Pancreatic cancer presents significant imaging challenges due to its poor vascularization, while the hypoxic tumor microenvironment further contributes to chemoresistance. To address these limitations, we engineered exosome-ultrasmall iron oxide (Exo-USIO), a targeted exosomal nanoprobe encapsulating USIO nanoparticles (USIO NPs), designed to enable precise tumor imaging and enhance chemotherapy efficacy in pancreatic cancer. Exosomes derived from Panc-02 pancreatic cancer cells were isolated and loaded with USIO NPs via electroporation to synthesize Exo-USIO. The nanoprobe's targeting specificity, MRI contrast enhancement, and catalase-like activity (converting H2O2 to O2) were systematically evaluated. In vitro assays assessed cellular uptake, hypoxia modulation, and chemosensitivity, while in vivo studies validated tumor-targeted MRI imaging, hypoxia alleviation, and synergistic therapeutic effects with gemcitabine (GEM). Exo-USIO demonstrated a 2.3-fold increase in T1-weighted MRI signal intensity compared to free USIO NPs (P 2O2 to O2, significantly reducing HIF-1α expression (P in vitro and suppressed tumor growth by 62% in vivo (P < 0.001). Biosafety evaluations revealed negligible systemic toxicity or metastatic risk. By leveraging exosome-mediated targeted delivery and the dual enzyme-mimetic activity of USIO NPs, Exo-USIO achieves dual functionality: enhanced MRI-guided tumor localization and catalytic alleviation of hypoxia to reverse chemoresistance. This strategy overcomes key limitations of the pancreatic tumor microenvironment, offering a translatable platform for precision theranostics.
Wu et al. (Tue,) studied this question.