Exosomal Composition, Biogenesis and Profiling using Point-of-Care Diagnostics - Implications for Cardiovascular Disease

Arteriosclerosis is an important age-dependent disease that encompasses atherosclerosis, in-stent restenosis (ISR), pulmonary hypertension, autologous bypass grafting and transplant arteriosclerosis. Endothelial dysfunction and the proliferation of vascular smooth muscle cell (vSMC)-like cells is a critical event in the pathology of arteriosclerotic disease leading to intimal-medial thickening (IMT), lipid retention and vessel remodelling. An important aspect in guiding clinical decision-making is the detection of biomarkers of subclinical arteriosclerosis and early cardiovascular risk. Crucially, relevant biomarkers need to be good indicators of injury which change in their circulating concentrations or structure, signalling functional disturbances. Extracellular vesicles (EVs) are nanosized membraneous vesicles secreted by cells that contain numerous bioactive molecules and act as a means of intercellular communication between different cell populations to maintain tissue homeostasis, gene regulation in recipient cells and the adaptive response to stress. This review will focus on the emerging field of EV research in cardiovascular disease (CVD) and discuss how key EV signatures in liquid biopsies may act as early pathological indicators of adaptive lesion formation and arteriosclerotic disease progression. EV profiling has the potential to provide important clinical information to complement current cardiovascular diagnostic platforms that indicate or predict myocardial injury. Finally, the development of fitting devices to enable rapid and/or high-throughput exosomal analysis that require adapted processing procedures will be evaluate

The Dichotomy of Vascular Smooth Muscle Differentiation/De- Differentiation in Health and Disease

Vascular smooth muscle cells (SMCs) are thought to display cellular plasticity by alternating between a quiescent ‘contractile’ differentiated phenotype and a proliferative ‘synthetic’ de-differentiated phenotype in response to induction of distinct developmental pathways or to local micro-environmental cues. This classic de-differentiation and re-programming process is associated with a significant loss in the expression of key SMC differentiation marker genes for a large number of proliferative vascular diseases in vivo and in sub-cultured cells in vitro. Regarded as essential for vascular regeneration and repair in vivo, phenotypic modulation represents a critical target for therapeutic intervention. However, recent evidence now suggests that this process of vascular regeneration may also involve differentiation of resident vascular stem cells and the accumulation of stem cell-derived myogenic, osteochondrogenic and macrophage-like phenotypes within vascular lesions in vivo and across sub-cultured SMC cell populations in vitro. This review summarises our current knowledge of vascular regeneration, de-differentiation and re-programming of vascular SMCs, and focuses on the accumulating evidence of a putative role for stem cell-derived progeny and the evolving dichotomy of the origin of SMC-like cells during intimal-medial thickening and the progression of arteriosclerotic disease

Reactive oxygen species (ROS), intimal thickening, and subclinical atherosclerotic disease

Arteriosclerosis causes significant morbidity and mortality worldwide. Central to this process is the development of subclinical non-atherosclerotic intimal lesions before the appearance of pathologic intimal thickening and advanced atherosclerotic plaques. Intimal thickening is associated with several risk factors, including oxidative stress due to reactive oxygen species (ROS), inflammatory cytokines and lipid. The main ROS producing systems in-vivo are reduced nicotinamide dinucleotide phosphate (NADPH) oxidase (NOX). ROS effects are context specific. Exogenous ROS induces apoptosis and senescence, whereas intracellular ROS promotes stem cell differentiation, proliferation, and migration. Lineage tracing studies using murine models of subclinical atherosclerosis have revealed the contributory role of medial smooth muscle cells (SMCs), resident vascular stem cells, circulating bone-marrow progenitors and endothelial cells that undergo endothelial-mesenchymal-transition (EndMT). This review will address the putative physiological and patho-physiological roles of ROS in controlling vascular cell fate and ROS contribution to vascular regeneration and disease progression

Moderate alcohol consumption targets S100β+ vascular stem cells and attenuates injury-induced neointimal hyperplasia

Background Stem cells present in the vessel wall may be triggered in response to injurious stimuli to undergo differentiation and contribute to vascular disease development. Our aim was to determine the effect of moderate alcohol (EtOH) exposure on the expansion and differentiation of S100 calcium-binding protein B positive (S100β+) resident vascular stem cells and their contribution to pathologic vessel remodeling in a mouse model of arteriosclerosis. Methods and Results Lineage tracing analysis of S100β+ cells was performed in male and female S100β-eGFP/Cre/ERT2–dTomato transgenic mice treated daily with or without EtOH by oral gavage (peak BAC: 15 mM or 0.07%) following left common carotid artery ligation for 14 days. Carotid arteries (ligated or sham-operated) were harvested for morphological analysis and confocal assessment of fluorescent-tagged S100 β + cells in FFPE carotid cross sections. Ligation-induced carotid remodeling was more robust in males than in females. EtOH-gavaged mice had less adventitial thickening and markedly reduced neointimal formation compared to controls, with a more pronounced inhibitory effect in males compared to females. There was significant expansion of S100β+-marked cells in vessels postligation, primarily in the neointimal compartment. EtOH treatment reduced the fraction of S100β+ cells in carotid cross sections, concomitant with attenuated remodeling. In vitro, EtOH attenuated Sonic Hedgehog-stimulated myogenic differentiation (as evidenced by reduced calponin and myosin heavy chain expression) of isolated murine S100β+ vascular stem cells. Conclusions These data highlight resident vascular S100β+ stem cells as a novel target population for alcohol and suggest that regulation of these progenitors in adult arteries, particularly in males, may be an important mechanism contributing to the antiatherogenic effects of moderate alcohol consumption

The calcium binding protein S100β marks hedgehog-responsive resident vascular stem cells within vascular lesions

A hallmark of subclinical atherosclerosis is the accumulation of vascular smooth muscle cell (SMC)-like cells leading to intimal thickening. While medial SMCs contribute, the participation of hedgehog-responsive resident vascular stem cells (vSCs) to lesion formation remains unclear. Using transgenic eGFP mice and genetic lineage tracing of S100β vSCs in vivo, we identified S100β/ Sca1 cells derived from a S100β non-SMC parent population within lesions that co-localise with smooth muscle α-actin (SMA) cells following iatrogenic flow restriction, an effect attenuated following hedgehog inhibition with the smoothened inhibitor, cyclopamine. In vitro, S100β/Sca1 cells isolated from atheroprone regions of the mouse aorta expressed hedgehog signalling components, acquired the di-methylation of histone 3 lysine 4 (H3K4me2) stable SMC epigenetic mark at the Myh11 locus and underwent myogenic differentiation in response to recombinant sonic hedgehog (SHh). Both S100β and PTCH1 cells were present in human vessels while S100β cells were enriched in arteriosclerotic lesions. Recombinant SHh promoted myogenic differentiation of human induced pluripotent stem cell-derived S100β neuroectoderm progenitors in vitro. We conclude that hedgehog-responsive S100β vSCs contribute to lesion formation and support targeting hedgehog signalling to treat subclinical arteriosclerosis

The differential translation capabilities of the human DHFR2 gene indicates a developmental and tissue specific endogenous protein of low abundance.

A functional role has been ascribed to the human Dihydrofolate reductase 2 (DHFR2) gene based on the enzymatic activity of recombinant versions of the predicted translated protein. However, the in vivo function is still unclear. The high amino acid sequence identity (92%) between DHFR2 and its parental homologue, DHFR, makes analysis of the endogenous protein challenging. This paper describes a targeted mass spectrometry proteomics approach in several human cell lines and tissue types to identify DHFR2 specific peptides as evidence of its translation. We show definitive evidence that the dihydrofolate reductase activity in the mitochondria is in fact mediated by DHFR, and not DHFR2. Analysis of Ribo-seq data and an experimental assessment of ribosome association using a sucrose cushion, showed that the two main Ensembl annotated mRNA isoforms of DHFR2, 201 and 202, show differential association with the ribosome. This indicates a functional role at both the RNA and protein level. However, we were unable to detect DHFR2 protein at a detectable level in most cell types examined despite various RNA isoforms of DHFR2 being relatively abundant. We did detect a DHFR2 specific peptide in embryonic heart, indicating that the protein may have a specific role during embryogenesis. We propose that the main functionality of the DHFR2 gene in adult cells is likely to arise at the RNA level

Diagnostic potential of extracellular vesicles (EVs) and single-cell photonics (scPH) in subclinical atherosclerotic disease

Arteriosclerosis is an important age-dependent disease encompassing atherosclerosis, in- stent restenosis, pulmonary hypertension, and autologous bypass grafting. The accumulation of neointimal vascular smooth muscle (VSMC)-like cells is a critical event in the pathology of vascular disease leading to intimal-medial thickening (IMT) and vessel remodelling, and is considered an essential marker of subclinical arteriosclerotic disease. Their origin remains controversial, with several cell fate-mapping studies in mice indicating that they are derived from medial VSMCs, resident Nestin/S100β + vascular stem cells, and/or endothelial cells (ECs) following endothelial-mesenchymal transition (EndoMT). It is widely accepted that exposure to pathologic reactive oxygen species (ROS) generating risk factors is central to this pathology. The effective pathophysiological response within the vessel wall following vascular injury is endothelial cell apoptosis rendering the vascular endothelium dysfunctional. In the past few years, compelling evidence now suggests a role for the generation of endothelial-derived extracellular vehicles (EVs) as crucial regulators in transferring biological information, either locally or remotely, to initiate the proliferation, migration, and accumulation of VSMC-like cells within subclinical arteriosclerotic lesions. Early detection of these lesions represents an important diagnostic objective. In this context, the main focus of this study was to develop novel strategies that interrogate and discriminate these discrete cell populations and detect the key signalling molecules within endothelial-derived EVs that dictate their fate. Specifically, single-cell photonic analysis using broadband light (autofluorescence), Raman and Fourier Transform Intra Red (FTIR) spectral datasets from normal VSMCs and lesional cells derived from human vessels ex vivo, in addition to human-induced pluripotent stem cell (HiPSC) progenitors and their myogenic progeny in vitro, were analysed using supervised machine learning as a novel diagnostic platform for early detection of vascular phenotypes within lesions. Moreover, the characteristics and effects of endothelial-derived EVs on resident vascular stem cell fate following hyperglycaemic-induced endothelial dysfunction were assessed using rat and HiPSC models in vitro as a potential surrogate marker for early lesion formation. The data clearly demonstrates that single cell photonic analysis can successfully discriminate and predict vascular phenotypes within lesions. Furthermore, endothelial derived EVs following hyperglycaemic-induced endothelial dysfunction promote resident vascular stem cell myogenic differentiation, growth and migration in vitro. These characteristics may represent important surrogate biomarkers for detection of early subclinical arteriosclerosis

Nox, Reactive Oxygen Species and Regulation of Vascular Cell Fate

The generation of reactive oxygen species (ROS) and an imbalance of antioxidant defence mechanisms can result in oxidative stress. Several pro-atherogenic stimuli that promote intimal-medial thickening (IMT) and early arteriosclerotic disease progression share oxidative stress as a common regulatory pathway dictating vascular cell fate. The major source of ROS generated within the vascular system is the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family of enzymes (Nox), of which seven members have been characterized. The Nox family are critical determinants of the redox state within the vessel wall that dictate, in part the pathophysiology of several vascular phenotypes. This review highlights the putative role of ROS in controlling vascular fate by promoting endothelial dysfunction, altering vascular smooth muscle phenotype and dictating resident vascular stem cell fate, all of which contribute to intimal medial thickening and vascular disease progression

Moderate Alcohol Consumption Targets S100β +

BACKGROUND. Stem cells present in the vessel wall may be triggered in response to injurious stimuli to undergo differentiation and contribute to vascular disease development. Our aim was to determine the effect of moderate alcohol (EtOH) exposure on the expansion and differentiation of S100 calcium-binding protein B positive (S100β(+)) resident vascular stem cells and their contribution to pathologic vessel remodeling in a mouse model of arteriosclerosis. METHODS AND RESULTS. Lineage tracing analysis of S100β(+) cells was performed in male and female S100β-eGFP/Cre/ERT2–dTomato transgenic mice treated daily with or without EtOH by oral gavage (peak BAC: 15mM or 0.07%) following left common carotid artery ligation for 14 days. Carotid arteries (ligated or sham-operated) were harvested for morphological analysis and confocal assessment of fluorescent-tagged S100β (+) cells in FFPE carotid cross sections. Ligation-induced carotid remodeling was more robust in males than in females. EtOH-gavaged mice had less adventitial thickening and markedly reduced neo-intimal formation compared to controls, with a more pronounced inhibitory effect in males compared to females. There was significant expansion of S100β (+) marked cells in vessels post-ligation, primarily in the neo-intimal compartment. EtOH treatment reduced the fraction of S100β (+) cells in carotid cross-sections, concomitant with attenuated remodeling. In vitro, EtOH attenuated Sonic Hedgehog-stimulated myogenic differentiation (as evidenced by reduced calponin and myosin heavy chain expression) of isolated murine S100β (+) vascular stem cells. CONCLUSIONS. These data highlight resident vascular S100β (+) stem cells as a novel target population for alcohol, and suggest that regulation of these progenitors in adult arteries, particularly in males, may be an important mechanism contributing to the anti-atherogenic effects of moderate alcohol consumption