Pathological thrombosis within a vessel hampers blood flow and is the mainspring of numerous fatal cardiovascular complications. In order to specifically image and dissolve a thrombus, we rationally designed a functionalized polymeric hybrid micelle (PHM) system self-assembled from amphiphilic polycaprolactone-polyethylenimine (PCL-PEI) and polycaprolactone-polyethylene glycol (PCL-PEG). Based on a biological component of thrombi, activated coagulation factor XIII (FXIIIa), which is responsible for fibrin crosslinking, we further developed FXIIIa-targeted near infrared imaging and thrombolytic nanoparticles, termed IR780/FPHM/LK NPs, through chemical conjugation of peptides to the system. In a ferric chloride (FeCl3)-induced mouse carotid thrombosis model, IR780/FPHM/LK NPs specifically targeted the thrombus and significantly enhanced the photoacoustic signal for an accurate diagnosis. When loaded with the fibrinolytic drug lumbrokinase (LK), FPHM remarkably dissociated the thrombus accompanied by an increase in the d-dimer level, a fibrin degradation product, and alleviation of fatal nonspecific hemorrhagic risk. Given its thrombus-specific imaging along with potent therapeutic activities, IR780/FPHM/LK NPs hold promise for developing nanotheranostic agents in preclinical thrombotic vascular disease models.
We developed a pH-activatable cell-penetrating peptide dimer LH2 with histidine residues, which can penetrate cells, specifically in weak acidic conditions, even at few tens of nanomolar concentrations. LH2 effectively delivered paclitaxel into triple-negative breast cancer cells, MDA-MB-231, via formation of non-covalent complexes (PTX-LH2(M)) or covalent conjugates (PTX-LH2(C)). Moreover, LH2 showed prolonged circulation in the body and enhanced accumulation in tumors. Both PTX-LH2(M) and PTX-LH2(C) showed strong antitumor effects in a triple-negative breast cancer grafted mouse model at an extremely low dosage.