Tumor microenvironment activated mussel-inspired hollow mesoporous nanotheranostic for enhanced synergistic photodynamic/chemodynamic therapy.

Anti-tumor therapies reliant on reactive oxygen species (ROS) as primary therapeutic agents face challenges due to a limited oxygen substrate. Photodynamic therapy (PDT) is particularly hindered by inherent hypoxia, while chemodynamic therapy (CDT) encounters obstacles from insufficient endogenous hydrogen peroxide (H2O2) levels. In this study, we engineered biodegradable tumor microenvironment (TME)-activated hollow mesoporous MnO2-based nanotheranostic agents, designated as HAMnO2A. This construct entails loading artemisinin (ART) into the cavity and surface modification with a mussel-inspired polymer ligand, namely hyaluronic acid-linked poly(ethylene glycol)-diethylenetriamine-conjugated (3,4-dihydroxyphenyl) acetic acid, and the photosensitizer Chlorin e6 (mPEG-HA-Dien-(Dhpa/Ce6)), facilitating dual-modal imaging-guided PDT/CDT synergistic therapy. In vitro experimentation revealed that HAMnO2A exhibited ideal physiological stability and enhanced cellular uptake capability via CD44-mediated endocytosis. Additionally, it was demonstrated that accelerated endo-lysosomal escape through the pH-dependent protonation of Dien. Within the acidic and highly glutathione (GSH)-rich TME, the active component of HAMnO2A, MnO2, underwent decomposition, liberating oxygen and releasing both Mn2+ and ART. This process alleviates hypoxia within the tumor region and initiates a Fenton-like reaction through the combination of ART and Mn2+, thereby enhancing the effectiveness of PDT and CDT by generating increased singlet oxygen (1O2) and hydroxyl radicals (•OH). Moreover, the presence of Mn2+ ions enabled the activation of T1-weighted magnetic resonance imaging. In vivo findings further validated that HAMnO2A displayed meaningful tumor-targeting capabilities, prolonged circulation time in the bloodstream, and outstanding efficacy in restraining tumor growth while inducing minimal damage to normal tissues. Hence, this nanoplatform serves as an efficient all-in-one solution by facilitating the integration of multiple functions, ultimately enhancing the effectiveness of tumor theranostics.

Dynamic contrast-enhanced MRI for assessing therapeutic response of choroidal neovascularization in a rat model.

PURPOSE: We evaluated the potential of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) as a noninvasive biomarker of choroidal neovascularization (CNV) and its utility as a tool for monitoring therapeutic response in laser-induced rat CNV models. METHODS: CNV was induced in the right eyes of 14 rats using a laser. Rats (n = 7) were treated daily for 14 days with a candidate drug (KR-31831, 50 mg/kg of body weight) having antiangiogenic effects, whereas control rats (n = 7) were treated with the vehicle alone (10% cremophor, 10% absolute ethyl alcohol, and 80% saline). DCE-MRI examinations were performed on the day before surgery (D - 1), and 3, 7, and 14 days after surgery (D + 3, D + 7, and D + 14), from which pharmacokinetic parameters (K(trans), v(e), v(p)) were calculated. Angiography was performed to visualize CNV using FITC-labeled high molecular weight dextran after MRI on D + 14. The paired Wilcoxon test and Mann-Whitney U test were performed for statistical analysis. RESULTS: The K(trans) and v(e) values of the CNV-induced right eyes were significantly higher than those of the intact eyes in control rats at D + 14 (P < 0.05). In the CNV-induced eyes, the relative K(trans) and v(e) values of the KR-31831-treated group were significantly lower than those of the nontreated group at D + 14 (P < 0.05). The angiography showed that decreased CNV was observed in rats treated with KR-31831. CONCLUSIONS: Quantitative DCE-MRI produces noninvasive biomarker of CNV, thus allowing monitoring of therapeutic response of antiangiogenic drugs in neovascular age-related macular degeneration (AMD).