Figure 2.

A) Macrophage polarization (M1 versus M2 traditional dichotomy) plays an important role in the uptake of nanoparticles [70, 82]. Traditional polarization of macrophages to an M1 phenotype enhances nanoparticle uptake, while M2 polarization appears to reduce particle uptake. B) This cell uptake variation may be explained by variations in functions of these macrophage polarization states outlined briefly in this cartoon (adapted with permission from [70]).