What Happens 250 Miles Up Could Change How Millions of Americans Heal

A biomedical engineer sent cartilage to the International Space Station to solve a problem that isn't rare: osteoarthritis, which affects 33 million Americans. 

Cartilage doesn't heal itself. Once it's damaged, whether as a tear in a knee, a worn hip or a nose crushed by trauma, the body has no way to grow more of it, and the injury typically gets worse from there, not better.  

That single fact drives osteoarthritis, which the CDC estimates affects 33 million American adults. It also shows up in combat medicine. In a six-year review of U.S. service members injured in Iraq and Afghanistan, 26% of battlefield-injured personnel had at least one craniomaxillofacial injury. Explosive devices were the primary mechanism, and the injuries commonly involved penetrating soft-tissue wounds and facial fractures. In total, one in four Americans suffer from cartilage afflictions. 

Wendy Brown, Ph.D., M.RSc., an associate research and translation specialist in the biomedical engineering department at UC Irvine, has spent her career trying to grow cartilage in the lab that's good enough to fix that. Real tissue, not a synthetic stand-in, that could someday be implanted into a damaged joint or a reconstructed nose and hold up like the original. A few years ago, part of that research took an unusual turn: some of it is happening on the International Space Station. 

The space station part has made headlines on its own. What's easy to miss underneath it is the actual question Brown is trying to answer and how many years of work it took just to get to the point of asking it. 

A Different Kind of Lab 

"The goal of cartilage tissue engineering in general is to create lab-grown cartilage that is as close to healthy, native cartilage as possible," Brown said.  

Her lab uses what she calls a developmentally inspired approach: it takes a small number of cartilage-forming cells and grows over 250,000 times more of them to supply enough cells to form cartilage that is highly similar to native tissue. The approach works. Brown's team can grow cartilage that's large and mechanically strong. But she says one variable has been impossible to remove in a normal lab: "the constant presence of gravity."  

Cartilage begins to form in the fetus at a time when it's essentially weightless in the womb, she said, and in the lab, gravity is always present. Getting rid of it, at least temporarily, meant leaving Earth. 

The Problem That Doesn't Heal Itself 

A lot of people know osteoarthritis firsthand, whether it's their own joint pain or a family member who eventually needed a hip or knee replacement. Globally, a 2023 Global Burden of Disease analysis put the number even higher, estimating that 15% of adults over 30 worldwide live with it. 

Brown's lab also works on nasal cartilage. A smaller-scale need, but an enormous one for the people who face it, including reconstructive surgery after skin cancer, burns, or trauma.  

Nasal and midface fractures, many caused by blasts, were the single most common injury among that combat trauma, which is part of why military personnel make up such a large share of the people who eventually need this kind of reconstruction.  

Without functional nasal cartilage, patients can develop chronic infections, sleep apnea and reduced cognition, on top of not being able to breathe properly. 

For nasal reconstruction, Brown's team engineers cartilage using cells from a patient's rib rather than their nose, since the nose is often too damaged or too small to spare additional tissue, while rib cartilage is abundant. Native rib cartilage grafts also tend to warp once implanted. Brown's engineered version, grown from those same cells, does not. 

Sending Cartilage to Orbit 

Brown had been interested in space long before it became part of her research. "I started looking into the impact of microgravity on native cartilage development, cartilage pathology in general," she said, and realized the station's microgravity environment could get her closer to replicating natural cartilage development than anything she could build on Earth. 

It's a different bet than most microgravity research. "A lot of the research that is done on the space station in microgravity has to do with disease progression, because a lot of body systems need gravity and they behave differently without it," Brown said. "But for us, with native cartilage development, the lack of gravity, we believe, is actually going to be advantageous." 

Getting there took years of preparation. Some of Brown's studies used frozen materials, shipped ahead of time to Kennedy Space Center. Others used live cartilage tissues that Brown and her team carried through airport security themselves, onto the plane, to a lab at Kennedy Space Center, where they packaged them into spaceflight hardware. "It was a nerve-wracking experience," she said. Then they watched it launch. 

Brown doesn't run the experiments herself once they're on the station. The astronauts do. Working with BioServe Space Technologies and NASA, her team developed the protocols and details in painstaking detail for the crew, down to which syringe goes in which port and how many milliliters to inject. One astronaut assigned to her studies had prior research experience in basic science and cell culture, which Brown said made a real difference: she was able to narrate what she was observing in real time, hold samples up to the camera, and problem-solve. 

"Everything was new and surprising for us because things behave so differently in microgravity," Brown said. Tasks that are trivial in an Earth-based lab, like mixing a solution and pipetting a small volume, turn out to be difficult without gravity to help liquids settle and separate from air.  

Bubbles, in particular, are hard to avoid and to remove. It was difficult to predict how the novel reagents they sent to the space station would behave in advance, Brown said; her team has had to rely on the astronauts' hands-on troubleshooting to understand what was happening and fix it in real time. 

Why She Does This 

Brown says she has always been drawn to understanding how the body works, but studying it was never enough on its own.  

"I wanted to create something that would help people," she said. Something she hopes will be her contribution to the field. What drew her specifically to biomedical engineering, she said, is that it's inherently interdisciplinary: biology, medicine, mechanical, chemical, and electrical engineering, and regulatory science, meaning how the FDA will eventually evaluate a given product, all have to work together. 

That kind of collaboration, sustained over years, is how Brown believes the field's biggest advances happen. Not in a single breakthrough, but through stepwise progress that translates basic science into engineering solutions. 

She points to two signs that tissue engineering specifically is gaining ground: the leading FDA-approved product for repairing knee cartilage today, called MACI, is itself grown from a patient's own cells in the lab, and in 2016, the 21st Century Cures Act created a new FDA designation, Regenerative Medicine Advanced Therapy, specifically to help advance cell, tissue, and gene therapy products toward patients. 

The World She's Working Toward 

When asked what success would look like, Brown didn't describe a lab result. She described a person.  

"My ultimate dream would be to create a tissue-engineered cartilage implant that behaves like healthy, normal cartilage that we can implant into a patient with an injury and heal their injury before it gets worse," she said, "so that they can continue on playing soccer, or skiing, or playing with their kids." 

She's candid that the field has further to go before that's routine. But she also grew up watching science fiction, and she doesn't think the bigger dream — fabricating whole functional organs in a lab to cure disease — is out of reach forever. "We're not there yet," she said, "but we're definitely moving in that direction." 

What she wants policymakers who've never heard of biomedical engineering to understand is that none of this happens quickly, and none of it happens alone. The advances that eventually reach patients, she said, are the result of "sometimes decades" of sustained, interdisciplinary research and of training the next generation of engineers and scientists to keep carrying it forward. 

That's the throughline of Brown's work, from the lab bench to the space station: a space experiment can sound small and strange right up until it's the reason a parent's knee, or a soldier's nose, works again. Multiply that by the 25% of Americans with cartilage afflictions, and the case for treating biomedical engineering research as worth sustaining — not funding in fits and starts — stops being abstract.