Development and Clinical Study of a Self-Dissolving Microneedle Patch for Transcutaneous Immunization Device

We previously reported the safety and efficacy in animal experiments of transcutaneous immunization (TCI) using a self-dissolving microneedle patch (MicroHyala; MH) made of hyaluronic acid and collagen. However, this MH was an unsuitable TCI device for the human skin, as collagen is suspected to induce inflammation. In this study, we developed an improved collagen-free MH (new-MH) and conducted clinical study to evaluate the fundamental properties and safety in human. Microneedle dissolution, skin irritation, and antigen-specific antibody production about new-MH were measured in mice and/or rats. On the basis of the results, the clinical study was conducted in healthy volunteers to evaluate local and systemic adverse events caused by new-MH application. We confirmed that the microneedles of new-MH, as well as those on our old-MH that contained collagen, could easily pierce stratum corneum without severe skin irritation, and that TCI using new-MH efficiently increased antibody titer with comparable to TCI using old-MH. Application of new-MH caused no severe adverse reactions in 20 healthy volunteers enrolled in a clinical study. These results verified that new-MH is a safe TCI device in human, and greatly encouraged us to advance PI/PII clinical studies of antigen-loaded new-MH.