Zero Gravity, Big Impact: Ken Savin Talks Redwire’s Space Bioprinting Breakthroughs

In space, microgravity isn’t just a challenge—it’s an advantage. Redwire, known for pioneering space-based biomanufacturing, made history by sending the first bioprinter to the International Space Station (ISS) in 2019. They have recently taken it a step further by successfully bioprinting a human meniscus in orbit. This breakthrough opens new possibilities for regenerative medicine, with space offering the perfect conditions for building complex tissues that are difficult to create on Earth. In an exclusive interview with 3DPrint.com, Redwire’s Chief Scientist Ken Savin explained that this achievement is far from science fiction but represents a real turning point in how we could heal the human body in the future.

In July 2023, Redwire took a significant leap in space-based bioprinting by successfully creating a human knee meniscus aboard the ISS. This achievement, part of the BFF-Meniscus-2 investigation, used the company’s upgraded bioprinter, the BioFabrication Facility (BFF), which returned to the ISS in 2022. The meniscus—a key piece of cartilage that cushions the knee joint—was printed using live human cells and then cultured for two weeks in Redwire’s Advanced Space Experiment Processor (ADSEP). This process allowed the tissue to mature and solidify in microgravity, bypassing the challenges of bioprinting on Earth, where gravity would cause the delicate structures to collapse. The meniscus was returned to Earth aboard the Crew-6 mission in September 2023, marking a major advance in space bioprinting.

One of the most fascinating aspects of Redwire’s bioprinting work is how microgravity changes how cells behave during printing. On Earth, gravity pulls on the printed tissue, causing cells to flatten and lose their natural shape.

“You see cells pressed flat in a Petri dish on Earth,” Savin explained. “But in space, they remain spherical, maintaining their three-dimensional structure. This allows for creating more realistic tissue structures that better mimic the complexity of human organs.”

However, creating tissue isn’t just about shape but also survival. On Earth, larger tissue structures require a vascular system to deliver nutrients and oxygen to the cells at the core. Without this, those cells die from lack of nutrients.

“If you make a tissue that’s a half-inch square, the cells in the middle aren’t getting a flow of nutrients and oxygen,” Savin noted.

In space, Redwire is working on overcoming this challenge by developing ways to perfuse cells—ensuring that the inner cells in a larger tissue structure receive the nutrients they need to stay viable. Savin explained that building this vasculature is one of the next major hurdles in the path toward fully functional, complex tissues. Redwire is already working on this challenge, with plans to print vasculature in the near future.

In addition, Savin said, “We’re not just doing science; we’re developing hardware in an environment that’s foreign to us. The absence of gravity complicates even the simplest tasks, like depositing material onto a surface. On Earth, a droplet just falls. In space, it sticks to the dropper and rolls up the side.”

This required the team to innovate new methods for handling materials in space, a challenge they continue to tackle with each mission. Bioinks play a critical role in this process. Savin explained that the development of bioinks is closely tied to how they are laid out in space.

“The bioinks are crucial to how the cells establish themselves once printed. The properties of these inks determine what type of cells you can use, how long the cells will survive, how they connect, and how effectively they form functional tissues once they have been printed,” Savin noted. For Redwire, perfecting these bioinks is an ongoing focus, as they are a key element to making more complex tissue engineering in microgravity.​

The Promise of Space-Based Bioprinting

While not Redwire’s first foray into bioprinting, the meniscus printing project was a milestone. This tissue, which plays a crucial role in knee function, was selected due to the high rate of meniscus injuries. Savin pointed out that there is no real way to repair a torn meniscus, so this project allowed Redwire to demonstrate its ability to print functional tissues that retain dimensionality in space, a feat much harder to achieve on Earth due to gravity’s impact on soft materials.

Redwire’s bioprinting efforts have already led to impressive results, but the potential applications of this technology stretch far beyond knee repairs: “We’re also looking at cardiovascular tissue, perhaps not to replace a heart, but to create heart patches. This is particularly exciting because of the ability to use stem cells derived from the patient, eliminating the need for anti-rejection drugs. The tissue would be genetically identical to the recipient,” Savin explained that this is a significant advantage over traditional transplantation.

In April 2024, Redwire successfully bioprinted live human heart tissue aboard the ISS. Redwire created the tissue using the BFF, which was later returned to Earth for further testing. The experiment aims to develop heart patches that could potentially treat damaged heart tissue, offering a pathway to more effective, personalized medical treatments without the risk of tissue rejection.

However, this potential doesn’t come without its logistical challenges. “Right now, what holds us back isn’t the number of printers; it’s access,” Savin said, referring to the need to send materials to and from space. Despite these obstacles, he remains optimistic about future advancements: “As our technology gets better, the logistics will become a smaller issue.”

Making these tissues is a well-coordinated process that takes about 30 to 45 days from when the materials are sent to space until the samples return to Earth. While astronauts help set up and manage the experiments in space, the printing is controlled by Redwire on the ground.

“The printing happens pretty quickly, in a day, but once the tissue is printed, it’s very liquidy, and the only reason it doesn’t fall apart is because of the microgravity. So it needs to be kept in an incubator for a few weeks to allow the cells to develop and strengthen before it’s ready to be returned to Earth for testing.”

Looking Ahead: Long-Term Impact of Bioprinting in Space

As exciting as the current achievements are, the long-term potential of bioprinting in space is even more profound. Savin is candid about the timeline: “We’re a ways off from printing fully functional organs. Primarily, scientific and technological breakthroughs are still required, not only by Redwire but also by the entire bioprinting field. Even on Earth, we’re facing challenges with vasculature. Also, if we did come up with something and it worked and it looked really good, there’s still an ethical process by which you have to test it, which involves in vitro, animal, and clinical trials on the ground, so we’re a long way from that.”

Savin says nearer-term applications of Redwire’s work could be quite impactful, such as using bioprinted tissues for pharmaceutical testing. “Imagine creating small clumps of human cells the size of a pin head that is very lifelike, which pharmaceutical companies could use to test drugs,” he suggested. “This could potentially replace animal testing, offering a more ethical and accurate model for human biology. It’s not as striking as replacing someone’s meniscus, but it could have a huge impact.”

In addition to pharmaceutical testing, Redwire is also working on new systems to improve biological research in space and on Earth. Savin mentioned that they are collaborating with biologists to create tools that make biological experiments easier and more automated. What they learn from these studies in space is helping to design better systems for labs on Earth. In the long run, this research could change how biology is done by allowing more automation, with important benefits for both space and Earth-based science.

Beyond that, Savin sees AI as a critical tool for the future, enabling real-time guidance for astronauts conducting experiments in space. AI could act as a “data interpreter” and a “team member,” helping scientists make quick and efficient decisions. The expert said this could open the door to even more complex experiments in space, with AI handling some of the most intricate aspects of bioprinting.

None of this would be possible without collaboration. “We rely heavily on partnerships with the best minds in the business,” Savin said, emphasizing that Redwire’s role is to provide the hardware and platform for experiments in space. Redwire’s expertise in microgravity environments, combined with the knowledge of their academic and industry partners, has been key to their success.

None of this would be possible without collaboration. The company relies heavily on partnerships with the best minds in the business, highlighted Savin, pointing out that Redwire’s role is to provide the hardware and platform for experiments in space. Many of its partners remain unnamed, but some significant collaborations include pharmaceutical giants. Savin spent 20 years at Eli Lilly and Company, where he began as a senior organic chemist in 1998. During his time there, he worked across various therapeutic areas, from anxiety and depression to inflammatory disorders. He later took on leadership roles, guiding drug disposition and clinical innovation efforts.

“We’ve done a number of efforts with Eli Lilly,” Savin added, pointing to his alma mater as one of the pharmaceutical partners Redwire is working with on space-based research.

Redwire’s work in bioprinting is helping move space-based medical research forward. Challenges are still ahead, but its progress shows the huge potential of working in microgravity. Savin concludes that with each mission, they are getting closer to new possibilities, from repairing damaged tissue to exploring the future of organ replacement. As space biomanufacturing continues to grow, Redwire is a leading force in the new space industry, helping make these breakthroughs possible.