Designing bioinks for space missions

The Problem

Space missions are a logistics nightmare. The further we travel from Earth, the worse it gets.

If we ever make it to Mars, there will be massive delays for any shipments from Earth. Everything that could possibly be needed must be on board when the rocket takes off. Even going to the international space station can take weeks after the cargo is loaded.

How will we grow food? Make medicine? Get oxygen? All the necessary components will have to be on the rockets. Since cargo space is obviously limited, things will need to be stored efficiently and not require many tools to use.

Importantly, the cargo has to stay functional during the journey. It doesn’t do anyone much good if everything goes bad by the time it arrives.

3D bioprinting uses living inks to make food, treat wounds, and produce oxygen. It’s an emerging technology with great potential for space missions because of its versatility. The prints can be programmed into desired shapes based on what they’re needed for.

There are companies putting fat and muscle cells into natural materials to make artificial steak. Countless labs use bioprinting for diseases/injuries. Plant cells, like algae, can be bioprinted and produce oxygen.

That’s all great and all, but there are some issues. The “living” part of living inks are normally kept alive through constant work and specialized equipment. Cells are normally grown separately and then placed into the bioink right before printing.

There isn’t room on a spaceship for the required equipment to grow cells from scratch. Everything needs to be ready to go once it gets on the ship.

The Solution

This week, scientists from Germany investigated how bioinks survive when they’re made in advance and stored for weeks before use. This mimics how astronauts would use bioinks in a space mission.

Their bioink was made of a mixture of alginate and cellulose. Both these materials are commonly used in bioprinting. Alginate is a natural material derived from seaweed while cellulose is often obtained from wood pulp or other plant sources. Different cell types were mixed into the alginate/cellulose blend and then let sit in the fridge for up to 4 weeks.

The authors mixed in a variety of cells that would be useful in different situations into the gels. These included microalgae and two different types of human stem cells. Microalgae reliably produce oxygen while human stem cells could be used to treat injuries or diseases.

Once the alginate/cellulose and the cells were mixed, they were placed in a 3D printing cartridge and stored in a fridge. The authors found that the bioinks storage time didn’t affect their ability to be printed. The microalgae didn’t seem fazed at all by the month-long storage; they survived and produced oxygen just as well after 4 weeks.

Storage didn’t work out as well in the human stem cells. Nearly 80% of the first stem cell type died after 4 weeks in storage. The 2nd type faired a bit better, with only 60% dying after 4 weeks.

Encouragingly, both stem cells were able to grow and become healthy again after their prolonged storage. The cells were able to function even after sitting in a fridge for a month. Remember, these are cells that are normally taken care of every day by a dedicated researcher. Having any alive and working after a month is amazing.

Every cell type is different and will survive better in different conditions. This work is just a starting point that the authors plan to build off of in future studies. They’re hoping to get their bioinks into space for experiments sometime soon.

See you next week for more science,

Neil