Four astronauts ended a six-month science expedition onboard the International Space Station (ISS) with the successful splashdown of the SpaceX Dragon Endeavour spacecraft off the coast of Florida early Monday morning. During their time in space, the crew members worked on dozens of research investigations and technology demonstration projects that were sponsored by the ISS National Laboratory. These included the use of Redwire‘s BioFabrication Facility to print a live human meniscus (knee cartilage). The tissue sample returned with the crew, and its properties will now be further analyzed on Earth.
The return of the Dragon spacecraft marked the conclusion of SpaceX’s 6th rotational crewed mission to the orbiting laboratory under NASA’s Commercial Crew Program. As part of Expedition 69, NASA astronauts Stephen Bowen (spacecraft commander) and Warren “Woody” Hoburg (pilot), along with United Arab Emirates astronaut Sultan Alneyadi (mission specialist) and Roscosmos cosmonaut Andrey Fedyaev (mission specialist), spent six months in space, conducting critical research for scientists on the ground.
During this time, the ISS National Lab-sponsored projects covered a wide range of disciplines—from life and physical sciences to advanced materials, technology development, in-space production applications, and even student-led research. Results from these studies will bring value to humanity, further our ability to explore, and enable a robust market in low Earth orbit.
Launching a new BFF
The upgraded BFF launched last November to the ISS on Northrop Grumman’s 18th Commercial Resupply Services (NG-18) mission. The installation of the new machine was completed in March of this year. The project, sponsored by the ISS National Laboratory, paved the way for in-space bioprinting of tissues—and possibly even organs in the future—that could one day help patients back on Earth. The materials needed to make prints using the BFF followed on a subsequent flight, and the human meniscus, a protective piece of cartilage between the bones in the knee, is the first tissue the bioprinter produced.
The BFF-Meniscus-2 investigation is a collaboration between Redwire and the Uniformed Services University of the Health Sciences Center for Biotechnology (4DBio3), a biomedical research center that explores and adapts promising biotechnologies for warfighter benefit. Meniscal injuries are one of the leading orthopedic injuries for U.S. military service members.
Long-term success of the BFF could lead to valuable medical breakthroughs for patients on Earth, said Rich Boling, a Redwire vice president. Printed tissues could not only be implanted in patients but also used as models for drug discovery, providing new avenues to test therapeutics. “Using the BFF, we can create true tissue-like structures in a better way and larger than you can terrestrially,” Boling said. “We can also use the BFF to print organoids, which could be used to test drug efficacy and reduce the need for laboratory animals.”
Exploring bioprinting in space
Using a combination of adult human cells and proteins to create human tissues, the BFF dispenses bioinks through four print heads, much like the methods for 3D printing with plastics here on Earth. The BFF was first launched to the ISS in 2019, and this upgraded version offers better temperature control to keep the bioinks at the ideal consistency for optimal printing. It also provides new camera views so that ground controllers can better control the prints.
Researchers on Earth have had some success in printing rigid human tissues like bone and cartilage, but soft tissues and blood vessels have proven to be much more difficult to print terrestrially. That’s due to a combination of Earth’s gravity and the low viscosity of the bioinks used, which require scaffolding for the printed tissues to hold their shape. However, in the absence of gravity, scaffolding is no longer needed for printed structures to keep their correct shape, and the prints can be cured into tissues that could one day be implanted into patients on Earth.
Redwire says the secret ingredient to their success is the BFF’s counterpart: the Advanced Space Experiment Processor (or ADSEP). This adjoining processing facility on the ISS is responsible for culturing and conditioning the cells once they are printed inside the BFF.
“The strengthening, or curing, process is what allows us to create these nice 3D structures that hold their shape,” said Molly Mulligan, Redwire’s business development director for in-space manufacturing and operations. “If you just brought back the print, it would collapse under Earth’s gravity, but once it’s cured, we can return it to Earth with no issue.”
Mulligan says that tissues are allowed to strengthen in the ADSEP for several weeks, enabling researchers to return solid tissue either alive or preserved for future analysis. “With this system, we can show that we can not only print but also culture these tissues, and that’s a real breakthrough.”
The BFF/ADSEP system also enables chemical and mechanical stimulation and potentially even vascularization of the tissues printed. The printed tissues can then be used to create models for drug discovery and to test novel therapies. Printed tissues could even eventually help address the organ shortage, which is the end goal for Boling and Redwire. “If we can speed up that process, or if this work discovers something to be able to mass produce organs, that would be ideal,” he said.