Plants as mRNA factories for edible vaccines

30 September 2021


University of California-Riverside (UCR) researchers say they are studying whether they can turn edible plants like lettuce into mRNA vaccines factories.

One of the challenges with this new technology is that it must be kept cold to maintain stability during transport and storage. If this new project is successful, plant-based mRNA vaccines, which can be eaten, could overcome this challenge with the ability to be stored at room temperature.

The project’s goals, made possible by a $500,000 grant from the National Science Foundation, are threefold: showing that DNA containing the mRNA vaccines can be successfully delivered into the part of plant cells where it will replicate, demonstrating the plants can produce enough mRNA to rival a traditional shot, and finally, determining the right dosage.

“Ideally, a single plant would produce enough mRNA to vaccinate a single person,” said Juan Pablo Giraldo, PhD, an associate professor in UCR’s department of botany and plant sciences. He is leading the research, done in collaboration with scientists from UC San Diego and Carnegie Mellon University.

“We are testing this approach with spinach and lettuce and have long-term goals of people growing it in their own gardens,” Giraldo explained. “Farmers could also eventually grow entire fields of it.”

Key to making this work are chloroplasts. “They’re tiny, solar-powered factories that produce sugar and other molecules which allow the plant to grow,” he continued. “They’re also an untapped source for making desirable molecules.”

In the past, Giraldo has shown that it is possible for chloroplasts to express genes that aren’t naturally part of the plant. He and his colleagues did this by sending foreign genetic material into plant cells inside a protective casing. Determining the optimal properties of these casings for delivery into plant cells is a specialty of Giraldo’s laboratory.

For this project Giraldo teamed up with Nicole Steinmetz, PhD, a UC San Diego professor of nanoengineering, to utilize nanotechnologies engineered by her team that will deliver genetic material to the chloroplasts.

“Our idea is to repurpose naturally occurring nanoparticles, namely plant viruses, for gene delivery to the plants,” noted Steinmetz. “Some engineering goes into this to make the nanoparticles go to the chloroplasts and also to render them non-infectious toward the plants.”

“One of the reasons I started working in nanotechnology was so I could apply it to plants and create new technology solutions. Not just for food, but for high-value products as well, like pharmaceuticals,” said Giraldo, who is also co-leading a related project using nanomaterials to deliver nitrogen, a fertilizer, directly to chloroplasts, where plants need it most.

The National Science Foundation has granted Giraldo and his colleagues $1.6 million to develop the targeted nitrogen delivery technology.

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Also published on Genengnews.com