2242P Engineering immune-cell targeting nanoparticles for precise delivery of loaded-cargo and enhanced immunotherapy efficacy

In recent years, cancer immunotherapy has gained significant attention for its ability to modulate immune cell functions. However, systemic administration of immunomodulatory agents can lead to side effects and limit drug efficacy. To overcome these challenges, we developed a targeted drug delivery platform using nanoparticles (NPs) made from biomaterials that can target specific immune cells. Our approach aims to increase drug efficacy and alleviate systemic side effects by delivering drugs directly to their intended sites. The NPs were prepared using a conventional emulsification method based on Poly(D,L-lactide-co-glycolide)-maleimide. To conjugate anti-mouse NK1.1 and CD8a antibodies (Abs) to the surface of the NPs, the Abs were cleaved into Fc and F(ab')2 fragments by protease. The F(ab')2 fragments were reduced to obtain thiol groups in the hinge region for coupling to the maleimide group on the NPs' surface. The NPs' morphology was confirmed using dynamic light scattering and scanning electron microscopy, while the in vitro and in vivo targeting efficiency was evaluated using fluorescently labeled NPs and flow cytometry. The NPs were confirmed to be monodisperse, spherical particles with a size of less than 200 nm. Further, in vitro studies showed that when fluorescently labeled and Abs-conjugated NPs were co-incubated with mouse splenocytes, the NPs' fluorescence was confirmed in each immune cell, whereas immune cells with non-conjugated NPs showed no fluorescence. In vivo studies showed that after injecting fluorescently labeled and Abs-conjugated NPs into the tail vein of mice, the fluorescence of the NPs was observed in the immune cells of the blood and spleen. Notably, fluorescence was barely detected in non-target immune cells, indicating the high specificity and targeting efficiency of the NPs. The findings demonstrate that Abs-conjugated NPs can effectively target specific immune cells both in vitro and in vivo with minimal non-specific binding. This indicates that the developed platform can potentially maximize drug efficacy and minimize systemic side effects by delivering immunotherapeutic agents specifically to certain immune cells.