Using Plants, Astronauts Could Grow Their Own Medicine in Deep Space
When astronauts venture beyond the familiar confines of Low Earth Orbit (LEO) to explore the Moon, Mars, and destinations even farther afield, the logistical realities of deep space will demand unprecedented levels of self-sufficiency. Unlike crews aboard the International Space Station (ISS), who can receive emergency resupply missions within hours, deep-space explorers will be cut off from Earth's resources for months or even years at a time. Every kilogram of cargo launched from Earth carries an enormous cost — both financial and operational — making it imperative that future missions find ways to produce or harvest what they need along the way.
This challenge falls broadly under the concept of In-Situ Resource Utilization (ISRU), a paradigm in which local materials and environmental conditions are leveraged to produce essentials such as breathable air, water, building materials, and propellant. But one critical resource has proven stubbornly difficult to replicate far from home: medicine. Now, a team of interdisciplinary engineers and scientists at the University of California San Diego (UCSD) believes they may have found an elegant biological solution — growing pharmaceuticals directly from plants cultivated aboard spacecraft.
The Challenge of Medicine in Deep Space
The human body was not designed for the rigors of interplanetary travel. Extended exposure to the microgravity environment of space causes well-documented physiological changes, including bone density loss, muscle atrophy, fluid shifts within the body, and significant alterations to the cardiovascular and immune systems. Compounding these challenges, astronauts in deep space are subjected to elevated levels of cosmic radiation and solar particle events, which can damage DNA and dramatically increase the risk of cancer and other diseases over time.
Perhaps most critically for mission planners, research conducted aboard the ISS has revealed an alarming phenomenon: pharmaceuticals degrade significantly faster in the space environment than they do on Earth. Studies have shown that more than half of all medications carried on long-duration missions may expire or lose their efficacy within three years — a timeline that is deeply problematic for a crewed Mars mission, where a single transit alone takes between six and nine months. By the time a Mars crew completes a round trip, the medications they launched with could be largely useless.
- Bone density loss of up to 1–2% per month has been recorded in astronauts on long-duration missions.
- Radiation exposure in deep space is estimated to be 100–1,000 times higher than on Earth's surface.
- More than 50% of medications carried on ISS missions have been found to degrade before their labeled expiration dates.
- The one-way transit time to Mars ranges from approximately 6 to 9 months depending on orbital alignment, making emergency resupply completely impractical.
- Current pharmaceutical manufacturing requires large, sterile industrial facilities that cannot feasibly be replicated on a spacecraft.
The solution, according to the UCSD research team, may be hiding in plain sight — or rather, in the soil of the plant growth chambers already being developed for future long-duration missions. Plants have long been recognized as invaluable life-support assets in space: they absorb carbon dioxide, generate oxygen, and provide a source of fresh nutrition. The UCSD team's new research demonstrates that these same plants could serve a far more sophisticated purpose, acting as living pharmaceutical factories capable of producing complex, potentially life-saving compounds on demand.
A Decade of Research Blossoms into a Spacefaring Solution
The research was led by Nicole Steinmetz, the Leo and Trude Szilard Chancellor's Endowed Chair at UCSD's Aiiso Yufeng Li Family Department of Chemical and Nano Engineering. For more than a decade, Steinmetz and her colleagues have been investigating the remarkable properties of a plant pathogen known as cowpea mosaic virus (CPMV). While CPMV is best known as an agricultural nuisance — infecting legumes such as black-eyed peas and causing significant crop damage — Steinmetz's team has been exploiting a far more constructive property of the virus: its extraordinary ability to stimulate the human immune system to attack cancer cells.
In a series of preclinical studies conducted in mice, and in clinical studies involving canine cancer patients, CPMV has demonstrated remarkable efficacy in combating solid tumors. The virus acts as a powerful immunostimulant when injected directly into tumor sites, effectively waking up the immune system and directing it to destroy cancer cells that it would otherwise overlook. This approach, known as in situ vaccination, has shown promise against a wide range of cancers including ovarian, colon, and breast cancer.
"With plants, you can grow complex therapeutic compounds using light, water and soil." — Nicole Steinmetz, Leo and Trude Szilard Chancellor's Endowed Chair, UC San Diego
The interdisciplinary team behind this breakthrough brought together expertise from across the UCSD research ecosystem, including the Center for Nano-ImmunoEngineering, the Shu and K.C. Chien and Peter Farrell Collaboratory, the Institute for Materials Discovery and Design, the Moores Cancer Center, and the Center for Engineering in Cancer at the Institute of Engineering in Medicine. Their combined findings were published on June 5th in the prestigious journal npj Science of Plants, a Nature Portfolio publication.
The Problem with Traditional Pharmaceutical Extraction
Growing CPMV in plants is, in principle, straightforward. Nicotiana benthamiana — a relative of the tobacco plant widely used in plant biology research — and black-eyed pea plants are both efficient producers of the virus, capable of generating substantial amounts of biological material in a short time. However, the traditional method of extracting CPMV from plant tissue presents an enormous logistical barrier to space-based production.
Patrick Opdensteinen, a postdoctoral researcher in Steinmetz's lab and the first author on the paper, described the challenge vividly:
"Growing the compound in these plants is simple. They can produce a whole lot of biomass in a short amount of time, and more biomass equals more product. The main difficulty now is figuring out how to get the product out of the plants. You end up with something that looks like a smoothie, and you can imagine getting your product out of that smoothie is challenging. The equipment that we use to do this fills our entire lab. You can't fit all that on a spacecraft."
The conventional extraction process involves harvesting plant leaves, grinding them into a slurry, and then subjecting the resulting mixture to a battery of separation and purification steps requiring large centrifuges, filtration systems, and sterile processing environments. This kind of industrial infrastructure is simply incompatible with the mass and volume constraints of a deep-space spacecraft. To make plant-based pharmaceutical production viable in space, an entirely new approach to extraction was needed.
Harnessing the Apoplast: A Elegant Solution
The UCSD team found their answer by turning to a technique borrowed from pharmaceutical manufacturing: product secretion. This approach, typically applied to bacterial or mammalian cell cultures, exploits the natural tendency of cells to export chemical products into surrounding spaces. The researchers adapted this concept for plant biology, focusing on a structure called the apoplast — a network of interconnected fluid-filled spaces located outside the plasma membrane within plant leaves.
The apoplastic extraction method developed by the team is elegantly simple and requires only a fraction of the equipment needed for traditional extraction. The process unfolds in four key steps:
- Infiltration: Intact plant leaves are submerged in a carefully prepared buffer solution containing the viral material to be expressed.
- Vacuum flooding: The leaves are placed in a sealed vessel and subjected to a vacuum, causing the air within the apoplastic spaces to be evacuated and replaced by the buffer fluid, effectively flooding the interior of the leaf.
- Centrifugal extraction: Once fully saturated, the leaves are transferred to vials and centrifuged at low speed. This gentle mechanical force draws the CPMV-rich liquid out of the apoplastic space without damaging the leaf tissue itself.
- Filtration and purification: The extracted fluid is passed through a specialized filter that separates the larger, therapeutically useful CPMV particles from smaller fragments of plant material and cellular debris.
Crucially, because the leaves remain structurally intact throughout this process, the plants can continue to grow and photosynthesize normally after extraction. This means the same plants can potentially be harvested multiple times over the course of a mission — a critical advantage when every biological resource aboard a spacecraft must be conserved and reused wherever possible. In a demonstration of the method's scalability, the team successfully harvested and purified CPMV particles from more than 50 plants in under two hours.
Simulating the Final Frontier in the Lab
Demonstrating that a technique works under terrestrial laboratory conditions is only the first step. For a method intended for use in deep space, researchers must also grapple with the profoundly alien physical environment that plants would encounter aboard a spacecraft. To address this challenge, the UCSD team collaborated with Professor Maziar Ghazinejad and his colleagues from the Department of Mechanical and Aerospace Engineering at UCSD, who specialize in studying how materials and biological systems behave under non-standard physical conditions.
Ghazinejad's team constructed a custom-built random positioning machine (RPM) — a sophisticated device that continuously rotates specimens along multiple axes, effectively averaging out the gravitational vector experienced by the plants and simulating the functional equivalent of microgravity. RPMs are established tools in space biology research, used extensively by agencies like the European Space Agency (ESA) to study how organisms respond to weightlessness without the expense of actual spaceflight. This was, however, a novel application of the technology for plant-based pharmaceutical research.
To make the simulation more comprehensive, the plants were also subjected to temperature fluctuations and oxidative stress intended to mimic the effects of space radiation on plant cellular processes. Oxidative stress, caused by an excess of reactive oxygen species (ROS) within cells, is a known consequence of ionizing radiation exposure and represents one of the primary mechanisms through which radiation damages living tissues.
The results of these simulations yielded a genuinely surprising finding: rather than inhibiting CPMV production, the simulated space stresses actually led to slight increases in viral yield in some of the tested plants. Opdensteinen offered an intriguing explanation for this counterintuitive outcome:
"Plants become more susceptible to disease when stressed, which is usually a disadvantage. But since our product is derived from a plant virus, we can use that stress response to increase yields."
This finding suggests that the physiological stress responses triggered by the space environment — responses that would normally be considered harmful to agricultural crops — may actually be leveraged as a production advantage in the context of pharmaceutical manufacturing. It represents a fascinating inversion of the usual relationship between plant health and viral infection, one with potentially significant implications for how space-based plant pharmaceutical systems are designed and optimized.
Broader Implications: From Mars to Underserved Communities on Earth
While the immediate application of this research is focused on supporting deep-space exploration — including NASA's Moon to Mars program and future long-duration crewed missions — the implications of the UCSD team's work extend far beyond the boundaries of space exploration. The researchers envision a parallel pathway in which their simplified, low-infrastructure pharmaceutical production method is deployed in resource-limited settings on Earth.
Traditional pharmaceutical manufacturing is extraordinarily capital-intensive, requiring large-scale sterile facilities, sophisticated cold-chain logistics, and substantial energy inputs. This makes the distribution of modern medicines deeply unequal: communities in economically disadvantaged regions, those affected by conflict or natural disaster, and populations increasingly disrupted by the accelerating effects of climate change often lack reliable access to the medications they need. A plant-based pharmaceutical production system requiring only light, water, soil, and modest processing equipment could represent a transformative democratization of medicine production.
The team is currently pursuing several important next steps to advance their research toward real-world application:
- Continuing to study how microgravity and space radiation affect fundamental plant physiological processes, including water and nutrient uptake, to ensure long-term plant health during multi-year missions.
- Collaborating with the Rocket Propulsion Laboratory at UCSD to investigate how plant seeds and the genetic materials involved in their process withstand the intense mechanical stresses of launch — including vibration, acoustic loads, and acceleration forces.
- Exploring whether the extraction and purification method can be extended to other plant-derived pharmaceuticals beyond CPMV, potentially creating a versatile platform for space-based medicine production.
- Working toward having their method tested on actual space missions, potentially aboard the ISS or future commercial space platforms, in the near future.
The research is also a compelling demonstration of the power of interdisciplinary science. By bringing together expertise in chemical engineering, nanotechnology, cancer immunology, mechanical engineering, and plant biology, the UCSD team has forged a solution that no single discipline could have achieved alone. It is precisely this kind of integrative thinking that will be required to meet the extraordinary challenges of sending humans to Mars and beyond.
A Living Pharmacy for the Stars
In the long arc of human spaceflight history, the image of astronauts tending to plant growth chambers has often been associated primarily with food production and psychological wellbeing. This new research fundamentally expands that vision. The humble plant — already a provider of nutrition, oxygen, and a psychological connection to Earth — may one day serve as a living, self-replenishing pharmacy capable of producing therapeutics against cancer, infection, and the host of other medical challenges that await crews on the journey to Mars and beyond.
For more information on the science of growing plants in space and the future of human deep-space exploration, readers can explore resources from NASA's Human Research Program and the UC San Diego Today newsroom. The original research paper is available in npj Science of Plants, published by the Nature Portfolio.
