2023-04-27 22:02:06
3D printed vaccines? MIT researchers have developed a portable 3D printer capable of printing ready-to-use and thermostable vaccine patches, that is to say, which can be stored for months at room temperature. Eventually, the machine could be able to print hundreds of vaccines per day.
This is not the first time that a vaccine has been 3D printed, and with this same patch structure housing micro-needles. The novelty here lies in particular in the fact that it is possible to store vaccines at room temperature. This last point responds to a major problem with regard to the transport and storage of vaccines. A large part of traditional vaccines, including RNA vaccines, must indeed be stored at low temperatures, which complicates their delivery and storage in areas that are difficult to access, desert, war, etc.
At the origin of the project, the objective of responding to the problem of Ebola-type epidemics by sending printers to the region concerned in order to quickly vaccinate the population, on the principle of production on demand.
With the appearance of the Covid-19 pandemic and the problem of population access to vaccination and the stability of vaccines, the team reoriented the project in order to produce messenger RNA (mRNA) vaccines against disease. Messenger ribonucleic acid (mRNA) is a molecule present in all cells of the body. Within each, the information encoded in the mRNA is read and converted into protein. In the case of vaccines against Covid-19, the mRNA is converted into protein S (Spike), also present on the envelope of the virus responsible for Covid-19, which makes it possible to trigger an immune response in the event of a disease infection.
Thus, in the study published in Nature Biotechnology, MIT researchers show that the printer is able to produce mRNA vaccines against Covid-19 that are thermostable. These vaccines, administered with the same dosage as vaccines administered by injection, elicit a comparable immune response in mice.
How are these 3D printed vaccines made?
Each patch, about the size of a thumbnail, is made up of hundreds of micro-needles filled with vaccine. To make them, the robotic arm of the printer injects ink into the molds of the micro-needles. A vacuum chamber located under each mold sucks the ink down to ensure it is present all the way to the end of the micro-needles.
To administer the vaccine, you do not need to be a health professional, just apply it to the skin: the end of the needles will dissolve, to gradually diffuse into the body.
The ink used to print the microneedles containing the vaccine is composed of mRNA vaccine molecules surrounded by lipid nanoparticles. They are what allow the vaccine molecules to remain stable over time, in conjunction with the polymers also incorporated into the ink. Researchers have identified the best formula for stiffness and stability: half-polyvinylpyrrolidone, half-polyvinyl alcohol, both of which are regularly used to make microneedles.
In order to verify the long-term stability of vaccines, the researchers developed an ink containing RNA that encodes luciferase, a luminescent protein. They then stored the patches that contained this ink either at 4°C or at 25°C for up to 6 months, and stored some of the particles at 37°C for 1 month, before administer to mice. The results proved to be successful: the affected patches retained their luminosity well when applied to the mice, unlike traditional vaccines administered by intramuscular injection which had also been stored for a long time at room temperature. Vaccine patches stored at room temperature for up to 3 months generated the same immune response as the others.
Currently, the production capacity of the printer made by MIT researchers is 100 patches in 48 hours. However, they hope to increase this figure to 100 patches per day by improving the machine.
For more information on this study, see the communiqué from MIT as well as all of the study.
A process adaptable to any type of vaccine
Researchers involved in the study plan to produce other types of vaccines by adapting the process used for mRNA vaccines. Vaccines made of inert proteins or viruses will also be affected. “The composition of the ink has been an essential element in the stabilization of mRNA vaccines, but the ink can contain different types of vaccines or even drugs. This micro-needle system therefore allows great flexibility and modularity of administration.”, says Ana Jaklenec, a researcher at the Koch Institute for Cancer Research at MIT, one of the senior authors of the study.
Photo credit: MIT
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