Transcutaneous vaccines: Novel advances in technology and delivery for overcoming the barriers

Transcutaneous immunization represents an attractive alternative to vaccine delivery via topical administration and has received wide attention due to its easy-to-use, needle-free and noninvasive delivery. However, the development of transcutaneous vaccine was kept a challenge because of the barrier function of stratum corneum which inhibits the transport of antigen and adjuvant. Nowadays, pharmaceutical methods and novel physical devices are extensively investigated to overcome the penetration barrier of the stratum corneum for transcutaneous vaccine. In this article, these pharmaceutical methods and novel devices used for the enhancement of transcutaneous immunization were reviewed. In addition, chemokines promoted the migration of Langerhans cells and the transcutaneous adjuvants enhancing the immune responses at certain levels are also discussed for the development of novel transcutaneous vaccines.