Needle-less, on-demand vaccines: A new frontier for nanoparticles

Chemical engineers at the University of Washington have developed a new type of vaccine that could be a “game changer” in the fight against the most difficult-to-treat viral infections. Their vaccine, which could be made quickly, cheaply and be administered without a needle, uses nanoparticle technology to create long-lasting immune responses. So far, the vaccine has shown promising results in mice.

“What we wanted to do was essentially find out possible ways of producing vaccines on the spot,” says chemical engineer and lead author of the study, François Baneyx.

Traditional vaccines are made en masse in centralized locations, far away from where they might be needed. A vaccine made on-demand would be invaluable to physicians in remote places, especially in developing countries.

“For instance, a field doctor could see the beginnings of an epidemic, make vaccine doses right away, and blanket vaccinate the entire population in the affected area to prevent the spread of an epidemic,” Baneyx said in a press release.

Vaccines work by preparing your immune system for a viral attack. When you get vaccinated, you’re injected with a small dose of a microbe, which has special surface proteins called antigens that are recognized by the immune system as foreign invaders. Large cells called macrophages deliver antigens to the lymphatic system, where T cells and B cells are activated and sent out to the fight the invasion. Once the microbes have been destroyed by the lymphocytes, some of them are converted into memory cells, which will “remember” the microbe if it ever enters your system again.

Baneyx and his team were inspired by the natural process of mineralization, the process by which animals like mollusks build their shells, and engineered a protein that can mineralize an inorganic material—in this case, calcium phosphate, a compound found in tooth and bone. The resulting nanoparticles consist of a core of calcium phosphate with a “shell” made up of the engineered protein, which also acts as the antigen. (Nanoparticles are categorized as less than 100 nanometers in diameter. To put it in perspective, a strand of hair is 75,000 nanometers thick).

In a study, the researchers injected one group of mice with the vaccinating nanoparticles and another group of mice with the protein alone. Eight months later, the team infected the mice with a derivative of the influenza virus and found that the mice that had received the nanoparticle showed a heightened production of a specific type of T-cell, called cytotoxic—or “killer”—T cells.

The nanoparticles are so small that they can freely enter the lymphatic system, according to the study. Baneyx suspects that once the nanoparticles are in the lymph nodes, they are able to directly stimulate special immune response cells called dendritic cells, which are “powerful inducers” of T-cell responses.

In a real life scenario, the vaccine could be produced by mixing a freeze-dried protein—engineered based on proteins that exist on the surface of pathogens—with a solution of water, calcium and phosphate to produce the nanoparticles. They could then be administered by a disposable application system like a bandage or a patch.

Baneyx emphasized that the promising results have only been shown in mice, and that this vaccine has not been made for humans yet. The research was published in the journal Nanomedicine.