Future astronauts heading to the Moon or Mars could eventually produce certain medicines using plants grown onboard their spacecraft or in planetary habitats. Researchers at the University of California San Diego have developed a method that allows pharmaceutical compounds to be harvested from living plants without destroying them.
Supplying astronauts with enough medication has long been a concern for mission planners. Deep-space voyages present challenges that do not exist in low Earth orbit, where cargo missions can regularly deliver fresh supplies. On journeys lasting months or years, every resource must be carefully managed.
Plants are already expected to play an important role in future exploration efforts. They can help recycle carbon dioxide, produce oxygen, and supplement food supplies. A new study suggests they could also serve as compact pharmaceutical factories, producing therapeutic compounds with relatively few resources.
A Plant Virus With Medical Promise
The research, published in npj Science of Plants, focused on the cowpea mosaic virus (CPMV), a virus that naturally infects legumes. While it is known as a plant pathogen, scientists at UC San Diego have spent more than a decade studying a different aspect of CPMV: its potential use in cancer treatment.
The team reports that CPMV can stimulate the immune system to attack cancer cells. Previous preclinical studies in mice and clinical studies involving canine cancer patients have shown encouraging results against tumors.
To produce the virus, researchers used Nicotiana benthamiana and black-eyed pea plants. These species can generate large amounts of biomass in a short period, making them attractive candidates for pharmaceutical production.
Growing CPMV inside the plants was relatively straightforward. Extracting it, though, posed a much bigger challenge. Conventional methods require leaves to be harvested and ground into a plant slurry before the desired compound can be isolated.
“You end up with something that looks like a smoothie, and you can imagine getting your product out of that smoothie is challenging,” said Patrick Opdensteinen, a postdoctoral researcher at UC San Diego and the study’s first author, in a statement released by the university.
He added that the equipment normally used for the process fills an entire laboratory and would not be practical aboard a spacecraft.
A Gentler Way To Harvest Plant Compounds
Researchers simplified production by using product secretion, a pharmaceutical technique commonly used with bacterial and mammalian cells to collect products released into cellular compartments. They targeted the plant’s apoplast, a network of interconnected spaces outside the plasma membrane.
The process involves submerging leaves in a buffer solution and applying vacuum to fill the apoplast with fluid. The leaves are then moved to vials and centrifuged at low speed to extract a liquid rich in CPMV particles. Filtration removes plant debris while retaining the larger virus particles.
A key advantage is that the leaves remain intact, allowing the plants to keep growing and be harvested again instead of being discarded. The researchers showed scalability by harvesting and purifying CPMV particles from more than 50 plants in under two hours, demonstrating the method’s ability to process many plants quickly.
Testing In Space-like Conditions
The team also wanted to know how the system would perform in an environment resembling space. Working withProfessor Maziar Ghazinejad and colleagues from UC San Diego’s Department of Mechanical and Aerospace Engineering, the researchers used a custom-built random positioning machine. The device continuously rotated the plants to effectively simulate microgravity conditions.
“Plants become more susceptible to disease when stressed, which is usually a disadvantage,” Opdensteinen said. “But since our product is derived from a plant virus, we can use that stress response to increase yields.”
The study addresses a concern highlighted by previous work conducted aboard theInternational Space Station. Researchers note that many medications degrade more rapidly in space, with more than half expiring within three years. For missions to Mars, where a one-way trip can take between six and nine months, maintaining a reliable supply of effective drugs remains a significant challenge.
“With plants, you can grow complex therapeutic compounds using light, water and soil,” said Nicole Steinmetz, the Leo and Trude Szilard Chancellor’s Endowed Chair at UC San Diego’s Aiiso Yufeng Li Family Department of Chemical and Nano Engineering.
The research team is continuing to study how space conditions influence plant growth and pharmaceutical production as they work toward future testing in spaceflight environments.
