via Positively Aware, Chicago
Scientists at King’s College, London, have demonstrated the ability to deliver a dried live vaccine to the skin without a traditional injection, and shown for the first time that this technique is powerful enough to enable specialized immune cells in the skin to kick-start the immunizing properties of the vaccine.
Funded by the Bill & Melinda Gates Foundation and published in Proceedings of the National Academy of Sciences, researchers say although it is an early study, this technical advance offers a potential solution to the challenges of delivering live vaccines without the need for refrigeration in resource-limited countries. A cheaper alternative to hypodermic needles, it would also remove safety risks from needle contamination and the pain-free administration could lead to more people being willing to take a vaccination.
The team at King’s used a silicone mold developed by U.S. company TheraJect to create a microneedle array—a tiny disc with several micro-needles made of sugar which dissolve when inserted into the skin. The team formulated a dried version of a live modified adenovirus-based candidate HIV vaccine in sugar (sucrose) and used the mold to create the microneedle array. They found that the dried live vaccine remained stable and effective at room temperature.
To test the effectiveness of the microneedle array, they applied it to mice. Using imaging, they observed how the vaccine dissolved in the skin and were able to identify exactly which specialized immune cells in the skin pick up this type of vaccine and activate the immune system. The researchers found the first evidence that a sub-set of specialized dendritic cells in the skin were responsible for triggering this immune response.
When compared with a traditional needle vaccine method, the immune response generated by the dried microneedle vaccine (kept at room temperature) was equivalent to that induced by the same dose of injected liquid vaccine that had been preserved at -80°C.
Dr. Linda Klavinskis from the Peter Gorer Department of Immunobiology at King’s College, said, “This work opens up the exciting possibility of being able to deliver live vaccines in a global context, without the need for refrigeration. It could potentially reduce the cost of manufacturing and transportation, improve safety (as there would be no loss in potency), and avoids the need for hypodermic needle injection, reducing the risk of transmitting blood-borne disease from contaminated needles and syringes.”
The new technique represents significant progress in overcoming the challenges of delivering a vaccination program for HIV and malaria, but it may also have wider implications for other infectious diseases or even inflammatory and autoimmune conditions such as diabetes.