A spontaneously formed and self-adjuvanted hydrogel vaccine triggers strong immune responses

Hydrogel is a promising vaccine delivery vehicle, and have been applied to deliver antigens and adjuvants to enhance the immunogenicity of antigens. However, the complexity of hydrogel design, and the high cost and safety hazards of immunostimulating adjuvants have prevented the widespread applications of hydrogel vaccine. In this study, we developed a spontaneously formed and self-adjuvanted hydrogel (SSH) which had both adjuvant potential and the ability to sustained release antigen in situ. Unlike conventional hydrogel vaccine, our SSH was formed without requirement of radiant light sources or any crosslinking initiators. The adjuvant potency of hydrogel was evaluated and results confirmed that hydrogel promoted antigen uptake by dendritic cells (DCs) and induced DCs maturation. Moreover, SSH loaded with ovalbumin increased the accumulation of antigens in lymph nodes. Finally, subcutaneous administration of SSH-based vaccine increased antigen-specific IgG production by 12.5-fold compared with the clinically used aluminum, and delayed tumor growth in vivo. Thus, easily manufactured SSH may serve as a new and powerful antigen delivery platform with immune-stimulating capabilities to promote antitumor immune responses, and has great potential for immunotherapy against different diseases.