Specific Targeting of Engineered Nanoparticles to Activated Macrophages

Background: Inflammation is an immune response that indicates several pathophysiological conditions, including pathogen infection, tissue injury, and tumor growth, in human diseases. During the processes of infection, tumor growth and autoimmune responses, tissue-associated macrophages distributed in the body play a central role in the onset of inflammation and are actively involved in maintaining homeostasis. Objective: Because the role of macrophages in diseases such as infectious diseases, chronic inflammatory diseases, and cancer are now well understood, strategies to target macrophages in uncontrollable diseases are of growing importance. The application of nanotechnology and nanoscience-based approaches for the treatment, diagnosis, monitoring, and control of biological systems has recently been referred to as “nanomedicine”. Nanoparticles not only are efficient for the delivery of therapeutic drugs and for imaging but also potentially facilitate cell activation and ablation. Certain unique types of nanoparticles naturally target cells of the mononuclear phagocyte system (MPS), and particularly macrophages. Results: This natural targeting capacity can be used for application in drug delivery and diagnosis. Controlling nanoparticles’ physicochemical properties, including size, charge, and composition, has emerged as a favored approach to target macrophages to achieve high endocytic activity. Ligand-receptor strategies for nanoparticle targeting to macrophages have been explored, including peptide, antibody, and lectin coating to specifically target drug-loaded nanoparticles to specific receptor types expressed on macrophages. Conclusion: This mini-review highlights rational approaches to the design and surface engineering of nanoparticles. Approaches to site-specific drug delivery and medical imaging for the treatment and diagnosis of macrophage-related human diseases are also discussed. Finally, recent nanotechnology-based approaches to devising macrophage-specific targeted therapy are highlighted.