shape, and the printed muscle looks much more like the real thing.

That matters, because these models are used to test treatments. If the model doesn’t look like real human tissue, it can’t give reliable results.

Growing organs in orbit

This achievement brings scientists another step closer to 3D-printing complex human tissues in space. The ultimate goal is to create entire organoids – tiny, simplified versions of real organs grown in the lab.

These miniature structures mimic the key features and functions of organs such as the heart, liver, or muscles. By studying them, researchers can observe how diseases emerge and progress at the cellular level.

Organoids can also be used to test how potential drugs work, offering safer and more accurate models than traditional experiments on animals or isolated cells.

Growing realistic human tissue

Scientists hope to keep building on this work aboard the International Space Station or other future platforms orbiting Earth.

“The successful production of muscle constructs in microgravity represents an important advance for tissue engineering in space research and biomedicine,” noted the researchers.

And while the focus is space, the benefits don’t stop there. Organs printed in zero gravity could also help doctors on Earth, where growing realistic human tissue is still a major challenge.

New chapter in space health research

This work points to a new direction in space health research. Being able to grow real human tissues in orbit would be a big leap toward keeping astronauts safe on long-distance flights into space.

The research may also help scientists get a clearer picture of just how some diseases, such as muscular dystrophy or muscle loss from zero gravity, really work.

With space missions to the Moon and Mars on the horizon, this kind of research isn’t just fascinating – it’s essential.

Growing muscle in space could allow crews to more closely monitor their health, test new treatments while still in orbit, or even help people on longer missions far away from Earth survive.

The full study was published in the journal Advanced Science.

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