Macrophage specificity: Imaging and characterization of interaction between macrophages and fluorescent organosilica nanoparticles depending on surface structure and size.

Abstract

Macrophages have key functions in tissue homeostasis and also diseases. Macrophages show marked heterogeneity in response to environmental stimuli. The heterogeneity of macrophages was characterized by using morphology, surface marker, single cell sequence, and so on. We are investigating macrophage specificity using our nanomedical technology. We are developing novel materials, functional organosilica nanoparticles, and performed imaging to evaluate the diversity and specificity of mouse macrophage uptake. The organosilica nanoparticles surface-functionalized with polyethylene glycol (PEGylated) were applied to time-lapse fluorescent microscopic imaging and flow cytometry analyses. Single-cell imaging and analysis revealed that PEGylated nanoparticles revealed a stealth function against most macrophages. Notably, we found that the “PEG-resistant macrophages” that could take up PEGylated nanoparticles at the same level as bare nanoparticles. In addition, size-dependent uptake of macrophages was also observed in various tissues. The size-dependent uptake of functional organosilica nanoparticles by macrophages in the mouse various organs in vivo. These results indicated imaging and characterization of interaction between macrophages and fluorescent organosilica nanoparticles depending on surface structure and size were very useful to evaluate the heterogeneity and possible specificity of macrophage.