Laser for skin vaccine delivery and adjuvantation

Abstract

Skin has received considerable attention for vaccination in the past decade owing to its rich in antigen-presenting cells (APCs) and better immune responses as compared to the muscle. Vaccination via the skin instead of the muscle may also make it possible to develop safer adjuvants and needle-free delivery systems. In the past 5 years we have developed a novel laser-based vaccine adjuvant (LVA) in which the inoculation site is briefly illuminated by a safe laser that enhances the motility and antigen-uptake of APCs. The brief illumination also facilitates emigration of APCs from the skin to draining lymph nodes. While greatly enhancing vaccination efficacies, LVA exhibits minimal local side effects and has no long-term side effects since no foreign or self materials are administered into the body apart from antigen itself. This novel strategy primes the inoculation site for better immune responses, in contrast to conventional vaccine adjuvants that all augment the immunogenicity by altering a form of the antigens. As such, LVA doesn’t require any formation with the antigen and can potentially act as a universal vaccine adjuvant. Indeed, this physical type LVA can sufficiently boost immune responses induced by ovalbumin (OVA), influenza vaccine, nicotine vaccine, and so on. Besides LVA, we have also explored a laser-facilitated patch delivery system for needle-free, painless transcutaneous immunization. The system is based on ablative fractional laser (AFL) treatment to generate an array of self-renewable microchannels (MCs) in the skin, through which topically applied vaccines can enter the skin readily. The laser treatment also results in active recruitment of APCs to the vicinity of each MC where APCs can more effectively take up antigens around or within the MCs, leading to ~100 times higher immune response against OVA than tape stripping-based patch delivery. In this chapter, we introduce these technologies and their preclinical studies and discuss their strengths and weaknesses.