Formulation and characterisation of PLGA microspheres as vaccine adjuvants

There appear to be several factors that confirm the viability of polymeric microspheres as vaccine delivery vehicles, including the ability to enhance targeting of antigen-presenting cells, the potential for controlled, sustained release of antigen-thereby potentially eliminating the need for multiple vaccination doses-as well as the ability of the polymer matrix to not only facilitate more efficient delivery by acting as a shield from the hostile external environment, but also the potential to reduce adverse reactions and abrogate problems caused by the vaccine strain in immunocompromised individuals. In addition, microspheres offer great variability in terms of manufacturing processes, constituents (including additional adjuvants), physico-chemical properties and immunological efficacy.This chapter investigates the advantageous properties of microspheres-and more specifically, those composed primarily of polylactide-co-glycolide-for the delivery of vaccine adjuvants by outlining the various preparation techniques and the effect of the related processing parameters, the subsequent in vivo efficacy, and, finally, the potential for a desirable product with an extended shelf-life.