There’s a good reason why astronauts tend not to stay on the International Space Station longer than six months: Microgravity is not kind to human bodies. Among other effects, it can flatten eyeballs and swell up fingers and faces, causing blinding headaches as blood, organs and cells react in ways they wouldn’t on Earth.
For the same reasons, though, space may be the perfect place to study cancer — and someday even treat it.
This year, tumors grown in laboratories on Earth are headed to the ISS as part of the first research project to use artificial organs for cancer testing in space. Scientists at Wake Forest University are working to develop cancer-screening tests that are faster and more sensitive. But the greater significance of their experiment may be as a trial run for a raft of other biomedical projects planned for low-gravity environments that spur cell growth.
“Microgravity is an accelerator of conditions. Every disease, every phenotype — everything we want to study can happen faster in less time,” says Davide Marotta, program director for In-Space Biomanufacturing at the ISS National Laboratory. “Instead of waiting 10 months, you can go up [to space] in 10 days” to see the same biological effects, he adds.
On Earth, gravity slows the development of cancer because cells normally need to be attached to a surface in order to function and grow. But in space, cancer cell clusters can expand in all directions as bubbles, like budding yeast or grapes, said Shay Soker, chief science program officer at Wake Forest’s Institute for Regenerative Medicine.
Since bubbles grow larger and more quickly in space, researchers can more easily test substances clinging to the edge of the larger bubbles, too. Scientists at the University of Notre Dame are taking advantage of this quirk to develop an in-space cancer test that needs just a single drop of blood. The work builds on a series of bubble-formation experiments that have already been conducted on the ISS.
“If cancer screening using our bubble technology in space is democratized and made inexpensive, many more cancers can be screened, and everyone can benefit,” said Tengfei Luo, a Notre Dame researcher who pioneered the technology, speaking to the ISS’ magazine, Upward. “It’s something we may be able to integrate into annual exams. It sounds far-fetched, but it’s achievable.”
Protecting astronauts from the health risks of space travel is another key priority for biomedical researchers working with NASA. On the ISS and other space missions, astronauts not only have to deal with all of the physiological changes blockociated with microgravity, but also the dangers of cosmic radiation, which can mutate DNA in human cells.
Astronaut Frank Rubio holds the NASA record for the longest continuous time spent in space at 371 days, with Russian cosmonaut Valeri Polyakov holding the overall record with 437 consecutive days — a venture he volunteered for to prove humans could survive the time it would take to travel to and from Mars. But NASA’s general rule is that astronauts should try to minimize their time in orbit to reduce health risks.
“For astronauts returning to Earth, they have difficulty just moving around,” said Ben Soares, who studies space medicine at Boston University. “Even sitting in a chair involves muscles. Everything just falls apart when you don’t use it.”
A study of astronaut twins Scott and Mark Kelly found that Scott aged faster than his brother, who remained on Earth while Scott was in space. Microgravity also altered Scott’s genetics, switching certain genes on or off.
Cancer risks are likely higher for astronauts, too, and not only because radiation can cause mutations in DNA. Cell membranes are held up by small proteins called microtubules that keep the cell’s shape rigid, but when the gravitational force changes — even though gravity on the ISS is only 10% weaker than on Earth — the cell’s structure changes with it.
On Earth, microtubule spindles ensure that a cell’s chromosome replicates the structure. But microgravity distorts microtubules and can lead to irregular cell division, making cancer more likely.
“You may think [astronauts] are just floating around in space, but all those microtubules, and the major deformations in the outer membranes, change rapidly when there’s microgravity exposure,” said Soares. “People are wondering more and more whether changes are happening at an actual genetic level.”
Again, though, these genetic effects also create unique opportunities for researchers seeking new diagnostic tests and treatments. For example, if scientists can pinpoint which genes are switched off in microgravity, then they might be able to activate them or deactivate them artificially for cancer patients on Earth.
Pharmaceutical research could benefit, too. In orbit, drug companies could drastically speed up a review and testing process that usually takes many years before the Food and Drug Administration approves the treatment. As the cost of in-orbit testing falls, it could become a key way to quickly evaluate all sorts of medications without having to spend years waiting to see if they work on diverse populations, according to the ISS National Laboratory’s Marotta.
“Every person has a different response to the same drug,” Marotta said. “We have drug resistance, failure of therapies, etc. Meanwhile, space costs will be lower and lower in the future.”
Chemotherapy patients could save precious time, too. In normal gravity, they typically have to spend a half-hour hooked up to a needle before the medicine begins to take effect, because most drugs don’t dissolve easily in water. But scientists at Merck have discovered that, in space, their widely used cancer drug pembrolizumab, or Keytruda, can be administered through a simple injection, because large crystalline molecules that would normally clump together are suspended in microgravity.
So far, though, Merck hasn’t been able to find a way to administer its drug via injection on Earth. Similarly, the blood test developed by Notre Dame researchers only works in space, with no ability yet to simulate low gravity effectively here on Earth.
These limitations raise the question of whether patients might someday be treated in space to take advantage of lower gravity. It’s not a completely far-fetched idea, according to Soker, though he acknowledged that it is prohibitively expensive for now. The ISS currently houses just seven astronauts, and SpaceX apparently charges space tourists approximately $55 million for a three- to eight-day trip into low Earth orbit. The hope is that those costs will come down drastically in the future.
The next big step, according to Soker, would be an orbiting facility dedicated to researching treatments for cancer and other debilitating conditions. “Maybe we can actually figure out which patients are the ones who are going to benefit from the space environment,” he says. “If you’re going to put several million dollars [into cancer treatment], I mean, you need to actually be sure that this is going to be helpful for you.”
Someday, microgravity could even help patients recovering from surgery heal faster than they would on Earth, Soker added. “Wound healing in high pressure is faster. That’s the hyperbaric treatment for wounds.”
Before they can dream of a new generation of orbiting laboratories, though, researchers are under pressure to make the most of the one they have now — but won’t be able to use for much longer. The ISS is set for destruction in 2031, after more than three decades in orbit, giving scientists only a handful of additional years to conduct their tests in the hopes of medical breakthroughs. “It’s run its course,” says Soker.
The key task now, he said, is for teams like his to deliver practical research results that could unlock funding for the next phase of biomedical research in space. Researchers are already benefiting from a recent increase in support thanks to the U.S. government’s Cancer Moonshot Initiative, which funnels research dollars into techniques to help Earth-bound patients as well as astronauts.
For the Wake Forest experiment, which is scheduled to launch next spring, scientists will cut out two sections of a cancer tumor from around 20 patients. One sample will stay on Earth while the other heads to the ISS, with scientists observing the difference. The testing will be completed within a week, to avoid any interference from cosmic radiation.
If successful, Soker said, it could set the stage for diagnostic cancer tests in space available to the general population — perhaps on a biomedical space station that could launch after the planned demise of the ISS.
“Can we actually design a special cancer space station that will be dedicated to cancer and maybe other diseases?” Shoker asked, answering his question in the affirmative. “Pharmaceutical companies that have deep pockets would certainly support that program.”
