Diet modification reverses diastolic dysfunction in rats with heart failure and preserved ejection fraction.

Dahl Salt-Sensitive (DSS) rats develop heart failure with preserved ejection fraction (HFpEF) when fed a high-salt (8 % NaCl) diet. Hypertension-induced inflammation and subsequent ventricular fibrosis are believed to underlie the development of HFpEF. We investigated the role of diet modification in the progression of HFpEF using male DSS rats, fed either a high-salt diet from7 weeks of age to induce HFpEF, ora normal-salt (0.3% NaCl) diet as controls. After echocardiographic confirmation of diastolic dysfunction at 14-15 weeks of age along with HF manifestations, the HFpEF rats were randomly assigned to either continue a high-salt diet or switch to a normal-salt diet for an additional 4 weeks. HFpEF rats with diet modification showed improved diastolic function (reduced E/E' ratio in echocardiogram), increased functional capacity (increased treadmill exercise distance), and reduced pulmonary congestions (lung/body weight ratio), compared to high-salt-fed HFpEF rats. Systolic blood pressure remained high (~200 mmHg), and ventricular hypertrophy remained unchanged. Ventricular arrhythmia inducibility (100 % inducible) and corrected QT interval (on ECG) did not change in HFpEF rats after diet modification. HFpEF rats with diet modification showed prolonged survival and reduced ventricular fibrosis (Masson's trichrome staining) compared to high-salt-fed HFpEF rats. Hence, the modification of diet (from high-salt to normal-salt diet) reversed HFpEF phenotypes without affecting blood pressure or ventricular hypertrophy.

Quantitative Biodistribution and Pharmacokinetics Study of GMP-Grade Exosomes Labeled with 89Zr Radioisotope in Mice and Rats.

For the successful clinical advancement of exosome therapeutics, the biodistribution and pharmacokinetic profile of exogenous exosomes in various animal models must be determined. Compared with fluorescence or bioluminescence imaging, radionuclide imaging confers multiple advantages for the in vivo tracking of biomolecular therapeutics because of its excellent sensitivity for deep tissue imaging and potential for quantitative measurement. Herein, we assessed the quantitative biodistribution and pharmacokinetics of good manufacturing practice-grade therapeutic exosomes labeled with zirconium-89 (89Zr) after systemic intravenous administration in mice and rats. Quantitative biodistribution analysis by positron emission tomography/computed tomography and gamma counting in mice and rats revealed that the total 89Zr signals in the organs were lower in rats than in mice, suggesting a higher excretion rate of exosomes in rats. A prolonged 89Zr signal for up to 7 days in most organs indicated that substantial amounts of exosomes were taken up by the parenchymal cells in those organs, highlighting the therapeutic potential of exosomes for the intracellular delivery of therapeutics. Exosomes were mainly distributed in the liver and to a lesser extent in the spleen, while a moderately distributed in the kidney, lung, stomach, intestine, urinary bladder, brain, and heart. Exosomes were rapidly cleared from the blood circulation, with a rate greater than that of free 89Zr, indicating that exosomes might be rapidly taken up by cells and tissues.

Exosome-based delivery of super-repressor IκBα ameliorates kidney ischemia-reperfusion injury.

Ischemia-reperfusion injury is a major cause of acute kidney injury. Recent studies on the pathophysiology of ischemia-reperfusion-induced acute kidney injury showed that immunologic responses significantly affect kidney ischemia-reperfusion injury and repair. Nuclear factor (NF)-ĸB signaling, which controls cytokine production and cell survival, is significantly involved in ischemia-reperfusion-induced acute kidney injury, and its inhibition can ameliorate ischemic acute kidney injury. Using EXPLOR, a novel, optogenetically engineered exosome technology, we successfully delivered the exosomal super-repressor inhibitor of NF-ĸB (Exo-srIĸB) into B6 wild type mice before/after kidney ischemia-reperfusion surgery, and compared outcomes with those of a control exosome (Exo-Naïve)-injected group. Exo-srIĸB treatment resulted in lower levels of serum blood urea nitrogen, creatinine, and neutrophil gelatinase-associated lipocalin in post-ischemic mice than in the Exo-Naïve treatment group. Systemic delivery of Exo-srIĸB decreased NF-ĸB activity in post-ischemic kidneys and reduced apoptosis. Post-ischemic kidneys showed decreased gene expression of pro-inflammatory cytokines and adhesion molecules with Exo-srIĸB treatment as compared with the control. Intravital imaging confirmed the uptake of exosomes in neutrophils and macrophages. Exo-srIĸB treatment also significantly affected post-ischemic kidney immune cell populations, lowering neutrophil, monocyte/macrophage, and T cell frequencies than those in the control. Thus, modulation of NF-ĸB signaling through exosomal delivery can be used as a novel therapeutic method for ischemia-reperfusion-induced acute kidney injury.

Chitosan Microgels Embedded with Catalase Nanozyme-Loaded Mesocellular Silica Foam for Glucose-Responsive Drug Delivery.

A glucose-responsive closed-loop insulin delivery system represents an ideal form of treatment for type 1 diabetes mellitus. Here, we develop a glucose-responsive protein delivery system based on chitosan microgels loaded with enzyme-mimicking inorganic nanoparticles. The pH-sensitive chitosan microgels, integrated with glucose-mediated pH-lowering enzymatic large-pore mesoporous silica (MCF), were fabricated via an electrospray process. Ceria nanoparticles (CeNPs), which is a catalase-mimicking inorganic artificial enzyme with a substantial stability compared to that of catalase, were incorporated into the MCF along with glucose oxidase. In hyperglycemic conditions, CeNPs successfully decomposed the toxic hydrogen peroxide that was generated from the glucose oxidation reaction mediated by glucose oxidase and regenerate oxygen; this protected glucose oxidase from denaturation. The pH-lowering induced by the enzymatic MCF in high glucose concentration resulted in swelling of the chitosan microgels and the subsequent release of the encapsulated model protein drug, such as bovine serum albumin and insulin. Finally, we successfully demonstrated self-regulated repetitive protein release from the chitosan microgels, which showed a basal release rate under normoglycemic conditions and an enhanced release rate under hyperglycemic conditions.