Cardiomyocyte uptake mechanism of a hydroxyapatite nanoparticle mediated gene delivery system

Hydrogen decreases susceptibility to AngII-induced atrial fibrillation and atrial fibrosis via the NOX4/ROS/NLRP3 and TGF-β1/Smad2/3 signaling pathways

Atrial fibrillation (AF) represents the commonly occurring cardiac arrhythmia and the main factor leading to stroke and heart failure. Hydrogen (H2) is a gaseous signaling molecule that has the effects of anti-inflammation and antioxidation. Our study provides evidence that hydrogen decreases susceptibility to AngII-mediated AF together with atrial fibrosis. Following continuous AngII administration for a 28-day period, AngII+H2 treated rats showed decreased susceptibility to AF, a decrease in atrial fibrosis, a decrease in ROS in atrial myocytes, an inhibition of NLRP3 inflammasome activation, an improvement in electrical remodeling, and an inhibition of proliferation and migration of cardiac fibroblasts. We further found that hydrogen regulates the activation of inflammasome and thus improves Ca2+ handling and IKAch and IKur by inhibiting the activity of NOX4 in vivo. In addition, hydrogen was involved in AngII-mediated atrial fibrosis through inhibiting TGF-β1/Smad2/3 pathway through suppressing TGF-β1 activation and secretion in vivo. Our findings suggest that hydrogen is important for preventing and treating AngII-mediated AF and atrial fibrosis, suggesting that hydrogen could be used as the candidate way to prevent and treat AF.

In vivo toxicity evaluation of tumor targeted glycol chitosan nanoparticles in healthy mice: repeated high-dose of glycol chitosan nanoparticles potentially induce cardiotoxicity

BACKGROUND

Glycol chitosan nanoparticles (CNPs) have emerged as an effective drug delivery system for cancer diagnosis and treatment. Although they have great biocompatibility owing to biodegradable chemical structure and low immunogenicity, sufficient information on in vivo toxicity to understand the potential risks depending on the repeated high-dose have not been adequately studied. Herein, we report the results of in vivo toxicity evaluation for CNPs focused on the number and dose of administration in healthy mice to provide a toxicological guideline for a better clinical application of CNPs.

RESULTS

The CNPs were prepared by conjugating hydrophilic glycol chitosan with hydrophobic 5β-cholanic acid and the amphiphilic glycol chitosan-5β-cholanic acid formed self-assembled nanoparticles with its concentration-dependent homogeneous size distributions (265.36-288.3 nm) in aqueous condition. In cell cultured system, they showed significantly high cellular uptake in breast cancer cells (4T1) and cardiomyocytes (H9C2) than in fibroblasts (L929) and macrophages (Raw264.7) in a dose- and time-dependent manners, resulting in severe necrotic cell death in H9C2 at a clinically relevant highly concentrated condition. In particular, when the high-dose (90 mg/kg) of CNPs were intravenously injected into the healthy mice, considerable amount was non-specifically accumulated in major organs (liver, lung, spleen, kidney and heart) after 6 h of injection and sustainably retained for 72 h. Finally, repeated high-dose of CNPs (90 mg/kg, three times) induced severe cardiotoxicity accompanying inflammatory responses, tissue damages, fibrotic changes and organ dysfunction.

CONCLUSIONS

This study demonstrates that repeated high-dose CNPs induce severe cardiotoxicity in vivo. Through the series of toxicological assessments in the healthy mice, this study provides a toxicological guideline that may expedite the application of CNPs in the clinical settings.