Micro-fractional Epidermal Powder Delivery for Skin Vaccination.

Skin is a highly immunogenic site for vaccine delivery due to its richness of antigen-presenting cells. Several vaccines have been approved for skin delivery and in particular intradermal delivery in the last two decades. Yet intradermal delivery often causes frequent and severe local reactions, preventing the incorporation of adjuvants to further boost skin vaccination. Here we describe a novel skin delivery technology, called micro-fractional epidermal powder delivery or EPD, with minimized local reactions for improved skin vaccination. EPD is based on laser or microneedle treatment to generate microchannel arrays in the epidermis followed by topical application of powder vaccine-coated array patches to deliver vaccines into the skin via microchannels. Due to the fractional delivery, EPD significantly reduces vaccine/adjuvant-induced local reactions without compromising vaccine immunogenicity and adjuvant potency. EPD also eliminates needle injection-associated pain and is promising to improve vaccine stability due to the direct powder delivery. This chapter describes detailed methods for the advantageous EPD in preclinical animal models.