Microneedle array for vaccine delivery developed

Researchers at the University of Pittsburgh School of Medicine have developed a new vaccine delivery system for vaccines using live or attenuated viral vectors: a fingertip-sized patch that contains 400 tiny needles, each just 0.5 mm in length and made from sugar and the specific cargo being delivered. Their work has been published in the Journal of Investigative Dermatology.

“We are developing this new delivery technology because while traditional vaccines are often effective in inducing antibody responses, they frequently fail to generate the cellular responses that are essential to prevent or treat many cancers or infectious diseases,” explained lead author Dr Louis D Falo Jr, Chairman of the Department of Dermatology at the School of Medicine and the University of Pittsburgh Medical Center (UPMC).

The skin is an ideal vaccination site because it contains an immune network that is highly responsive and encourages the generation of strong and long-lasting immunity. Dissolvable microneedle arrays (MNAs) are designed to mechanically penetrate the superficial cutaneous layers, absorb moisture from the skin and then rapidly dissolve and release molecules that prompt the immune system to make antibodies to attack the virus. The technology also has the potential to improve cellular immune responses in patients and expand global immunisation capabilities.

Using in vivo mouse models, investigators generated the 3D multicomponent dissolvable vaccine platform combining a live adenovirus-encoded antigen with an added component, polyinosinic:polycytidylic acid (poly I:C) — an immunostimulant used to simulate the skin immune system. This successfully induced both antibody responses and stronger cellular immune responses. Induction of antigen-specific cellular immunity is a point of emphasis in the vaccine field, as evidenced by recent efforts to generate ‘universal vaccines’ for mutable infectious diseases like influenza, HIV and coronaviruses by targeting infected cells.

“Remarkably, the MNA vaccine platforms incorporating both antigen-encoding adenovirus and poly I:C augmented the destruction of targeted cells significantly compared to MNA delivery of the same adenovirus alone,” Dr Falo said.

The researchers also found that the MNAs integrating both poly I:C and adenovirus retained their immunogenicity after one month of storage at 4°C. MNA-delivered vaccines also have advantages in their ease of fabrication, application and storage compared to other vaccine delivery platforms.

“Our results suggest that multicomponent MNA vaccine platforms uniquely enable delivery of both adjuvant and antigen-encoding viral vectors to the same skin microenvironment, resulting in improved immunogenicity including cellular immune responses,” Dr Falo said. “This MNA delivery approach could improve the effectiveness of adenoviral vaccines now in development for the prevention of coronavirus disease (COVID-19).”

Image caption: The vaccine is delivered into the skin through a fingertip-sized patch of microscopic needles. Image credit: UPMC.

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