LAUSR

Macrophages are abundant immune cells, which serve as a primary cell population capable of interacting with foreign substances, including engineered nanomaterials (NMs). In addition to the phagocytic activity, macrophages also play a central role in innate immunity and contribute to the initiation of adaptive immunity. Since macrophages are a natural reservoir for NMs, nanoparticles (or nano‐enabled strategies) are commonly utilized to target this cell type and fine tune its polarization status in different disease scenarios. In this review, a high‐level description of macrophage biology is first introduced. It is followed by the discussion on the impact of therapeutic NMs on macrophages in solid tumors and how macrophages, in turn, impact the immune system and heterogeneity in the tumor microenvironment. Another major thrust is to discuss the applications of NMs in noncancer diseases with a focus on how NMs can be used to influence macrophages in the process of tissue repair, wound healing, myocardial infarction, and certain autoimmune diseases. In addition to the design of nanocarriers to impact macrophage function, whether the same response outcome can be achieved by intrinsic NM's physicochemical properties, allowing the potential usage of the active pharmaceutical ingredient‐free nanomaterials for therapeutic purposes, is also discussed.