The following is an edited version of the original article, which appeared on the MIT website.
MIT researchers have come up with a mobile vaccine printer that could be scaled up to produce hundreds of vaccine doses in a day. The printer, which can fit on a tabletop, could be deployed anywhere vaccines are needed, the researchers say.
The printer produces patches with hundreds of microneedles containing vaccine. The patch can be attached to the skin, allowing the vaccine to dissolve without the need for a traditional injection. Once printed, the vaccine patches can be stored for months at room temperature.
In a study appearing in Nature Biotechnology, the researchers showed they could use the printer to produce thermostable Covid-19 RNA vaccines that could induce a comparable immune response to that generated by injected RNA vaccines, in mice.
Most vaccines, including mRNA vaccines, must be refrigerated while stored. Furthermore, they require syringes, needles, and trained health care professionals to administer them.
Instead of producing traditional injectable vaccines, the researchers decided to work with a novel type of vaccine delivery based on patches about the size of a thumbnail, which contain hundreds of microneedles. Such vaccines are now in development for many diseases, including polio, measles, and rubella. When the patch is applied to the skin, the tips of the needles dissolve under the skin, releasing the vaccine.
The “ink” the researchers use to print the vaccine-containing microneedles includes RNA vaccine molecules that are encapsulated in lipid nanoparticles, which help them to remain stable for long periods of time.
The ink also contains polymers that can be easily molded into the right shape and then remain stable for weeks or months, even when stored at room temperature or higher. The researchers found that a 50/50 combination of polyvinylpyrrolidone and polyvinyl alcohol, both of which are commonly used to form microneedles, had the best combination of stiffness and stability.
Inside the printer, a robotic arm injects ink into microneedle molds, and a vacuum chamber below the mold sucks the ink down to the bottom, making sure that ink reaches all the way to the tips of the needles. Once the molds are filled, they take a day or two to dry. The current prototype can produce 100 patches in 48 hr, but the researchers anticipate future versions could be designed to have higher capacity.
“This work is particularly exciting as it realizes the ability to produce vaccines on demand,” says Joseph DeSimone, a professor of translational medicine and chemical engineering at Stanford University, who was not involved in the research. “With the possibility of scaling up vaccine manufacturing and improved stability at higher temperatures, mobile vaccine printers can facilitate widespread access to RNA vaccines.”
While this study focused on Covid-19 RNA vaccines, the researchers plan to adapt the process to produce other types of vaccines, including vaccines made from proteins or inactivated viruses.