A bioinspired hyperthermic macrophage-based polypyrrole-polyethylenimine (Ppy-PEI) nanocomplex carrier to prevent and disrupt thrombotic fibrin clots.

Fibrinolytic treatments for venous or arterial thrombotic syndromes using systemic administration of thrombolytics, such as streptokinase, can induce life-threatening bleeding complications. In this study, we offer the first proof of concept for a targeted photothermal fibrin clot prevention and reduction technology using macrophages loaded with polypyrrole-polyethylenimine nanocomplexes (Ppy-PEI NCs) and subjected to near-infrared radiation (NIR). We first show that the developed Ppy-PEI NCs could be taken up by defensive macrophages in vitro through endocytosis. The Ppy-PEI NCs generated local hyperthermia upon NIR treatment, which appeared to produce reactive oxygen species in Ppy-PEI NC-loaded macrophages. Preliminary evidence of efficacy as an antithrombotic tool is provided, in vitro, using fibrinogen-converted fibrin clots, and in vivo, in a rat femoral vascular thrombosis model generated by exposure to ferric chloride substance. The in vivo biocompatibility, photothermal behavior, biodistribution, and histological observation of cellular interactions with the Ppy-PEI NCs in the rat model provide rationale in support of further preclinical studies. This Ppy-PEI NC/NIR-based method, which uses a unique macrophage-guided targeting approach to prevent and lyse fibrin clots, may potentially overcome some of the disadvantages of current thrombolytic treatments. STATEMENT OF SIGNIFICANCE: Fibrinolytic treatments for venous or arterial thrombotic syndromes using systemic administration of thrombolytics, such as streptokinase, can induce life-threatening bleeding complications. In this study, we offer the first proof of concept for a targeted photothermal fibrin clot reduction technology using macrophages loaded with polypyrrole-polyethylenimine nanocomplexes (Ppy-PEI NCs) and subjected to near-infrared radiation (NIR). We first show that the developed Ppy-PEI NCs can be taken up by defensive macrophages in vitro through endocytosis. The Ppy-PEI NCs generated local hyperthermia upon NIR treatment, which appeared to produce reactive oxygen species in Ppy-PEI NC-loaded macrophages. Preliminary evidence of efficacy as an antithrombotic tool is provided, in vitro, using fibrinogen-converted fibrin clots, and in vivo, in a rat femoral vascular thrombosis model generated by exposure to ferric chloride substance. The in vivo biocompatibility, photothermal behavior, biodistribution, and histological observation of cellular interactions with the Ppy-PEI NCs in the rat model provide rationale in support of further preclinical studies. This Ppy-PEI NC/NIR-based method, which uses a unique macrophage-guided targeting approach to disintegrate fibrin clots, may potentially overcome some of the disadvantages of current thrombolytic treatments.