The Effect of Size and Charge of Lipid Nanoparticles Prepared by Microfluidic Mixing on Their Lymph Node Transitivity and Distribution.

Because the lymph node (LN) is a critical organ for inducing immune responses against pathogens and cancers, the transport of immune functional molecules such as antigens and adjuvants to LNs by delivery systems is a useful strategy for the effective outcome of an immune response. The size and charge of a delivery system largely affect the transitivity to and distribution within LN. Although pH-sensitive lipid nanoparticles (LNPs) prepared by microfluidic mixing are the latest delivery system to be applied clinically, the effects of their size and charge on the transitivity to and distribution within LN are currently unknown. We investigated the size and charge effect of LNPs prepared by microfluidic mixing on transitivity to and distribution within LNs. A 30 nm-sized LNP (30-LNP) was efficiently translocated to LNs and was taken up by CD8+ dendritic cells, while the efficiency was drastically decreased in the cases of 100 and 200 nm-sized LNPs. Furthermore, a comparative study between neutral, positively, and negatively charged 30-LNP revealed that the negative 30-LNP moved to the LN more efficiently than the other LNPs. Interestingly, the negative 30-LNP reached the deep cortex, namely, the T cell zone. Our findings provide informative insights for designing LN-targeting LNPs prepared by microfluidic mixing and for the translocation of nanoparticles in LNs.

DNA-loaded nano-adjuvant formed with a vitamin E-scaffold intracellular environmentally-responsive lipid-like material for cancer immunotherapy.

Cytoplasmic DNA triggers cellular immunity via activating the stimulator of interferon genes pathway. Since DNA is degradable and membrane impermeable, delivery system would permit cytoplasmic delivery by destabilizing the endosomal membrane for the use as an adjuvant. Herein, we report on the development of a plasmid DNA (pDNA)-encapsulating lipid nanoparticle (LNP). The structural components include an SS-cleavable and pH-activated lipid-like material that mounts vitamin E as a hydrophobic scaffold, and dual sensing motifs that are responsive to the intracellular environment (ssPalmE). The pDNA-encapsulating LNP (ssPalmE-LNP) induced a high interferon-ß production in Raw 264.7 cells. The subcutaneous injection of ssPalmE-LNP strongly enhanced antigen-specific cytotoxic T cell activity. The ssPalmE-LNP treatment efficiently induced antitumor effects against E.G7-OVA tumor and B16-F10 melanoma metastasis. Furthermore, when combined with an anti-programmed death 1 antibody, an extensive therapeutic antitumor effect was observed. Therefore, the ssPalmE-LNP is a promising carrier of adjuvants for cancer immunotherapy.