Inside the Destiny laboratory module aboard the International Space Station, NASA flight engineer Zena Cardman recently peered through a microscope at clusters of stem cells drifting in microgravity. Hundreds of miles below, patients with leukemia and blood disorders wait for therapies that those cells might one day help deliver. Cardman’s work is part of Expedition 74, a mission that as of late April 2026 is running two biomedical experiments with potential to change how doctors treat cancer, blood diseases, and radiation injuries, both in orbit and on the ground.
Growing stem cells where gravity can’t interfere
The experiment Cardman supports is called StemCellEx-IP1, and its premise is straightforward: microgravity may allow stem cells to multiply faster and more uniformly than they do in Earth-based labs. The cells in question are induced pluripotent stem cells, or iPSCs, created by reprogramming ordinary skin or blood cells into a flexible state. Once reprogrammed, iPSCs can be guided to become nearly any cell type in the body: heart muscle, neurons, insulin-producing pancreatic cells, or the blood-forming stem cells critical to bone marrow transplants.
On Earth, growing iPSCs at clinical scale is expensive and slow. Cells settle under gravity, clump unevenly, and require constant mechanical agitation to stay suspended in culture. In microgravity, those physical constraints largely disappear. NASA has described the goal of StemCellEx-IP1 as demonstrating “successful production of superior stem cells in space,” though the agency has not yet released quantitative yield data from the current round of orbital work.
The investigation builds on a precursor called StemCellEx-H Pathfinder, which focused on hematopoietic stem cells, the blood and immune progenitors used in transplants for leukemia, lymphoma, and sickle cell disease. Earlier ISS research suggested that hematopoietic cells cultured in microgravity could be produced in greater numbers than ground-based methods allow. If StemCellEx-IP1 confirms and extends those findings with iPSCs, the clinical implications would reach well beyond blood cancers into organ repair and degenerative disease.
Cardman and her Expedition 74 crewmates have been running the stem cell observations alongside balance and vestibular studies that track how the human body adapts to weightlessness. That pairing is deliberate: NASA wants to understand the physiological toll of spaceflight and develop biological tools to counter it at the same time.
DNA nanotherapy moves into active sample processing
A second experiment advanced this week when NASA’s Chris Williams and European Space Agency astronaut Sophie Adenot processed genetic-material samples for DNA Nano Therapeutics-3 inside Japan’s Kibo laboratory module. The investigation uses DNA-inspired assembly techniques to build nano-scale therapeutic agents, structures so small they can enter individual cells and deliver targeted treatments. Potential applications include cholesterol-lowering drugs and agents designed to repair radiation-induced DNA damage.
Radiation is one of the most persistent hazards facing crews on long-duration missions. Beyond the protective cocoon of Earth’s magnetic field, astronauts absorb elevated doses of galactic cosmic rays and solar particle radiation, raising their lifetime risk of cancer, cardiovascular disease, and central nervous system damage. Current countermeasures rely heavily on shielding and mission-duration limits. A therapy that could repair DNA damage at the molecular level after exposure would represent a fundamentally different approach, one that treats the injury rather than simply trying to prevent it.
If DNA nanotherapies can be reliably assembled in orbit, they could eventually function as an on-demand medical countermeasure, reducing the need to carry large pharmaceutical inventories on missions to the Moon or Mars. NASA’s Biological and Physical Sciences Division frames the work as part of its broader cell and molecular biology program, connecting station research to longer-term goals in regenerative medicine. Findings from the program also feed back into Earth-based clinical research, creating a two-way pipeline between orbital science and hospital care.
What the experiments have not yet proven
Neither StemCellEx-IP1 nor DNA Nano Therapeutics-3 has published outcome data from the current Expedition 74 work. That is typical for active station experiments: biological samples often return to Earth aboard SpaceX Dragon capsules for months of post-flight analysis before results reach peer-reviewed journals. The claim that microgravity produces “superior” stem cells rests on pre-mission projections and earlier pathfinder results, not finalized findings from this mission. Similarly, the DNA nanotherapy experiment’s potential for cancer treatment and radiation repair remains a research objective, not a demonstrated outcome.
There are also open questions about the path from orbit to clinic. Even if iPSCs grow more efficiently in microgravity, manufacturing them at scale for patients on Earth would require either frequent cargo returns from the station or the development of automated orbital bioreactors, neither of which exists as a commercial service today. For DNA nanotherapies, affordability and regulatory approval outside a space station laboratory are hurdles that current NASA communications do not address.
Why the research matters now
NASA is preparing for Artemis missions that will send crews to the lunar surface and, eventually, toward Mars. Those missions will expose astronauts to radiation levels and isolation durations that dwarf anything experienced on the ISS. Having biological countermeasures, whether stem cell therapies that can regenerate damaged tissue or nanotherapies that can patch broken DNA, could determine whether deep-space missions are medically sustainable.
Back on Earth, the same science has a parallel audience. More than 180,000 Americans are diagnosed with blood cancers each year, according to the Leukemia & Lymphoma Society, and bone marrow transplant waitlists remain long. If orbital stem cell production proves superior and scalable, it could shorten those waits. If DNA nanotherapies work as designed, oncologists could gain a new class of precision tools.
For now, the strongest evidence is operational: NASA’s station logs confirm that Cardman, Williams, and Adenot are actively conducting the experiments, processing samples, and collecting observations aboard the ISS. The medical breakthroughs those samples might yield are still months or years from confirmation. But the work is under way, and the questions it aims to answer, about how cells behave without gravity and whether nano-scale therapies can be built in orbit, sit at the intersection of space exploration and medicine in ways that could benefit both.
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*This article was researched with the help of AI, with human editors creating the final content.
