Myocardium-Targeted Micelle Nanomedicine That Salvages the Heart from Ischemia/Reperfusion Injury

Ferroptosis mechanisms and regulations in cardiovascular diseases in the past, present, and future

Cardiovascular diseases (CVDs) are the main diseases that endanger human health, and their risk factors contribute to high morbidity and a high rate of hospitalization. Cell death is the most important pathophysiology in CVDs. As one of the cell death mechanisms, ferroptosis is a new form of regulated cell death (RCD) that broadly participates in CVDs (such as myocardial infarction, heart transplantation, atherosclerosis, heart failure, ischaemia/reperfusion (I/R) injury, atrial fibrillation, cardiomyopathy (radiation-induced cardiomyopathy, diabetes cardiomyopathy, sepsis-induced cardiac injury, doxorubicin-induced cardiac injury, iron overload cardiomyopathy, and hypertrophic cardiomyopathy), and pulmonary arterial hypertension), involving in iron regulation, metabolic mechanism and lipid peroxidation. This article reviews recent research on the mechanism and regulation of ferroptosis and its relationship with the occurrence and treatment of CVDs, aiming to provide new ideas and treatment targets for the clinical diagnosis and treatment of CVDs by clarifying the latest progress in CVDs research.

SIRT1 is a regulator of autophagy: Implications for the progression and treatment of myocardial ischemia-reperfusion

SIRT1 is a highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase. It is involved in the regulation of various pathophysiological processes, including cell proliferation, survival, differentiation, autophagy, and oxidative stress. Therapeutic activation of SIRT1 protects the heart and cardiomyocytes from pathology-related stress, particularly myocardial ischemia/reperfusion (I/R). Autophagy is an important metabolic pathway for cell survival during energy or nutrient deficiency, hypoxia, or oxidative stress. Autophagy is a double-edged sword in myocardial I/R injury. The activation of autophagy during the ischemic phase removes excess metabolic waste and helps ensure cardiomyocyte survival, whereas excessive autophagy during reperfusion depletes the cellular components and leads to autophagic cell death. Increasing research on I/R injury has indicated that SIRT1 is involved in the process of autophagy and regulates myocardial I/R. SIRT1 regulates autophagy through various pathways, such as the deacetylation of FOXOs, ATGs, and LC3. Recent studies have confirmed that SIRT1-mediated autophagy plays different roles at different stages of myocardial I/R injury. By targeting the mechanism of SIRT1-mediated autophagy at different stages of I/R injury, new small-molecule drugs, miRNA activators, or blockers can be developed. For example, resveratrol, sevoflurane, quercetin, and melatonin in the ischemic stage, coptisine, curcumin, berberine, and some miRNAs during reperfusion, were involved in regulating the SIRT1-autophagy axis, exerting a cardioprotective effect. Here, we summarize the possible mechanisms of autophagy regulation by SIRT1 in myocardial I/R injury and the related molecular drug applications to identify strategies for treating myocardial I/R injury.

Silica Cross-Linked Micelle-Based Theranostic System for the Imaging and Treatment of Acute and Chronic Kidney Injury

Acute kidney injury (AKI) is a common and serious disease with high mortality and morbidity, and the persistent inflammatory environment brought about by AKI promotes its deterioration into chronic kidney disease (CKD). An efficient and timely targeted drug delivery to the renal tubules is crucial for AKI treatment. Here, we prepared silica cross-linked micelles (SCLMs) with different sizes and studied their targeting ability to the injured kidney. It is found that the SCLMs with a size of 13 nm could rapidly accumulate and remain in the damaged kidney. Immunofluorescence results confirmed that SCLMs are selectively located in the damaged tubular cells but cannot be found in healthy renal tissue. Therefore, fluorescent dye-labeled SCLMs were used for the imaging of the injured kidney, which could reflect the status of the kidney injury. Furthermore, atorvastatin, an antioxidative and anti-inflammatory drug, was loaded in SCLMs as the therapeutic agents for the treatment of ischemia/reperfusion-induced AKI and CKD. Renal function indexes, such as tubular necrosis, collagen deposition, and inflammation, were effectively improved after the treatment.

Real-Time Visualization of the Antioxidative Potency of Drugs for the Prevention of Myocardium Ischemia-Reperfusion Injury by a NIR Fluorescent Nanoprobe

The burst of the reactive oxygen species (ROS) is the culprit of myocardial ischemia-reperfusion injury. As direct ROS scavengers, antioxidants are clinically documented drugs for the prevention of reperfusion injury. However, some drugs give disappointing therapeutic performance despite their good in vitro effects. Therefore, in vivo assessments are necessary to screen the antioxidants before clinical trials. However, traditional methods such as histological study require invasive and complicated preprocessing of the biological samples, which may fail to reflect the actual level of the unstable ROS with a very short lifetime. Peroxynitrite (ONOO^-) is a characteristic endogenous ROS produced during reperfusion. Here, we modified the ONOO^--responsive near-infrared fluorescent probe on a myocardium-targeting silica cross-linked micelle to prepare a nanoprobe for the real-time monitoring of ONOO^- during coronary reperfusion. A ROS-stable cyanine dye was co-labeled as an internal reference to achieve ratiometric sensing. The nanoprobe can passively target the infarcted myocardium and monitor the generation of ONOO^- during reperfusion in real-time. The antioxidants, carvedilol, atorvastatin, and resveratrol, were used as model drugs to demonstrate the capability of the nanoprobe to evaluate the antioxidative potency in situ. The drugs were either loaded and delivered by the nanoprobe to compare their in vivo efficacy under similar concentrations or administered intraperitoneally as a free drug to take their pharmacokinetics into account. The imaging results revealed that pharmacokinetics might be the determinant factor that influences the efficacy of the antioxidants.