You might call it a giant leap for 3D bioprinting: Human heart cells have been 3D printed on the International Space Station (ISS) and are making their way back to Earth this week inside a SpaceX capsule. The 3D BioFabrication Facility (BFF) was developed by Techshot Inc., a commercial operator of microgravity research and manufacturing equipment, in partnership with nScrypt, a manufacturer of industrial 3D bioprinters and electronics printers.

“Our BFF has the potential to transform human healthcare in ways not previously possible,” said Techshot President and CEO John Vellinger. ”We’re laying the foundation for an entire industry in space.”

The 3D BioFabrication Facility is the first U.S. 3D printer capable of manufacturing human tissue under microgravity conditions, according to Techshot Inc.

If you’re wondering why they don’t just print the cells here on Earth, the answer is gravity. When attempting to print with soft, easily flowing biomaterials on Earth, the tissues collapse under their own weight, resulting in little more than a puddle, explained Techshot in a press release. “But when these same materials are used in the microgravity environment of space, the 3D-printed structures maintain their shapes.” The bio-ink used in the space station, consequently, did not contain the scaffolding materials or thickening agents normally required to resist the Earth's gravitational pull.

The test prints made in space are large by terrestrial bioprinting standards, measuring 30 mm long by 20 mm wide by 12.6 mm high. The BFF printed inside a Techshot-developed cell-culturing cassette that strengthens the assemblage of cells over time. The tissue-like structure is expected to be viable and self-supporting once it is back in Earth’s gravity.

More 3D bioprinting in space will take place in March following the delivery of additional bio-inks to the ISS National Laboratory aboard SpaceX mission CRS-20.

Following that round of test prints, Techshot expects to declare BFF open for business to industrial and institutional life science customers. Including the bioprinter, Techshot owns and operates five commercial research and manufacturing payloads aboard the ISS, reportedly the largest catalog of any American company operating inside the orbiting lab. A sixth payload, the Techshot Cell Factory, is under development. It will enable the company’s customers to continuously generate multiple cell types in space and not rely entirely on cargo resupply spacecraft transporting the cells.

Although the prospect of manufacturing human hearts and other organs via a 3D bioprinter in space is at least a decade away, Techshot is hopeful that the long-term success of the BFF could lead to a reduction in the shortage of donor organs.

Founded more than 30 years ago, Techshot operates its own commercial research payloads in space and serves as the manager of three NASA-owned ISS payloads. Test experiments, such as the one described in this article, aside, the company rarely conducts its own research. Its business model entails providing equipment on board the station for a fee to those with their own independent research programs, serving as a one-stop resource for organizations that want access to space.

Headquartered in Greenville, IN, and with an office at the Kennedy Space Center in Florida, Techshot is an official Implementation Partner for the ISS U.S. National Laboratory. It has agreements with NASA that provide the company and its customers with access to space cargo transfer services and assistance from the on-orbit crew.