Differential uptake of nanoparticles by human M1 and M2 polarized macrophages: Protein corona as a critical determinant

Aim: To investigate the interaction behavior of M1- and M2-type macrophages with nanoparticles of different sizes with/without the presence of serum. Materials & methods: THP-1 human monocytes were differentiated into M1 and M2 macrophages, and the uptake of silica nanoparticle (50-1000 nm) was studied using flow cytometry and different microscopies. Results: Without serum, higher uptake of all-sized nanoparticles was observed by M1 compared with M2. With serum, uptake of nanoparticles (200-1000 nm) was dramatically increased by M2. Furthermore, serum proteins adsorbed (corona) by nanoparticles were found to be the ligands for receptors expressed by M2, as revealed by SDS-PAGE and gene profiling analyses. Conclusion: The observed differential uptake by M1 and M2 macrophages will help understand the fate of nanoparticles in vivo.