It goes without saying that there aren't any doctors in space – which is a problem, given that the harsh environment is conducive to injuries. Now researchers from Dresden Technical University (TUD) have developed a 3D bioprinting method for use in space, creating new skin and bone tissue out of resources that might be available to astronauts.

Life isn't easy for astronauts living in the International Space Station (ISS). Humans evolved to live on Earth's gravity, so our bodies don't function properly once removed from that environment. Fluids don't move as they should, muscles wither, and bones lose mass and become more susceptible to fractures.

That means astronauts could benefit greatly from 3D bioprinting, which here on Earth could help surgeons and doctors patch up wounds or even print new functioning organs for transplant. Regular 3D printing has already been considered for space travel, helping astronauts make new tools or even shelters out of Mars dust.

So the TUD researchers aimed to combine the two, with the goal of allowing astronauts to 3D print new skin patches to patch up wounds, or pieces of bone to help heal fractures. But there are two main hurdles to this idea: first, it might be hard to source these "bio-inks" in space, and secondly, liquid inks won't always stay where they're needed in micro-gravity.

To solve the first problem, the TUD team suggested that the astronauts themselves could be a source of bioinks. Plasma from the blood could be used to make the skin cells, while stem cells could be turned into bone.

"Skin cells can be bioprinted using human blood plasma as a nutrient-rich 'bio-ink' – which would be easily accessible from the mission crew members," says Nieves Cubo, a team member on the project. "Producing the bone sample involved printing human stem cells with a similar bio-ink composition, with the addition of a calcium phosphate bone cement as a structure-supporting material, which is subsequently absorbed during the growth phase."

The second problem, micro-gravity, was tackled by changing the viscosity of the plasma-derived bio-ink, which is normally quite fluid. The researchers added methylcellulose and alginate to the mix, which increases the viscosity of the ink and keeps it from running everywhere. These ingredients can be sourced from plants and algae, which astronauts on long trips would likely have on hand.

While we can't artificially recreate a low gravity environment on Earth, the team showed that the new bio-ink won't spill by running the 3D printer upside down. That means the arm was pointing upwards, drawing the shapes on the underside of a surface. And it worked, with the patch staying put and keeping its shape, suggesting the mixture is suitable for use in space.

"A 3D bioprinting capability will let [astronauts] respond to medical emergencies as they arise," says Cubo. "In the case of burns, for instance, brand new skin could be bioprinted instead of being grafted from elsewhere on the astronaut's body, doing secondary damage that may not heal easily in the orbital environment.

"Or in the case of bone fractures – rendered more likely by the weightlessness of space, coupled with the partial 0.38 Earth gravity of Mars – replacement bone could be inserted into injured areas. In all cases the bioprinted material would originate with the astronaut themselves, so there would be no issue with transplant rejection."

The upside down 3D bioprinter can be seen in action in the time-lapse video below.

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