“Self-boosting vaccines” load multiple drug doses into a single shot


Researchers at MIT have developed microparticles that can release doses of drugs at specific times over days, weeks or months. The platform could be useful for creating what the team calls “self-boosting vaccines.”

Vaccines and other drugs often require multiple doses, but getting them at the optimal time can be tricky for many people who don’t have easy access to medical services. To help remove that pressure, the MIT team developed a drug delivery system that can be given just once, and release extra doses at the required time.

The system consists of microparticles that the team describes as being like tiny coffee cups, which are made of a biocompatible polymer called PLGA. Drug particles are loaded into the cup, then a lid is fused to the top using a gentle heat. As the polymer degrades over time, it releases the drug payload.

The general design has been tested over a few years, but for the new study, the researchers investigated exactly how it works, and created new techniques to scale up production. The team was surprised to find that particle size didn’t affect the timing of the drug release – instead, it all came down to the type of polymer used.

The PLGA is slowly cleaved by water, the team observed, until the lid eventually breaks open and spills the drug into the body. Different compositions of polymers break down at different rates, which could allow scientists to tweak the design to release drugs after a few days, weeks, or months as needed.

“If you want the particle to release after six months for a certain application, we use the corresponding polymer, or if we want it to release after two days, we use another polymer,” said Morteza Sarmadi, lead author of the study. “A broad range of applications can benefit from this observation.”

The team says the technique could be applied to a range of vaccine types, including those based on DNA, RNA or recombinant proteins. The first example in development is a self-boosting polio vaccine currently being tested in animals, which normally requires up to four injections.

The research was published in the journal Science Advances.

New Atlas, 17 July 2022
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