Novel mechanisms of endothelial mechanotransduction

Mechanoresponsive patterns of KLF2, 4, 5, and 6 expression differ among subclones from a single mammary tumor

A number of Krüppel-like transcription factor (KLF) family members display mechanoresponsive behaviors, and function as mechanosensitive transcription factors. There are many normal and pathological conditions where their roles in mechanotransduction and mechanoadaptation are not well understood, however. In this study, two basic questions regarding KLF mechanoresponsiveness were addressed: 1) are KLF 2, 4, 5, and 6 expressed at different levels among subclones of tumor cells adapted to specific microenvironmental conditions; and 2) is the expression of these KLFs responsive to rapid changes in the physical environment? To address these questions, the heterogeneous and differentially metastatic murine mammary tumor subclones 4T1, 4T07, and 67NR were subjected to physical changes in their culture conditions, and KLF responses assessed. The results show that the expression of different KLFs exhibit distinct responses to reductions in cell tension, as well as cell detachment from 2D and 3D environments. KLF2 and 4 expression is rapidly and temporarily induced upon release of cells from a stiff 2D substrate into liquid suspension culture in all three subclones, and similar responses are observed in two of the subclones upon the release of tension in 3D collagen gel cultures. By contrast, expression patterns of KLF5 and 6 were generally less affected by physical changes in most, but not all, of the cell lines examined. These results support the concept that KLFs differentially participate in transducing physical differences among intratumoral neighborhoods into distinct responses among heterogeneous subclones, thereby contributing to tumor cell behavioral complexity.

p66Shc Mediates SUMO2-induced Endothelial Dysfunction

Background

Sumoylation is a post-translational modification that can regulate different physiological functions. Increased sumoylation, specifically conjugation of SUMO2/3 (small ubiquitin-like modifier 2/3), is detrimental to vascular health. However, the molecular mechanism mediating this effect is poorly understood.

Methods

We used cell-based assays and mass spectrometry to show that p66Shc is a direct target of SUMO2 and SUMO2 regulates p66Shc function via lysine-81 modification. To determine the effects of SUMO2-p66ShcK81 on vascular function, we generated p66ShcK81R knockin mice and crossbred to LDLr -/- mice to induce hyperlipidemia. Next, to determine p66ShcK81-SUMO2ylation-induced changes in endothelial cell signaling, we performed mass spectrometry followed by Ingenuity Pathway Analysis.

Results

Our data reveal that p66Shc mediates the effects of SUMO2 on endothelial cells. Mass spectrometry identified that SUMO2 modified lysine-81 in the unique collagen homology-2 domain of p66Shc. SUMO2ylation of p66Shc increased phosphorylation at serine-36, causing it to translocate to the mitochondria, a step critical for oxidative function of p66Shc. Notably, sumoylation-deficient p66Shc (p66ShcK81R) was resistant to SUMO2-induced p66ShcS36 phosphorylation and mitochondrial translocation. P66ShcK81R knockin mice were resistant to endothelial dysfunction induced by SUMO2ylation and hyperlipidemia. Ingenuity Pathway Analysis revealed multiple signaling pathways regulated by p66ShcK81-SUMO2ylation in endothelial cells, highlighting Rho-GTPase as a major pathway affected by SUMO2-p66ShcK81.

Conclusions

Collectively, our work reveals SUMO2-p66Shc signaling as a fundamental regulator of vascular endothelial function. We discovered that p66ShcK81 is an upstream modification regulating p66Shc signaling and mediates hyperlipidemia-induced endothelial dysfunction and oxidative stress.

Aortic Stenosis Prevention: Is a New Cardiovascular Disease Paradigm Coming of Age?

Calcific aortic stenosis (CAS) is currently recognized as the third most frequent cardiovascular disorder in persons aged above 60 years, after atherosclerotic disease and hypertension, and together with its precursor aortic sclerosis it has been found in more than 30% of elderly individuals. CAS is an active multifactorial process characterized by a progressive fibro-calcific remodeling and thickening of the AV leaflets caused by hemodynamic flow factors, genetic factors, lipoprotein deposition, oxidation, chronic inflammation, immunomodulators, and finally osteoblastic transformation of cardiac. Herein a comprehensive state-of-the-art paper is presented regarding the underlying pathophysiological mechanisms of CAS and the potential preventive strategies as an alternative to surgical and interventional treatment.

Exploring the Revolutionary Impact of YAP Pathways on Physical and Rehabilitation Medicine

Cellular behavior is strongly influenced by mechanical signals in the surrounding microenvironment, along with external factors such as temperature fluctuations, changes in blood flow, and muscle activity, etc. These factors are key in shaping cellular states and can contribute to the development of various diseases. In the realm of rehabilitation physical therapies, therapeutic exercise and manual treatments, etc., are frequently employed, not just for pain relief but also to support recovery from diverse health conditions. However, the detailed molecular pathways through which these therapies interact with tissues and influence gene expression are not yet fully understood. The identification of YAP has been instrumental in closing this knowledge gap. YAP is known for its capacity to perceive and translate mechanical signals into specific transcriptional programs within cells. This insight has opened up new perspectives on how physical and rehabilitation medicine may exert its beneficial effects. The review investigates the involvement of the Hippo/YAP signaling pathway in various diseases and considers how different rehabilitation techniques leverage this pathway to aid in healing. Additionally, it examines the therapeutic potential of modulating the Hippo/YAP pathway within the context of rehabilitation, while also addressing the challenges and controversies that surround its use in physical and rehabilitation medicine.

Polycomb Repressive Complex 2 promotes atherosclerotic plaque vulnerability

Atherosclerotic cardiovascular disease (ASCVD), the leading cause of mortality worldwide, is driven by endothelial cell inflammatory activation and counter-balanced by anti-inflammatory transcription factors Klf2 and Klf4 (Klf2/4). Understanding vascular endothelial inflammation to develop effective treatments is thus essential. Here, we identify, Polycomb Repressive Complex (PRC) 2, which blocks gene transcription by trimethylating histone3 Lysine27 in gene promoter/enhancers, as a potent, therapeutically targetable determinant of vascular inflammation and ASCVD progression. Bioinformatics identified PRC2 as a direct suppressor of Klf2/4 transcription. Klf2/4 transcription requires Notch signaling, which reverses PRC2 modification of Klf2/4 promoter/enhancers. PRC2 activity is elevated in human ASCVD endothelium. Treating mice with established ASCVD with tazemetostat, an FDA approved pharmacological inhibitor of PRC2, slowed plaque progression by 50% and drastically improved markers of plaque stability. This study elucidates a fundamental mechanism of vascular inflammation, thus identifying a potential method for treating ASCVD and possibly other vascular inflammatory diseases.

Impact of zirconia-based oxide on endothelial cell dynamics and extracellular matrix remodeling

INTRODUCTION

Zirconia (ZrO2) is highly regarded in dental restoration due to its aesthetic compatibility and mechanical properties that align with biological tissues. This study explores the effects of stabilized ZrO2 on endothelial cell function and extracellular matrix (ECM) remodeling, processes critical to successful osseointegration in dental implants.

METHODOLOGY

Human Umbilical Vein Endothelial Cells (HUVECs) were cultured in ZrO2 -enriched medium under both static and shear stress conditions. Newly implemented techniques, including detailed zirconia surface characterization using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD), were used to verify material properties. Gene and protein expression related to cell adhesion, proliferation, and ECM remodeling were assessed through RT-qPCR and Western blotting. Zymography was used to evaluate the activity of matrix metalloproteinases (MMP2 and MMP9) involved in ECM remodeling.

RESULTS

Characterization data confirmed the stability and structural properties of ZrO2, revealing a tetragonal crystalline structure and rough surface morphology conducive to cell adhesion. ZrO2 exposure led to the downregulation of Src, a key regulator of cell adhesion, while upregulating cell cycle regulators p15, CDK2, and CDK4, indicating enhanced cell proliferation. Under shear stress, ZrO2 modulated TGF-β and MAPK signaling, affecting cell proliferation and angiogenesis. MMP2 and MMP9 activity increased in static conditions but decreased under shear stress, suggesting ZrO2 dynamic role in ECM remodeling.

CONCLUSION

This study shows that stabilized zirconia (ZrO2) modulates endothelial cell dynamics and ECM remodeling, key for osseointegration. ZrO2 downregulated Src expression and upregulated cell cycle regulators, enhancing endothelial proliferation. It also affected TGF-β and MAPK pathways, influencing angiogenesis, and differentially modulated MMP2 and MMP9 activity depending on mechanical conditions. These findings highlight ZrO2 has potential ability to enhance vascular and tissue integration in dental applications.

Endothelial KDM5B Regulated by Piezo1 Contributes to Disturbed Flow Induced Atherosclerotic Plaque Formation

Epigenetic modifications play an important role in disturbed flow (d-flow) induced atherosclerotic plaque formation. By analysing a scRNA-seq dataset of the left carotid artery (LCA) under d-flow conditions, we found that Jarid1b (KDM5B) was upregulated primarily in a subcluster of endothelial cells in response to d-flow stimulation. We therefore investigated the mechanism of KDM5B expression and the role of KDM5B in endothelial cell. Intriguingly, activation of Piezo1, a major endothelial mechanosensor, was found to promote KDM5B expression, which was reversed by Piezo1 inhibition in HUVECs. Downstream of Piezo1, ETS1 expression and c-JUN phosphorylation were enhanced by d-flow or Piezo1 activation, leading to an increase in KDM5B expression. Furthermore, knockdown of either KDM5B or Piezo1 was found to prevent d-flow induced H3K4me3 demethylation, which was supported by the pharmacological inhibition of Piezo1 in HUVECs. RNA sequencing on shKdm5b HUVECs implied that KDM5B is associated with endothelial inflammation and atherosclerosis. Using partial carotid ligation surgery on Kdm5bf/f Cdh5cre mice with mAAV-PCSK9D377Y infected, we showed that endothelial KDM5B deficiency reduced atherosclerotic lesions in hypercholesterolemic mice. Our findings indicate that endothelial KDM5B expression induced by d-flow via the Piezo1 pathway promotes atherosclerotic plaque formation, providing targets for the prevention or therapeutic intervention of atherosclerosis.

Less-deformable erythrocyte subpopulations biomechanically induce endothelial inflammation in sickle cell disease

ABSTRACT

Sickle cell disease (SCD) is canonically characterized by reduced red blood cell (RBC) deformability, leading to microvascular obstruction and inflammation. Although the biophysical properties of sickle RBCs are known to influence SCD vasculopathy, the contribution of poor RBC deformability to endothelial dysfunction has yet to be fully explored. Leveraging interrelated in vitro and in silico approaches, we introduce a new paradigm of SCD vasculopathy in which poorly deformable sickle RBCs directly cause endothelial dysfunction via mechanotransduction, during which endothelial cells sense and pathophysiologically respond to aberrant physical forces independently of microvascular obstruction, adhesion, or hemolysis. We demonstrate that perfusion of sickle RBCs or pharmacologically-dehydrated healthy RBCs into small venule-sized "endothelialized" microfluidics leads to pathologic physical interactions with endothelial cells that directly induce inflammatory pathways. Using a combination of computational simulations and large venule-sized endothelialized microfluidics, we observed that perfusion of heterogeneous sickle RBC subpopulations with varying deformability, as well as suspensions of dehydrated normal RBCs admixed with normal RBCs, leads to aberrant margination of the less-deformable RBC subpopulations toward the vessel walls, causing localized, increased shear stress. Increased wall stress is dependent on the degree of subpopulation heterogeneity and oxygen tension and leads to inflammatory endothelial gene expression via mechanotransductive pathways. Our multifaceted approach demonstrates that the presence of sickle RBCs with reduced deformability leads directly to pathological physical (ie, direct collisions and/or compressive forces) and shear-mediated interactions with endothelial cells and induces an inflammatory response, thereby elucidating the ubiquity of vascular dysfunction in SCD.

MicroRNA-specific therapeutic targets and biomarkers of apoptosis following myocardial ischemia-reperfusion injury

MicroRNAs are single-stranded non-coding RNAs that participate in post-transcriptional regulation of gene expression, it is involved in the regulation of apoptosis after myocardial ischemia-reperfusion injury. For example, the alteration of mitochondrial structure is facilitated by MicroRNA-1 through the regulation of apoptosis-related proteins, such as Bax and Bcl-2, thereby mitigating cardiomyocyte apoptosis. MicroRNA-21 not only modulates the expression of NF-κB to suppress inflammatory signals but also activates the PI3K/AKT pathway to mitigate ischemia-reperfusion injury. Overexpression of MicroRNA-133 attenuates reactive oxygen species (ROS) production and suppressed the oxidative stress response, thereby mitigating cellular apoptosis. MicroRNA-139 modulates the extrinsic death signal of Fas, while MicroRNA-145 regulates endoplasmic reticulum calcium overload, both of which exert regulatory effects on cardiomyocyte apoptosis. Therefore, the article categorizes the molecular mechanisms based on the three classical pathways and multiple signaling pathways of apoptosis. It summarizes the targets and pathways of MicroRNA therapy for ischemia-reperfusion injury and analyzes future research directions.

Endothelial γ-protocadherins inhibit KLF2 and KLF4 to promote atherosclerosis

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality worldwide. Laminar shear stress from blood flow, sensed by vascular endothelial cells, protects from ASCVD by upregulating the transcription factors KLF2 and KLF4, which induces an anti-inflammatory program that promotes vascular resilience. Here we identify clustered γ-protocadherins as therapeutically targetable, potent KLF2 and KLF4 suppressors whose upregulation contributes to ASCVD. Mechanistic studies show that γ-protocadherin cleavage results in translocation of the conserved intracellular domain to the nucleus where it physically associates with and suppresses signaling by the Notch intracellular domain. γ-Protocadherins are elevated in human ASCVD endothelium; their genetic deletion or antibody blockade protects from ASCVD in mice without detectably compromising host defense against bacterial or viral infection. These results elucidate a fundamental mechanism of vascular inflammation and reveal a method to target the endothelium rather than the immune system as a protective strategy in ASCVD.

Vascular remodelling in cardiovascular diseases: hypertension, oxidation, and inflammation

Optimal vascular structure and function are essential for maintaining the physiological functions of the cardiovascular system. Vascular remodelling involves changes in vessel structure, including its size, shape, cellular and molecular composition. These changes result from multiple risk factors and may be compensatory adaptations to sustain blood vessel function. They occur in diverse cardiovascular pathologies, from hypertension to heart failure and atherosclerosis. Dynamic changes in the endothelium, fibroblasts, smooth muscle cells, pericytes or other vascular wall cells underlie remodelling. In addition, immune cells, including macrophages and lymphocytes, may infiltrate vessels and initiate inflammatory signalling. They contribute to a dynamic interplay between cell proliferation, apoptosis, migration, inflammation, and extracellular matrix reorganisation, all critical mechanisms of vascular remodelling. Molecular pathways underlying these processes include growth factors (e.g., vascular endothelial growth factor and platelet-derived growth factor), inflammatory cytokines (e.g., interleukin-1β and tumour necrosis factor-α), reactive oxygen species, and signalling pathways, such as Rho/ROCK, MAPK, and TGF-β/Smad, related to nitric oxide and superoxide biology. MicroRNAs and long noncoding RNAs are crucial epigenetic regulators of gene expression in vascular remodelling. We evaluate these pathways for potential therapeutic targeting from a clinical translational perspective. In summary, vascular remodelling, a coordinated modification of vascular structure and function, is crucial in cardiovascular disease pathology.

The roles of Hippo/YAP signaling pathway in physical therapy

Cellular behavior is regulated by mechanical signals within the cellular microenvironment. Additionally, changes of temperature, blood flow, and muscle contraction also affect cellular state and the development of diseases. In clinical practice, physical therapy techniques such as ultrasound, vibration, exercise, cold therapy, and hyperthermia are commonly employed to alleviate pain and treat diseases. However, the molecular mechanism about how these physiotherapy methods stimulate local tissues and control gene expression remains unknow. Fortunately, the discovery of YAP filled this gap, which has been reported has the ability to sense and convert a wide variety of mechanical signals into cell-specific programs for transcription, thereby offering a fresh perspective on the mechanisms by which physiotherapy treat different diseases. This review examines the involvement of Hippo/YAP signaling pathway in various diseases and its role in different physical therapy approaches on diseases. Furthermore, we explore the potential therapeutic implications of the Hippo/YAP signaling pathway and address the limitations and controversies surrounding its application in physiotherapy.

Low Shear in Short-Term Impacts Endothelial Cell Traction and Alignment in Long-Term

Within the vascular system, endothelial cells (ECs) are exposed to fluid shear stress (FSS), a mechanical force exerted by blood flow that is critical for regulating cellular tension and maintaining vascular homeostasis. The way ECs react to FSS varies significantly; while high, laminar FSS supports vasodilation and suppresses inflammation, low or disturbed FSS can lead to endothelial dysfunction and increase the risk of cardiovascular diseases. Yet, the adaptation of ECs to dynamically varying FSS remains poorly understood. This study focuses on the dynamic responses of ECs to brief periods of low FSS, examining its impact on endothelial traction-a measure of cellular tension that plays a crucial role in how endothelial cells respond to mechanical stimuli. By integrating traction force microscopy (TFM) with a custom-built flow chamber, we analyzed how human umbilical vein endothelial cells (HUVECs) adjust their traction in response to shifts from low to high shear stress. We discovered that initial exposure to low FSS prompts a marked increase in traction force, which continues to rise over 10 hours before slowly decreasing. In contrast, immediate exposure to high FSS causes a quick spike in traction followed by a swift reduction, revealing distinct patterns of traction behavior under different shear conditions. Importantly, the direction of traction forces and the resulting cellular alignment under these conditions indicate that the initial shear experience dictates long-term endothelial behavior. Our findings shed light on the critical influence of short-lived low-shear stress experiences in shaping endothelial function, indicating that early exposure to low FSS results in enduring changes in endothelial contractility and alignment, with significant consequences for vascular health and the development of cardiovascular diseases.

Gamma protocadherins in vascular endothelial cells inhibit Klf2/4 to promote atherosclerosis

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of mortality worldwide1. Laminar shear stress (LSS) from blood flow in straight regions of arteries protects against ASCVD by upregulating the Klf2/4 anti-inflammatory program in endothelial cells (ECs)2-8. Conversely, disturbed shear stress (DSS) at curves or branches predisposes these regions to plaque formation9,10. We previously reported a whole genome CRISPR knockout screen11 that identified novel inducers of Klf2/4. Here we report suppressors of Klf2/4 and characterize one candidate, protocadherin gamma A9 (Pcdhga9), a member of the clustered protocadherin gene family12. Pcdhg deletion increases Klf2/4 levels in vitro and in vivo and suppresses inflammatory activation of ECs. Pcdhg suppresses Klf2/4 by inhibiting the Notch pathway via physical interaction of cleaved Notch1 intracellular domain (NICD Val1744) with nuclear Pcdhg C-terminal constant domain (CCD). Pcdhg inhibition by EC knockout (KO) or blocking antibody protects from atherosclerosis. Pcdhg is elevated in the arteries of human atherosclerosis. This study identifies a novel fundamental mechanism of EC resilience and therapeutic target for treating inflammatory vascular disease.

Macrophage KLF15 prevents foam cell formation and atherosclerosis via transcriptional suppression of OLR-1

BACKGROUND

Macrophage-derived foam cells are a hallmark of atherosclerosis. Scavenger receptors, including lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (OLR-1), are the principal receptors responsible for the uptake and modification of LDL, facilitating macrophage lipid load and the uptake of oxidized LDL by arterial wall cells. Krüppel-like factor 15 (KLF15) is a transcription factor that regulates the expression of genes by binding to the promoter during transcription. Therefore, this study aimed to investigate the precise role of macrophage KLF15 in atherogenesis.

METHODS

We used two murine models of atherosclerosis: mice injected with an adeno-associated virus (AAV) encoding the Asp374-to-Tyr mutant version of human PCSK9, followed by 12 weeks on a high-fat diet (HFD), and ApoE-/-- mice on a HFD. We subsequently injected mice with AAV-KLF15 and AAV-LacZ to assess the role of KLF15 in the development of atherosclerosis in vivo. Oil Red O, H&E, and Masson's trichome staining were used to evaluate atherosclerotic lesions. Western blots and RT-qPCR were used to assess protein and mRNA levels, respectively.

RESULTS

We determined that KLF15 expression was downregulated during atherosclerosis formation, and KLF15 overexpression prevented atherosclerosis progression. KLF15 expression levels did not affect body weight or serum lipid levels in mice. However, KLF15 overexpression in macrophages prevented foam cell formation by reducing OLR-1-meditated lipid uptake. KLF15 directly targeted and transcriptionally downregulated OLR-1 levels. Restoration of OLR-1 reversed the beneficial effects of KLF15 in atherosclerosis.

CONCLUSION

Macrophage KLF15 transcriptionally downregulated OLR-1 expression to reduce lipid uptake, thereby preventing foam cell formation and atherosclerosis. Thus, our results suggest that KLF15 is a potential therapeutic target for atherosclerosis.

Mechanosignaling-related angiocrine factors drive osteoblastic phenotype in response to zirconia

BACKGROUND

The growing use of zirconia as a ceramic material in dentistry is attributed to its biocompatibility, mechanical properties, esthetic appearance, and reduced bacterial adhesion. These favorable properties make ceramic materials a viable alternative to commonly used titanium alloys. Mimicking the physiological properties of blood flow, particularly the mechanosignaling in endothelial cells (ECs), is crucial for enhancing our understanding of their role in the response to zirconia exposure.

METHODS

In this study, EC cultures were subjected to shear stress while being exposed to zirconia for up to 3 days. The conditioned medium obtained from these cultures was then used to expose osteoblasts for a duration of 7 days. To investigate the effects of zirconia on osteoblasts, we examined the expression of genes associated with osteoblast differentiation, including Runx2, Osterix, bone sialoprotein, and osteocalcin genes. Additionally, we assessed the impact of mechanosignaling-related angiocrine factors on extracellular matrix (ECM) remodeling by measuring the activities of matrix metalloproteinases 2 and 9 (MMP2 and MMP9) during the acquisition of the osteogenic phenotype, which precedes mineralization.

RESULTS

Our data revealed that mechanosignaling-related angiocrine factors play a crucial role in promoting an osteoblastic phenotype in response to zirconia exposure. Specifically, exposed osteoblasts exhibited significantly higher expression levels of genes associated with osteoblast differentiation, such as Runx2, Osterix, bone sialoprotein, and osteocalcin genes. Furthermore, the activities of MMP2 and MMP9, which are involved in ECM remodeling, were modulated by mechanosignaling-related angiocrine factors. This modulation is likely an initial event preceding the mineralization phase.

CONCLUSION

Based on our findings, we propose that mechanosignaling drives the release of angiocrine factors capable of modulating the osteogenic phenotype at the biointerface with zirconia. This process creates a microenvironment that promotes wound healing and osseointegration. Moreover, these results highlight the importance of considering the mechanosignaling of endothelial cells in the modulation of bone healing and osseointegration in the context of blood vessel effects. Our data provide new insights and open avenues for further investigation into the influence of mechanosignaling on bone healing and the osseointegration of dental devices.

Tissue-specific Cre driver mice to study vascular diseases

Vascular diseases, including atherosclerosis and abdominal aneurysms, are the primary cause of mortality and morbidity among the elderly worldwide. The life quality of patients is significantly compromised due to inadequate therapeutic approaches and limited drug targets. To expand our comprehension of vascular diseases, gene knockout (KO) mice, especially conditional knockout (cKO) mice, are widely used for investigating gene function and mechanisms of action. The Cre-loxP system is the most common method for generating cKO mice. Numerous Cre driver mice have been established to study the main cell types that compose blood vessels, including endothelial cells, smooth muscle cells, and fibroblasts. Here, we first discuss the characteristics of each layer of the arterial wall. Next, we provide an overview of the representative Cre driver mice utilized for each of the major cell types in the vessel wall and their most recent applications in vascular biology. We then go over Cre toxicity and discuss the practical methods for minimizing Cre interference in experimental outcomes. Finally, we look into the future of tissue-specific Cre drivers by introducing the revolutionary single-cell RNA sequencing and dual recombinase system.

Marginated aberrant red blood cells induce pathologic vascular stress fluctuations in a computational model of hematologic disorders

Red blood cell (RBC) disorders such as sickle cell disease affect billions worldwide. While much attention focuses on altered properties of aberrant RBCs and corresponding hemodynamic changes, RBC disorders are also associated with vascular dysfunction, whose origin remains unclear and which provoke severe consequences including stroke. Little research has explored whether biophysical alterations of RBCs affect vascular function. We use a detailed computational model of blood that enables characterization of cell distributions and vascular stresses in blood disorders and compare simulation results with experimental observations. Aberrant RBCs, with their smaller size and higher stiffness, concentrate near vessel walls (marginate) because of contrasts in physical properties relative to normal cells. In a curved channel exemplifying the geometric complexity of the microcirculation, these cells distribute heterogeneously, indicating the importance of geometry. Marginated cells generate large transient stress fluctuations on vessel walls, indicating a mechanism for the observed vascular inflammation.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Endothelial activation and fibrotic changes are impeded by laminar flow-induced CHK1-SENP2 activity through mechanisms distinct from endothelial-to-mesenchymal cell transition

Background

The deSUMOylase sentrin-specific isopeptidase 2 (SENP2) plays a crucial role in atheroprotection. However, the phosphorylation of SENP2 at T368 under disturbed flow (D-flow) conditions hinders its nuclear function and promotes endothelial cell (EC) activation. SUMOylation has been implicated in D-flow-induced endothelial-to-mesenchymal transition (endoMT), but the precise role of SENP2 in counteracting this process remains unclear.

Method

We developed a phospho-specific SENP2 S344 antibody and generated knock-in (KI) mice with a phospho-site mutation of SENP2 S344A using CRISPR/Cas9 technology. We then investigated the effects of SENP2 S344 phosphorylation under two distinct flow patterns and during hypercholesteremia (HC)-mediated EC activation.

Result

Our findings demonstrate that laminar flow (L-flow) induces phosphorylation of SENP2 at S344 through the activation of checkpoint kinase 1 (CHK1), leading to the inhibition of ERK5 and p53 SUMOylation and subsequent suppression of EC activation. We observed a significant increase in lipid-laden lesions in both the aortic arch (under D-flow) and descending aorta (under L-flow) of female hypercholesterolemic SENP2 S344A KI mice. In male hypercholesterolemic SENP2 S344A KI mice, larger lipid-laden lesions were only observed in the aortic arch area, suggesting a weaker HC-mediated atherogenesis in male mice compared to females. Ionizing radiation (IR) reduced CHK1 expression and SENP2 S344 phosphorylation, attenuating the pro-atherosclerotic effects observed in female SENP2 S344A KI mice after bone marrow transplantation (BMT), particularly in L-flow areas. The phospho-site mutation SENP2 S344A upregulates processes associated with EC activation, including inflammation, migration, and proliferation. Additionally, fibrotic changes and up-regulated expression of EC marker genes were observed. Apoptosis was augmented in ECs derived from the lungs of SENP2 S344A KI mice, primarily through the inhibition of ERK5-mediated expression of DNA damage-induced apoptosis suppressor (DDIAS).

Summary

In this study, we have revealed a novel mechanism underlying the suppressive effects of L-flow on EC inflammation, migration, proliferation, apoptosis, and fibrotic changes through promoting CHK1-induced SENP2 S344 phosphorylation. The phospho-site mutation SENP2 S344A responds to L-flow through a distinct mechanism, which involves the upregulation of both mesenchymal and EC marker genes.

Insulin Resistance and Hypertension: Mechanisms Involved and Modifying Factors for Effective Glucose Control

Factors such as aging, an unhealthy lifestyle with decreased physical activity, snacking, a standard Western diet, and smoking contribute to raising blood pressure to a dangerous level, increasing the risk of coronary artery disease and heart failure. Atherosclerosis, or aging of the blood vessels, is a physiological process that has accelerated in the last decades by the overconsumption of carbohydrates as the primary sources of caloric intake, resulting in increased triglycerides and VLDL-cholesterol and insulin spikes. Classically, medications ranging from beta blockers to angiotensin II blockers and even calcium channel blockers were used alone or in combination with lifestyle modifications as management tools in modern medicine to control arterial blood pressure. However, it is not easy to control blood pressure or the associated complications. A low-carbohydrate, high-fat (LCHF) diet can reduce glucose and insulin spikes, improve insulin sensitivity, and lessen atherosclerosis risk factors. We reviewed articles describing the etiology of insulin resistance (IR) and its impact on arterial blood pressure from databases including PubMed, PubMed Central, and Google Scholar. We discuss how the LCHF diet is beneficial to maintaining arterial blood pressure at normal levels, slowing down the progression of atherosclerosis, and reducing the use of antihypertensive medications. The mechanisms involved in IR associated with hypertension are also highlighted.

Metabolic regulation of endothelial senescence

Endothelial cell (EC) senescence is increasingly recognized as a significant contributor to the development of vascular dysfunction and age-related disorders and diseases, including cancer and cardiovascular diseases (CVD). The regulation of cellular senescence is known to be influenced by cellular metabolism. While extensive research has been conducted on the metabolic regulation of senescence in other cells such as cancer cells and fibroblasts, our understanding of the metabolic regulation of EC senescence remains limited. The specific metabolic changes that drive EC senescence are yet to be fully elucidated. The objective of this review is to provide an overview of the intricate interplay between cellular metabolism and senescence, with a particular emphasis on recent advancements in understanding the metabolic changes preceding cellular senescence. I will summarize the current knowledge on the metabolic regulation of EC senescence, aiming to offer insights into the underlying mechanisms and future research directions.

The Action of Angiocrine Molecules Sourced from Mechanotransduction-Related Endothelial Cell Partially Explain the Successful of Titanium in Osseointegration

Since Branemark's findings, titanium-based alloys have been widely used in implantology. However, their success in dental implants is not known when considering the heterogenicity of housing cells surrounding the peri-implant microenvironment. Additionally, they are expected to recapitulate the physiological coupling between endothelial cells and osteoblasts during appositional bone growth during osseointegration. To investigate whether this crosstalk was happening in this context, we considered the mechanotransduction-related endothelial cell signaling underlying laminar shear stress (up to 3 days), and this angiocrine factor-enriched medium was harvested further to use exposing pre-osteoblasts (pOb) for up to 7 days in vitro. Two titanium surfaces were considered, as follows: double acid etching treatment (w_DAE) and machined surfaces (wo_DAE). These surfaces were used to conditionate the cell culture medium as recommended by ISO10993-5:2016, and this titanium-enriched medium was later used to expose ECs. First, our data showed that there is a difference between the surfaces in releasing Ti molecules to the medium, providing very dynamic surfaces, where the w_DAE was around 25% higher (4 ng/mL) in comparison to the wo_DAE (3 ng/mL). Importantly, the ECs took up some of this titanium content for up to 3 days in culture. However, when this conditioned medium was used to expose pOb for up to 7 days, considering the angiocrine factors released from ECs, the concentration of Ti was lesser than previously reported, reaching around 1 ng/mL and 2 ng/mL, respectively. Thereafter, pOb exposed to this angiocrine factor-enriched medium presented a significant difference when considering the mechanosignaling subjected to the ECs. Shear-stressed ECs showed adequate crosstalk with osteoblasts, stimulating the higher expression of the Runx2 gene and driving higher expressions of Alkaline phosphatase (ALP), bone sialoprotein (BSP), and osteocalcin. Mechanotransduction-related endothelial cell signaling as a source of angiocrine molecules also stimulated the higher expression of the Col3A1 gene in osteoblasts, which suggests it is a relevant protagonist during trabecular bone growth. In fact, we investigated ECM remodeling by first evaluating the expression of genes related to it, and our data showed a higher expression of matrix metalloproteinase (MMP) 2 and MMP9 in response to mechanosignaling-based angiocrine molecules, independent of considering w_DAE or the wo_DAE, and this profile reflected on the MMP2 and MMP9 activities evaluated via gelatin-based zymography. Complimentarily, the ECM remodeling seemed to be a very regulated mechanism in mature osteoblasts during the mineralization process once both TIMP metallopeptidase inhibitor 1 and 2 (TIMP1 and TIMP2, respectively) genes were significantly higher in response to mechanotransduction-related endothelial cell signaling as a source of angiocrine molecules. Altogether, our data show the relevance of mechanosignaling in favoring ECs' release of bioactive factors peri-implant, which is responsible for creating an osteogenic microenvironment able to drive osteoblast differentiation and modulate ECM remodeling. Taking this into account, it seems that mechanotransduction-based angiocrine molecules explain the successful use of titanium during osseointegration.

Possible molecular mechanisms underlying the development of atherosclerosis in cancer survivors

Cancer survivors undergone treatment face an increased risk of developing atherosclerotic cardiovascular disease (CVD), yet the underlying mechanisms remain elusive. Recent studies have revealed that chemotherapy can drive senescent cancer cells to acquire a proliferative phenotype known as senescence-associated stemness (SAS). These SAS cells exhibit enhanced growth and resistance to cancer treatment, thereby contributing to disease progression. Endothelial cell (EC) senescence has been implicated in atherosclerosis and cancer, including among cancer survivors. Treatment modalities for cancer can induce EC senescence, leading to the development of SAS phenotype and subsequent atherosclerosis in cancer survivors. Consequently, targeting senescent ECs displaying the SAS phenotype hold promise as a therapeutic approach for managing atherosclerotic CVD in this population. This review aims to provide a mechanistic understanding of SAS induction in ECs and its contribution to atherosclerosis among cancer survivors. We delve into the mechanisms underlying EC senescence in response to disturbed flow and ionizing radiation, which play pivotal role in atherosclerosis and cancer. Key pathways, including p90RSK/TERF2IP, TGFβR1/SMAD, and BH4 signaling are explored as potential targets for cancer treatment. By comprehending the similarities and distinctions between different types of senescence and the associated pathways, we can pave the way for targeted interventions aim at enhancing the cardiovascular health of this vulnerable population. The insights gained from this review may facilitate the development of novel therapeutic strategies for managing atherosclerotic CVD in cancer survivors.

Marginated aberrant red blood cells induce pathologic vascular stress fluctuations in a computational model of hematologic disorders

Red blood cell (RBC) disorders affect billions worldwide. While alterations in the physical properties of aberrant RBCs and associated hemodynamic changes are readily observed, in conditions such as sickle cell disease and iron deficiency, RBC disorders can also be associated with vascular dysfunction. The mechanisms of vasculopathy in those diseases remain unclear and scant research has explored whether biophysical alterations of RBCs can directly affect vascular function. Here we hypothesize that the purely physical interactions between aberrant RBCs and endothelial cells, due to the margination of stiff aberrant RBCs, play a key role in this phenomenon for a range of disorders. This hypothesis is tested by direct simulations of a cellular scale computational model of blood flow in sickle cell disease, iron deficiency anemia, COVID-19, and spherocytosis. We characterize cell distributions for normal and aberrant RBC mixtures in straight and curved tubes, the latter to address issues of geometric complexity that arise in the microcirculation. In all cases aberrant RBCs strongly localize near the vessel walls (margination) due to contrasts in cell size, shape, and deformability from the normal cells. In the curved channel, the distribution of marginated cells is very heterogeneous, indicating a key role for vascular geometry. Finally, we characterize the shear stresses on the vessel walls; consistent with our hypothesis, the marginated aberrant cells generate large transient stress fluctuations due to the high velocity gradients induced by their near-wall motions. The anomalous stress fluctuations experienced by endothelial cells may be responsible for the observed vascular inflammation.

Pathophysiology and Outcomes of Endothelium Function in Coronary Microvascular Diseases: A Systematic Review of Randomized Controlled Trials and Multicenter Study

BACKGROUND

Coronary macrovascular disease is a concept that has been well-studied within the literature and has long been the subject of debates surrounding coronary artery bypass grafting (CABG) vs. Percutaneous Coronary Intervention (PCI). ISCHEMIA trial reported no statistical difference in the primary clinical endpoint between initial invasive management and initial conservative management, while in the ORBITA trial PCI did not improve angina frequency score significantly more than placebo, albeit PCI resulted in more patient-reported freedom from angina than placebo. However, these results did not prove the superiority of the PCI against OMT, therefore do not indicate the benefit of PCI vs. the OMT. Please rephrase the sentence. We reviewed the role of different factors responsible for endothelial dysfunction from recent randomized clinical trials (RCTs) and multicentre studies.

METHODS

A detailed search strategy was performed using a dataset that has previously been published. Data of pooled analysis include research articles (human and animal models), CABG, and PCI randomized controlled trials (RCTs). Details of the search strategy and the methods used for data pooling have been published previously and registered with Open-Source Framework.

RESULTS

The roles of nitric oxide (NO), endothelium-derived contracting factors (EDCFs), and vasodilator prostaglandins (e.g., prostacyclin), as well as endothelium-dependent hyperpolarization (EDH) factors, are crucial for the maintenance of vasomotor tone within the coronary vasculature. These homeostatic mechanisms are affected by sheer forces and other several factors that are currently being studied, such as vaping. The role of intracoronary testing is crucial when determining the effects of therapeutic medications with further studies on the horizon.

CONCLUSION

The true impact of coronary microvascular dysfunction (CMD) is perhaps underappreciated, which supports the role of medical therapy in determining outcomes. Ongoing trials are underway to further investigate the role of therapeutic agents in secondary prevention.

Endothelium-Derived Relaxing Factors and Endothelial Function: A Systematic Review

BACKGROUND

The endothelium plays a pivotal role in homeostatic mechanisms. It specifically modulates vascular tone by releasing vasodilatory mediators, which act on the vascular smooth muscle. Large amounts of work have been dedicated towards identifying mediators of vasodilation and vasoconstriction alongside the deleterious effects of reactive oxygen species on the endothelium. We conducted a systematic review to study the role of the factors released by the endothelium and the effects on the vessels alongside its role in atherosclerosis.

METHODS

A search was conducted with appropriate search terms. Specific attention was offered to the effects of emerging modulators of endothelial functions focusing the analysis on studies that investigated the role of reactive oxygen species (ROS), perivascular adipose tissue, shear stress, AMP-activated protein kinase, potassium channels, bone morphogenic protein 4, and P2Y2 receptor.

RESULTS

530 citations were reviewed, with 35 studies included in the final systematic review. The endpoints were evaluated in these studies which offered an extensive discussion on emerging modulators of endothelial functions. Specific factors such as reactive oxygen species had deleterious effects, especially in the obese and elderly. Another important finding included the shear stress-induced endothelial nitric oxide (NO), which may delay development of atherosclerosis. Perivascular Adipose Tissue (PVAT) also contributes to reparative measures against atherosclerosis, although this may turn pathological in obese subjects. Some of these factors may be targets for pharmaceutical agents in the near future.

CONCLUSION

The complex role and function of the endothelium is vital for regular homeostasis. Dysregulation may drive atherogenesis; thus, efforts should be placed at considering therapeutic options by targeting some of the factors noted.

G3BP1 regulates breast cancer cell proliferation and metastasis by modulating PKCζ

Breast cancer is a leading cause of death and morbidity among female cancers. Several factors, including hormone levels, lifestyle, and dysregulated RNA-binding proteins, have been associated with the development of breast cancer. Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) and protein kinase C, Zeta isoform (PKCζ) are oncogenes implicated in numerous cancers, including breast cancer. However, their interaction and role in promoting breast cancer proliferation and metastasis have not been well-characterized. In the present study, we demonstrated that G3BP1 expression was elevated in breast cancer and that knockdown of G3BP1 diminished the proliferation and metastasis of breast cancer cells. Mechanistically, we identified proliferation and a series of metastasis-related properties, including chemotaxis, migration, Golgi polarity localization, and actin polymerization, that were modulated by G3BP1 knockdown. We found that G3BP1 and PKCζ were co-localized and interacted intracellularly, and they co-underwent membrane translocation under EGF stimulation. Following the knockdown of G3BP1, we observed the membrane translocation and phosphorylation of PKCζ were significantly impaired, suggesting that G3BP1 regulates the activation of PKCζ. Our findings indicate that G3BP1 plays multiple roles in breast cancer cell proliferation and metastasis. The activation of PKCζ by G3BP1 may be the specific mechanism underlying the process.

Pathologic mechanobiological interactions between red blood cells and endothelial cells directly induce vasculopathy in iron deficiency anemia

The correlation between cardiovascular disease and iron deficiency anemia (IDA) is well documented but poorly understood. Using a multi-disciplinary approach, we explore the hypothesis that the biophysical alterations of red blood cells (RBCs) in IDA, such as variable degrees of microcytosis and decreased deformability may directly induce endothelial dysfunction via mechanobiological mechanisms. Using a combination of atomic force microscopy and microfluidics, we observed that subpopulations of IDA RBCs (idRBCs) are significantly stiffer and smaller than both healthy RBCs and the remaining idRBC population. Furthermore, computational simulations demonstrated that the smaller and stiffer idRBC subpopulations marginate toward the vessel wall causing aberrant shear stresses. This leads to increased vascular inflammation as confirmed with perfusion of idRBCs into our "endothelialized" microfluidic systems. Overall, our multifaceted approach demonstrates that the altered biophysical properties of idRBCs directly lead to vasculopathy, suggesting that the IDA and cardiovascular disease association extends beyond correlation and into causation.

A mitochondrial contribution to anti-inflammatory shear stress signaling in vascular endothelial cells

Atherosclerosis, the major cause of myocardial infarction and stroke, results from converging inflammatory, metabolic, and biomechanical factors. Arterial lesions form at sites of low and disturbed blood flow but are suppressed by high laminar shear stress (LSS) mainly via transcriptional induction of the anti-inflammatory transcription factor, Kruppel-like factor 2 (Klf2). We therefore performed a whole genome CRISPR-Cas9 screen to identify genes required for LSS induction of Klf2. Subsequent mechanistic investigation revealed that LSS induces Klf2 via activation of both a MEKK2/3-MEK5-ERK5 kinase module and mitochondrial metabolism. Mitochondrial calcium and ROS signaling regulate assembly of a mitophagy- and p62-dependent scaffolding complex that amplifies MEKK-MEK5-ERK5 signaling. Blocking the mitochondrial pathway in vivo reduces expression of KLF2-dependent genes such as eNOS and inhibits vascular remodeling. Failure to activate the mitochondrial pathway limits Klf2 expression in regions of disturbed flow. This work thus defines a connection between metabolism and vascular inflammation that provides a new framework for understanding and developing treatments for vascular disease.

Radiation-Induced Cardiovascular Disease: Mechanisms, Prevention, and Treatment

PURPOSE OF REVIEW

Despite the advancements of modern radiotherapy, radiation-induced cardiovascular disease (RICVD) remains a common cause of morbidity and mortality among cancer survivors.

RECENT FINDINGS

Proposed pathogenetic mechanisms of RICVD include endothelial cell damage with accelerated atherosclerosis, pro-thrombotic alterations in the coagulation pathway as well as inflammation and fibrosis of the myocardial, pericardial, valvular, and conduction tissues. Prevention of RICVD can be achieved by minimizing the exposure of the cardiovascular system to radiation, by treatment of underlying cardiovascular risk factors and cardiovascular disease, and possibly by prophylactic pharmacotherapy post exposure. Herein we summarize current knowledge on the mechanisms underlying the pathogenesis of RICVD and propose prevention and treatment strategies.

High Output Heart Failure in Multiple Myeloma: Pathogenetic Considerations

Simple Summary

Multiple myeloma is a plasma cell disorder that accounts for around 10% of all haematological malignancies. This neoplasia is often associated with a significant prevalence of cardiovascular complications resulting from several factors, unrelated and/or related to the disease. Among cardiovascular complications, the high output heart failure is of great importance as it is related to a worse prognosis for patients. It is important to point out that, despite the availability of more and more numerous and effective drugs, myeloma remains an incurable disease, with frequent relapses and several treatment lines, with the need, therefore, for a careful evaluation of patients, especially from a cardiological point of view. For this reason, we are proposing a comprehensive overview of different pathogenetic mechanisms responsible for high output heart failure in multiple myeloma, including artero-venous shunts, enhanced angiogenesis, glutamminolysis, hyperammonemia and hemorheological alterations, with the belief that a multidisciplinary approach, in clinical evaluation is critical for the optimal management of the patient.

Abstract

The high output heart failure is a clinical condition in which the systemic congestion is associated to a high output state, and it can be observed in a non-negligible percentage of hematological diseases, particularly in multiple myeloma, a condition in which the risk of adverse cardiovascular events may increase, with a worse prognosis for patients. For this reason, though an accurate literature search, we provided in this review a complete overview of different pathogenetic mechanisms responsible for high output heart failure in multiple myeloma. Indeed, this clinical finding is present in the 8% of multiple myeloma patients, and it may be caused by artero-venous shunts, enhanced angiogenesis, glutamminolysis, hyperammonemia and hemorheological alterations with increase in plasma viscosity. The high output heart failure in multiple myeloma is associated with significant morbidity and mortality, emphasizing the need for a multidisciplinary approach.

Endothelial Dysfunction in Hypertension: Current Concepts and Clinical Implications

Endothelium plays a fundamental role in the cardiovascular system, forming an interface between blood and adjacent tissues by regulating the vascular tone through the synthesis of nitric oxide, prostaglandins and other relaxing factors. Endothelial dysfunction is characterized by vasoconstriction, cell proliferation and shifting toward a proinflammatory and prothrombic state. In hypertension endothelial dysfunction may be involved in the initiation and development of vascular inflammation, vascular remodeling, and atherosclerosis and is independently associated with increased cardiovascular risk. Different conditions such as impaired vascular shear stress, inflammation and oxidative stress, activation of the renin angiotensin system have been described as important pathophysiological mechanisms involved in the development of endothelial dysfunction. The release of extracellular vesicles by neighboring cells in the vascular wall has emerged as an important regulator of endothelial function and with potential antihypertensive properties and beneficial effects by counteracting the hypertension mediated organ damage. Furthermore, macrovesicles are emerging as an innovative therapeutic approach for vascular protection, allowing the delivery of bioactive molecules, such as miRNA and drugs interacting with the renin angiotensin system. In this review we summarize the available evidence about the pathophysiological implications of endothelial dysfunction in cardiovascular diseases, focusing on hypertension and its sequelae, and the potential innovative therapeutic strategies targeting the endothelium with the aim to improve vascular function and remodeling.

Endothelium in Coronary Macrovascular and Microvascular Diseases

ABSTRACT

The endothelium plays a pivotal role in the regulation of vascular tone by synthesizing and liberating endothelium-derived relaxing factors inclusive of vasodilator prostaglandins (eg, prostacyclin), nitric oxide (NO), and endothelium-dependent hyperpolarization factors in a distinct blood vessel size-dependent manner. Large conduit arteries are predominantly regulated by NO and small resistance arteries by endothelium-dependent hyperpolarization factors. Accumulating evidence over the past few decades has demonstrated that endothelial dysfunction and coronary vasomotion abnormalities play crucial roles in the pathogenesis of various cardiovascular diseases. Structural and functional alterations of the coronary microvasculature have been coined as coronary microvascular dysfunction (CMD), which is highly prevalent and associated with adverse clinical outcomes in many clinical settings. The major mechanisms of coronary vasomotion abnormalities include enhanced coronary vasoconstrictive reactivity at epicardial and microvascular levels, impaired endothelium-dependent and endothelium-independent coronary vasodilator capacities, and elevated coronary microvascular resistance caused by structural factors. Recent experimental and clinical research has highlighted CMD as the systemic small artery disease beyond the heart, emerging modulators of vascular functions, novel insights into the pathogenesis of cardiovascular diseases associated with CMD, and potential therapeutic interventions to CMD with major clinical implications. In this article, we will summarize the current knowledge on the endothelial modulation of vascular tone and the pathogenesis of coronary macrovascular and microvascular diseases from bench to bedside, with a special emphasis placed on the mechanisms and clinical implications of CMD.

Disturbed flow-induced FAK K152 SUMOylation initiates the formation of pro-inflammation positive feedback loop by inducing reactive oxygen species production in endothelial cells

Focal adhesion kinase (FAK) activation plays a crucial role in vascular diseases. In endothelial cells, FAK activation is involved in the activation of pro-inflammatory signaling and the progression of atherosclerosis. Disturbed flow (D-flow) induces endothelial activation and senescence, but the exact role of FAK in D-flow-induced endothelial activation and senescence remains unclear. The objective of this study is to investigate the role of FAK SUMOylation in D-flow-induced endothelial activation and senescence. The results showed that D-flow induced reactive oxygen species (ROS) production via NADPH oxidase activation and activated a redox-sensitive kinase p90RSK, leading to FAK activation by upregulating FAK K152 SUMOylation and the subsequent Vav2 phosphorylation, which in turn formed a positive feedback loop by upregulating ROS production. This feedback loop played a crucial role in regulating endothelial activation and senescence. D-flow-induced endothelial activation and senescence were significantly inhibited by mutating a FAK SUMOylation site lysine152 to arginine. Collectively, we concluded that FAK K152 SUMOylation plays a key role in D-flow-induced endothelial activation and senescence by forming a positive feedback loop through ROS production.

Metabolic effects of CoCr-enriched medium on shear-stressed endothelial cell and osteoblasts: A possible mechanism involving a hypoxic condition on bone healing

Cobalt-chromium (CoCr)-based alloys have emerged as an interesting biomaterial within biomedical field, mainly considering their biocompatibility, resistance to corrosion and absence of magnetism; however, its effect on cell metabolism is barely known and this prompted us better evaluating whether CoCr-enriched medium affects the metabolism of both osteoblast and endothelial cells, and also if there is a coupling between them. This is also considered here the already-known effect of Cobalt (Co) as a hypoxic element. Firstly, discs of CoCr [subjecting (W) or not (Wo) to dual acid-etched (DAE)] were incubated into FBS-free cell culture medium up to 24 h (37 °C). This CoCr-enriched medium was further used to treat shear-stressed endothelial cells cultures up to 72 h. Thereafter, the conditioned medium containing metabolites of shear-stressed endothelial cells in response to CoCr-enriched medium was further used to subject osteoblast's cultures, when the samples were properly harvested to allow the analysis of the molecular issues. Our data shows that CoCr-enriched medium contains 1.5 ng-2.0 ng/mL of Co, which was captured by endothelial cells and osteoblasts in about 30% in amount and it seems modulate their metabolic pathways: shear-stressed endothelial cells expressed higher profile of HIF1α, VEGF and nNOS genes, while their global profile of protein carbonylation was lower than the control cultures, suggesting lower oxidative stress commitment. Additionally, osteoblasts responding to metabolites of CoCr-challenged endothelial cells show dynamic expression of marker genes in osteogenic differentiation, with alkaline phosphatase (ALP), osteocalcin, and bone sialoprotein (BSP) genes being significantly increased. Additionally, tensional shear-stress forces decrease the stimulus for ColA1gene expression in osteoblasts responding to endothelial cells metabolites, as well as modifying the extracellular matrix remodeling related genes. Analyzing the activities of matrix metalloproteinases (MMPs), the data shows that shear-stressed endothelial cells metabolites increase the activities of both MMP9 and MMP2 in osteoblasts. Altogether, our data shows for the first time that shear-stressed endothelial metabolites responding to CoCr discs contribute to osteogenic phenotype in vitro, and this predicts an active crosstalk between angiogenesis and osteogenesis during osseointegration of CoCr alloy and bone healing, maybe guided by the Co-induced hypoxic condition.

Coronary Microvascular Dysfunction

[Figure: see text].

Challenges and Possibilities of Cell-Based Tissue-Engineered Vascular Grafts

There is urgent demand for biologically compatible vascular grafts for both adult and pediatric patients. The utility of conventional nonbiodegradable materials is limited because of their thrombogenicity and inability to grow, while autologous vascular grafts involve considerable disadvantages, including the invasive procedures required to obtain these healthy vessels from patients and insufficient availability in patients with systemic atherosclerosis. All of these issues could be overcome by tissue-engineered vascular grafts (TEVGs). A large body of evidence has recently emerged in support of TEVG technologies, introducing diverse cell sources (e.g., somatic cells and stem cells) and novel fabrication methods (e.g., scaffold-guided and self-assembled approaches). Before TEVG can be applied in a clinical setting, however, several aspects of the technology must be improved, such as the feasibility of obtaining cells, their biocompatibility and mechanical properties, and the time needed for fabrication, while the safety of supplemented materials, the patency and nonthrombogenicity of TEVGs, their growth potential, and the long-term influence of implanted TEVGs in the body must be assessed. Although recent advances in TEVG fabrication have yielded promising results, more research is needed to achieve the most feasible methods for generating optimal TEVGs. This article reviews multiple aspects of TEVG fabrication, including mechanical requirements, extracellular matrix components, cell sources, and tissue engineering approaches. The potential of periodic hydrostatic pressurization in the production of scaffold-free TEVGs with optimal elasticity and stiffness is also discussed. In the future, the integration of multiple technologies is expected to enable improved TEVG performance.

Flow-induced segregation and dynamics of red blood cells in sickle cell disease

Blood flow in sickle cell disease (SCD) can substantially differ from normal blood flow due to significant alterations in the physical properties of the red blood cells (RBCs). Chronic complications, such as inflammation of the endothelial cells lining blood vessel walls, are associated with SCD, for reasons that are unclear. Here, detailed boundary integral simulations are performed to investigate an idealized model flow flow in SCD, a binary suspension of flexible biconcave discoidal fluid-filled capsules and stiff curved prolate capsules that represent healthy and sickle RBCs, respectively, subjected to pressure-driven flow in a planar slit. The stiff component is dilute. The key observation is that, unlike healthy RBCs that concentrate around the center of the channel and form an RBC-depleted layer (i.e. cell-free layer) next to the walls, sickle cells are largely drained from the bulk of the suspension and aggregate inside the cell-free layer, displaying strong margination. These cells are found to undergo a rigid-body-like rolling orbit near the walls. A binary suspension of flexible biconcave discoidal capsules and stiff straight (non-curved) prolate capsules is also considered for comparison, and the curvature of the stiff component is found to play a minor role in the behavior. Additionally, by considering a mixture of flexible and stiff biconcave discoids, we reveal that rigidity difference by itself is sufficient to induce the segregation behavior in a binary suspension. Furthermore, the additional shear stress on the walls induced by the presence of cells is computed for the various cases. Compared to the small fluctuations in wall shear stress for a suspension of healthy RBCs, large local peaks in wall shear stress are observed for the binary suspensions, due to the proximity of the marginated stiff cells to the walls. This effect is most marked for the straight prolate capsules. As endothelial cells are known to mechanotransduce physical forces such as aberrations in shear stress and convert them to physiological processes such as activation of inflammatory signals, these results may aid in understanding mechanisms for endothelial dysfunction associated with SCD.

Titanate nanotubes at non-cytotoxic concentrations affect NO signaling pathway in human umbilical vein endothelial cells

Titanate nanotubes (TiNTs) have been considered as biocompatible nanomaterials (NMs) for biomedical uses. Hereby, we compared the toxicity of TiNTs and TiO2 nanoparticles (NPs) to human umbilical vein endothelial cells (HUVECs). Our results showed that TiNTs were less effectively internalized into HUVECs compared with TiO2 NPs, but none of the NMs induced cytotoxicity or activation of endoplasmic reticulum (ER) stress biomarkers. In addition, intracellular reactive oxygen species (ROS) was only modestly induced by TiNTs and TiO2 NPs. However, both types of NMs significantly promoted the protein levels of vascular cell adhesion molecule-1 (VCAM-1). TiNTs also promoted the release of soluble (sVCAM-1), but THP-1 monocyte adhesion onto HUVECs was only induced by TiO2 NPs. TiNTs decreased the production of NO, associated with a decrease of protein levels of endothelial NO synthase (eNOS). The transcription factors of eNOS, including kruppel-like factor 2 (KLF2) and KLF4, were more effectively down-regulated by TiNTs compared with TiO2 NPs. In conclusion, our results indicated that TiNTs, albeit not cytotoxic, might impair NO signaling pathway in human endothelial cells leading to the activation of endothelial cells.

Biomechanical studies on biomaterial degradation and co-cultured cells: mechanisms, potential applications, challenges and prospects

Biomechanics contains a wide variety of research fields related to biology and mechanics. Actually, to better study or develop a tissue-engineered system, it is now widely recognized that there is no complete nor meaningful study without considering biomechanical factors and the cell response or adaptation to biomechanics. In that respect, this review will focus on not only the influence of biomechanics in biomaterial degradation and co-cultured cells, based on current major frontier research findings, but also the challenges and prospects in biomechanical research. Particularly, through the elaboration of certain typical forces affecting biomaterial degradation and celluar functions, this paper tries to reveal the possible mechanisms, and thus provide ideas on how to design or optimize co-culture systems and apply external forces for proper cell and tissue engineering. Furthermore, while emphasizing the importance of the mechanical control of the cell phenotype and fate, it is expected that these achievements can pave the way to materials-based therapies for different pathological conditions, including diagnosis and treatment of cancer.

Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products

Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.

Acute Effect of High-Intensity Interval Cycling on Carotid Arterial Stiffness and Hemodynamics

Background

Cardiovascular disease (CVD) contributes to be one of the leading causes of death in the population worldwide. Carotid arterial stiffness and local hemodynamics are associated with the occurrence and development of CVD. Therefore, understanding the alterations of human carotid arterial stiffness and hemodynamics is of great clinical value in the prevention and treatment of CVD.

Objective

In this study, we aimed to investigate the acute effect of high-intensity interval cycling (HIIC) on carotid arterial stiffness and hemodynamics in sedentary.

Methods

Thirty volunteered healthy sedentary males were enrolled in this study. HIIC intervention (3 sets, 20 s per set) was performed individually. A color Doppler ultrasound was applied to detect the images of the arterial inner diameters and center-line velocity waveforms at the right common carotid artery at different time points (at rest, 3 min, 15 min, and 30 min) after HIIC. Synchronously, electronic manometer was used to measure the systolic and diastolic pressures at the left brachial artery.

Results

Arterial stiffness increased and arterial diameter decreased significantly after acute HIIC. The variation in stiffness persisted for 30 min, at least 15 min longer than the change in diameter. At 3 min after exercise, maximum and mean wall shear stresses (WSS) increased and minimum WSS was also higher than the resting value. At 30 min after exercise, WSS returned to the baseline, but oscillating shear index was still higher than the resting value.

Conclusions

In summary, arterial stiffness and hemodynamics changed significantly not only at 3 min but also at 30 min after acute HIIC.

The Role of Protein SUMOylation in the Pathogenesis of Atherosclerosis

Atherosclerosis is a progressive, inflammatory cardiovascular disorder characterized by the development of lipid-filled plaques within arteries. Endothelial cell dysfunction in the walls of blood vessels results in an increase in vascular permeability, alteration of the components of the extracellular matrix, and retention of LDL in the sub-endothelial space, thereby accelerating plaque formation. Epigenetic modification by SUMOylation can influence the surface interactions of target proteins and affect cellular functionality, thereby regulating multiple cellular processes. Small ubiquitin-like modifier (SUMO) can modulate NFκB and other proteins such as p53, KLF, and ERK5, which have critical roles in atherogenesis. Furthermore, SUMO regulates leukocyte recruitment and cytokine release and the expression of adherence molecules. In this review, we discuss the regulation by SUMO and SUMOylation modifications of proteins and pathways involved in atherosclerosis.

Biomechanical Forces and Atherosclerosis: From Mechanism to Diagnosis and Treatment

The article provides an overview of current views on the role of biomechanical forces in the pathogenesis of atherosclerosis. The importance of biomechanical forces in maintaining vascular homeostasis is considered. We provide descriptions of mechanosensing and mechanotransduction. The roles of wall shear stress and circumferential wall stress in the initiation, progression and destabilization of atherosclerotic plaque are described. The data on the possibilities of assessing biomechanical factors in clinical practice and the clinical significance of this approach are presented. The article concludes with a discussion on current therapeutic approaches based on the modulation of biomechanical forces.

Collateral Vessels Have Unique Endothelial and Smooth Muscle Cell Phenotypes

Collaterals are unique blood vessels present in the microcirculation of most tissues that, by cross-connecting a small fraction of the outer branches of adjacent arterial trees, provide alternate routes of perfusion. However, collaterals are especially susceptible to rarefaction caused by aging, other vascular risk factors, and mouse models of Alzheimer’s disease—a vulnerability attributed to the disturbed hemodynamic environment in the watershed regions where they reside. We examined the hypothesis that endothelial and smooth muscle cells (ECs and SMCs, respectively) of collaterals have specializations, distinct from those of similarly-sized nearby distal-most arterioles (DMAs) that maintain collateral integrity despite their continuous exposure to low and oscillatory/disturbed shear stress, high wall stress, and low blood oxygen. Examination of mouse brain revealed the following: Unlike the pro-inflammatory cobble-stoned morphology of ECs exposed to low/oscillatory shear stress elsewhere in the vasculature, collateral ECs are aligned with the vessel axis. Primary cilia, which sense shear stress, are present, unexpectedly, on ECs of collaterals and DMAs but are less abundant on collaterals. Unlike DMAs, collaterals are continuously invested with SMCs, have increased expression of Pycard, Ki67, Pdgfb, Angpt2, Dll4, Ephrinb2, and eNOS, and maintain expression of Klf2/4. Collaterals lack tortuosity when first formed during development, but tortuosity becomes evident within days after birth, progresses through middle age, and then declines—results consistent with the concept that collateral wall cells have a higher turnover rate than DMAs that favors proliferative senescence and collateral rarefaction. In conclusion, endothelial and SMCs of collaterals have morphologic and functional differences from those of nearby similarly sized arterioles. Future studies are required to determine if they represent specializations that counterbalance the disturbed hemodynamic, pro-inflammatory, and pro-proliferative environment in which collaterals reside and thus mitigate their risk factor-induced rarefaction.

Biomechanics and Mechanobiology of Saphenous Vein Grafts

Within several weeks of use as coronary artery bypass grafts (CABG), saphenous veins (SV) exhibit significant intimal hyperplasia (IH). IH predisposes vessels to thrombosis and atherosclerosis, the two major modes of vein graft failure. The fact that SV do not develop significant IH in their native venous environment coupled with the rapidity with which they develop IH following grafting into the arterial circulation suggests that factors associated with the isolation and preparation of SV and/or differences between the venous and arterial environments contribute to disease progression. There is strong evidence suggesting that mechanical trauma associated with traditional techniques of SV preparation can significantly damage the vessel and might potentially reduce graft patency though modern surgical techniques reduces these injuries. In contrast, it seems possible that modern surgical technique, specifically endoscopic vein harvest, might introduce other mechanical trauma that could subtly injure the vein and perhaps contribute to the reduced patency observed in veins harvested using endoscopic techniques. Aspects of the arterial mechanical environment influence remodeling of SV grafted into the arterial circulation. Increased pressure likely leads to thickening of the medial wall but its role in IH is less clear. Changes in fluid flow, including increased average wall shear stress, may reduce IH while disturbed flow likely increase IH. Nonmechanical stimuli, such as exposure to arterial levels of oxygen, may also have a significant but not widely recognized role in IH. Several potentially promising approaches to alter the mechanical environment to improve graft patency are including extravascular supports or altered graft geometries are covered.

A three-step approach identifies novel shear stress-sensitive endothelial microRNAs involved in vasculoprotective effects of high-intensity interval training (HIIT)

Circulatory microRNAs (c-miRNAs) are regulated in response to physical activity and may exert anti-atherosclerotic effects. Since the vascular endothelium is an abundant source of c-miRNAs, we aimed to identify novel vasculoprotective exercise-induced c-miRNAs by the combined analysis of published endothelial miRNA array data followed by in vivo and in vitro validation. We identified 8 different array-based publications reporting 185 endothelial shear stress-regulated miRNAs of which 13 were identified in ≥3 independent reports. Nine miRNAs had already been associated with physical activity. Of the remaining novel miRNAs, miR-98-3p and miR-125-5p were selected for further analysis due to reported vasculoprotective effects. Analysis in two different 4-week high-intensity interval training (HIIT) groups (group 1 [n=27]: 4x30 s, group 2 [n=25]: 8x15 s; all-out running) suggested significantly elevated miR-98 and miR-125a-5p levels in response to acute exercise at baseline and at follow-up. Endothelial in vitro shear stress experiments revealed increased miR-125a-5p and miR-98-3p levels in medium of human umbilical vein endothelial cells at 30 dyn/cm² after 20 and 60 min, respectively. Our results suggest that miR-98-3p and miR-125a-5p can be rapidly secreted by endothelial cells, which might be the source of increased c-miR-98-3p and -125a-5p levels in response to HIIT. Both miRNAs attenuate endothelial inflammation and may mediate vasculoprotective effects of physical exercise including HIIT.