A novel targeted iron oxide nanocarrier for inhibiting M2-type macrophages in the tumor microenvironment.

BACKGROUND

Tumor-associated macrophages (TAMs) are vital to the tumor microenvironment. They are classified as antitumor M1-type or protumor M2-type macrophages. M2-type macrophages accumulate in the tumor stroma and are related to poor prognosis. Iron oxide nanoparticles are used as drug delivery vehicles because of the structure of carboxyl groups on their surface and their ability to be easily phagocytosed by macrophages.

AIM: The signal transducer and activator of transcription 6 (STAT6) signaling pathway controls M2 macrophage polarization, but the STAT6 signaling pathway inhibitor AS1517499 lacks efficient targeting in vivo. Thus, our study aimed to block the polarization of TAMs to M2-type macrophages.

METHODS AND MATERIAL: We used ultrasmall superparamagnetic iron oxide nanoparticles (USPIONs) as drug carriers coated with the STAT6 signaling pathway inhibitors AS1517499 and CD163 monoclonal antibodies to synthesize the targeted nanocomplex AS1517499-USPION-CD163 utilizing the carbodiimide method. Then, we determined its physicochemical properties, including hydrodynamic size distribution, ultrastructure, iron concentration, protein content and activity of the CD163 monoclonal antibody, AS1517499 content, and selectivity for M2-type macrophages, and its biological applications.

RESULTS

The hydrodynamic size distribution was stable (average size = 95.37 nm). Regarding biological applications, the targeted nanocomplex selectively inhibited M2-type macrophages.

CONCLUSIONS

The targeted nanocomplex AS1517499-USPION-CD163 showed high selectivity for M2-type macrophages. Therefore, iron oxide nanoparticles targeting TAMs may be an effective approach to TAM therapy.