An All-in-One Vaccine

Getting a vaccine to the low- and middle-income areas that need them the most is a difficult task, as discussed in a recent feature in The Medicine Maker on corporate social responsibility (1) – and many regions need multiple vaccines delivered to its people, which make the logistics even more complex. A recent project by the Langer Lab at MIT – funded by the Bill and Melinda Gates foundation – aims to help with the challenge by investigating whether multiple vaccines can co-exist in a single injection, with a little help from microparticles.

Their solution is to create individually packaged droplets of vaccine, stored inside microparticles. This isolates each vaccine and prevents different drugs from interacting with each other, ultimately allowing several different vaccines to co-exist and remain viable in a single syringe.

“The particles are made from FDA-approved polymers, with a core shell structure that can be filled with a drug or vaccine, and are small enough to be injected. We initially tried 3D printing the particles, but were not successful, so we explored other methods,” says Ana Jaklenec, a research scientist at the Langer Lab. The technique the team came up with is SEAL (StampEd Assembly of polymer Layers), which creates a hollow cube in two parts: a “cup” into which the drug is deposited, and a “lid”. After the drug is poured into the cup, the lid is placed on top and the particle is heated slightly until the two form a tight seal.

The particles are made from poly(lactic-co-glycolic acid) (PLGA) – although Jaklenec adds that the particles could be made from any thermoplastic polymer – and the molecular weight can be altered to allow a variable release period for different drugs. In the lab’s study, they were able to time drug release between a range of 9 to 41 days after injection (2). “Any drug can be encapsulated into the particles. Drugs which require repeated injections might be good candidates for this technology, including RNA therapeutics, peptides, and immunotherapies,” says Jaklenec.

The lab is now focusing on ensuring the drugs remain stable and viable at body temperature before being released, and are already working on developing clinical and R&D vaccines.

“Our hope is that many vaccines – if not all – can be given in a single injection. The particles are very small (~400µm x 400 µm x 300 µm) so our goal is to have up to 1000 particles injected at once,” says Jaklenec. “Perhaps one day we can have a single shot containing all infant vaccines and boosters, so children would only need one injection. We’re also expanding the type of particles we have, to achieve a wider range of release times, from days to years.”