On vasa vasorum: A history of advances in understanding the vessels of vessels

Pericoronary adipose tissue: potential for pathological diagnosis and therapeutic applications

Excessive accumulation of epicardial adipose tissue (EAT) is known to be a risk factor for coronary artery disease and heart failure. In particular, it is thought that inflammation of pericoronary adipose tissue (PCAT) affects the pathology of various coronary artery diseases (CAD). EAT and PCAT are thought to be new therapeutic targets for preventing cardiovascular disease. Although there are no established drugs that specifically reduce inflammation of EAT or PCAT, the basic approach is to improve lifestyle-related diseases through exercise and diet, and to use metabolic improvement drugs and anti-inflammatory drugs as soft support. Potential candidates include statins, SGLT2 inhibitors, and GLP- 1 receptor agonists. In addition to conventional treatments that target substances within blood vessels, treatments that target EAT and PCAT by directly enveloping the coronary arteries and myocardium from outside the body are expected to further suppress cardiovascular events.

Exosomes Derived from the Serum of Mice That Received a Huoxue Yiqi Recipe Promote Angiogenesis Following Myocardial Infarction

Proangiogenic therapy offers a promising strategy for treating and preventing heart failure and cardiac remodeling following a myocardial infarction (MI). Although exosome-based proangiogenic therapy has significant potential in regenerative medicine and MI treatment, its application remains limited by suboptimal therapeutic efficacy. Here, we present exosomes (HXYQR-Exo) derived from the serum of mice treated with the Huoxue Yiqi Recipe (HXYQR) to promote angiogenesis and repair cardiac tissue post-MI, with a systematic elucidation of the underlying mechanisms. Our findings show that HXYQR-Exo incorporates pharmaceutically active components of HXYQR, enhancing the proliferation, invasion, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) under hypoxic conditions. In vivo studies demonstrate significant improvements in cardiac function and angiogenesis. Mechanistic investigations reveal that these effects are mediated through the activation of the HIF-1α/VEGF, Focal Adhesion Kinase (FAK), and p38/Mitogen-Activated Protein Kinase-Activated Protein Kinase (MAPKAPK)/Heat Shock Protein 27 (HSP27) pathways. This study introduces an exosome-based approach for MI treatment and cardiac repair, offering an effective strategy to enhance exosome biological activities and functions via traditional Chinese medicine preconditioning.

Deficiency of fibroblast growth factor 2 promotes contractile phenotype of pericytes in ascending thoracic aortic aneurysm

Pericytes exhibit progenitor cell-like qualities and associate with the vasa vasorum-vital microvessels nourishing larger arteries and veins. How pericytes change in human ascending thoracic aortic aneurysm (ATAA) remains unknown. Here, we used the public single-nuclei sequencing data to reveal a contractile phenotype transition of pericytes in human ATAA specimens. In addition, we found that a protective factor, fibroblast growth factor 2 (FGF2), is decreased in the aortic adventitia of both male and female patients with ATAA and impacts pericytes. We demonstrated that FGF2 maintained pericytes in a less contractile and high angiogenic phenotype via MAPK and PI3K-AKT signaling pathways. These findings suggested the latent engagement of pericytes in ATAA, providing insights that could guide the development of new therapies against aortic disease.NEW & NOTEWORTHY Here, we revealed that pericytes transition into a contractile phenotype in human ATAA. We demonstrated that FGF2 maintained pericytes in a less contractile and high angiogenic stage via MAPK and PI3K-AKT signaling pathway, whereas we found FGF2 is decreased in the aortic adventitia of patients with ATAA. Our findings suggest how growth factor deficiency in the microenvironment affects pericytes during ATAA, offering leads for potential new therapies for aortic diseases.

Magnetic resonance imaging to monitor disease activity in giant cell arteritis treated with ultra-short glucocorticoids and tocilizumab

OBJECTIVES

MRI is well established for diagnosing GCA. Its role in monitoring disease activity has yet to be determined. We investigated vascular and musculoskeletal inflammation using MRI in the patients of the GUSTO trial to assess the utility of MRI in monitoring disease activity.

METHODS

Eighteen patients with newly diagnosed GCA received 500 mg methylprednisolone intravenously for three consecutive days followed by tocilizumab monotherapy from day 3 until week 52. Cranial, thoracic and abdominal MRI exams were performed at baseline (active, new-onset disease), and at weeks 24, 52 (remission on-treatment) and 104 (remission off-treatment). MRI findings typical for PMR as well as extent and severity of vasculitic disease were rated.

RESULTS

In total, 673 vascular segments and 943 musculoskeletal regions in 55 thoracic/abdominal MRI and 490 vascular segments in 49 cranial MRI scans of 18 patients were analysed. Vasculitic vessels were still detectable in one in four cranial segments at week 24. At weeks 52 and 104, no cranial vascular segment showed a vasculitic manifestation. Large vessels, except for the ascending aorta, and PMR displayed little or no decrease in inflammatory findings over time.

CONCLUSION

Vasculitic manifestations in the cranial vessels normalized after 52 weeks of treatment, whereas large vessel and PMR findings persisted despite lasting full remission. The dynamics of cranial vessel signals suggest that MRI of these arteries might qualify as a potential diagnostic tool for monitoring disease activity and for detecting relapse after 52 weeks of treatment.

The vascular microenvironment and its stem cells regulate vascular homeostasis

The vascular microenvironment comprises of anatomical structures, extracellular matrix components, and various cell populations, which play a crucial role in regulating vascular homeostasis and influencing vascular structure and function. Under physiological conditions, intrinsic regulation of the vascular microenvironment is required to sustain vascular homeostasis. In contrast, under pathological conditions, alterations to this microenvironment lead to vascular injury and pathological remodeling. According to the anatomy, the vascular microenvironment can be subdivided into three sections from the inside out. The vascular endothelial microenvironment, centered on vascular endothelial cells (VECs), includes the extracellular matrix and various vascular physicochemical factors. The VECs interact with vascular physicochemical factors to regulate the function of various parenchymal cells, including hepatocytes, neurons and tumor cells. The vascular wall microenvironment, comprising the vasa vasorum and their unique stem/progenitor cell niches, plays a pivotal role in vascular inflammation and pathological remodeling. Additionally, the perivascular microenvironment, which includes perivascular adipose tissue, consists of adipocytes and stem cells, which contribute to the pathological processes of atherosclerosis. It is anticipated that targeted regulation of the vascular microenvironment will emerge as a novel approach for the treatment of various diseases. Accordingly, this review will examine the structure of the vascular microenvironment, the regulation of vascular function by vascular cells and stem/progenitor cells, and the role of the vascular microenvironment in regulating cardiovascular diseases.

Angiogenesis within atherosclerotic plaques: Mechanical regulation, molecular mechanism and clinical diagnosis

Atherosclerosis (AS) is a disease characterized by focal cholesterol accumulation and insoluble inflammation in arterial intima, leading to the formation of an atherosclerotic plaque consisting of lipids, cells, and fibrous matrix. The presence of plaque can restrict or obstruct blood flow, resulting in arterial stenosis and local mechanical microenvironment changes including flow shear stress, vascular matrix stiffness, and plaque structural stress. Neovascularization within the atherosclerotic plaque plays a crucial role in both plaque growth and destabilization, potentially leading to plaque rupture and fatal embolism. However, the exact interactions between neovessels and plaque remain unclear. In this review, we provide a comprehensive analysis of the origin of intraplaque neovessels, the contributing factors, underlying molecular mechanisms, and associated signaling pathways. We specifically emphasize the role of mechanical factors contributing to angiogenesis in atherosclerotic plaques. Additionally, we summarize the imaging techniques and therapeutic strategies for intraplaque neovessels to enhance our understanding of this field.

A novel vessel enhancement method based on Hessian matrix eigenvalues using multilayer perceptron

BACKGROUND

Vessel segmentation is a critical aspect of medical image processing, often involving vessel enhancement as a preprocessing step. Existing vessel enhancement methods based on eigenvalues of Hessian matrix face challenges such as inconsistent parameter settings and suboptimal enhancement effects across different datasets.

OBJECTIVE

This paper aims to introduce a novel vessel enhancement algorithm that overcomes the limitations of traditional methods by leveraging a multilayer perceptron to fit a vessel enhancement filter function using eigenvalues of Hessian matrix. The primary goal is to simplify parameter tuning while enhancing the effectiveness and generalizability of vessel enhancement.

METHODS

The proposed algorithm utilizes eigenvalues of Hessian matrix as input for training the multilayer perceptron-based vessel enhancement filter function. The diameter of the largest blood vessel in the dataset is the only parameter to be set.

RESULTS

Experiments were conducted on public datasets such as DRIVE, STARE, and IRCAD. Additionally, optimal parameter acquisition methods for traditional Frangi and Jerman filters are introduced and quantitatively compared with the novel approach. Performance metrics such as AUROC, AUPRC, and DSC show that the proposed algorithm outperforms traditional filters in enhancing vessel features.

CONCLUSION

The findings of this study highlight the superiority of the proposed vessel enhancement algorithm in comparison to traditional methods. By simplifying parameter settings, improving enhancement effects, and showcasing superior performance metrics, the algorithm offers a promising solution for enhancing vessel parts in medical image analysis applications.

Distinct inflammatory pathways shape atherosclerosis in different vascular beds

Studies suggest varying atherosclerotic cardiovascular disease (ASCVD) prevalence across arterial beds. Factors such as smoking expedite ASCVD progression in the abdominal aorta, while diabetes accelerates plaque development in lower limb arteries, and hypertension plays a significant role in ASCVD development in the coronary and carotid arteries. Moreover, superficial femoral atherosclerosis advances slower compared with atherosclerosis in coronary and carotid arteries. Furthermore, femoral atherosclerosis exhibits higher levels of ossification and calcification, but lower cholesterol concentrations compared with atherosclerotic lesions of other vascular beds. Such disparities exemplify the diverse progression of ASCVD across arterial beds, pointing towards differential mechanistic pathways in each vascular bed. Hence, this review summarizes current literature on immune-inflammatory mechanisms in various arterial beds in ASCVD to advance our understanding of this disease in an aging society with increased need of vascular bed and patient-specific treatment options.

Emerging role of mesenchymal cells in cardiac and cerebrovascular diseases: Physiology, pathology, and therapeutic implications

In recent years, the therapeutic utility of mesenchymal stem cells (MSCs) has received substantial attention from investigators, owing to their pleiotropic properties. The emerging insights from the developments in tissue engineering provide perspectives for the repair of damaged tissue and the replacement of failing organs. Perivascular cells including MSC-like pericytes, vascular smooth muscles, and other cells located around blood vessels, have been acknowledged to contribute to in situ angiogenesis and repair process. MSCs offer a wide array of therapeutic applications in different pathological states. However, in the current article, we have highlighted the recent updates on MSCs and their key applications in cardiac and cerebrovascular diseases, evident in different preclinical and clinical studies. We believe the present article would assist the investigators in understanding the recent advances of MSCs and exploring their therapeutic potential in varied ailments, especially cardiac and cerebrovascular diseases.

Caesalpinia sappan L. ethyl acetate extract regulated angiogenesis in atherosclerosis by modulating the miR-126/VEGF signalling pathway

Aims of the study

To investigate the regulatory mechanism of Caesalpinia sappan L. ethyl acetate extract (CSEAE) on angiogenesis in atherosclerosis (AS) based on the miR-126/VEGF signalling pathway.

Materials and methods

Our study first screened for differentially expressed microRNAs (miRNAs) associated with AS using the Gene Expression Omnibus (GEO) public database at the National Center for Biotechnology Information (NCBI) and R language software. Subsequently, our study verified the target-regulatory relationship between miR-126 and vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs) by using the "TargetScan" website and dual-luciferase reporter assay. In cellular experiments, Our study used cell proliferation assays and flow cytometry to assess the effects of CSEAE-Mediated serum on the proliferation and apoptosis of HUVECs. In animal experiments, our study used HE staining, Oil Red O staining and immunohistochemistry (IHC) staining to detect plaque area/lumen area (%), lipid area/plaque area (%) and microvessel density (MVD) in mouse aortas. In addition, our study performed RT‒PCR, ELISA and Western blot assays in ex vivo and in vivo experiments.

Results

A total of 39 differentially expressed miRNAs of AS were identified, among which the miR-126 expression level was significantly downregulated. Dual luciferase reporter gene assay results showed that miR-126 and VEGF have a targeting relationship, and the miR-126 mimic could inhibit the luciferase activity of the wild-type VEGF reporter gene vector (p value < 0.01). In cellular experiments, cell proliferation assays and flow cytometry results showed that CSEAE-Mediated serum significantly increased the proliferative activity after 24-72 h of treatment (p-value <0.01) and decreased the apoptotic level of HUVECs (p value < 0.01), and RT‒PCR results showed that CSEAE-Mediated serum significantly upregulated the expression of miR-126 (p value < 0.01) and downregulated the expression of VEGF mRNA in HUVECs (p value < 0.01). In vivo experiments, HE staining and IHC staining showed that CSEAE significantly reduced the MVD in the aorta and plaques of mice (p value < 0.01) and significantly reduced the aortic plaque area/lumen area (%) (p value < 0.01). Moreover, RT‒PCR assay and Western blot analysis results showed that CSEAE significantly upregulated the expression of miR-126 (p value < 0.01), downregulated the expression of VEGF mRNA (p value < 0.01), and decreased the protein expression levels of VEGF (p value < 0.01), phosphatidyl-inositol-3-kinase (PI3K) (p value < 0.01), and Ser/Thr-protein kinase (AKT1) (p value < 0.01) in mouse aortas, while ELISA showed that CSEAE significantly reduced the serum levels of vascular endothelial growth factor receptor (VEGFR2) (p value < 0.01) and hypoxia-inducible factor-1 (HIF-1) (p value < 0.01) in mice.

Conclusion

This study emphasises CSEAE as a natural medicinal extract for the treatment of AS that can improve the migratory viability and reduce the apoptosis of HUVECs to maintain the health of the arterial endothelial microenvironment, while CSEAE also inhibits angiogenesis and delays plaque formation in ApoE-/- mice, suggesting that the therapeutic effect of CSEAE for AS may be related to its inhibition of neovascularisation and that its molecular mechanism may be related to the miR-126/VEGF signalling pathway.

Roles of perivascular adipose tissue in the pathogenesis of atherosclerosis - an update on recent findings

Lifestyle-related diseases, such as atherosclerosis and diabetes, are now considered to be a series of diseases caused by chronic inflammation. Adipose tissue is considered to be an endocrine organ that not only plays a role in lipid storage, heat production, and buffering, but also produces physiologically active substances and is involved in chronic inflammation. Perivascular adipose tissue (PVAT) surrounding blood vessels similarly produces inflammatory and anti-inflammatory physiologically active substances that act on blood vessels either directly or via the bloodstream. Epicardial adipose tissue (EAT), which is in direct contact with the coronary arteries inside the pericardium, is thought to have a direct effect on the coronary arteries as well. The presence and inflammatory status of these adipose tissues can be evaluated by imaging tests, and has been shown to be associated with the presence of current cardiovascular disease (CVD) and to be a prognostic factor. It is also expected to become a new diagnostic and therapeutic target for CVD.

Feasibility and Clinical Outcomes of Vasa Vasorum Embolization for Atypical Type 2 or Type 5 Endoleaks after Endovascular Aneurysm Repair

Objectives: The purpose of this study is to evaluate the feasibility and clinical outcomes of vasa vasorum embolization for preventing continuous aneurysmal expansion after endovascular aneurysm repair (EVAR). Methods: We retrospectively reviewed the medical records of patients who underwent vasa vasorum embolization between August 2018 and May 2022. Vasa vasorum embolization was attempted in cases of continuous aneurysmal expansion after EVAR, where the vasa vasorum was identified through catheter angiography. The vasa vasorum was accessed and embolized with a microcatheter. The outcomes of vasa vasorum embolization were evaluated based on technical success, defined as the successful completion of the embolization procedure, and clinical success, defined as the prevention of continuous aneurysmal expansion after the embolization. Results: Seven cases of endoleak with developed vasa vasorum were confirmed by catheter angiography. The mean age was 83.7 years, and the mean aneurysmal diameter was 60.6 mm. Technical success was achieved in 6 cases, while clinical success was not achieved in any of the cases. The mean observation period was 16.5 months, and the mean increase in aneurysmal diameter was 9.7 mm. Conclusions: Although the vasa vasorum embolization is a technically feasible procedure, it is not effective in preventing continuous aneurysmal expansion.

Multiscale structure and function of the aortic valve apparatus

Whereas studying the aortic valve in isolation has facilitated the development of life-saving procedures and technologies, the dynamic interplay of the aortic valve and its surrounding structures is vital to preserving their function across the wide range of conditions encountered in an active lifestyle. Our view is that these structures should be viewed as an integrated functional unit, here referred to as the aortic valve apparatus (AVA). The coupling of the aortic valve and root, left ventricular outflow tract, and blood circulation is crucial for AVA's functions: unidirectional flow out of the left ventricle, coronary perfusion, reservoir function, and support of left ventricular function. In this review, we explore the multiscale biological and physical phenomena that underlie the simultaneous fulfillment of these functions. A brief overview of the tools used to investigate the AVA, such as medical imaging modalities, experimental methods, and computational modeling, specifically fluid-structure interaction (FSI) simulations, is included. Some pathologies affecting the AVA are explored, and insights are provided on treatments and interventions that aim to maintain quality of life. The concepts explained in this article support the idea of AVA being an integrated functional unit and help identify unanswered research questions. Incorporating phenomena through the molecular, micro, meso, and whole tissue scales is crucial for understanding the sophisticated normal functions and diseases of the AVA.

Pulmonary Artery Vasa Vasorum Damage in Severe COVID-19-Induced Pulmonary Fibrosis

Background

COVID-19 patients exhibit higher incidence of thrombosis in arteries and veins, including those in lungs. Vasa vasorum, which support large blood vessels, have shown involvement in these pathologic processes.

Methods

To further explore the extent of microvascular damage caused by COVID-19 infection, we examined resected main, right, or left pulmonary artery specimens from patients undergoing bilateral lung transplantation for COVID-19- or non-COVID-19-induced pulmonary fibrosis compared with organ donors by histologic and immunohistologic analyses.

Results

Vasa vasorum density was found to be higher in specimens procured from patients with COVID-19 and associated with pulmonary artery hypertension compared with lung transplant donors. In addition, we found immunothrombosis within vasa vasorum in specimens from COVID-19 patients with more immune infiltration, including CD15+, CD44+, and CD68+ cells.

Conclusions

These findings reveal that COVID-19 affects the vasa vasorum of pulmonary arteries and suggest that infection may lead to large-vessel dysfunction and organ failure.

Extracellular purines in lung endothelial permeability and pulmonary diseases

The purinergic signaling system is an evolutionarily conserved and critical regulatory circuit that maintains homeostatic balance across various organ systems and cell types by providing compensatory responses to diverse pathologies. Despite cardiovascular diseases taking a leading position in human morbidity and mortality worldwide, pulmonary diseases represent significant health concerns as well. The endothelium of both pulmonary and systemic circulation (bronchial vessels) plays a pivotal role in maintaining lung tissue homeostasis by providing an active barrier and modulating adhesion and infiltration of inflammatory cells. However, investigations into purinergic regulation of lung endothelium have remained limited, despite widespread recognition of the role of extracellular nucleotides and adenosine in hypoxic, inflammatory, and immune responses within the pulmonary microenvironment. In this review, we provide an overview of the basic aspects of purinergic signaling in vascular endothelium and highlight recent studies focusing on pulmonary microvascular endothelial cells and endothelial cells from the pulmonary artery vasa vasorum. Through this compilation of research findings, we aim to shed light on the emerging insights into the purinergic modulation of pulmonary endothelial function and its implications for lung health and disease.

Overcoming big bottlenecks in vascular regeneration

Bioengineering and regenerative medicine strategies are promising for the treatment of vascular diseases. However, current limitations inhibit the ability of these approaches to be translated to clinical practice. Here we summarize some of the big bottlenecks that inhibit vascular regeneration in the disease applications of aortic aneurysms, stroke, and peripheral artery disease. We also describe the bottlenecks preventing three-dimensional bioprinting of vascular networks for tissue engineering applications. Finally, we describe emerging technologies and opportunities to overcome these challenges to advance vascular regeneration.

Hypoxic perfusion of pulmonary arterial vasa vasorum increases pulmonary arterial pressure

The pathophysiology of pulmonary hypertension (PH) is not fully understood. Here, we tested the hypothesis that hypoxic perfusion of the vasa vasorum of the pulmonary arterial (PA) wall causes PH. Young adult pig lungs were explanted and placed into a modified ex vivo lung perfusion unit (organ care system, OCS) allowing the separate adjustment of parameters for mechanical ventilation, as well as PA perfusion and bronchial arterial (BA) perfusion. The PA vasa vasorum are branches of the BA. The lungs were used either as the control group (n = 3) or the intervention group (n = 8). The protocol for the intervention group was as follows: normoxic ventilation and perfusion (steady state), hypoxic BA perfusion, steady state, and hypoxic BA perfusion. During hypoxic BA perfusion, ventilation and PA perfusion maintained normal. Control lungs were kept under steady-state conditions for 105 min. During the experiments, PA pressure (PAP) and blood gas analysis were frequently monitored. Hypoxic perfusion of the BA resulted in an increase in systolic and mean PAP, a reaction that was reversible upon normoxic BA perfusion. The PAP increase was reproducible during the second hypoxic BA perfusion. Under control conditions, the PAP stayed constant until about 80 min of the experiment. In conclusion, the results of the current study prove that hypoxic perfusion of the vasa vasorum of the PA directly increases PAP in an ex situ lung perfusion setup, suggesting that PA vasa vasorum function and wall ischemia may contribute to the development of PH.NEW & NOTEWORTHY Hypoxic perfusion of the vasa vasorum of the pulmonary artery directly increased pulmonary arterial pressure in an ex vivo lung perfusion setup. This suggests that the function of pulmonary arterial vasa vasorum and wall ischemia may contribute to the development of pulmonary hypertension.

Vasa vasorum: The role in intracranial physiology and pathophysiology

Background

Vasa vasorum (VVs) is a Latin word representing vessels of vessels. VVs are usually found on the adventitia of the parent vessel and infrequently reach the media and intima, depending on the size and type of the parent vessels and physiological and pathological conditions. The VVs include arteries, capillaries, veins, and lymphatic vessels, involving the oxygenation and nourishment of the vessel's wall to sustain its healthy state. Accumulated studies have revealed that VVs are involved in various intracranial lesions, including atherosclerotic diseases, aneurysms, and shunt diseases. The current review aims to review and integrate past and recent findings and knowledge on VVs and to facilitate our understanding of VVs and intracranial pathology involving VVs.

Methods

A literature review was carried out with a focus on the role of VVs by searching the Pubmed database.

Results

We identified 71 articles that discuss the role of VVs. We discussed the anatomical structure, physiological significance, and pathological significance of the VV.

Conclusion

VV is not only involved in the nutrition and metabolism of the vascular wall but is also deeply involved in the pathogenesis of inflammation, ischemia, and thrombosis of the vascular wall. In addition, in the central nervous system, intracranial vascular wall nutrient particularities and VVs are closely related to the pathogenesis of cerebral aneurysms, subarachnoid hemorrhage, arteriovenous shunt disease, atherosclerotic lesions, and other conditions.

Thrombosis of the vasa vasorum of the large and medium size pulmonary artery and vein leads to pulmonary thromboembolism in COVID-19

The vasa vasorum of the large pulmonary vessels is involved in the pathology of COVID-19. This specialized microvasculature plays a major role in the biology and pathology of the pulmonary vessel walls. We have evidence that thrombosis of the vasa vasorum of the large and medium-sized pulmonary vessels during severe COVID-19 causes ischemia and subsequent death of the pulmonary vasculature endothelium. Subsequent release of thrombi from the vasa interna into the pulmonary circulation and pulmonary embolism generated at the ischemic pulmonary vascular endothelium site, are the central pathophysiological mechanisms in COVID-19 responsible for pulmonary thromboembolism. The thrombosis of the vasa vasorum of the large and medium-sized pulmonary vessels is an internal event leading to pulmonary thromboembolism in COVID-19.

Decoding the Cell Atlas and Inflammatory Features of Human Intracranial Aneurysm Wall by Single-Cell RNA Sequencing

BACKGROUND

Intracranial aneurysm (IA) is common and occasionally results in life-threatening hemorrhagic strokes. However, the cell architecture and inflammation in the IA dome remain less understood.

METHODS AND RESULTS

Single-cell RNA sequencing was performed on ruptured and unruptured human IA domes for delineating the cell atlas, gene expression perturbations, and inflammation features. Two external bulk mRNA sequencing-based data sets and serological results of 126 patients were collected for validation. As a result, a total of 21 332 qualified cells were captured. Vascular cells, including endothelial cells, smooth muscle cells, fibroblasts, and pericytes, were assigned in extremely sparse numbers (4.84%), and were confirmed by immunofluorescence staining. Pericytes, characterized by ABCC9 and HIGD1B, were identified in the IA dome for the first time. Abundant immune cells were identified, with the proportion of monocytes/macrophages and neutrophils being remarkably higher in ruptured IA. The lymphocyte compartment was also thoroughly categorized. By leveraging external data sets and machine learning algorithms, macrophages were robustly associated with IA rupture, irrespective of their polarization status. The single nucleotide polymorphism rs2280543, which is identified in East Asian populations, was associated with macrophage metabolic reprogramming through regulating TALDO1 expression.

CONCLUSIONS

This study provides insights into the cellular architecture and inflammatory features in the IA dome and may enlighten novel therapeutics for unruptured IA.

Current Insights into Tissue Injury of Giant Cell Arteritis: From Acute Inflammatory Responses towards Inappropriate Tissue Remodeling

Giant cell arteritis (GCA) is an autoimmune disease affecting large vessels in patients over 50 years old. It is an exemplary model of a classic inflammatory disorder with IL-6 playing the leading role. The main comorbidities that may appear acutely or chronically are vascular occlusion leading to blindness and thoracic aorta aneurysm formation, respectively. The tissue inflammatory bulk is expressed as acute or chronic delayed-type hypersensitivity reactions, the latter being apparent by giant cell formation. The activated monocytes/macrophages are associated with pronounced Th1 and Th17 responses. B-cells and neutrophils also participate in the inflammatory lesion. However, the exact order of appearance and mechanistic interactions between cells are hindered by the lack of cellular and molecular information from early disease stages and accurate experimental models. Recently, senescent cells and neutrophil extracellular traps have been described in tissue lesions. These structures can remain in tissues for a prolonged period, potentially favoring inflammatory responses and tissue remodeling. In this review, current advances in GCA pathogenesis are discussed in different inflammatory phases. Through the description of these-often overlapping-phases, cells, molecules, and small lipid mediators with pathogenetic potential are described.

Diabetic microvascular disease in non-classical beds: the hidden impact beyond the retina, the kidney, and the peripheral nerves

Diabetes microangiopathy, a hallmark complication of diabetes, is characterised by structural and functional abnormalities within the intricate network of microvessels beyond well-known and documented target organs, i.e., the retina, kidney, and peripheral nerves. Indeed, an intact microvascular bed is crucial for preserving each organ's specific functions and achieving physiological balance to meet their respective metabolic demands. Therefore, diabetes-related microvascular dysfunction leads to widespread multiorgan consequences in still-overlooked non-traditional target organs such as the brain, the lung, the bone tissue, the skin, the arterial wall, the heart, or the musculoskeletal system. All these organs are vulnerable to the physiopathological mechanisms that cause microvascular damage in diabetes (i.e., hyperglycaemia-induced oxidative stress, inflammation, and endothelial dysfunction) and collectively contribute to abnormalities in the microvessels' structure and function, compromising blood flow and tissue perfusion. However, the microcirculatory networks differ between organs due to variations in haemodynamic, vascular architecture, and affected cells, resulting in a spectrum of clinical presentations. The aim of this review is to focus on the multifaceted nature of microvascular impairment in diabetes through available evidence of specific consequences in often overlooked organs. A better understanding of diabetes microangiopathy in non-target organs provides a broader perspective on the systemic nature of the disease, underscoring the importance of recognising the comprehensive range of complications beyond the classic target sites.

Analyzing the contribution of vasa vasorum in oxygenation of the aneurysmal wall: A computational study

The mechanisms of abdominal aortic aneurysm (AAA) formation and rupture are controversial in the literature. While the intraluminal thrombus (ILT) plays a crucial role in reducing oxygen flux to the tissue and therefore decreasing the aortic wall strength, other physiological parameters such as the vasa vasorum (VV) oxygen flow and its consumption contribute to altered oxygenation responses of the arterial tissue as well. The goal of this research is to analyse the importance of the aforementioned parameters on oxygen delivery to the aneurysmal wall in a patient-specific AAA. Numerical simulations of coupled blood flow and mass transport with varying levels of VV concentration and oxygen reaction rate coefficient are performed. The hypoperfusion of the adventitial VV and high oxygen consumption are observed to have critical effects on reducing aneurysmal tissue oxygen supply and can therefore exacerbate localized oxygen deprivation.

Vasa Vasorum in Saphenous Vein for CABG: A Review of Morphological Characteristics

This short article discusses selected scanning electron microscope and transmission electron microscope features of vasa vasorum including pericytes and basement membrane of the human saphenous vein (SV) harvested with either conventional (CON) or no-touch (NT) technique for coronary artery bypass grafting. Scanning electron microscope data shows the general damage to vasa vasorum of CON-SV, while the transmission electron microscope data presents ultrastructural features of the vasa in more detail. Hence there are some features suggesting pericyte involvement in the contraction of vasa blood vessels, particularly in CON-SV. Other features associated with the vasa vasorum of both CON-SV and NT-SV preparations include thickened and/or multiplied layers of the basement membrane. In some cases, multiple layers of basement membrane embrace both pericyte and vasa microvessel making an impression of a "unit" made by basement membrane-pericyte-endothelium/microvessel. It can be speculated that this structural arrangement has an effect on the contractile and/or relaxing properties of the vessels involved. Endothelial colocalization of immunoreactive inducible nitric oxide synthase and endothelin-1 can be observed (with laser confocal microscope) in some of the vasa microvessels. It can be speculated that this phenomenon, particularly of the expression of inducible nitric oxide synthase, might be related to structurally changed vasa vessels, e.g., with expanded basement membrane. Fine physiological relationships between vasa vasorum endothelium, basement membrane, pericyte, and perivascular nerves have yet to be uncovered in the detail needed for better understanding of the cells'specific effects in SV preparations for coronary artery bypass grafting.

Adventitial Vasa Vasorum Neovascularization in Femoral Artery of Type 2 Diabetic Patients with Macroangiopathy Is Associated with Macrophages and Lymphocytes as well as the Occurrence of Cardiovascular Events

OBJECTIVES

 This study was conducted to assess the relationship between adventitial vasa vasorum neovascularization (VVn) in femoral artery of type 2 diabetic patients with macroangiopathy and the recruitment of macrophages and lymphocytes, and to relate the density of VVn to the occurrence of cardiovascular events.

MATERIALS

 Femoral artery samples were obtained from amputation cases. A total of 55 type 2 diabetic patients with macroangiopathy, 15 autopsy cases with type 2 diabetes without atherosclerosis.

METHODS

 Hematoxylin and eosin (H&E) staining to observe the histopathological features; Victoria blue staining to analyze the histological features; immunohistochemistry (CD34, CD68, CD20, and CD3) to determine the VVn density and the expression of macrophages, B lymphocytes, and T lymphocytes.

RESULTS

 Type 2 diabetic patients with macroangiopathy showed a higher mean adventitial VVn density in femoral artery (48.40 ± 9.39 no./mm2) than patients with type 2 diabetes without atherosclerosis (19.75 ± 6.28 no./mm2) (p < 0.01). In addition, the VVn density was positively associated with the expression of CD68 macrophages (r = 0.62, p < 0.01) and CD20 B lymphocytes (r = 0.59, p < 0.01). Type 2 diabetic patients with high VVn density showed more adverse cardiovascular events (27/35 vs. 8/20 events, p = 0.006). In multivariable analysis adjusted for main risk factors for cardiovascular disease, VVn was still independently associated with adverse cardiovascular events (p = 0.01).

CONCLUSION

 VVn density in type 2 diabetic patients with macroangiopathy is positively correlated with the adventitial immune-inflammatory cell numbers and the development of atherosclerotic lesions. Furthermore, VVn density is associated with adverse cardiovascular events.

Extracellular Matrix Remodeling in Vascular Disease: Defining Its Regulators and Pathological Influence

Because of structural and cellular differences (ie, degrees of matrix abundance and cross-linking, mural cell density, and adventitia), large and medium-sized vessels, in comparison to capillaries, react in a unique manner to stimuli that induce vascular disease. A stereotypical vascular injury response is ECM (extracellular matrix) remodeling that occurs particularly in larger vessels in response to injurious stimuli, such as elevated angiotensin II, hyperlipidemia, hyperglycemia, genetic deficiencies, inflammatory cell infiltration, or exposure to proinflammatory mediators. Even with substantial and prolonged vascular damage, large- and medium-sized arteries, persist, but become modified by (1) changes in vascular wall cellularity; (2) modifications in the differentiation status of endothelial cells, vascular smooth muscle cells, or adventitial stem cells (each can become activated); (3) infiltration of the vascular wall by various leukocyte types; (4) increased exposure to critical growth factors and proinflammatory mediators; and (5) marked changes in the vascular ECM, that remodels from a homeostatic, prodifferentiation ECM environment to matrices that instead promote tissue reparative responses. This latter ECM presents previously hidden matricryptic sites that bind integrins to signal vascular cells and infiltrating leukocytes (in coordination with other mediators) to proliferate, invade, secrete ECM-degrading proteinases, and deposit injury-induced matrices (predisposing to vessel wall fibrosis). In contrast, in response to similar stimuli, capillaries can undergo regression responses (rarefaction). In summary, we have described the molecular events controlling ECM remodeling in major vascular diseases as well as the differential responses of arteries versus capillaries to key mediators inducing vascular injury.

Modeling human anti-pig xenoimmune responses in a pig artery tissue grafted humanized mouse model

BACKGROUND

Blood vessels that contain endothelial cells (ECs) on the surface are in direct contact with host blood and are the first target of xenograft rejection. Currently, our understanding of human anti-pig vessel immune responses is primarily based on in vitro assays using pig ECs. Therefore, it is necessary to develop an animal model that permits in vivo study of human immunological rejection of pig vessels.

METHODS

Pig artery tissues (PAT) were transplanted into human immune system (HIS) mice or immunodeficient NSG mice (as controls). Intragraft human immune cell infiltration and antibody deposition were quantified using histology and immunohistochemistry. Donor antigen-specific immune responses were quantified using a mixed lymphocyte reaction and a complement-dependent killing assay.

RESULTS

Pig CD31+ ECs were detected and increased 2-fold from weeks 3 to 5 in PAT xenografts from immunodeficient NSG mice. However, compared with NSG mice, PAT xenografts in HIS mice had significantly lower numbers of porcine CD31+ ECs and showed a marked reduction from week 3 to week 5. PAT xenograft rejection in HIS mice is associated with intensive infiltration of human immune cells, deposition of human IgM and IgG antibodies, and the formation of a tertiary lymphoid structure. Robust donor pig antigen-specific human T cells and antibody responses were detected in PAT-transplanted HIS mice.

CONCLUSION

We have developed a humanized mouse model to evaluate human anti-pig xenoimmune responses by PAT transplantation in vivo. This model is expected to facilitate the refinement of pig gene-editing strategies (the expression on EC surface) and the testing of local immunosuppressive strategies for clinical pig organ xenotransplantation.

Validating human and mouse tissues commonly used in atherosclerosis research with coronary and aortic reference tissue: similarities but profound differences in disease initiation and plaque stability

Objective

Characterization of the atherosclerotic process fully relies on histological evaluation and staging through a consensus grading system. So far, a head-to-head comparison of atherosclerotic process in experimental models and tissue resources commonly applied in atherosclerosis research with the actual human atherosclerotic process is missing.

Material and Methods

Aspects of the atherosclerotic process present in established murine atherosclerosis models and human carotid endarterectomy specimen were systematically graded using the modified American Heart Association histological classification (Virmani classification). Aspects were aligned with the atherosclerotic process observed in human coronary artery and aortic atherosclerosis reference tissues that were available through biobanks based on human tissue/organ donor material.

Results

Apart from absent intraplaque hemorrhages in aortic lesions, the histological characteristics of the different stages of human coronary and aortic atherosclerosis are similar. Carotid endarterectomy samples all represent end-stage "fibrous calcified plaque" lesions, although secondary, progressive, and vulnerable lesions with gross morphologies similar to coronary/aortic lesions occasionally present along the primary lesions. For the murine lesions, clear histological parallels were observed for the intermediate lesion types ("pathological intimal thickening," and "early fibroatheroma"). However, none of the murine lesions studied progressed to an equivalent of late fibroatheroma or beyond. Notable contrasts were observed for disease initiation: whereas disease initiation in humans is characterized by a mesenchymal cell influx in the intima, the earliest murine lesions are exclusively intimal, with subendothelial accumulation foam cells. A mesenchymal (and medial) response are absent. In fact, it is concluded that the stage of "adaptive intimal thickening" is absent in all mouse models included in this study.

Conclusions

The Virmani classification for coronary atherosclerosis can be applied for systematically grading experimental and clinical atherosclerosis. Application of this histological grading tool shows clear parallels for intermediate human and murine atherosclerotic lesions. However, clear contrasts are observed for disease initiation, and late stage atherosclerotic lesions. Carotid endarterectomy all represent end-stage fibrous calcified plaque lesions, although secondary earlier lesions may present in a subset of samples.

Advances in the Physiology of Transvascular Exchange and A New Look At Rational Fluid Prescription

The Starling principle is a model that explains the transvascular distribution of fluids essentially governed by hydrostatic and oncotic forces, which dynamically allow vascular refilling according to the characteristics of the blood vessel. However, careful analysis of fluid physiology has shown that the principle, while correct, is not complete. The revised Starling principle (Michel-Weinbaum model) provides relevant information on fluid kinetics. Special emphasis has been placed on the endothelial glycocalyx, whose subendothelial area allows a restricted oncotic pressure that limits the reabsorption of fluid from the interstitial space, so that transvascular refilling occurs mainly from the lymphatic vessels. The close correlation between pathological states of the endothelium (eg: sepsis, acute inflammation, or chronic kidney disease) and the prescription of fluids forces the physician to understand the dynamics of fluids in the organism; this will allow rational fluid prescriptions. A theory that integrates the physiology of exchange and transvascular refilling is the "microconstant model", whose variables include dynamic mechanisms that can explain edematous states, management of acute resuscitation, and type of fluids for common clinical conditions. The clinical-physiological integration of the concepts will be the hinges that allow a rational and dynamic prescription of fluids.

Incremental value of enhanced plaque length for identifying intracranial atherosclerotic culprit plaques: a high-resolution magnetic resonance imaging study

OBJECTIVES

Besides plaque enhancement grade, the incremental value of enhancement-related high-resolution MRI features in defining culprit plaques needs further evaluation. This study was focused on assessing whether plaque enhancement features contribute to culprit plaque identification and further risk stratification.

METHODS

We retrospectively studied patients who experienced an acute ischaemic stroke and transient ischaemic attack due to intracranial atherosclerosis from 2016 to 2022. The enhancement features included enhancement grade, enhanced length, and enhancement quadrant. Associations between plaque enhancement features and culprit plaques, as well as diagnostic value, were investigated using logistic regression and receiver operating characteristic analyses.

RESULTS

Overall, 287 plaques were identified, of which 231 (80.5%) and 56 (19.5%) were classified as culprit and non-culprit plaques, respectively. Comparison of the pre- and post-enhancement images revealed enhanced length longer than the plaque length in 46.32% of the culprit plaques. Multivariate logistic regression showed that enhanced length longer than plaque length (OR 6.77; 95% CI 2.47-18.51) and grade II enhancement (OR 7.00; 95% CI 1.69-28.93) were independently associated with culprit plaques. The area under the curve value for the combination of stenosis and plaque enhancement grade for the diagnosis of culprit plaques was 0.787, which increased significantly to 0.825 on the addition of enhanced length longer than the plaque length (p = 0.026 for DeLong's test).

CONCLUSIONS

Enhanced length longer than the plaque length and grade II enhancement were independently associated with culprit plaques. The combination of the enhanced plaque features resulted in better culprit plaque identification.

Condition "Vasa Vasorum" in Patients with Thoracic Aortic Aneurysm

It is known that vasa vasorum contributes substantially to the blood supply and nutrition of one-third of the wall of the ascending thoracic aorta. Therefore, we focused on studying the relationship between inflammatory cells and vasa vasorum vessels in patients with aortic aneurysm. The material for the study was biopsies of thoracic aortic aneurysms taken from patients during an aneurysmectomy (34 men, 14 women, aged 33 to 79 years). The biopsies belonged to patients with non-hereditary thoracic aortic aneurysm. An immunohistochemical study was carried out using antibodies to antigens of T cells (CD3, CD4, CD8); macrophages (CD68); B cells (CD20); endothelium (CD31, CD34, von Willebrand factor (vWF)); and smooth muscle cells (alpha actin). Samples without inflammatory infiltrates contained less vasa vasorum in the tunica adventitia than samples with inflammatory infiltrates, and this difference was statistically significant p < 0.05. T cell infiltrates in the adventitia of aortic aneurysms were found in 28 of 48 patients. In the vessels of the vasa vasorum, surrounded by inflammatory infiltrates, T cells that adhered to the endothelium were found. The same cells were also localized in the subendothelial area. The number of adherent T cells in patients with inflammatory infiltrates in the aortic wall dominated the number of these cells in patients without inflammation of the aortic wall. This difference was statistically significant, p < 0.0006. Hypertrophy and sclerosis of the arteries of the vasa vasorum system, the narrowing of their lumen, and, as a result, impaired blood supply to the aortic wall, were found in 34 patients with hypertension. In 18 patients (both in patients with hypertension and in patients without hypertension), T cells that adhered to the vasa vasorum endothelium were found. In nine cases, massive infiltrates of T cells and macrophages were found, which surrounded and squeezed the vasa vasorum, preventing blood circulation. In six patients, parietal and obturating blood clots were found in the vasa vasorum vessels, which disrupted the normal blood supply to the aortic wall. We believe that this indicates the importance of the state of the vessels of the vasa vasorum in the development of an aortic aneurysm. In addition, pathological changes in these vessels may not always play a primary role, but always a very important role, in the pathogenesis of this disease.

Isolation of vasa vasorum endothelial cells from pulmonary artery adventitia: Implementation to vascular biology research

Isolated endothelial cells are valuable in vitro model for vascular research. At present, investigation of disease-relevant changes in vascular endothelium at the molecular level requires established endothelial cell cultures, preserving vascular bed-specific phenotypic characteristics. Vasa vasorum (VV) form a microvascular network around large blood vessels, in both the pulmonary and systemic circulations, that are critically important for maintaining the integrity and oxygen supply of the vascular wall. However, despite the pathophysiological significance of the VV, methods for the isolation and culture of vasa vasorum endothelial cells (VVEC) have not yet been reported. In our prior studies, we demonstrated the presence of hypoxia-induced angiogenic expansion of the VV in the pulmonary artery (PA) of neonatal calves; an observation which has been followed by a series of in vitro studies on isolated PA VVEC. Here we present a detailed protocol for reproducible isolation, purification, and culture of PA VVEC. We show these cells to express generic endothelial markers, (vWF, eNOS, VEGFR2, Tie1, and CD31), as well as progenitor markers (CD34 and CD133), bind lectin Lycopersicon Esculentum, and incorporate acetylated low-density lipoproteins labeled with acetylated LDL (DiI-Ac-LDL). qPCR analysis additionally revealed the expression of CD105, VCAM-1, ICAM-1, MCAM, and NCAM. Ultrastructural electron microscopy and immunofluorescence staining demonstrated that VVEC are morphologically characterized by a developed actin and microtubular cytoskeleton, mitochondrial network, abundant intracellular vacuolar/secretory system, and cell-surface filopodia. VVEC exhibit exponential growth in culture and can be mitogenically activated by multiple growth factors. Thus, our protocol provides the opportunity for VVEC isolation from the PA, and potentially from other large vessels, enabling advances in VV research.

B-vitamin treatment modifies the mortality risk associated with calcium channel blockers in patients with suspected stable angina pectoris: A prospective cohort study

BACKGROUND

Calcium channel blockers (CCBs) are used for the treatment of cardiovascular disease (CVD), including angina pectoris, and hypertension; however, the effect on survival remains uncertain. CCBs impair fibrinolysis and have been linked to elevated plasma homocysteine (Hcy), a CVD risk marker.

OBJECTIVE

We explored the association between CCB use and mortality in a large prospective cohort of patients with suspected stable angina pectoris (SAP), and potential effect modifications by Hcy-lowering B-vitamin treatment (folic acid, B₁₂ and/or B₆) as 61.8% of the patients participated in a randomized placebo-controlled B-vitamin intervention trial.

METHODS

Patient baseline continuous characteristics according to CCB treatment were tested by linear regression. Hazard ratios (HRs) for mortality associated with CCB treatment, also according to B-vitamin intervention, were examined using Cox regression analysis. The multivariable model included cardiovascular risk factors, medical histories, and use of CVD medications.

RESULTS

A total of 3991 patients (71.5 % men) were included, of whom 907 were prescribed CCBs at discharge. During 10.3 years of median follow-up, 20.6% died and 8.9% from cardiovascular- and 11.6% from non-cardiovascular causes. Patients treated with CCBs had higher plasma Hcy, fibrinogen levels and erythrocyte sedimentation rate (all P<0.001). Further, CCB use was positively associated with mortality, also after multivariable adjustments (HRs [95% CIs]: 1.34 [1.15-1.57], 1.35 [1.08-1.70] and 1.33 [1.09-1.64] for total, CVD and non-CVD death, respectively). Numerically stronger associations were observed among patients not treated with B-vitamins (HR [95% CI]: 1.54 [1.25-1.88], 1.69 [1.25-2.30] and 1.41 [1.06- 1.86] for total, CVD and non-CVD death, respectively), whereas, no association was seen in patients treated with B-vitamins (HR [95% CI]: 1.15 [0.91-1.46], 1.09 [0.76-1.57] and 1.20 [0.88-1.65]).

CONCLUSIONS

In patients with suspected SAP, CCB treatment was associated with increased mortality risk primarily among patients not treated with B-vitamins.

CLINICAL TRIAL REGISTRATION-URL

https://clinicaltrials.gov/ct2/show/NCT00354081?term=NCT00354081&draw=2&rank=1. Clinical Trial Registration-Unique identifier (NCT number): NCT00354081.

Tricaprin can prevent the development of AAA by attenuating aortic degeneration

Medical therapeutic options to prevent rupture of abdominal aortic aneurysm (AAA), a critical event, must be developed. Moreover, further understanding of the process of AAA development and rupture is crucial. Previous studies have revealed that aortic hypoperfusion can induce the development of AAA, and we successfully developed a hypoperfusion-induced AAA animal model. In this study, we examined the effects of medium-chain triglycerides (MCTs), tricaprylin (C8-TG) and tricaprin (C10-TG), on hypoperfusion-induced AAA rat model. We estimated the effects of MCTs on aortic pathologies, mechanical properties of the aorta, and development of AAA. C10-TG, but not C8-TG, significantly suppressed AAA development and completely prevented the rupture. We observed that C10-TG prevented the development and rupture of AAA, but not C8-TG. Additionally, regression of AAA diameter was observed in the C10-TG group. Pathological analysis revealed C10-TG improved the hypoperfusion-induced increase in hypoxia-inducible factor-1α levels, medial smooth muscle cells (SMCs) loss, degeneration of aortic elastin and collagen fibers, and loss of aortic wall elasticity. In addition, regression of the formed AAA was observed by administration of C10-TG after AAA formation. C10-TG administration after AAA formation improved degeneration of AAA wall including degradation of aortic elastin and collagen fibers, stenosis of vasa vasorum, and loss of medial SMCs. These data suggest C10-TG can prevent AAA by attenuating aortic hypoperfusion and degeneration. Considering the clinical safety of C10-TG, C10-TG can be a promising AAA drug candidate.

Animal models for large vessel vasculitis - The unmet need

Our understanding of the pathogenesis of large vessel vasculitis (LVV) are mainly achieved by studying the arteries taken from temporal artery biopsy in giant cell arteries (GCA) or surgical or autopsy specimens in Takayasu arteritis (TAK). These artery specimens provide invaluable information about pathological changes in these conditions that GCA and TAK are similar but are distinctly different in immune cell infiltrate and distribution of inflammatory cells in anatomical locations. However, these specimens of established arteritis do not provide information of the arteritis initiation and early events which are impossible to obtain in human artery specimens. Animal models for LVV are needed but not available. Here, several approaches are proposed for experimentation to generate animal models to aid in delineating the interaction of immune reaction with arterial wall components.

Immune and non-immune mechanisms that determine vasculitis and coronary artery aneurysm topography in Kawasaki disease and MIS-C

The overlap between multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) including coronary artery aneurysms (CAA) and broadly shared gastrointestinal and mucocutaneous disease is poorly defined. In this perspective, we highlight common age-related extravascular epicardial microanatomical and immunological factors that might culminate in CAA expression in both MIS-C and KD. Specifically, the coronary vasa vasorum originates outside the major coronary arteries. Widespread inflammation in the epicardial interstitial compartment in shared between KD and MIS-C. Age-related changes in the neonatal and immature coronary vasculature including the impact of coronary artery biomechanical factors including coronary vessel calibre, age-related vessel distensibility, flow, and vessel neurovascular innervation may explain the decreasing CAA frequency from neonates to older children and the virtual absence of CAA in young adults with the MIS-C phenotype. Other KD and MIS-C features including mucocutaneous disease with keratinocyte-related immunopathology corroborate that disease phenotypes are centrally influenced by inflammation originating outside vessel walls but a potential role for primary coronary artery vascular wall inflammation cannot be excluded. Hence, common extravascular originating tissue-specific responses to aetiologically diverse triggers including superantigens may lead to widespread interstitial tissue inflammation characteristically manifesting as CAA development, especially in younger subjects. Given that CAA is virtually absent in adults, further studies are needed to ascertain whether epicardial interstitial inflammation may impact on both coronary artery physiology and cardiac conduction tissue and contribute to cardiovascular disease- a hitherto unappreciated consideration.

Single Cell Transcriptomics of Fibrotic Lungs Unveils Aging-associated Alterations in Endothelial and Epithelial Cell Regeneration

Lung regeneration deteriorates with aging leading to increased susceptibility to pathologic conditions, including fibrosis. Here, we investigated bleomycin-induced lung injury responses in young and aged mice at single-cell resolution to gain insights into the cellular and molecular contributions of aging to fibrosis. Analysis of 52,542 cells in young (8 weeks) and aged (72 weeks) mice identified 15 cellular clusters, many of which exhibited distinct injury responses that associated with age. We identified Pdgfra + alveolar fibroblasts as a major source of collagen expression following bleomycin challenge, with those from aged lungs exhibiting a more persistent activation compared to young ones. We also observed age-associated transcriptional abnormalities affecting lung progenitor cells, including ATII pneumocytes and general capillary (gCap) endothelial cells (ECs). Transcriptional analysis combined with lineage tracing identified a sub-population of gCap ECs marked by the expression of Tropomyosin Receptor Kinase B (TrkB) that appeared in bleomycin-injured lungs and accumulated with aging. This newly emerged TrkB + EC population expressed common gCap EC markers but also exhibited a distinct gene expression signature associated with aberrant YAP/TAZ signaling, mitochondrial dysfunction, and hypoxia. Finally, we defined ACKR1 + venous ECs that exclusively emerged in injured lungs of aged animals and were closely associated with areas of collagen deposition and inflammation. Immunostaining and FACS analysis of human IPF lungs demonstrated that ACKR1 + venous ECs were dominant cells within the fibrotic regions and accumulated in areas of myofibroblast aggregation. Together, these data provide high-resolution insights into the impact of aging on lung cell adaptability to injury responses.

Endothelial Cell Markers Are Inferior to Vascular Smooth Muscle Cells Markers in Staining Vasa Vasorum and Are Non-Specific for Distinct Endothelial Cell Lineages in Clinical Samples

Current techniques for the detection of vasa vasorum (VV) in vascular pathology include staining for endothelial cell (EC) markers such as CD31 or VE-cadherin. However, this approach does not permit an objective assessment of vascular geometry upon vasospasm and the clinical relevance of endothelial specification markers found in developmental biology studies remains unclear. Here, we performed a combined immunostaining of rat abdominal aorta (rAA) and human saphenous vein (hSV) for various EC or vascular smooth muscle cell (VSMC) markers and found that the latter (e.g., alpha smooth muscle actin (α-SMA) or smooth muscle myosin heavy chain (SM-MHC)) ensure a several-fold higher signal-to-noise ratio irrespective of the primary antibody origin, fluorophore, or VV type (arterioles, venules, or capillaries). Further, α-SMA or SM-MHC staining allowed unbiased evaluation of the VV area under vasospasm. Screening of the molecular markers of endothelial heterogeneity (mechanosensitive transcription factors KLF2 and KLF4, arterial transcription factors HES1, HEY1, and ERG, venous transcription factor NR2F2, and venous/lymphatic markers PROX1, LYVE1, VEGFR3, and NRP2) have not revealed specific markers of any lineage in hSV (although KLF2 and PROX1 were restricted to venous endothelium in rAA), suggesting the need in high-throughput searches for the clinically relevant signatures of arterial, venous, lymphatic, or capillary differentiation.

Arterial dissections: Common features and new perspectives

Arterial dissections, which involve an abrupt tear in the wall of a major artery resulting in the intramural accumulation of blood, are a family of catastrophic disorders causing major, potentially fatal sequelae. Involving diverse vascular beds, including the aorta or coronary, cervical, pulmonary, and visceral arteries, each type of dissection is devastating in its own way. Traditionally they have been studied in isolation, rather than collectively, owing largely to the distinct clinical consequences of dissections in different anatomical locations - such as stroke, myocardial infarction, and renal failure. Here, we review the shared and unique features of these arteriopathies to provide a better understanding of this family of disorders. Arterial dissections occur commonly in the young to middle-aged, and often in conjunction with hypertension and/or migraine; the latter suggesting they are part of a generalized vasculopathy. Genetic studies as well as cellular and molecular investigations of arterial dissections reveal striking similarities between dissection types, particularly their pathophysiology, which includes the presence or absence of an intimal tear and vasa vasorum dysfunction as a cause of intramural hemorrhage. Pathway perturbations common to all types of dissections include disruption of TGF-β signaling, the extracellular matrix, the cytoskeleton or metabolism, as evidenced by the finding of mutations in critical genes regulating these processes, including LRP1, collagen genes, fibrillin and TGF-β receptors, or their coupled pathways. Perturbances in these connected signaling pathways contribute to phenotype switching in endothelial and vascular smooth muscle cells of the affected artery, in which their physiological quiescent state is lost and replaced by a proliferative activated phenotype. Of interest, dissections in various anatomical locations are associated with distinct sex and age predilections, suggesting involvement of gene and environment interactions in disease pathogenesis. Importantly, these cellular mechanisms are potentially therapeutically targetable. Consideration of arterial dissections as a collective pathology allows insight from the better characterized dissection types, such as that involving the thoracic aorta, to be leveraged to inform the less common forms of dissections, including the potential to apply known therapeutic interventions already clinically available for the former.

Intramural Hematoma in Vertebrobasilar Dolichoectasia-Related Stroke: A Retrospective Analysis of Six Consecutive Patients

BACKGROUND

The pathophysiology underlying vertebrobasilar dolichoectasia (VBD) is largely unknown. However, a few reports have demonstrated that acute intramural hematoma (IMH) in VBD is associated with stroke. We aimed to investigate the clinical and radiological features of IMH in VBD and the role of IMH in predicting rupture and patient outcomes.

METHODS

We retrospectively reviewed the medical records of patients treated in 2 stroke centers between January 2012 and December 2021. Patients presenting with VBD and stroke were eligible for study inclusion. We excluded patients with stroke caused by arterial dissection or artery-to-artery embolism. IMH was defined as a crescent-shaped area of high signal density in the vessel wall on axial computed tomography in the absence of an intimal flap, double lumen, and pearl-and-string sign.

RESULTS

Six patients were analyzed. All presented with symptoms of brainstem/cerebellar infarction without headache. Interobserver agreement for the presence or absence of IMH was excellent (100%). IMH was detected in 5 patients. The positive predictive value of IMH for rupture was 80% (95% confidence interval, 28%-99.5%). The median time from symptom onset to rupture was 2.5 days (range, 1.5-4). Median computed tomography values were significantly higher within the IMH than those in the lumen of the basilar artery (70 vs. 44.5 Hounsfield units; P = 0.008). The modified Rankin scale score on day 30 after onset was 5 in 1 patient and 6 in the remaining 5.

CONCLUSIONS

IMH in patients with VBD presenting with brainstem/cerebellar infarction should be regarded as a sign associated with a high risk of rupture.

A Comparative Study on Two Types of Porcine Acellular Dermal Matrix Sponges Prepared by Thermal Crosslinking and Thermal-Glutaraldehyde Crosslinking Matrix Microparticles

Common commercial porcine acellular dermal matrix (PADM) products take the form of a thin membrane. Given its dense structure, delaying vascularization after implantation remains an issue to be solved. In addition, overlaying multiple sheets to address deep wounds and large tissue defects that are difficult to repair by self-tissues could hinder tissue ingrowth, angiogenesis, and integration. Here, we creatively prepared PADM microparticles through a homogenizing treatment and crosslinked them to ADM sponges by thermal crosslinking (VT-ADM) and thermal-glutaraldehyde crosslinking (GA-ADM). The resulting VT-ADM was thicker than GA-ADM, and both maintained the natural dermal matrix microstructure and thermal stability. The porosity of GA-ADM (mean 82%) was lower than that of VT-ADM (mean 90.2%), but the mechanical strength and hydrophilicity were significantly higher. The two types of ADM sponges showed no obvious difference in cell adhesion and proliferation without cytotoxicity. Furthermore, the human adipose stem cells were co-cultured with ADM sponges which promoted proliferation, tube formation, and migration of endothelial cells, and the GA-ADM group exhibited better migration behavior. There were no markable differences among expressions of pro-angiogenesis genes, including vascular endothelial growth factor, insulin-like growth factor-1, and epidermal growth factor. In a nude mouse model, the VT-ADM and GA-ADM pre-cultured with human adipose stem cells for 1 week in advance were implanted subcutaneously. The VT-ADM and the GA-ADM showed great histocompatibility without local redness, swelling, or necrosis. The vascular density of the local skin flap above the material was visualized using indocyanine green and showed no statistical difference between the two groups. The collagen tissue deposition in the pores and vessel formation within the sponges increased with time. Although VT-ADM had a higher degradation rate in vivo, the integrity of the two scaffolds was preserved. Collectively, the VT-ADM and the GA-ADM retained a natural matrix structure and presented biocompatibility. Thus, the above-mentioned two crosslinking methods for ADM sponges are safe and practicable. The novel ADM sponges with good physicochemical and biological properties are no longer limited to membrane tissue regeneration but could also realize structure remodeling where they act as scaffolds for a soft tissue filler and three-dimensional reconstruction of the tissue with strength requirements.