Stretching the skin could enable vaccines to be given without a needle

Topical administration of vaccines could become a reality thanks to new research suggesting that skin stretching techniques using a suction device may eliminate the need for needles.

Our skin acts as an essential barrier against pathogens, with intriguing links to immune system functioning. For example, gentle scratching has been shown to activate receptors that strengthen immune defenses.

To explore if skin stretching could induce similar effects, Stuart Jones from King’s College London and his team applied a suction device to samples of mouse and human skin. This device significantly increased skin tension from a normal state of about 1.5 newtons to approximately 6 newtons over a 20-minute period. The application of moisturizing lotions can double tension at the skin.

Utilizing a microscope with fluorescently labeled molecules, the researchers found that stretching reorganized collagen fibers and opened hair follicles, thereby enhancing permeability. Interestingly, the skin remained in this more permeable state for around 15 minutes after the suction was released.

The stretching action also activated stromal cells, which provide structural support within the skin. This induced a mild inflammatory reaction locally, which in turn stimulated an immune response, according to team member Elodie Segura from INSERM, France.

In laboratory tests involving mice, the researchers observed an increase in immune cell populations at the skin surface, along with gene activity shifts related to immune signaling molecules known as cytokines.

Further experiments assessed the impact of injecting an H1N1 flu vaccine in mice versus administering the same dosage of the vaccine topically after skin stretching. Remarkably, the resulting immune response from both methods was found to be similar, a surprising and promising outcome noted by Jones.

“The idea that we could potentially deliver a vaccine through the skin using a nanoparticle after stretching is very exciting,” said Dan Kaplan from the University of Pittsburgh, Pennsylvania.

Furthermore, the topical vaccine demonstrated robust efficacy with or without adjuvants—substances commonly added to vaccines to bolster immune responses but which may cause allergic reactions in some individuals. “In this scenario, the stretching itself serves as the immunostimulatory component,” added Jones.

Jones envisions a future where individuals could self-administer vaccines at home using a suction device, thus avoiding invasive procedures. “There would be no needles and no blood drawn,” he described.

While Darcy Dunn-Lawless from the University of Oxford expressed intrigue in the study, he raised critical questions regarding its practical applications. “How deep can this technique penetrate? And how precise can dosing be?”

Further research is required to determine the efficacy of this method in humans, whose thicker skin poses different challenges compared to that of mice. However, Jones is optimistic, noting that permeability results appeared consistent across species.

“Despite rabbits possessing a greater number of hair follicles, human hair follicles tend to be larger,” Jones explained. “This suggests that humans may have larger gaps around hair follicles that could facilitate molecule passage. Therefore, we expect the method to be even more effective in human applications.”