Vaccination is considered to be one of the most significant milestones in medical history due to its impact in saving millions of lives from infectious diseases worldwide. However, traditional needle-based vaccination strategies suffer from several limitations including: (1) needle-phobia, (2) accidental needle-stick injuries, (3) transmission of blood-borne diseases, such as, HIV and hepatitis B, due to needle reuse, and (4) the inability to induce a strong CD8 or Cytotoxic T Cell (CTL) response. A strong CTL response is essential for an effective vaccine against intracellular pathogens such as HIV and cancer.
The skin is an ideal target of vaccination because it is enriched with efficient Antigen Presenting Cells (APCs), i.e., Langerhans Cells and Dermal Dendritic Cells, where APCs are the most potent activators of CTLs. Our research group is working on a needle-less ultrasound technology to overcome the outermost skin diffusion barrier (stratum corneum), including activating the skin APCs in an immunogenic setting. The activated APCs subsequently induce a potent CTL response, which is successful in eradicating established subcutaneous tumors, thereby mediating effective tumor immunotherapy.
In addition, our research group is working on a lipid nanoparticle platform which encapsulates vaccine coding mRNA. An intra-cellular delivered mRNA molecule could potentially translate to many protein molecules, with preferential presentation to the MHC Class I and effective activation of downstream CTLs.