Poly Lactic-co-Glycolic Acid Nanoparticles Containing Human Gastric Tumor Lysates as Antigen Delivery Vehicles for Dendritic Cell-Based Antitumor Immunotherapy.

Stimulating antitumor T cells using dendritic cells (DCs) is a novel and promising method in cancer therapy. Poly lactic-co-glycolic acid is one of the best-known polymers used for encapsulating antigen to protect them against proteolytic enzymes. In this study, poly lactic-co-glycolic acid nanoparticles (NPs) were used as DC antigen delivery vehicles in a preclinical model of immunotherapy of gastric cancer. The DCs were generated from peripheral blood monocytes by conventional in vitro differentiation and loaded with either soluble tumor lysate or lysate encapsulated in NPs using a double emulsion/solvent evaporation technique. Morphology of NPs was determined by scanning electron microscopy. Tumor lysate, either in the soluble form or encapsulated in NPs, was loaded into DC and stimulatory capacity was compared using patient-derived autologous CD3+ T cells as responders. The amount of relevant cytokines produced by Ag-loaded DC and in DC/T cell cocultures was evaluated as a measure of initial DC stimulation and T-cell responses, respectively. Significance increases in expression of DC surface molecules (i.e., CD80, CD83, CD86, and Human Leukocyte Antigen-DR (HLA-DR)) and cytokine production by both DC and DC/T cell cocultures (i.e., interleukin (IL)-12:IL-10 and interferon [IFN]-γ:IL-4 ratios) was observed following loading with lysate NP versus controls. The results suggest that NP-encapsulated antigen can shift antitumor T-cell responses toward a Th1 bias, which potentially increases DC vaccine potency in clinical settings.