- Microparticles are being developed through 3-D fabrication to deliver multiple doses of vaccines or a drug through a single injection
- The microparticles vary in structure so that they release their contents at different times
- Further research, if successful, could result in better coverage of vaccines, especially in the developing world
have developed microparticles that can release drugs or vaccines at different
times, thus possibly eliminating the need for administering multiple injections. The
research was published in Science.
The microparticles are made up of a biocompatible polymer called PLGA which is molded into tiny cups and lids with the help of silicon molds. Each cup is then filled with the drug or vaccine, covered with the lid, and sealed with slight heating. This method of manufacturing the microparticles is called SEAL (StampEd Assembly of polymer Layers). Since PLGA is fully biodegradable, the chances of a foreign body reaction are minimal.
The particles are extremely tiny and can therefore be injected like any other drug or vaccine through an 18-gauge needle. Depending on variations in the structure, the microparticles dissolve and release their contents at different predetermined times. Thus, multiple doses of a vaccine, multiple vaccines or multiple doses of drugs can be administered through a single injection.
The scientists carried out several tests to evaluate their model:
- The scientists tested the property of pulsed release from the microparticles by filling microparticles with varying structural properties with fluorescent- labeled dextran. They found that the structurally-different particles released the dextran at different times, in vitro, as well as, when administered to mice. Leakage of the contents before time was not observed.
- The heating of the microparticles to seal them did not affect the enclosed trivalent inactivated polio vaccine (IPV), which is among the most thermolabile vaccines in use.
- The scientists injected mice with structurally-variant microparticles containing ovalbumin, a substance that is used experimentally to achieve an immune response. The particles released the ovalbumin at two different times. The final immune response obtained with the single dose was similar to that produced by two separate injections with double the doses.
Further research would be needed to ensure that the medication or the vaccine remains stable within the particles over longer durations.
The new technology of developing such microparticles could also have several other applications in medicine. It may be possible to bring about the release of the medication or vaccine on the application of a stimulus. For example, in the presence of certain bacteria in the body, the microparticles can be designed to release an antibiotic to fight against the infection.
- McHugh KJ, Nguyen TD, Linehan AR, Yang D, Behrens AM, Rose S, Tochka ZL, Tzeng SY, Norman JJ, Anselmo AC, Xu X, Tomasic S, Taylor MA, Lu J, Guarecuco R, Langer, Jaklenec A. Fabrication of fillable microparticles and other complex 3D microstructures. Science 2017:Vol. 357, Issue 6356, pp. 1138-1142. DOI: 10.1126/science.aaf7447