Embryonic origins of human vascular smooth muscle cells: implications for in vitro modeling and clinical application

Xenogeneic-free platform for the isolation and scalable expansion of human bladder smooth muscle cells

Introduction

Smooth muscle cells (SMC) play a crucial role in bladder tissue engineering strategies. Scalable, Good Manufacturing Practice (GMP)-compliant platforms are essential for producing clinically relevant cell numbers.

Materials & Methods

A gamma-irradiated human platelet lysate (HPL) supplement was used to develop a xeno(geneic)-free process for the isolation and scalable expansion of human bladder-derived SMC.

Results

Cells were isolated using an explant-based technique and expanded ex vivo, expressing typical SMC markers (α-SMA, desmin, caldesmon and SM22-α). Cell culture was successfully scaled-up using spinner flasks combined with plastic microcarriers, starting with a 2.8 × 103 cells/cm2 inoculum (i.e. 1 × 106 cells). Cell-microcarrier adhesion rates exceeded 80% within 24 hours with fold expansion ranging from 3.5 to 16.8 after 7 days, dependent on donor variability. Harvested cells retained their SMC phenotype.

Conclusions

This xeno-free, GMP compliant process enables scalable manufacturing of human bladder-derived SMC while preserving cell identity, potentially advancing clinical applications in bladder engineering.

Single-Cell Transcriptomics and Lineage Tracing Unveil Parallels in Lymphatic Muscle and Venous Smooth Muscle Development, Identity, and Function

BACKGROUND

Lymphatic muscle cells (LMCs) are indispensable for lymphatic vessel contraction, and their aberrant recruitment or absence is associated with both primary and secondary lymphedema. Despite their critical role in lymphatic vessel function, the cellular and molecular bases that confer the unique contractile properties to LMCs are largely undefined, limiting the development of therapeutic interventions that precisely target LMCs.

METHODS

We used single-cell RNA sequencing, genetic lineage tracing, whole mount immunostaining, and intravital imaging to investigate the basis for the hybrid cardiomyocyte and blood vascular smooth muscle cell (SMC) characteristics that have been described for LMCs.

RESULTS

Using single-cell RNA sequencing, the transcriptomes of LMCs and venous SMCs exhibited more similarities than differences, with both cell types exhibiting enrichment in overlapping molecular markers. Notably, LMCs and venous SMCs were both markedly distinct from that of arteriole SMCs. Functionally, both lymphatic vessels and blood vessels in the murine hind limb displayed pulsatile contractility, and their functions were regulated by gabapentin and nifedipine, which target the activity of voltage-gated calcium channels. Although LMCs express genes that overlap with the venous SMC transcriptome, lineage tracing demonstrates that LMCs do not originate from Myh11 (myosin heavy chain 11) lineage-derived SMCs, Nkx2.5 (NK2 homeobox 5) cardiomyocyte progenitors, or Wnt1 (Wnt family member 1) neural crest progenitors. Instead, most LMCs and SMCs in the hind limb and inguinal-axillary region originate from WT1+ (Wilms tumor gene 1) mesodermal progenitors from the lateral plate mesoderm. LMCs derived from WT1+ progenitors were critical for the maintenance of lymphatic vessel contractility.

CONCLUSIONS

Overall, our findings suggest that venous SMCs and LMCs derive from a related mesodermal progenitor and acquire a similar gene expression program that facilitates their contractile properties.

Establishment of a murine chronic proximal thoracic aortic aneurysm model by combining periaortic elastase application with oral BAPN administration

This study aimed to develop a chronic proximal thoracic aortic aneurysm (PTAA) model by combining periaortic elastase application with oral administration of 3-aminopropionitrile fumarate salt (BAPN) after surgery. Sixty 8-week-old C57BL/6J male mice were divided into four groups: Sham, Sham + BAPN, Elastase, and Elastase + BAPN. High-resolution micro-ultrasound was performed on days 7, 14, 21, 28, 56, and 90 post-operation to measure aortic diameter. Histopathological, transcriptomic, and bioinformatics analyses were conducted to assess the model's relevance to human PTAA. The operative mortality rate was 10 % (6/60). During follow-up, 4 animals in the elastase + BAPN group and 1 in the elastase group died from aortic rupture. Significant continuous dilation of the proximal thoracic aorta was observed only in the elastase + BAPN group, with average dilation rates of 116.60 %, 178.99 %, and 231.90 % on days 28, 56, and 90, respectively, compared to 66.46 %, 61.13 %, and 68.73 % in the elastase group. Histopathology revealed greater aortic wall thickening, collagen deposition, MMP2 expression, elastin degradation, smooth muscle cell loss, calcification, and immune cell infiltration in the elastase + BAPN group. Transcriptomic analysis identified 3039 differentially expressed genes, enriched in immune and inflammation-related pathways. Weighted gene co-expression network analysis showed significant overlap in the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment results between human and murine PTAA-related gene modules which were most positively correlated with PTAA diameters. This study establishes a chronic PTAA model that mimics key features of human disease, providing a valuable tool for investigating PTAA mechanisms and developing new therapies.

Origins of Aortic Coarctation: A Vascular Smooth Muscle Compartment Boundary Model

Compartment boundaries divide the embryo into segments with distinct fates and functions. In the vascular system, compartment boundaries organize endothelial cells into arteries, capillaries, and veins that are the fundamental units of a circulatory network. For vascular smooth muscle cells (SMCs), such boundaries produce mosaic patterns of investment based on embryonic origins with important implications for the non-uniform distribution of vascular disease later in life. The morphogenesis of blood vessels requires vascular cell movements within compartments as highly-sensitive responses to changes in fluid flow shear stress and wall strain. These movements underline the remodeling of primitive plexuses, expansion of lumen diameters, regression of unused vessels, and building of multilayered artery walls. Although the loss of endothelial compartment boundaries can produce arterial-venous malformations, little is known about the consequences of mislocalization or the failure to form SMC-origin-specific boundaries during vascular development. We propose that the failure to establish a normal compartment boundary between cardiac neural-crest-derived SMCs of the 6th pharyngeal arch artery (future ductus arteriosus) and paraxial-mesoderm-derived SMCs of the dorsal aorta in mid-gestation embryos leads to aortic coarctation observed at birth. This model raises new questions about the effects of fluid flow dynamics on SMC investment and the formation of SMC compartment borders during pharyngeal arch artery remodeling and vascular development.

Coronary Artery Spasm: From Physiopathology to Diagnosis

Coronary artery spasm (CAS) is a reversible vasoconstriction of normal or atherosclerotic epicardial coronary arteries with a subsequent reduction in myocardial blood flow, leading to myocardial ischemia, myocardial infarction, severe arrhythmias, or even sudden death. It is an entity that should be recognized based on a particular clinical presentation. Numerous differences exist between CAS and obstructive coronary disease in terms of mechanisms, risk factors, and therapeutic solutions. The gold standard for CAS diagnosis is represented by transitory and reversible occlusion of the coronary arteries at spasm provocation test, which consists of an intracoronary administration of Ach, ergonovine, or methylergonovine during angiography. The pathophysiology of CAS is not fully understood. However, the core of CAS is represented by vascular smooth muscle cell contraction, with a circadian pattern. The initiating event of this contraction may be represented by endothelial dysfunction, inflammation, or autonomic nervous system unbalance. Our study explores the intricate balance of these factors and their clinical relevance in the management of CAS.

Decreased Lactococcus lactis and Propionic Acid in Feces of Patients with Moyamoya Disease: Possible Implications of Immune Dysregulation

INTRODUCTION

Moyamoya disease (MMD) is a cerebrovascular disease characterized by progressive steno-occlusive lesions in the terminal portion of the internal carotid artery. Despite its unknown etiology, immune dysregulation is regarded as a critical trigger for delineating the pathophysiology of MMD. The gut microbiota produces short-chain fatty (SCFA) and organic acids, influencing immune regulation and vascular remodeling. We aimed to characterize the gut microbiota in patients with MMD.

METHODS

Sixteen patients with MMD and sixteen healthy controls (CON) were included in this study. We performed 16S rRNA sequencing of fecal samples, analyzed microbiome diversity and composition, and quantified SCFA and organic acid levels using liquid chromatography.

RESULTS

There were no significant differences in α- and β-diversities among feces from the MMD patients and CON. However, 16S rRNA sequencing identified defective Lactococcus lactis (0 ± 0 in the MMD patients vs. 0.026 ± 0.084 in healthy CON, p = 0.0181) and abundant Gordinobacter pamelaeae (0.030 ± 0.039 in the patients vs. 0.001 ± 0.005 in healthy CON, p = 0.003) are strongly linked to MMD. Propionic acid levels were significantly lower in feces of the MMD patients compared to healthy CON (0.83 ± 0.34 mg/g in the MMD patients vs. 1.20 ± 0.55 mg/g in healthy CON, p = 0.028).

CONCLUSION

Decreased L. lactis can result in reduced lactic acid and propionic acid levels in the feces of the patients. This imbalance in the gut microbiome and SCFA/organic acid levels could contribute to immune dysregulation underlying the vascular remodeling seen in MMD.

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.

Differential Gene Expression Analysis in a Lumbar Spinal Stenosis Rat Model via RNA Sequencing: Identification of Key Molecular Pathways and Therapeutic Insights

BACKGROUND/OBJECTIVES

Lumbar spinal stenosis (LSS) is a degenerative condition characterized by the narrowing of the spinal canal, resulting in chronic pain and impaired mobility. However, the molecular mechanisms underlying LSS remain unclear. In this study, we performed RNA sequencing (RNA-seq) to investigate differential gene expression in a rat LSS model and identify the key genes and pathways involved in its pathogenesis.

METHODS

We used bioinformatics analysis to identify significant alterations in gene expression between the LSS-induced and sham groups.

RESULTS

Pearson's correlation analysis demonstrated strongly consistent intragroup expression (r > 0.9), with distinct gene expression between the LSS and sham groups. A total of 113 differentially expressed genes (DEGs) were identified, including upregulated genes such as Slc47a1 and Prg4 and downregulated genes such as Higd1c and Mln. Functional enrichment analysis revealed that these DEGs included those involved in key biological processes, including synaptic plasticity, extracellular matrix organization, and hormonal regulation. Gene ontology analysis highlighted critical molecular functions such as mRNA binding and integrin binding, as well as cellular components such as contractile fibers and the extracellular matrix, which were significantly affected by LSS.

CONCLUSIONS

Our findings provide novel insights into the molecular mechanisms underlying LSS and offer potential avenues for the development of targeted therapies aimed at mitigating disease progression and improving patient outcomes.

Multifocal neuromuscular hamartoma with smooth muscle and Schwannian components

A male in his early 20s with gastro-oesophageal reflux disease and severe weight loss was found to have two intrabdominal masses causing his symptoms: one in the gastro-oesophageal junction and the other occupying the coeliac plexus in the cardiophrenic region. These masses were surgically removed and sent to pathology where they were found to be smooth muscle hamartomas with Schwannian components. These represent a unique presentation of benign smooth muscle tumours that is not typically seen in young adults, especially in the cardiophrenic region involving the coeliac plexus.

Overview of Lymphatic Muscle Cells in Development, Physiology, and Disease

Lymphatic muscle cells (LMCs) are indispensable for proper functioning of the lymphatic system, as they provide the driving force for lymph transport. Recent studies have advanced our understanding of the molecular mechanisms that regulate LMCs, which control rhythmic contraction and vessel tone of lymphatic vessels-traits also found in cardiac and vascular smooth muscle. In this review, we discuss the molecular pathways that orchestrate LMC-mediated contractility and summarize current knowledge about their developmental origin, which may shed light on the distinct contractile characteristics of LMCs. Further, we highlight the growing evidence implicating LMC dysregulation in the pathogenesis of lymphedema and other diseases related to lymphatic vessel dysfunction. Given the limited number and efficacy of existing therapies to treat lymphedema, LMCs present a promising focus for identifying novel therapeutic targets aimed at improving lymphatic vessel contractility. Here, we discuss LMCs in health and disease, as well as therapeutic strategies aimed at targeting them to improve lymphatic vessel function.

Thoracic aortic pseudoaneurysm: Inside its pathophysiology

OBJECTIVES

Our aim was to investigate pathophysiology of pseudoaneurysm of the thoracic aorta, an acute or chronic pathology, respectively, secondary to blunt thoracic trauma and aortitis, or complicating a deep penetrating aortic ulcer, intraparietal hematoma, aortic aneurysm, and even aortic graft, often with atherosclerosis as a common background.

METHODS

Given the relative rarity of this disease, an "inductive" retrospective method made it possible to retrieve clinical, radiological, and histopathological elements, which were mutually compared and validated through a "deductive" process of reinterpretation.

RESULTS

We have identified three main structural constituents of this disease: a cavity, a single blood entry port, communicating with the aortic lumen, and a pseudocapsule. It is often caused by a chronic degenerative pathology of the intima and medial layers of the aorta, typically involving elastic fibers and smooth muscle cells, with possible intermediate stages of deep aortic ulcer or intraparietal hematoma. Otherwise, the acute onset may be secondary to acute aortitis or aortic injury.

CONCLUSIONS

Today, thanks to the current angiographic tools represented by 3-D high resolution multidetector CT and MRI angiography, the diagnosis of thoracic aortic pseudoaneurysm is easier, as well as its surgical indications.

Transcriptional, developmental, and functional parallels of lymphatic and venous smooth muscle

Lymphatic muscle cells (LMCs) are indispensable for lymphatic vessel contraction and their aberrant recruitment or absence is associated with both primary and secondary lymphedema. Despite their critical role in lymphatic vessel function, the transcriptomic and developmental basis that confer the unique contractile properties to LMCs are largely undefined. In this study, we employed single-cell RNA sequencing (scRNAseq), lineage tracing and in vivo imaging to investigate the basis for the hybrid cardiomyocyte and blood vascular smooth muscle cell (SMC) characteristics that have been described for LMCs. Using scRNAseq, the transcriptomes of LMC and venous SMCs from the murine hindlimb exhibited more similarities than differences, although both were markedly distinct from that of arteriole SMCs in the same tissue. Functionally, both lymphatic vessels and blood vessels in the murine hindlimb displayed pulsatile contractility. However, despite expressing genes that overlap with the venous SMC transcriptome, through lineage tracing we show that LMCs do not originate from Myh11+ SMC progenitors. Previous studies have shown that LMCs express cardiac-related genes, whereas in our study we found that arteriole SMCs, but not LMCs, expressed cardiac-related genes. Through lineage tracing, we demonstrate that a subpopulation of LMCs and SMCs originate from WT1+ mesodermal progenitors, which are known to give rise to SMCs. LMCs, however, do not derive from Nkx2.5+ cardiomyocyte progenitors. Overall, our findings suggest that venous SMCs and LMCs and may derive from a related mesodermal progenitor and adopt a similar gene expression program that enable their contractile properties.

Use of iPSC-Derived Smooth Muscle Cells to Model Physiology and Pathology

The implementation of human induced pluripotent stem cell (hiPSC) models has introduced an additional tool for identifying molecular mechanisms of disease that complement animal models. Patient-derived or CRISPR/Cas9-edited induced pluripotent stem cells differentiated into smooth muscle cells (SMCs) have been leveraged to discover novel mechanisms, screen potential therapeutic strategies, and model in vivo development. The field has evolved over almost 15 years of research using hiPSC-SMCs and has made significant strides toward overcoming initial challenges such as the lineage specificity of SMC phenotypes. However, challenges both specific (eg, the lack of specific markers to thoroughly validate hiPSC-SMCs) and general (eg, a lack of transparency and consensus around methodology in the field) remain. In this review, we highlight the recent successes and remaining challenges of the hiPSC-SMC model.

Applications, challenges, and prospects of induced pluripotent stem cells for vascular disease

Vascular disease, including heart disease, stroke, and peripheral arterial disease, is one of the leading causes of death and disability and represents a significant global health issue. Since the development of human induced pluripotent stem cells (hiPSCs) in 2007, hiPSCs have provided unique and tremendous opportunities for studying human pathophysiology, disease modeling, and drug discovery in the field of regenerative medicine. In this review, we discuss vascular physiology and related diseases, the current methods for generating vascular cells (eg, endothelial cells, smooth muscle cells, and pericytes) from hiPSCs, and describe the opportunities and challenges to the clinical applications of vascular organoids, tissue-engineered blood vessels, and vessels-on-a-chip. We then explore how hiPSCs can be used to study and treat inherited vascular diseases and discuss the current challenges and future prospects. In the future, it will be essential to develop vascularized organoids or tissues that can simultaneously undergo shear stress and cyclic stretching. This development will not only increase their maturity and function but also enable effective and innovative disease modeling and drug discovery.

Unveiling cellular and molecular aspects of ascending thoracic aortic aneurysms and dissections

Ascending thoracic aortic aneurysm (ATAA) remains a significant medical concern, with its asymptomatic nature posing diagnostic and monitoring challenges, thereby increasing the risk of aortic wall dissection and rupture. Current management of aortic repair relies on an aortic diameter threshold. However, this approach underestimates the complexity of aortic wall disease due to important knowledge gaps in understanding its underlying pathologic mechanisms.Since traditional risk factors cannot explain the initiation and progression of ATAA leading to dissection, local vascular factors such as extracellular matrix (ECM) and vascular smooth muscle cells (VSMCs) might harbor targets for early diagnosis and intervention. Derived from diverse embryonic lineages, VSMCs exhibit varied responses to genetic abnormalities that regulate their contractility. The transition of VSMCs into different phenotypes is an adaptive response to stress stimuli such as hemodynamic changes resulting from cardiovascular disease, aging, lifestyle, and genetic predisposition. Upon longer exposure to stress stimuli, VSMC phenotypic switching can instigate pathologic remodeling that contributes to the pathogenesis of ATAA.This review aims to illuminate the current understanding of cellular and molecular characteristics associated with ATAA and dissection, emphasizing the need for a more nuanced comprehension of the impaired ECM-VSMC network.

Current understanding of subclinical diabetic retinopathy informed by histology and high-resolution in vivo imaging

The escalating incidence of diabetes mellitus has amplified the global impact of diabetic retinopathy. There are known structural and functional changes in the diabetic retina that precede the fundus photography abnormalities which currently are used to diagnose clinical diabetic retinopathy. Understanding these subclinical alterations is important for effective disease management. Histology and high-resolution clinical imaging reveal that the entire neurovascular unit, comprised of retinal vasculature, neurons and glial cells, is affected in subclinical disease. Early functional manifestations are seen in the form of blood flow and electroretinography disturbances. Structurally, there are alterations in the cellular components of vasculature, glia and the neuronal network. On clinical imaging, changes to vessel density and thickness of neuronal layers are observed. How these subclinical disturbances interact and ultimately manifest as clinical disease remains elusive. However, this knowledge reveals potential early therapeutic targets and the need for imaging modalities that can detect subclinical changes in a clinical setting.

Endothelial to mesenchymal transition in the interleukin-1 pathway during aortic aneurysm formation

OBJECTIVE

Endothelial to mesenchymal transition may represent a key link between inflammatory stress and endothelial dysfunction seen in aortic aneurysm disease. Endothelial to mesenchymal transition is regulated by interleukin-1β, and previous work has demonstrated an essential role of interleukin-1 signaling in experimental aortic aneurysm models. We hypothesize that endothelial to mesenchymal transition is present in murine aortic aneurysms, and loss of interleukin-1 signaling attenuates this process.

METHODS

Murine aortic aneurysms were created in novel CDH5-Cre lineage tracking mice by treating the intact aorta with peri-adventitial elastase. Endothelial to mesenchymal transition transcription factors as well as endothelial and mesenchymal cell markers were analyzed via immunohistochemistry and immunofluorescence (n = 10/group). To determine the role of interleukin-1 signaling, endothelial-specific interleukin-1 receptor 1 knockout and wild-type mice (n = 10/group) were treated with elastase. Additionally, C57/BL6 mice were treated with the interleukin-1 receptor 1 antagonist Anakinra (n = 7) or vehicle (n = 8).

RESULTS

Elastase treatment yielded greater aortic dilation compared with controls (elastase 97.0% ± 34.0%; control 5.3% ± 4.8%; P < .001). Genetic deletion of interleukin-1 receptor 1 attenuated aortic dilation (control 126.7% ± 38.7%; interleukin-1 receptor 1 knockout 35.2% ± 14.7%; P < .001), as did pharmacologic inhibition of interleukin-1 receptor 1 with Anakinra (vehicle 146.3% ± 30.1%; Anakinra 63.5% ± 23.3%; P < .001). Elastase treatment resulted in upregulation of endothelial to mesenchymal transition transcription factors (Snail, Slug, Twist, ZNF) and mesenchymal cell markers (S100, alpha smooth muscle actin) and loss of endothelial cell markers (vascular endothelial cadherin, endothelial nitric oxide synthase, von Willebrand factor). These changes were attenuated by interleukin-1 receptor 1 knockout and Anakinra treatment.

CONCLUSIONS

Endothelial to mesenchymal transition occurs in aortic aneurysm disease and is attenuated by loss of interleukin-1 signaling. Endothelial dysfunction through endothelial to mesenchymal transition represents a new and novel pathway in understanding aortic aneurysm disease and may be a potential target for future treatment.

Mesenchymal stem cells in craniofacial reconstruction: a comprehensive review

Craniofacial reconstruction faces many challenges, including high complexity, strong specificity, severe injury, irregular and complex wounds, and high risk of bleeding. Traditionally, the "gold standard" for treating craniofacial bone defects has been tissue transplantation, which involves the transplantation of bone, cartilage, skin, and other tissues from other parts of the body. However, the shape of craniofacial bone and cartilage structures varies greatly and is distinctly different from ordinary long bones. Craniofacial bones originate from the neural crest, while long bones originate from the mesoderm. These factors contribute to the poor effectiveness of tissue transplantation in repairing craniofacial defects. Autologous mesenchymal stem cell transplantation exhibits excellent pluripotency, low immunogenicity, and minimally invasive properties, and is considered a potential alternative to tissue transplantation for treating craniofacial defects. Researchers have found that both craniofacial-specific mesenchymal stem cells and mesenchymal stem cells from other parts of the body have significant effects on the restoration and reconstruction of craniofacial bones, cartilage, wounds, and adipose tissue. In addition, the continuous development and application of tissue engineering technology provide new ideas for craniofacial repair. With the continuous exploration of mesenchymal stem cells by researchers and the continuous development of tissue engineering technology, the use of autologous mesenchymal stem cell transplantation for craniofacial reconstruction has gradually been accepted and promoted. This article will review the applications of various types of mesenchymal stem cells and related tissue engineering in craniofacial repair and reconstruction.

Control of coronary vascular cell fate in development and regeneration

The coronary vasculature consists of a complex hierarchal network of arteries, veins, and capillaries which collectively function to perfuse the myocardium. However, the pathways controlling the temporally and spatially restricted mechanisms underlying the formation of this vascular network remain poorly understood. In recent years, the increasing use and refinement of transgenic mouse models has played an instrumental role in offering new insights into the cellular origins of the coronary vasculature, as well as identifying a continuum of transitioning cell states preceding the full maturation of the coronary vasculature. Coupled with the emergence of single cell RNA sequencing platforms, these technologies have begun to uncover the key regulatory factors mediating the convergence of distinct cellular origins to ensure the formation of a collectively functional, yet phenotypically diverse, vascular network. Furthermore, improved understanding of the key regulatory factors governing coronary vessel formation in the embryo may provide crucial clues into future therapeutic strategies to reactivate these developmentally functional mechanisms to drive the revascularisation of the ischaemic adult heart.

Understanding genomic medicine for thoracic aortic disease through the lens of induced pluripotent stem cells

Thoracic aortic disease (TAD) is often silent until a life-threatening complication occurs. However, genetic information can inform both identification and treatment at an early stage. Indeed, a diagnosis is important for personalised surveillance and intervention plans, as well as cascade screening of family members. Currently, only 20% of heritable TAD patients have a causative mutation identified and, consequently, further advances in genetic coverage are required to define the remaining molecular landscape. The rapid expansion of next generation sequencing technologies is providing a huge resource of genetic data, but a critical issue remains in functionally validating these findings. Induced pluripotent stem cells (iPSCs) are patient-derived, reprogrammed cell lines which allow mechanistic insights, complex modelling of genetic disease and a platform to study aortic genetic variants. This review will address the need for iPSCs as a frontline diagnostic tool to evaluate variants identified by genomic discovery studies and explore their evolving role in biological insight through to drug discovery.

Modulation of Smooth Muscle Cell Phenotype for Translation of Tissue-Engineered Vascular Grafts

Translation of small-diameter tissue-engineered vascular grafts (TEVGs) for the treatment of coronary artery disease (CAD) remains an unfulfilled promise. This is largely due to the limited integration of TEVGs into the native vascular wall-a process hampered by the insufficient smooth muscle cell (SMC) infiltration and extracellular matrix deposition, and low vasoactivity. These processes can be promoted through the judicious modulation of the SMC toward a synthetic phenotype to promote remodeling and vascular integration; however, the expression of synthetic markers is often accompanied by a decrease in the expression of contractile proteins. Therefore, techniques that can precisely modulate the SMC phenotypical behavior could have the potential to advance the translation of TEVGs. In this review, we describe the phenotypic diversity of SMCs and the different environmental cues that allow the modulation of SMC gene expression. Furthermore, we describe the emerging biomaterial approaches to modulate the SMC phenotype in TEVG design and discuss the limitations of current techniques. In addition, we found that current studies in tissue engineering limit the analysis of the SMC phenotype to a few markers, which are often the characteristic of early differentiation only. This limited scope has reduced the potential of tissue engineering to modulate the SMC toward specific behaviors and applications. Therefore, we recommend using the techniques presented in this review, in addition to modern single-cell proteomics analysis techniques to comprehensively characterize the phenotypic modulation of SMCs. Expanding the holistic potential of SMC modulation presents a great opportunity to advance the translation of living conduits for CAD therapeutics.

Bioprocessing Considerations towards the Manufacturing of Therapeutic Skeletal and Smooth Muscle Cells

Tissue engineering approaches within the muscle context represent a promising emerging field to address the current therapeutic challenges related with multiple pathological conditions affecting the muscle compartments, either skeletal muscle or smooth muscle, responsible for involuntary and voluntary contraction, respectively. In this review, several features and parameters involved in the bioprocessing of muscle cells are addressed. The cell isolation process is depicted, depending on the type of tissue (smooth or skeletal muscle), followed by the description of the challenges involving the use of adult donor tissue and the strategies to overcome the hurdles of reaching relevant cell numbers towards a clinical application. Specifically, the use of stem/progenitor cells is highlighted as a source for smooth and skeletal muscle cells towards the development of a cellular product able to maintain the target cell's identity and functionality. Moreover, taking into account the need for a robust and cost-effective bioprocess for cell manufacturing, the combination of muscle cells with biomaterials and the need for scale-up envisioning clinical applications are also approached.

DDX24 Is Essential for Cell Cycle Regulation in Vascular Smooth Muscle Cells During Vascular Development via Binding to FANCA mRNA

BACKGROUND

The DEAD-box family is essential for tumorigenesis and embryogenesis. Previously, we linked the malfunction of DDX (DEAD-box RNA helicase)-24 to a special type of vascular malformation. Here, we aim to investigate the function of DDX24 in vascular smooth muscle cells (VSMCs) and embryonic vascular development.

METHODS

Cardiomyocyte (CMC) and VSMC-specific Ddx24 knockout mice were generated by crossing Tagln-Cre mice with Ddx24flox/flox transgenic mice. The development of blood vessels was explored by stereomicroscope photography and immunofluorescence staining. Flow cytometry and cell proliferation assays were used to verify the regulation of DDX24 on the function of VSMCs. RNA sequencing and RNA immunoprecipitation coupled with quantitative real-time polymerase chain reaction were combined to investigate DDX24 downstream regulatory molecules. RNA pull-down and RNA stability experiments were performed to explore the regulation mechanism of DDX24.

RESULTS

CMC/VSMC-specific Ddx24 knockout mice died before embryonic day 13.5 with defects in vessel formation and abnormal vascular remodeling in extraembryonic tissues. Ddx24 knockdown suppressed VSMC proliferation via cell cycle arrest, likely due to increased DNA damage. DDX24 protein bound to and stabilized the mRNA of FANCA (FA complementation group A) that responded to DNA damage. Consistent with the function of DDX24, depletion of FANCA also impacted cell cycle and DNA repair of VSMCs. Overexpression of FANCA was able to rescue the alterations caused by DDX24 deficiency.

CONCLUSIONS

Our study unveiled a critical role of DDX24 in VSMC-mediated vascular development, highlighting a potential therapeutic target for VSMC-related pathological conditions.

Biology of vascular mural cells

The vasculature consists of vessels of different sizes that are arranged in a hierarchical pattern. Two cell populations work in concert to establish this pattern during embryonic development and adopt it to changes in blood flow demand later in life: endothelial cells that line the inner surface of blood vessels, and adjacent vascular mural cells, including smooth muscle cells and pericytes. Despite recent progress in elucidating the signalling pathways controlling their crosstalk, much debate remains with regard to how mural cells influence endothelial cell biology and thereby contribute to the regulation of blood vessel formation and diameters. In this Review, I discuss mural cell functions and their interactions with endothelial cells, focusing on how these interactions ensure optimal blood flow patterns. Subsequently, I introduce the signalling pathways controlling mural cell development followed by an overview of mural cell ontogeny with an emphasis on the distinguishing features of mural cells located on different types of blood vessels. Ultimately, I explore therapeutic strategies involving mural cells to alleviate tissue ischemia and improve vascular efficiency in a variety of diseases.

A Descriptive Whole-Genome Transcriptomics Study in a Stem Cell-Based Tool Predicts Multiple Tissue-Specific Beneficial Potential and Molecular Targets of Carnosic Acid

Carnosic acid (CA) is a phenolic diterpene widely distributed in herbal plants, rosemary and sage. Although its medicinal properties, such as antioxidant, antimicrobial, and neuroprotective effects, have been well-documented, its relevant biochemical processes and molecular targets have not been fully explored yet. In the present study, we conducted an untargeted whole-genome transcriptomics analysis to investigate CA-induced early biological and molecular events in human amniotic epithelial stem cells (hAESCs) with the aim of exploring its multiple tissue-specific functionalities and potential molecular targets. We found that seven days of CA treatment in hAESCs could induce mesoderm-lineage-specific differentiation. Tissue enrichment analysis revealed that CA significantly enriched lateral plate mesoderm-originated cardiovascular and adipose tissues. Further tissue-specific PPI analysis and kinase and transcription factor enrichment analyses identified potential upstream regulators and molecular targets of CA in a tissue-specific manner. Gene ontology enrichment analyses revealed the metabolic, antioxidant, and antifibrotic activities of CA. Altogether, our comprehensive whole-genome transcriptomics analyses offer a thorough understanding of the possible underlying molecular mechanism of CA.

Single-cell transcriptomics uncovers a non-autonomous Tbx1-dependent genetic program controlling cardiac neural crest cell development

Disruption of cardiac neural crest cells (CNCCs) results in congenital heart disease, yet we do not understand the cell fate dynamics as these cells differentiate to vascular smooth muscle cells. Here we performed single-cell RNA-sequencing of NCCs from the pharyngeal apparatus with the heart in control mouse embryos and when Tbx1, the gene for 22q11.2 deletion syndrome, is inactivated. We uncover three dynamic transitions of pharyngeal NCCs expressing Tbx2 and Tbx3 through differentiated CNCCs expressing cardiac transcription factors with smooth muscle genes. These transitions are altered non-autonomously by loss of Tbx1. Further, inactivation of Tbx2 and Tbx3 in early CNCCs results in aortic arch branching defects due to failed smooth muscle differentiation. Loss of Tbx1 interrupts mesoderm to CNCC cell-cell communication with upregulation and premature activation of BMP signaling and reduced MAPK signaling, as well as alteration of other signaling, and failed dynamic transitions of CNCCs leading to disruption of aortic arch artery formation and cardiac outflow tract septation.

SMAD4: A Critical Regulator of Cardiac Neural Crest Cell Fate and Vascular Smooth Muscle Differentiation

Background

The pharyngeal arch arteries (PAAs) are precursor vessels which remodel into the aortic arch arteries (AAAs) during embryonic cardiovascular development. Cardiac neural crest cells (NCs) populate the PAAs and differentiate into vascular smooth muscle cells (vSMCs), which is critical for successful PAA-to-AAA remodeling. SMAD4, the central mediator of canonical TGFβ signaling, has been implicated in NC-to-vSMC differentiation; however, its distinct roles in vSMC differentiation and NC survival are unclear.

Results

Here, we investigated the role of SMAD4 in cardiac NC differentiation to vSMCs using lineage-specific inducible mouse strains in an attempt to avoid early embryonic lethality and NC cell death. We found that with global SMAD4 loss, its role in smooth muscle differentiation could be uncoupled from its role in the survival of the cardiac NC in vivo . Moreover, we found that SMAD4 may regulate the induction of fibronectin, a known mediator of NC-to-vSMC differentiation. Finally, we found that SMAD4 is required in NCs cell-autonomously for NC-to-vSMC differentiation and for NC contribution to and persistence in the pharyngeal arch mesenchyme.

Conclusions

Overall, this study demonstrates the critical role of SMAD4 in the survival of cardiac NCs, their differentiation to vSMCs, and their contribution to the developing pharyngeal arches.

Murine model of elastase-induced proximal thoracic aortic aneurysm through a midline incision in the anterior neck

Objective

This study was performed to develop a murine model of elastase-induced proximal thoracic aortic aneurysms (PTAAs).

Methods

The ascending thoracic aorta and aortic arch of adult C57BL/6J male mice were exposed through a midline incision in the anterior neck, followed by peri-adventitial elastase or saline application. The maximal ascending thoracic aorta diameter was measured with high-resolution micro-ultrasound. Twenty-eight days after the operation, the aortas were harvested and analyzed by histopathological examination and qualitative polymerase chain reaction to determine the basic characteristics of the aneurysmal lesions.

Results

Fourteen days after the operation, the dilation rate (mean ± standard error) in the 10-min elastase application group (n = 10, 71.44 ± 10.45%) or 5-min application group (n = 9, 42.67 ± 3.72%) were significantly higher than that in the saline application group (n = 9, 7.37 ± 0.94%, P < 0.001 for both). Histopathological examination revealed aortic wall thickening, degradation of elastin fibers, loss of smooth muscle cells, more vasa vasorum, enhanced extracellular matrix degradation, augmented collagen synthesis, upregulated apoptosis and proliferation capacity of smooth muscle cells, and increased macrophages and CD4⁺ T cells infiltration in the PTAA lesions. Qualitative analyses indicated higher expression of the proinflammatory markers, matrix metalloproteinase-2 and -9 as well as Collagen III, Collagen I in the PTAAs than in the controls.

Conclusion

We established a novel in vivo mouse model of PTAAs through a midline incision in the anterior neck by peri-adventitial application of elastase. This model may facilitate research into the pathogenesis of PTAA formation and the treatment strategy for this devastating disease.

Differentiation and Engineering of Human Stem Cells for Smooth Muscle Generation

Cardiovascular diseases are responsible for 31% of global deaths and are considered the main cause of death and disability worldwide. Stem cells from various sources have become attractive options for a range of cell-based therapies for smooth muscle tissue regeneration. However, for efficient myogenic differentiation, the stem cell characteristics, cell culture conditions, and their respective microenvironments need to be carefully assessed. This review covers the various approaches involved in the regeneration of vascular smooth muscles by conditioning human stem cells. This article delves into the different sources of stem cells used in the generation of myogenic tissues, the role of soluble growth factors, use of scaffolding techniques, biomolecular cues, relevance of mechanical stimulation, and key transcription factors involved, aimed at inducing myogenic differentiation. Impact statement The review article's main goal is to discuss the recent advances in the field of smooth muscle tissue regeneration. We look at various cell sources, growth factors, scaffolds, mechanical stimuli, and factors involved in smooth muscle formation. These stem cell-based approaches for vascular muscle formation will provide various options for cell-based therapies with long-term beneficial effects on patients.

Extracellular Vesicles and Vascular Inflammation

Vascular inflammation is the most common pathological feature in the pathogenesis of human disease. It is a complex immune process involved with many different types of cells including platelet, monocytes, macrophages, endothelial cells, and others. It is widely accepted that both innate and adaptive immune responses are important for the initiation and progression of vascular inflammation. The cell-cell interaction constitutes an important aspect of those immune responses in the vascular inflammation. Extracellular vesicles (EVs) are nanometer-sized double-layer lipid membrane vesicles released from most types of cells. They have been proved to play critical roles in intercellular communication in the occurrence and development of multisystem diseases. With the advancement of basal medical science, the biological roles of EVs in vascular inflammation have been clearer today. In this chapter, we will summarize the advance progress of extracellular vesicles in regulating vascular inflammation and its potential application in the clinical.

Multiple Arterial Dissections and Connective Tissue Abnormalities

Background: Although patients with multiple arterial dissections in distinct arterial regions rarely present with known connective tissue syndromes, we hypothesized that mild connective tissue abnormalities are common findings in these patients. Methods: From a consecutive register of 322 patients with cervical artery dissection (CeAD), we identified and analyzed 4 patients with a history of additional dissections in other vascular beds. In three patients, dermal connective tissue was examined by electron microscopy. DNA from all four patients was studied by whole-exome sequencing and copy number variation (CNV) analysis. Results: The collagen fibers of dermal biopsies were pathologic in all three analyzed patients. One patient carried a CNV disrupting the COL3A1 and COL5A2 genes (vascular or hypermobility type of Ehlers–Danlos syndrome), and another patient a CNV in MYH11 (familial thoracic aortic aneurysms and dissections). The third patient carried a missense substitution in COL5A2. Conclusion: Three patients showed morphologic alterations of the dermal connective tissue, and two patients carried pathogenic variants in genes associated with arterial connective tissue dysfunction. The findings suggest that genetic testing should be recommended after recurrent arterial dissections, independently of apparent phenotypical signs of connective tissue disorders.

Poisoning by Nierembergia veitchii: Effects on vascular smooth muscle cells in the pathogenesis of enzootic calcinosis

Vascular mineralization is a hallmark of enzootic calcinosis. Histopathological, ultrastructural, and immunohistochemical investigations were performed on the external carotid arteries of seven sheep naturally poisoned by Nierembergia veitchii. Histologically, moderate to marked hyperplasia of the tunica intima was observed without mineralization. The tunica media exhibited mild to severe mineralization and osteochondroid metaplasia. Sheep with enzootic calcinosis showed arterial overexpression of osteopontin and tissue-nonspecific alkaline phosphatase and immunolabeling for osteonectin and osteocalcin in both intima and media layers of the tested arteries. The main ultrastructural finding in the tunica media was a marked phenotypic change of vascular smooth muscle cells from a contractile phenotype (VSMC-C) into a synthetic phenotype (VSMC-S). In the tunica media, VSMC-S produced matrix and extracellular vesicles, forming mineralizable granules associated with arterial mineralization. VSMC-S were also present in the tunica intima, but matrix and extracellular vesicles and mineralization were not observed. The absence of matrix and extracellular vesicles in the intimal hyperplasia, even in the presence of noncollagenous bone proteins, tissue-nonspecific alkaline phosphatase, and vitamin D receptors, reinforces the hypothesis that the presence of matrix and extracellular vesicles are crucial for the development of vascular mineralization in enzootic calcinosis. It is proposed that the two different VSMC-S phenotypes in calcinosis are due to the expression of at least two genetically different types of these cells induced by the action of 1,25(OH)₂D₃.

Skeletal muscle differentiation of human iPSCs meets bioengineering strategies: perspectives and challenges

Although skeletal muscle repairs itself following small injuries, genetic diseases or severe damages may hamper its ability to do so. Induced pluripotent stem cells (iPSCs) can generate myogenic progenitors, but their use in combination with bioengineering strategies to modulate their phenotype has not been sufficiently investigated. This review highlights the potential of this combination aimed at pushing the boundaries of skeletal muscle tissue engineering. First, the overall organization and the key steps in the myogenic process occurring in vivo are described. Second, transgenic and non-transgenic approaches for the myogenic induction of human iPSCs are compared. Third, technologies to provide cells with biophysical stimuli, biomaterial cues, and biofabrication strategies are discussed in terms of recreating a biomimetic environment and thus helping to engineer a myogenic phenotype. The embryonic development process and the pro-myogenic role of the muscle-resident cell populations in co-cultures are also described, highlighting the possible clinical applications of iPSCs in the skeletal muscle tissue engineering field.

The role of vascular smooth muscle cells in the development of aortic aneurysms and dissections

BACKGROUND

Aortic aneurysms (AA) are pathological dilations of the aorta, associated with an overall mortality rate up to 90% in case of rupture. In addition to dilation, the aortic layers can separate by a tear within the layers, defined as aortic dissections (AD). Vascular smooth muscle cells (vSMC) are the predominant cell type within the aortic wall and dysregulation of vSMC functions contributes to AA and AD development and progression. However, since the exact underlying mechanism is poorly understood, finding potential therapeutic targets for AA and AD is challenging and surgery remains the only treatment option.

METHODS

In this review, we summarize current knowledge about vSMC functions within the aortic wall and give an overview of how vSMC functions are altered in AA and AD pathogenesis, organized per anatomical location (abdominal or thoracic aorta).

RESULTS

Important functions of vSMC in healthy or diseased conditions are apoptosis, phenotypic switch, extracellular matrix regeneration and degradation, proliferation and contractility. Stressors within the aortic wall, including inflammatory cell infiltration and (epi)genetic changes, modulate vSMC functions and cause disturbance of processes within vSMC, such as changes in TGF-β signalling and regulatory RNA expression.

CONCLUSION

This review underscores a central role of vSMC dysfunction in abdominal and thoracic AA and AD development and progression. Further research focused on vSMC dysfunction in the aortic wall is necessary to find potential targets for noninvasive AA and AD treatment options.

CCAAT/Enhancer-Binding Protein Alpha Is a Novel Regulator of Vascular Smooth Muscle Cell Osteochondrogenic Transition and Vascular Calcification

Aims

Vascular calcification is a common clinical complication of chronic kidney disease (CKD), atherosclerosis (AS), and diabetes, which is associated with increased cardiovascular morbidity and mortality in patients. The transdifferentiation of vascular smooth muscle cells (VSMCs) to an osteochondrogenic phenotype is a crucial step during vascular calcification. The transcription factor CCAAT/enhancer-binding protein alpha (C/EBPα) plays an important role in regulating cell proliferation and differentiation, but whether it regulates the calcification of arteries and VSMCs remains unclear. Therefore, this study aims to understand the role of C/EBPα in the regulation of vascular calcification.

Methods and Results

Both mRNA and protein expression levels of C/EBPα were significantly increased in calcified arteries from mice treated with a high dose of vitamin D3 (vD3). Upregulation of C/EBPα was also observed in the high phosphate- and calcium-induced VSMC calcification process. The siRNA-mediated knockdown of C/EBPα significantly attenuated VSMC calcification in vitro. Moreover, C/EBPα depletion in VSMCs significantly reduced the mRNA expression of the osteochondrogenic genes, e.g., sex-determining region Y-box 9 (Sox9). C/EBPα overexpression can induce SOX9 overexpression. Similar changes in the protein expression of SOX9 were also observed in VSMCs after C/EBPα depletion or overexpression. In addition, silencing of Sox9 expression significantly inhibited the phosphate- and calcium-induced VSMC calcification in vitro.

Conclusion

Findings in this study indicate that C/EBPα is a key regulator of the osteochondrogenic transdifferentiation of VSMCs and vascular calcification, which may represent a novel therapeutic target for vascular calcification.

Adult Human Vascular Smooth Muscle Cells on 3D Silk Fibroin Nonwovens Release Exosomes Enriched in Angiogenic and Growth-Promoting Factors

BACKGROUND

Our earlier works showed the quick vascularization of mouse skin grafted Bombyx mori 3D silk fibroin nonwoven scaffolds (3D-SFnws) and the release of exosomes enriched in angiogenic/growth factors (AGFs) from in vitro 3D-SFnws-stuck human dermal fibroblasts (HDFs). Here, we explored whether coronary artery adult human smooth muscle cells (AHSMCs) also release AGFs-enriched exosomes when cultured on 3D-SFnws in vitro.

METHODS

Media with exosome-depleted FBS served for AHSMCs and human endothelial cells (HECs) cultures on 3D-SFnws or polystyrene. Biochemical methods and double-antibody arrays assessed cell growth, metabolism, and intracellular TGF-β and NF-κB signalling pathways activation. AGFs conveyed by CD9+/CD81+ exosomes released from AHSMCs were double-antibody array analysed and their angiogenic power evaluated on HECs in vitro.

RESULTS

AHSMCs grew and consumed D-glucose more intensely and showed a stronger phosphorylation/activation of TAK-1, SMAD-1/-2/-4/-5, ATF-2, c-JUN, ATM, CREB, and an IκBα phosphorylation/inactivation on SFnws vs. polystyrene, consistent overall with a proliferative/secretory phenotype. SFnws-stuck AHSMCs also released exosomes richer in IL-1α/-2/-4/-6/-8; bFGF; GM-CSF; and GRO-α/-β/-γ, which strongly stimulated HECs' growth, migration, and tubes/nodes assembly in vitro.

CONCLUSIONS

Altogether, the intensified AGFs exosomal release from 3D-SFnws-attached AHSMCs and HDFs could advance grafts' colonization, vascularization, and take in vivo-noteworthy assets for prospective clinical applications.

Single-Cell Analysis Uncovers Osteoblast Factor Growth Differentiation Factor 10 as Mediator of Vascular Smooth Muscle Cell Phenotypic Modulation Associated with Plaque Rupture in Human Carotid Artery Disease

(1) Background: Vascular smooth muscle cells (VSMCs) undergo a complex phenotypic switch in response to atherosclerosis environmental triggers, contributing to atherosclerosis disease progression. However, the complex heterogeneity of VSMCs and how VSMC dedifferentiation affects human carotid artery disease (CAD) risk has not been clearly established. (2) Method: A single-cell RNA sequencing analysis of CD45- cells derived from the atherosclerotic aorta of Apolipoprotein E-deficient (Apoe-/-) mice on a normal cholesterol diet (NCD) or a high cholesterol diet (HCD), respecting the site-specific predisposition to atherosclerosis was performed. Growth Differentiation Factor 10 (GDF10) role in VSMCs phenotypic switch was investigated via flow cytometry, immunofluorescence in human atherosclerotic plaques. (3) Results: scRNAseq analysis revealed the transcriptomic profile of seven clusters, five of which showed disease-relevant gene signature of VSMC macrophagic calcific phenotype, VSMC mesenchymal chondrogenic phenotype, VSMC inflammatory and fibro-phenotype and VSMC inflammatory phenotype. Osteoblast factor GDF10 involved in ossification and osteoblast differentiation emerged as a hallmark of VSMCs undergoing phenotypic switch. Under hypercholesteremia, GDF10 triggered VSMC osteogenic switch in vitro. The abundance of GDF10 expressing osteogenic-like VSMCs cells was linked to the occurrence of carotid artery disease (CAD) events. (4) Conclusions: Taken together, these results provide evidence about GDF10-mediated VSMC osteogenic switch, with a likely detrimental role in atherosclerotic plaque stability.

Exosomes in cardiovascular diseases: a blessing or a sin for the mankind

Cardiovascular diseases (CVDs) comprises disorders of blood vessels and heart. Multiple cells in the heart suggests that hetero-cellular communication, which is an important aspect in heart functioning and there is a need to elucidate the way in which this inter-cellular communication occurs. Now a days, exosomal research has gained much attention. Exosomes, nano-shuttles, are EVs with diameters ranging from 40 to 160 nm (average 100 nm), secreted by body cells. These vesicles act as cell-to-cell communicators and are carriers of important biomolecules such as RNAs, miRNAs, Proteins and lipids. Exosomes can change the gene expression of the recipient cells, thereby, changes the cellular characteristics. Exosomes have known to play an essential role in protection as well as progression of various cardiovascular diseases. In the present review, role of exosomes in various CVDs have been discussed.

Ion Channels and Transporters in Muscle Cell Differentiation

Investigations on ion channels in muscle tissues have mainly focused on physiological muscle function and related disorders, but emerging evidence supports a critical role of ion channels and transporters in developmental processes, such as controlling the myogenic commitment of stem cells. In this review, we provide an overview of ion channels and transporters that influence skeletal muscle myoblast differentiation, cardiac differentiation from pluripotent stem cells, as well as vascular smooth muscle cell differentiation. We highlight examples of model organisms or patients with mutations in ion channels. Furthermore, a potential underlying molecular mechanism involving hyperpolarization of the resting membrane potential and a series of calcium signaling is discussed.

Organ-on-a-chip technology: a novel approach to investigate cardiovascular diseases

The development of organs-on-chip (OoC) has revolutionized in vitro cell-culture experiments by allowing a better mimicry of human physiology and pathophysiology that has consequently led researchers to gain more meaningful insights into disease mechanisms. Several models of hearts-on-chips and vessels-on-chips have been demonstrated to recapitulate fundamental aspects of the human cardiovascular system in the recent past. These 2D and 3D systems include synchronized beating cardiomyocytes in hearts-on-chips and vessels-on-chips with layer-based structures and the inclusion of physiological and pathological shear stress conditions. The opportunities to discover novel targets and to perform drug testing with chip-based platforms have substantially enhanced, thanks to the utilization of patient-derived cells and precise control of their microenvironment. These organ models will provide an important asset for future approaches to personalized cardiovascular medicine and improved patient care. However, certain technical and biological challenges remain, making the global utilization of OoCs to tackle unanswered questions in cardiovascular science still rather challenging. This review article aims to introduce and summarize published work on hearts- and vessels-on chips but also to provide an outlook and perspective on how these advanced in vitro systems can be used to tailor disease models with patient-specific characteristics.

Single-cell transcriptomic landscape of cardiac neural crest cell derivatives during development

The migratory cardiac neural crest cells (CNCCs) contribute greatly to cardiovascular development. A thorough understanding of the cell lineages, developmental chronology, and transcriptomic states of CNCC derivatives during normal development is essential for deciphering the pathogenesis of CNCC‐associated congenital anomalies. Here, we perform single‐cell transcriptomic sequencing of 34,131 CNCC‐derived cells in mouse hearts covering eight developmental stages between E10.5 and P7. We report the presence of CNCC‐derived mural cells that comprise pericytes and microvascular smooth muscle cells (mVSMCs). Furthermore, we identify the transition from the CNCC‐derived pericytes to mVSMCs and the key regulators over the transition. In addition, our data support that many CNCC derivatives had already committed or differentiated to a specific lineage when migrating into the heart. We explore the spatial distribution of some critical CNCC‐derived subpopulations with single‐molecule fluorescence in situ hybridization. Finally, we computationally reconstruct the differentiation path and regulatory dynamics of CNCC derivatives. Our study provides novel insights into the cell lineages, developmental chronology, and regulatory dynamics of CNCC derivatives during development.

Human Induced Pluripotent Stem Cell-Derived Vascular Cells: Recent Progress and Future Directions

Human induced pluripotent stem cells (hiPSCs) hold great promise for cardiovascular regeneration following ischemic injury. Considerable effort has been made toward the development and optimization of methods to differentiate hiPSCs into vascular cells, such as endothelial and smooth muscle cells (ECs and SMCs). In particular, hiPSC-derived ECs have shown robust potential for promoting neovascularization in animal models of cardiovascular diseases, potentially achieving significant and sustained therapeutic benefits. However, the use of hiPSC-derived SMCs that possess high therapeutic relevance is a relatively new area of investigation, still in the earlier investigational stages. In this review, we first discuss different methodologies to derive vascular cells from hiPSCs with a particular emphasis on the role of key developmental signals. Furthermore, we propose a standardized framework for assessing and defining the EC and SMC identity that might be suitable for inducing tissue repair and regeneration. We then highlight the regenerative effects of hiPSC-derived vascular cells on animal models of myocardial infarction and hindlimb ischemia. Finally, we address several obstacles that need to be overcome to fully implement the use of hiPSC-derived vascular cells for clinical application.

Platelet-Derived Microvesicles Promote VSMC Dedifferentiation After Intimal Injury via Src/Lamtor1/mTORC1 Signaling

Phenotypic switch of vascular smooth muscle cells (VSMCs) is important in vascular remodeling which causes hyperplasia and restenosis after intimal injury. Platelets are activated at injured intima and secrete platelet-derived microvesicles (PMVs). Herein, we demonstrated the role of PMVs in VSMC phenotypic switch and the potential underlying mechanisms. In vivo, platelets were locally adhered and activated at intimal injury site, while Lamtor1 was promoted and VSMCs were dedifferentiated. PMVs, collected from collagen-activated platelets in vitro which mimicked collagen exposure during intimal injury, promoted VSMC dedifferentiation, induced Lamtor1 expression, and activated mTORC1 signaling, reflected by the phosphorylation of two downstream targets, i.e., S6K and 4E-BP1. Knockdown of Lamtor1 with small interfering RNA attenuated these processes induced by PMVs. Based on the previously published proteomic data, Ingenuity Pathway Analysis revealed that Src may participate in regulating effects of PMVs. Src inhibitor significantly reversed the effects of PMVs on VSMC dedifferentiation, Lamtor1 expression and mTORC1 activation. Furthermore, in SMC-specific Lamtor1 knockout mice, intimal hyperplasia was markedly attenuated after intimal injury compared with the wild type. Our data suggested that PMVs secreted by activated platelets promoted VSMC dedifferentiation via Src/Lamtor1/mTORC1 signaling pathway. Lamtor1 may be a potential therapeutic target for intimal hyperplasia after injury.

RAGE Differentially Altered in vitro Responses in Vascular Smooth Muscle Cells and Adventitial Fibroblasts in Diabetes-Induced Vascular Calcification

The Advanced Glycation End-Products (AGE)/Receptor for AGEs (RAGE) signaling pathway exacerbates diabetes-mediated vascular calcification (VC) in vascular smooth muscle cells (VSMCs). Other cell types are involved in VC, such as adventitial fibroblasts (AFBs). We hope to elucidate some of the mechanisms responsible for differential signaling in diabetes-mediated VC with this work. This work utilizes RAGE knockout animals and in vitro calcification to measure calcification and protein responses. Our calcification data revealed that VSMCs calcification was AGE/RAGE dependent, yet AFBs calcification was not an AGE-mediated RAGE response. Protein expression data showed VSMCs lost their phenotype marker, α-smooth muscle actin, and had a higher RAGE expression over non-diabetics. RAGE knockout (RKO) VSMCs did not show changes in phenotype markers. P38 MAPK, a downstream RAGE-associated signaling molecule, had significantly increased activation with calcification in both diabetic and diabetic RKO VSMCs. AFBs showed a loss in myofibroblast marker, α-SMA, due to calcification treatment. RAGE expression decreased in calcified diabetic AFBs, and P38 MAPK activation significantly increased in diabetic and diabetic RKO AFBs. These findings point to potentially an alternate receptor mediating the calcification response in the absence of RAGE. Overall, VSMCs and AFBs respond differently to calcification and the application of AGEs.

Clinical Approach to Vascular Calcification in Patients With Non-dialysis Dependent Chronic Kidney Disease: Mineral-Bone Disorder-Related Aspects

Chronic kidney disease (CKD) is associated with a very high morbimortality, mainly from cardiovascular origin, and CKD is currently considered in the high- or very high risk- cardiovascular risk category. CKD-mineral and bone disorders (CKD-MBDs), including vascular and/or valvular calcifications, are also associated with these poor outcomes. Vascular calcification (VC) is very prevalent (both intimal and medial), even in non-dialysis dependent patients, with a greater severity and more rapid progression. Simple X-ray based-scores such as Adragão's (AS) are useful prognostic tools and AS (even AS based on hand-X-ray only) may be superior to the classic Kauppila's score when evaluating non-dialysis CKD patients. Thus, in this mini-review, we briefly review CKD-MBD-related aspects of VC and its complex pathophysiology including the vast array of contributors and inhibitors. Furthermore, although VC is a surrogate marker and is not yet considered a treatment target, we consider that the presence of VC may be relevant in guiding therapeutic interventions, unless all patients are treated with the mindset of reducing the incidence or progression of VC with the currently available armamentarium. Avoiding phosphate loading, restricting calcium-based phosphate binders and high doses of vitamin D, and avoiding normalizing (within the normal limits for the assay) parathyroid hormone levels seem logical approaches. The availability of new drugs and future studies, including patients in early stages of CKD, may lead to significant improvements not only in patient risk stratification but also in attenuating the accelerated progression of VC in CKD.

Differentiation and Application of Human Pluripotent Stem Cells Derived Cardiovascular Cells for Treatment of Heart Diseases: Promises and Challenges

Human pluripotent stem cells (hPSCs) are derived from human embryos (human embryonic stem cells) or reprogrammed from human somatic cells (human induced pluripotent stem cells). They can differentiate into cardiovascular cells, which have great potential as exogenous cell resources for restoring cardiac structure and function in patients with heart disease or heart failure. A variety of protocols have been developed to generate and expand cardiovascular cells derived from hPSCs in vitro. Precisely and spatiotemporally activating or inhibiting various pathways in hPSCs is required to obtain cardiovascular lineages with high differentiation efficiency. In this concise review, we summarize the protocols of differentiating hPSCs into cardiovascular cells, highlight their therapeutic application for treatment of cardiac diseases in large animal models, and discuss the challenges and limitations in the use of cardiac cells generated from hPSCs for a better clinical application of hPSC-based cardiac cell therapy.

Vascular Calcification in Chronic Kidney Disease: Diversity in the Vessel Wall

Vascular calcification (VC) is one of the major causes of cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). VC is a complex process expressing similarity to bone metabolism in onset and progression. VC in CKD is promoted by various factors not limited to hyperphosphatemia, Ca/Pi imbalance, uremic toxins, chronic inflammation, oxidative stress, and activation of multiple signaling pathways in different cell types, including vascular smooth muscle cells (VSMCs), macrophages, and endothelial cells. In the current review, we provide an in-depth analysis of the various kinds of VC, the clinical significance and available therapies, significant contributions from multiple cell types, and the associated cellular and molecular mechanisms for the VC process in the setting of CKD. Thus, we seek to highlight the key factors and cell types driving the pathology of VC in CKD in order to assist in the identification of preventative, diagnostic, and therapeutic strategies for patients burdened with this disease.

Induced Pluripotent Stem Cells (iPSCs) in Vascular Research: from Two- to Three-Dimensional Organoids

Stem cell technology has been around for almost 30 years and in that time has grown into an enormous field. The stem cell technique progressed from the first successful isolation of mammalian embryonic stem cells (ESCs) in the 1990s, to the production of human induced-pluripotent stem cells (iPSCs) in the early 2000s, to finally culminate in the differentiation of pluripotent cells into highly specialized cell types, such as neurons, endothelial cells (ECs), cardiomyocytes, fibroblasts, and lung and intestinal cells, in the last decades. In recent times, we have attained a new height in stem cell research whereby we can produce 3D organoids derived from stem cells that more accurately mimic the in vivo environment. This review summarizes the development of stem cell research in the context of vascular research ranging from differentiation techniques of ECs and smooth muscle cells (SMCs) to the generation of vascularized 3D organoids. Furthermore, the different techniques are critically reviewed, and future applications of current 3D models are reported.

Generation of Vascular Smooth Muscle Cells From Induced Pluripotent Stem Cells: Methods, Applications, and Considerations

The developmental origin of vascular smooth muscle cells (VSMCs) has been increasingly recognized as a major determinant for regional susceptibility or resistance to vascular diseases. As a human material-based complement to animal models and human primary cultures, patient induced pluripotent stem cell iPSC-derived VSMCs have been leveraged to conduct basic research and develop therapeutic applications in vascular diseases. However, iPSC-VSMCs (induced pluripotent stem cell VSMCs) derived by most existing induction protocols are heterogeneous in developmental origins. In this review, we summarize signaling networks that govern in vivo cell fate decisions and in vitro derivation of distinct VSMC progenitors, as well as key regulators that terminally specify lineage-specific VSMCs. We then highlight the significance of leveraging patient-derived iPSC-VSMCs for vascular disease modeling, drug discovery, and vascular tissue engineering and discuss several obstacles that need to be circumvented to fully unleash the potential of induced pluripotent stem cells for precision vascular medicine.