Chapter 1: Bidirectional Interaction between Nanoparticles and Carrier-Mediated Agents and Cells of the Mononuclear Phagocytic System

Nanoparticle (NP) uptake by the mononuclear phagocytic system (MPS) has been described through several in vitro and in vivo studies, and is a field of research that is constantly evolving and continuing to grow. While many NP agents contain traditional small molecules that have been used therapeutically for decades, the unique delivery system of NPs allows for greater exposure and efficacy of the active chemical entity in the body. Once an NP enters the body, they encounter a much different host response than that observed with small molecule administration. The network of opsonins and circulating and tissue phagocytes is very complex, and their interaction with NPs often depends on the biological atmosphere as well as the physicochemical properties of the NP. Moreover, these factors, and MPS function in general, appear to be highly variable across animal models and in patients. This chapter will discuss NP uptake by the MPS and the resulting clinical manifestations. More specifically, key concepts will include differences in NP physicochemical properties, cell lines and/or animal models used, and the bidirectional interaction between the MPS and NPs in patients.