Abnormal Lysosomal Positioning and Small Extracellular Vesicle Secretion in Arterial Stiffening and Calcification of Mice Lacking Mucolipin 1 Gene

Alleviating vascular calcification with Bushen Huoxue formula in rats with chronic kidney disease by inhibiting the PTEN/PI3K/AKT signaling pathway through exosomal microRNA-32

BACKGROUND

Vascular calcification (VC) significantly raises cardiovascular mortality in chronic kidney disease (CKD) patients. VC is characterized by the phenotypic transformation of vascular smooth muscle cells (VSMCs) to osteoblast-like cells, mediated by exosomes derived from calcified VSMCs and the exosomal microRNAs (miRNA) which may trigger some signals to recipient VSMCs. Bushen Huoxue (BSHX) formula has demonstrated its clinical efficacy in CKD and its protective role in CKD-VC rats has also been observed. However, little is known about its underlying mechanism.

METHODS

To establish a VC model, aortic VSMCs from rats were induced to osteogenic differentiation by high-level phosphate (HP) in vitro. The expression of exosome and calcification makers were analyzed by western blot, including CD9, CD63, α-SMA, BMP-2, and Runx2, respectively. Differential expression of exosomal miRNAs in normal and HP-induced VSMCs were identified by using whole miRNA microarray technology. GO and KEGG analyses were performed to determine the significant enrichment of functions and signaling pathways in the target genes. In vivo, the CKD-VC rat model was established by administering adenine gavage combined with a high phosphorus diet. The rats were divided into normal control, model, low-dose BSHX, medium-dose BSHX, high-dose BSHX groups, and sevelamer groups. The blood biochemical parameters were measured. Renal histopathology and aortic calcification were observed. Western blot detected the levels of the calcification markers. Quantitative real-time PCR (qPCR) assay detected exosomal microRNA-32 (miR-32) mRNA expression in the aorta, the most differentially expressed exosomal miRNA previously identified. Phosphatase and tensin homolog located on chromosome ten (PTEN)/phosphatidylinositol-3 kinase (PI3K)/protein kinase B (AKT) signaling pathway components were also tested by western blot.

RESULTS

Exosomal miRNA-32 and PI3K/AKT signaling pathways were highly differentially expressed between normal and HP-induced VSMCs. In vivo, BSHX improved blood biochemical parameters, renal histopathology, and aortic calcification in CKD-VC rats. BSHX increased the expression level of α-SMA and decreased the level of BMP-2 and Runx2. BSHX also lowered the expression level of exosomal miR-32 mRNA, enhanced PTEN expression, therefore, reduced p-PI3K and p-AKT levels in the aorta.

CONCLUSION

BSHX alleviated VC in CKD rats by downregulating exosomal miR-32 expression in the aorta, thereby promoting PTEN expression and inhibiting the PI3K/AKT signaling pathway.

Peripheral Lysosomal Positioning in Inflamed Odontoblasts Facilitates Mineralization

INTRODUCTION

Odontoblasts, terminally differentiated dentin-producing cells, critically rely on lysosomal functions for intracellular recycling and renewal. Beyond their traditional degradative role, lysosomes actively orchestrate cellular responses to external stimuli through precise and rapid intracellular trafficking and positioning. This study aimed to explore the influence of lysosomal positioning on odontoblast mineralization and the underlying mechanisms implicated in carious inflammation.

METHODS

Human dental pulp stem cells were induced to differentiate into human odontoblast-like cells (hOBLCs). hOBLCs were treated with various doses of LPS (0.1, 1, 5 μg/mL) to mimic carious inflammation. Lysosomal positioning was examined by immunofluorescence staining of lysosomal associated membrane protein 1 in healthy and carious human teeth, LPS-treated hOBLCs, mouse lower incisors at postnatal day 2.5, and mineralization medium cultured human dental pulp stem cells. Lysosomal positioning was manipulated by knockdown or overexpression of SNAPIN or ARL8B. Mineralization was assessed by ARS staining and expression of DSPP and DMP1. Lysosomal exocytosis was examined by detection of lysosomal-plasma membrane fusion, surface exposure of lysosomal associated membrane protein 1 luminal epitopes (1D4B), and extracellularly released lysosomal enzymes.

RESULTS

Peripheral lysosomal positioning was markedly increased in odontoblasts within moderate and extensive carious lesions (P < .001) and in hOBLCs following LPS treatment. Increased peripheral dispersion of lysosomes was similarly observed during odontoblastic differentiation in vivo and in vitro. Moreover, peripheral lysosomal positioning promoted mineralization in inflamed hOBLCs, potentially via mTORC1 signaling pathway and lysosomal exocytosis.

CONCLUSION

Inflammatory stimuli prompted a relocation of lysosomes in odontoblasts, redistributing them from perinuclear location toward the cell periphery, which in turn facilitated mineralization, potentially via mTORC1 signaling and lysosomal exocytosis.

Exosomes based strategies for cardiovascular diseases: Opportunities and challenges

Exosomes, as nanoscale extracellular vesicles (EVs), are secreted by all types of cells to facilitate intercellular communication in living organisms. After being taken up by neighboring or distant cells, exosomes can alter the expression levels of target genes in recipient cells and thereby affect their pathophysiological outcomes depending on payloads encapsulated therein. The functions and mechanisms of exosomes in cardiovascular diseases have attracted much attention in recent years and are thought to have cardioprotective and regenerative potential. This review summarizes the biogenesis and molecular contents of exosomes and details the roles played by exosomes released from various cells in the progression and recovery of cardiovascular disease. The review also discusses the current status of traditional exosomes in cardiovascular tissue engineering and regenerative medicine, pointing out several limitations in their application. It emphasizes that some of the existing emerging industrial or bioengineering technologies are promising to compensate for these shortcomings, and the combined application of exosomes and biomaterials provides an opportunity for mutual enhancement of their performance. The integration of exosome-based cell-free diagnostic and therapeutic options will contribute to the further development of cardiovascular regenerative medicine.

Circulating miR-6821-5p levels and coronary calcification in asymptomatic familial hypercholesterolemia patients

BACKGROUND AND AIMS

Premature atherosclerotic cardiovascular disease (CVD) is a clinic characteristic of familial hypercholesterolemia (FH). Coronary calcium score (CCS) is a highly used imaging modality to evidence atherosclerotic plaque burden. microRNAs (miRNAs) are non-coding RNAs that epigenetically regulate gene expression. Here, we investigated whether CCS associates with a specific miRNA-signature in FH-patients.

METHODS

Patients with genetic diagnosis of FH (N = 86) from the nationwide SAFEHEART-cohort were investigated by computed tomography angiography imaging and classified depending on the presence of coronary calcification in FH-CCS (+) and FH-CCS (-) groups by the Agatston score. Differential miRNA profiling was performed in two stages: first by Affymetrix microarray technology (high-throughput differential profiling-studies) and second by RT-PCR using TaqMan-technology (analytical RT-qPCR study) in plasma of the two patient groups.

RESULTS

miR-193a-5p, miR-30e-5p and miR-6821-5p levels were significantly higher in FH-CCS (+) compared to FH-CCS (-). miR-6821-5p was the best miRNA to discriminate FH-patients CCS(+), according to receiver operating characteristic (ROC) analysis (AUC: 0.70 ± 0.06, p = 0.006). High miR-6821-5p levels were associated with older age (p = 0.03) and high LDL-burden (p = 0.014) using a ROC-derived cut-off value. However, miR-6821-5p did not correlate with age in either the CCS- or CCS + group. Genes involved in calcification processes were identified by in silico analysis. The relation of cell-calcification and expression levels of miR-6821-5p, BMP2 and SPP1 was validated experimentally in human vascular smooth muscle cell cultures.

CONCLUSIONS

Up-regulated levels of miR-6821-5p are found in the plasma of asymptomatic FH-patients with coronary calcified atherosclerotic plaques, as well as in isolated human vascular smooth muscle cells expressing the pro-calcification genes BMP2 and SPP1. These findings highlight the impact of epigenetic regulation on the development of subclinical atherosclerosis.

Potential actions of capsaicin for preventing vascular calcification of vascular smooth muscle cells in vitro and in vivo

Vascular calcification (VC) is an accurate risk factor and predictor of adverse cardiovascular events; however, there is currently no effective therapy to specifically prevent VC progression. Capsaicin (Cap) is a bioactive alkaloid isolated from Capsicum annuum L., a traditional medicinal and edible plant that is beneficial for preventing cardiovascular diseases. However, the effect of Cap on VC remains unclear. This study aimed to explore the effects and related mechanisms of Cap on aortic calcification in a mouse and on Pi-induced calcification in vascular smooth muscle cells (VSMCs). First, we established a calcification mouse model with vitamin D3 and evaluated the effects of Cap on calcification mice using von Kossa staining, calcium content, and alkaline phosphatase activity tests. The results showed that Cap significantly improved calcification in mice. VSMCs were then cultured in 2.6 mM Na2HPO4 and 50 μg/mL ascorbic acid for 7 days to obtain a calcification model, and we investigated the effects and mechanisms of Cap on VSMCs calcification by assessing the changes of calcium deposition, calcium content, and subsequent VC biomarkers. These results showed that Cap alleviated VSMCs calcification by upregulating the expressions of TRPV1. Moreover, Cap reduced the expression of Wnt3a and β-catenin, whereas DKK1 antagonised the inhibitory effect of Cap on VSMC calcification. This study is the first to offer direct evidence that Cap inhibits the Wnt/β-catenin signaling pathway by upregulating the expression of the TRPV1 receptor, resulting in the decreased expression of Runx2 and BMP-2, thereby reducing VSMC calcification. Our study may provide novel strategies for preventing the progression of VC. This could serve as a theoretical basis for clinically treating VC with spicy foods.

UBA6 Inhibition Accelerates Lysosomal TRPML1 Depletion and Exosomal Secretion in Lung Cancer Cells

Ubiquitin-like modifier-activating enzyme 6 (UBA6) is a member of the E1 enzyme family, which initiates the ubiquitin-proteasome system (UPS). The UPS plays critical roles not only in protein degradation but also in various cellular functions, including neuronal signaling, myocardial remodeling, immune cell differentiation, and cancer development. However, the specific role of UBA6 in cellular functions is not fully elucidated in comparison with the roles of the UPS. It has been known that the E1 enzyme is associated with the motility of cancer cells. In this study, we verified the physiological roles of UBA6 in lung cancer cells through gene-silencing siRNA targeting UBA6 (siUBA6). The siUBA6 treatment attenuated the migration of H1975 cells, along with a decrease in lysosomal Ca2+ release. While autophagosomal proteins remained unchanged, lysosomal proteins, including TRPML1 and TPC2, were decreased in siUBA6-transfected cells. Moreover, siUBA6 induced the production of multivesicular bodies (MVBs), accompanied by an increase in MVB markers in siUBA6-transfected H1975 cells. Additionally, the expression of the exosomal marker CD63 and extracellular vesicles was increased by siUBA6 treatment. Our findings suggest that knock-down of UBA6 induces lysosomal TRPML1 depletion and inhibits endosomal trafficking to lysosome, and subsequently, leads to the accumulation of MVBs and enhanced exosomal secretion in lung cancer cells.

Vascular calcification: from the perspective of crosstalk

Vascular calcification (VC) is highly correlated with cardiovascular disease morbidity and mortality, but anti-VC treatment remains an area to be tackled due to the ill-defined molecular mechanisms. Regardless of the type of VC, it does not depend on a single cell but involves multi-cells/organs to form a complex cellular communication network through the vascular microenvironment to participate in the occurrence and development of VC. Therefore, focusing only on the direct effect of pathological factors on vascular smooth muscle cells (VSMCs) tends to overlook the combined effect of other cells and VSMCs, including VSMCs-VSMCs, ECs-VMSCs, Macrophages-VSMCs, etc. Extracellular vesicles (EVs) are a collective term for tiny vesicles with a membrane structure that are actively secreted by cells, and almost all cells secrete EVs. EVs docked on the surface of receptor cells can directly mediate signal transduction or transfer their contents into the cell to elicit a functional response from the receptor cells. They have been proven to participate in the VC process and have also shown attractive therapeutic prospects. Based on the advantages of EVs and the ability to be detected in body fluids, they may become a novel therapeutic agent, drug delivery vehicle, diagnostic and prognostic biomarker, and potential therapeutic target in the future. This review focuses on the new insight into VC molecular mechanisms from the perspective of crosstalk, summarizes how multi-cells/organs interactions communicate via EVs to regulate VC and the emerging potential of EVs as therapeutic methods in VC. We also summarize preclinical experiments on crosstalk-based and the current state of clinical studies on VC-related measures.

Pathophysiology of Lysosomes in a Nutshell

Lysosomes are acidic organelles present in all nucleated mammalian cells [...].

Regulation of exosome release by lysosomal acid ceramidase in coronary arterial endothelial cells: Role of TRPML1 channel

Lysosomal acid ceramidase (AC) has been reported to determine multivesicular body (MVB) fate and exosome secretion in different mammalian cells including coronary arterial endothelial cells (CAECs). However, this AC-mediated regulation of exosome release from CAECs and associated underlying mechanism remain poorly understood. In the present study, we hypothesized that AC controls lysosomal Ca2+ release through TRPML1 channel to regulate exosome release in murine CAECs. To test this hypothesis, we isolated and cultured CAECs from WT/WT and endothelial cell-specific Asah1 gene (gene encoding AC) knockout mice. Using these CAECs, we first demonstrated a remarkable increase in exosome secretion and significant reduction of lysosome-MVB interaction in CAECs lacking Asah1 gene compared to those cells from WT/WT mice. ML-SA1, a TRPML1 channel agonist, was found to enhance lysosome trafficking and increase lysosome-MVB interaction in WT/WT CAECs, but not in CAECs lacking Asah1 gene. However, sphingosine, an AC-derived sphingolipid, was able to increase lysosome movement and lysosome-MVB interaction in CAECs lacking Asah1 gene, leading to reduced exosome release from these cells. Moreover, Asah1 gene deletion was shown to substantially inhibit lysosomal Ca2+ release through suppression of TRPML1 channel activity in CAECs. Sphingosine as an AC product rescued the function of TRPML1 channel in CAECs lacking Asah1 gene. These results suggest that Asah1 gene defect and associated deficiency of AC activity may inhibit TRPML1 channel activity, thereby reducing MVB degradation by lysosome and increasing exosome release from CAECs. This enhanced exosome release from CAECs may contribute to the development of coronary arterial disease under pathological conditions.

Application of meso-CF3-Fluorophore BODIPY with Phenyl and Pyrazolyl Substituents for Lifetime Visualization of Lysosomes

A bright far-red emitting unsymmetrical meso-CF₃-BODIPY fluorescent dye with phenyl and pyrazolyl substituents was synthesized by condensation of trifluoropyrrolylethanol with pyrazolyl-pyrrole, with subsequent oxidation and complexation of the formed dipyrromethane. This BODIPY dye exhibits optical absorption at λ_ab ≈ 610-620 nm and emission at λ_em ≈ 640-650 nm. The BODIPY was studied on Ehrlich carcinoma cells as a lysosome-specific fluorescent dye that allows intravital staining of cell structures with subsequent real-time monitoring of changes occurring in the cells. It was also shown that the rate of uptake by cells, the rate of intracellular transport into lysosomes, and the rate of saturation of cells with the dye depend on its concentration in the culture medium. A concentration of 5 μM was chosen as the most suitable BODIPY concentration for fluorescent staining of living cell lysosomes, while a concentration of 100 μM was found to be toxic to Ehrlich carcinoma cells.

The potential role of extracellular vesicles in bioactive compound-based therapy: A review of recent developments

Recent studies have explored the field of extracellular vesicles (EVs), driving an increasing interest in their application to human health. EVs have unique physicochemical traits to participate in intercellular communication, thus fostering the idea of using EVs to yield synergistic, preventive, and therapeutic effects. Many reports have shown that EVs contain natural bioactive compounds, such as lipids, proteins, RNA, and other active components that regulate biological processes, thereby contributing to human health. Therefore, in this review, we comprehensively elucidate various facets of the relationship between EVs and bioactive compounds that modulate EVs contents, including RNAs and proteins, discussing different forms of biological regulation. The use of EVs for cargo-loading bioactive compounds to exert biological functions and methods to load bioactive compounds into EVs are also discussed. This review highlighted the effect of EV-delivered bioactive compounds on several therapeutic mechanisms and applications, providing new insight into nutrition and pharmacology.

Cellular Crosstalk in the Vascular Wall Microenvironment: The Role of Exosomes in Vascular Calcification

Vascular calcification is prevalent in aging, diabetes, chronic kidney disease, cardiovascular disease, and certain genetic disorders. However, the pathogenesis of vascular calcification is not well-understood. It has been progressively recognized that vascular calcification depends on the bidirectional interactions between vascular cells and their microenvironment. Exosomes are an essential bridge to mediate crosstalk between cells and organisms, and thus they have attracted increased research attention in recent years. Accumulating evidence has indicated that exosomes play an important role in cardiovascular disease, especially in vascular calcification. In this review, we introduce vascular biology and focus on the crosstalk between the different vessel layers and how their interplay controls the process of vascular calcification.

Programmed cell death in atherosclerosis and vascular calcification

The concept of cell death has been expanded beyond apoptosis and necrosis to additional forms, including necroptosis, pyroptosis, autophagy, and ferroptosis. These cell death modalities play a critical role in all aspects of life, which are noteworthy for their diverse roles in diseases. Atherosclerosis (AS) and vascular calcification (VC) are major causes for the high morbidity and mortality of cardiovascular disease. Despite considerable advances in understanding the signaling pathways associated with AS and VC, the exact molecular basis remains obscure. In the article, we review the molecular mechanisms that mediate cell death and its implications for AS and VC. A better understanding of the mechanisms underlying cell death in AS and VC may drive the development of promising therapeutic strategies.

Matrix Vesicles as a Therapeutic Target for Vascular Calcification

Vascular calcification (VC) is linked to an increased risk of heart disease, stroke, and atherosclerotic plaque rupture. It is a cell-active process regulated by vascular cells rather than pure passive calcium (Ca) deposition. In recent years, extracellular vesicles (EVs) have attracted extensive attention because of their essential role in the process of VC. Matrix vesicles (MVs), one type of EVs, are especially critical in extracellular matrix mineralization and the early stages of the development of VC. Vascular smooth muscle cells (VSMCs) have the potential to undergo phenotypic transformation and to serve as a nucleation site for hydroxyapatite crystals upon extracellular stimulation. However, it is not clear what underlying mechanism that MVs drive the VSMCs phenotype switching and to result in calcification. This article aims to review the detailed role of MVs in the progression of VC and compare the difference with other major drivers of calcification, including aging, uremia, mechanical stress, oxidative stress, and inflammation. We will also bring attention to the novel findings in the isolation and characterization of MVs, and the therapeutic application of MVs in VC.

Lysosome Function in Cardiovascular Diseases

The lysosome is a single ubiquitous membrane-enclosed intracellular organelle with an acidic pH present in all eukaryotic cells, which contains large numbers of hydrolytic enzymes with their maximal enzymatic activity at a low pH (pH ≤ 5) such as proteases, nucleases, and phosphatases that are able to degrade extracellular and intracellular components. It is well known that lysosomes act as a center for degradation and recycling of large numbers of macromolecules delivered by endocytosis, phagocytosis, and autophagy. Lysosomes are recognized as key organelles for cellular clearance and are involved in many cellular processes and maintain cellular homeostasis. Recently, it has been shown that lysosome function and its related pathways are of particular importance in vascular regulation and related diseases. In this review, we highlighted studies that have improved our understanding of the connection between lysosome function and vascular physiological and pathophysiological activities in arterial smooth muscle cells (SMCs) and endothelial cells (ECs). Sphingolipids-metabolizingenzymes in lysosomes play critical roles in intracellular signaling events that influence cellular behavior and function in SMCs and ECs. The focus of this review will be to define the mechanism by which the lysosome contributes to cardiovascular regulation and diseases. It is believed that exploring the role of lysosomal function and its sphingolipid metabolism in the initiation and progression of vascular disease and regulation may provide novel insights into the understanding of vascular pathobiology and helps develop more effective therapeutic strategies for vascular diseases.

Endolysosomal Ca2+ signaling in cardiovascular health and disease

An increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) regulates a plethora of functions in the cardiovascular (CV) system, including contraction in cardiomyocytes and vascular smooth muscle cells (VSMCs), and angiogenesis in vascular endothelial cells and endothelial colony forming cells. The sarco/endoplasmic reticulum (SR/ER) represents the largest endogenous Ca²⁺ store, which releases Ca²⁺ through ryanodine receptors (RyRs) and/or inositol-1,4,5-trisphosphate receptors (InsP₃Rs) upon extracellular stimulation. The acidic vesicles of the endolysosomal (EL) compartment represent an additional endogenous Ca²⁺ store, which is targeted by several second messengers, including nicotinic acid adenine dinucleotide phosphate (NAADP) and phosphatidylinositol 3,5-bisphosphate [PI(3,5)P₂], and may release intraluminal Ca²⁺ through multiple Ca²⁺ permeable channels, including two-pore channels 1 and 2 (TPC1-2) and Transient Receptor Potential Mucolipin 1 (TRPML1). Herein, we discuss the emerging, pathophysiological role of EL Ca²⁺ signaling in the CV system. We describe the role of cardiac TPCs in β-adrenoceptor stimulation, arrhythmia, hypertrophy, and ischemia-reperfusion injury. We then illustrate the role of EL Ca²⁺ signaling in VSMCs, where TPCs promote vasoconstriction and contribute to pulmonary artery hypertension and atherosclerosis, whereas TRPML1 sustains vasodilation and is also involved in atherosclerosis. Subsequently, we describe the mechanisms whereby endothelial TPCs promote vasodilation, contribute to neurovascular coupling in the brain and stimulate angiogenesis and vasculogenesis. Finally, we discuss about the possibility to target TPCs, which are likely to mediate CV cell infection by the Severe Acute Respiratory Disease-Coronavirus-2, with Food and Drug Administration-approved drugs to alleviate the detrimental effects of Coronavirus Disease-19 on the CV system.

The Progress of Advanced Ultrasonography in Assessing Aortic Stiffness and the Application Discrepancy between Humans and Rodents

Aortic stiffening is a fundamental pathological alteration of atherosclerosis and other various aging-associated vascular diseases, and it is also an independent risk factor of cardiovascular morbidity and mortality. Ultrasonography is a critical non-invasive method widely used in assessing aortic structure, function, and hemodynamics in humans, playing a crucial role in predicting the pathogenesis and adverse outcomes of vascular diseases. However, its applications in rodent models remain relatively limited, hindering the progress of the research. Here, we summarized the progress of the advanced ultrasonographic techniques applied in evaluating aortic stiffness. With multiple illustrative images, we mainly characterized various ultrasound techniques in assessing aortic stiffness based on the alterations of aortic structure, hemodynamics, and tissue motion. We also discussed the discrepancy of their applications in humans and rodents and explored the potential optimized strategies in the experimental research with animal models. This updated information would help to better understand the nature of ultrasound techniques and provide a valuable prospect for their applications in assessing aortic stiffness in basic science research, particularly with small animals.

Lysosomal TRPML1 Channel: Implications in Cardiovascular and Kidney Diseases

Lysosomal ion channels mediate ion flux from lysosomes and regulate membrane potential across the lysosomal membrane, which are essential for lysosome biogenesis, nutrient sensing, lysosome trafficking, lysosome enzyme activity, and cell membrane repair. As a cation channel, the transient receptor potential mucolipin 1 (TRPML1) channel is mainly expressed on lysosomes and late endosomes. Recently, the normal function of TRPML1 channels has been demonstrated to be important for the maintenance of cardiovascular and renal glomerular homeostasis and thereby involved in the pathogenesis of some cardiovascular and kidney diseases. In arterial myocytes, it has been found that Nicotinic Acid Adenine Dinucleotide Phosphate (NAADP), an intracellular second messenger, can induce Ca²⁺ release through the lysosomal TRPML1 channel, leading to a global Ca²⁺ release response from the sarcoplasmic reticulum (SR). In podocytes, it has been demonstrated that lysosomal TRPML1 channels control lysosome trafficking and exosome release, which contribute to the maintenance of podocyte functional integrity. The defect or functional deficiency of lysosomal TRPML1 channels has been shown to critically contribute to the initiation and development of some chronic degeneration or diseases in the cardiovascular system or kidneys. Here we briefly summarize the current evidence demonstrating the regulation of lysosomal TRPML1 channel activity and related signaling mechanisms. We also provide some insights into the canonical and noncanonical roles of TRPML1 channel dysfunction as a potential pathogenic mechanism for certain cardiovascular and kidney diseases and associated therapeutic strategies.

The Protective Effects of the Autophagic and Lysosomal Machinery in Vascular and Valvular Calcification: A Systematic Review

BACKGROUND

Autophagy is a highly conserved catabolic homeostatic process, crucial for cell survival. It has been shown that autophagy can modulate different cardiovascular pathologies, including vascular calcification (VCN).

OBJECTIVE

To assess how modulation of autophagy, either through induction or inhibition, affects vascular and valvular calcification and to determine the therapeutic applicability of inducing autophagy.

DATA SOURCES

A systematic review of English language articles using MEDLINE/PubMed, Web of Science (WoS) and the Cochrane library. The search terms included autophagy, autolysosome, mitophagy, endoplasmic reticulum (ER)-phagy, lysosomal, calcification and calcinosis. Study characteristics: Thirty-seven articles were selected based on pre-defined eligibility criteria. Thirty-three studies (89%) studied vascular smooth muscle cell (VSMC) calcification of which 27 (82%) studies investigated autophagy and six (18%) studies lysosomal function in VCN. Four studies (11%) studied aortic valve calcification (AVCN). Thirty-four studies were published in the time period 2015-2020 (92%).

CONCLUSION

There is compelling evidence that both autophagy and lysosomal function are critical regulators of VCN, which opens new perspectives for treatment strategies. However, there are still challenges to overcome, such as the development of more selective pharmacological agents and standardization of methods to measure autophagic flux.

Roles of exosomal miRNA in vascular aging

Aging is a major risk factor for human diseases. As global average life expectancy has lengthened, delaying or reducing aging and age-related diseases has become an urgent issue for improving the quality of life. The vascular aging process represents an important link between aging and age-related diseases. Exosomes are small extracellular vesicles (EV) that can be secreted by almost all eukaryotic cells, and they deliver characteristic biological information about donor cells to regulate the cellular microenvironment, mediate signal transmission between neighboring or distant cells, and affect the expression of target genes in recipient cells. Many recent studies have shown that exosomal microribonucleic acids (miRNA) are involved in the regulation of vascular aging by participating in the physiological functions of vascular cells and the destruction and remodeling of the extracellular matrix (ECM). This review summarizes the regulatory functions of exosomal miRNA in vascular aging because they interact with the ECM, and participate in vascular cell senescence, and the regulation of senescence-related functions such as proliferation, migration, apoptosis, inflammation, and differentiation.

ADSC-Exos containing MALAT1 promotes wound healing by targeting miR-124 through activating Wnt/β-catenin pathway

Cutaneous wound is a soft tissue injury that is difficult to heal during aging. It has been demonstrated that adipose-derived stem cells (ADSCs) and its secreted exosomes exert crucial functions in cutaneous wound healing. The present study aimed to elucidate the mechanism of exosomes derived from ADSCs (ADSC-Exos) containing MALAT1 in wound healing. ADSCs were isolated from human normal subcutaneous adipose tissues and identified by flow cytometry analysis. Exosomes were extracted from ADSC supernatants and MALAT1 expression was determined using qRT-PCR analysis. HaCaT and HDF cells were exposed to hydrogen peroxide (H2O2) for simulating the skin lesion model. Subsequently, CCK-8, flow cytometry, wound healing and transwell assays were employed to validate the role of ADSC-Exos containing MALAT1 in the skin lesion model. Besides, cells were transfected with sh-MALAT1 to verify the protective role of MALAT1 in wound healing. The binding relationship between MALAT1 and miR-124 were measured by dual-luciferase reporter assay. ADSC-Exos promoted cell proliferation, migration, and inhibited cell apoptosis of HaCaT and HDF cells impaired by H2O2. However, the depletion of MALAT1 in ADSC-Exos lose these protective effects on HaCaT and HDF cells. Moreover, miR-124 was identified to be a target of MALAT1. Furthermore, ADSC-Exos containing MALAT1 could mediate H2O2-induced wound healing by targeting miR-124 and activating Wnt/β-catenin pathway. ADSC-Exos containing MALAT1 play a positive role in cutaneous wound healing possibly via targeting miR-124 through activating the Wnt/β-catenin pathway, which may provide novel insights into the therapeutic target for cutaneous wound healing.

The Role of Vitamin D in Modulating Mesenchymal Stem Cells and Endothelial Progenitor Cells for Vascular Calcification

Vascular calcification, which involves the deposition of calcifying particles within the arterial wall, is mediated by atherosclerosis, vascular smooth muscle cell osteoblastic changes, adventitial mesenchymal stem cell osteoblastic differentiation, and insufficiency of the calcification inhibitors. Recent observations implied a role for mesenchymal stem cells and endothelial progenitor cells in vascular calcification. Mesenchymal stem cells reside in the bone marrow and the adventitial layer of arteries. Endothelial progenitor cells that originate from the bone marrow are an important mechanism for repairing injured endothelial cells. Mesenchymal stem cells may differentiate osteogenically by inflammation or by specific stimuli, which can activate calcification. However, the bioactive substances secreted from mesenchymal stem cells have been shown to mitigate vascular calcification by suppressing inflammation, bone morphogenetic protein 2, and the Wingless-INT signal. Vitamin D deficiency may contribute to vascular calcification. Vitamin D supplement has been used to modulate the osteoblastic differentiation of mesenchymal stem cells and to lessen vascular injury by stimulating adhesion and migration of endothelial progenitor cells. This narrative review clarifies the role of mesenchymal stem cells and the possible role of vitamin D in the mechanisms of vascular calcification.