Biomimetic engineered nanoparticles target drug-resistant tumor cells and heterogeneous blood vessels for combination therapy of osteosarcoma.

• Innovative tumor drug-resistant mechanistic research. • Innovative multifunctional bionic nanomaterial design. • Good biosafety, circulatory system stability, and tumor targeting ability. • Drug/Fenton-like reaction/low-temperature photothermal combined tumor killing. • Improvement of the immune microenvironment in chemo-resistant tumor. Given that the treatment of drug-resistant osteosarcoma is a significant clinical challenge, in drug-resistant tumors, the role of endothelial cells has been recently emphasized. We noted that heterogeneous vascular endothelial cells (ONHVECs) in drug-resistant osteosarcoma tissues may inhibit macrophage-mediated killing of tumor cells, thus promoting the occurrence of drug resistance. Accordingly, we designed a type of hybrid membrane-coated multifunctional nanoparticle (NP), SiO 2 @PDA/Fe3+@Cis@HM. The NPs had good biocompatibility and enhanced the occurrence of low-temperature photothermal Fenton-like reactions. The hybrid membrane endowed the NPs with a tumor homing ability and homologous cell targeting ability, thus simultaneously targeting drug-resistant tumor cells and ONHVECs, in addition to killing tumor cells via efficient delivery of cisplatin and ROS produced by accelerated Fenton-like reactions. Through in vivo and in vitro experiments, we confirmed that SiO 2 @PDA/Fe3+@Cis@HM NPs efficiently killed tumor cells as well as ONHVECs. The endogenous exosomes produced by damaged ONHVECs induced anti-tumor M1 macrophage polarization to indirectly kill tumor cells and achieve synergistic therapy. This immune regulation was completely inherent and exhibited consistent efficacy, without ethical connotations. In conclusion, this multifunctional treatment strategy is the first to adopt a tumor cell/vascular endothelial cell double-targeted concept, which realized the direct killing of drug-resistant tumor cells and a natural immune enhancement response and could become a new paradigm for the treatment of drug-resistant osteosarcoma. [ABSTRACT FROM AUTHOR]