Figure 5.

Macrophages as a theranostic tool. Macrophages can be used as drug delivery systems and as therapeutic targets for anti-inflammatory or anti-tumor therapy. Due to their ability to infiltrate the tumor microenvironment, macrophages can be used as drug vehicles for tumor therapy. Various types of theranostic nanoparticles were developed to simultaneously combine imaging and therapeutic approaches. Different types of electromagnetic radiations were used for functional and anatomical imaging. To favor the phagocytosis of nanoparticles, various methods of coating were proposed, including nanoparticle repolarization. Once macrophages were located in the regions of interest (inflammatory or tumor regions), these irradiation sources were also used to activate nanoparticle elements for PTT (e.g. WO, AuNRs) and delivery of chemotherapy agents (e.g. siRNA, oncolytic viruses). As macrophages markedly contribute to the development of tumors or inflammatory diseases, specific targeting of macrophages leading to their elimination or repolarization was proposed as theranostic tools. Macrophage ablation is based on PTT, ROS therapies or blocking antibodies. Macrophage reprogramming methods are based on the generation of nanoparticles with bacterial or viral elements that activate macrophage TRL signaling and induce the production of pro-inflammatory molecules which reprogram TAMs into a M1 subtype.