Viability, Ultrastructure, and Migration Activity of Neutrophils after Phagocytosis of Synthetic Microcapsules

© 2020, Pleiades Publishing, Ltd. Abstract: Neutrophils are the most numerous leukocyte population, which is part of the innate immunity system and provides antibacterial protection to the body. The ability of neutrophils to phagocytosis and chemotaxis make it possible to consider them for potential targeted delivery of drugs to the inflammatory foci. Loading of migrating neutrophils with encapsulated medicinal drugs makes it possible to reduce its toxic effect on the carrier cell, as well as to avoid changes in the concentration and bioactivity of the transported substance. In this work, we studied the interaction of synthetic microcapsules (potential “cargo containers”) with human neutrophils, namely, their phagocytic activity, ultrastructural changes, and capability for migration after phagocytosis. The results showed that, during short-term neutrophil cultivation with microcapsules, the cells phagocytized the microcapsules in proportion to their number in the extracellular medium. Neutrophils partially retained viability and migratory activity. However, prolonged cultivation of neutrophils in vitro with microcapsules decreased the neutrophil population and migration ability of the surviving cells, which indicated the cytotoxic effect of microcapsules. The internalization of microcapsules was accompanied by changes in the ultrastructure of neutrophils. Altered nuclear shape, plasma membrane disruption, vacuolization of the cytoplasm, and even complete destruction of individual cells were observed. Thus, neutrophils are potentially suitable for the transfer of encapsulated substances, but the development of targeted delivery systems using neutrophils and synthetic microcapsules requires optimization and further research