Evaluation of Nanoparticle Formulation for Novel Synthetic Immune Stimulating Agents

ABSTRACT The objective of this research was to investigate the efficacy of poly (D,L lactic-coglycolic acid) nanoparticles (PLGA-NPs) as a delivery system to deliver a single immunostimulatory molecule (adjuvant) or co-delivering different adjuvants in the elicitation of immune responses. The PLGA biodegradable nanoparticles encapsulating the various adjuvants were characterized through their physicochemical properties in terms of encapsulation efficiency, size, zeta potential, and the loading of the adjuvants. Pathogen-mimicking PLGA-NPs containing ovalbumin (OVA), as a model antigen, and a Muramyl dipeptide analogue (ARC-004) as an adjuvant were also developed and tested for quantitative and functional aspects of dendritic cell responses. endritic cell responses were investigated by measuring the increase in the expression of activation markers (CD86, CD40, and MHCII molecule) and secretion of cytokines (IFN-gamma, TNF-alpha, and IL-6), following treatment with either PLGA-NPs incorporating the adjuvants or the adjuvants in solution. Our results showed that particulate delivery of adjuvants provided suitable properties for DC targeting and uptake. Also, the concentration and ratio of the adjuvant-loaded PLGA NPs was investigated and optimized to achieve the maximum expression of DC markers, secretion of cytokines, and induction of effective immunotherapeutic responses. The safety of the free and NP formulations was also confirmed in this study by experiments on DCs and normal epithelial cell line (CCD841). Our results support the potential use of PLGA-NPs as competent vaccine delivery system for these adjuvants. Our research on introducing these promising immunostimulatory adjuvants (ARC-007 (also referred as 7-acyl lipid A), ARC-004, and ARC-005) to the field sets the stage for further studies such as induction of an antigen-specific immune response in tumor-bearing animals. If successful, it would be the basis for future cancer vaccine trials