Sweat the small stuff: The human microvasculature and heart disease

Vasodilator reactive oxygen species ameliorate perturbed myocardial oxygen delivery in exercising swine with multiple comorbidities

Multiple common cardiovascular comorbidities produce coronary microvascular dysfunction. We previously observed in swine that a combination of diabetes mellitus (DM), high fat diet (HFD) and chronic kidney disease (CKD) induced systemic inflammation, increased oxidative stress and produced coronary endothelial dysfunction, altering control of coronary microvascular tone via loss of NO bioavailability, which was associated with an increase in circulating endothelin (ET). In the present study, we tested the hypotheses that (1) ROS scavenging and (2) ETA+B-receptor blockade improve myocardial oxygen delivery in the same female swine model. Healthy female swine on normal pig chow served as controls (Normal). Five months after induction of DM (streptozotocin, 3 × 50 mg kg-1 i.v.), hypercholesterolemia (HFD) and CKD (renal embolization), swine were chronically instrumented and studied at rest and during exercise. Sustained hyperglycemia, hypercholesterolemia and renal dysfunction were accompanied by systemic inflammation and oxidative stress. In vivo ROS scavenging (TEMPOL + MPG) reduced myocardial oxygen delivery in DM + HFD + CKD swine, suggestive of a vasodilator influence of endogenous ROS, while it had no effect in Normal swine. In vitro wire myography revealed a vasodilator role for hydrogen peroxide (H2O2) in isolated small coronary artery segments from DM + HFD + CKD, but not Normal swine. Increased catalase activity and ceramide production in left ventricular myocardial tissue of DM + HFD + CKD swine further suggest that increased H2O2 acts as vasodilator ROS in the coronary microvasculature. Despite elevated ET-1 plasma levels in DM + HFD + CKD swine, ETA+B blockade did not affect myocardial oxygen delivery in Normal or DM + HFD + CKD swine. In conclusion, loss of NO bioavailability due to 5 months exposure to multiple comorbidities is partially compensated by increased H2O2-mediated coronary vasodilation.

Generation and characterisation of scalable and stable human pluripotent stem cell-derived microvascular-like endothelial cells for cardiac applications

Coronary microvascular disease (CMD) and its progression towards major adverse coronary events pose a significant health challenge. Accurate in vitro investigation of CMD requires a robust cell model that faithfully represents the cells within the cardiac microvasculature. Human pluripotent stem cell-derived endothelial cells (hPSC-ECs) offer great potential; however, they are traditionally derived via differentiation protocols that are not readily scalable and are not specified towards the microvasculature. Here, we report the development and comprehensive characterisation of a scalable 3D protocol enabling the generation of phenotypically stable cardiac hPSC-microvascular-like ECs (hPSC-CMVECs) and cardiac pericyte-like cells. These were derived by growing vascular organoids within 3D stirred tank bioreactors and subjecting the emerging 3D hPSC-ECs to high-concentration VEGF-A treatment (3DV). Not only did this promote phenotypic stability of the 3DV hPSC-ECs; single cell-RNA sequencing (scRNA-seq) revealed the pronounced expression of cardiac endothelial- and microvascular-associated genes. Further, the generated mural cells attained from the vascular organoid exhibited markers characteristic of cardiac pericytes. Thus, we present a suitable cell model for investigating the cardiac microvasculature as well as the endothelial-dependent and -independent mechanisms of CMD. Moreover, owing to their phenotypic stability, cardiac specificity, and high angiogenic potential, the cells described within would also be well suited for cardiac tissue engineering applications.

Noninvasive assessment of human microvascular function in health and disease using incident dark-field microscopy

Reduced peripheral microvascular reactivity is associated with an increased risk for major adverse cardiac events (MACEs). Tools for noninvasive assessment of peripheral microvascular function are limited, and existing technology is poorly validated in both healthy populations and patients with cardiovascular disease (CVD). Here, we used a handheld incident dark-field imaging tool (CytoCam) to test the hypothesis that, compared with healthy individuals (no risk factors for CVD), subjects formally diagnosed with coronary artery disease (CAD) or those with ≥2 risk factors for CAD (at risk) would exhibit impaired peripheral microvascular reactivity. A total of 17 participants (11 healthy, 6 at risk) were included in this pilot study. CytoCam was used to measure sublingual microvascular total vessel density (TVD), perfused vessel density (PVD), and microvascular flow index (MFI) in response to the topical application of acetylcholine (ACh) and sublingual administration of nitroglycerin (NTG). Baseline MFI and PVD were significantly reduced in the at-risk cohort compared with healthy individuals. Surprisingly, following the application of acetylcholine and nitroglycerin, both groups showed a significant improvement in all three microvascular perfusion parameters. These results suggest that, despite baseline reductions in both microvascular density and perfusion, human in vivo peripheral microvascular reactivity to both endothelial-dependent and -independent vasoactive agents remains intact in individuals with CAD or multiple risk factors for disease.NEW & NOTEWORTHY To our knowledge, this is the first study to comprehensively characterize in vivo sublingual microvascular structure and function (endothelium-dependent and -independent) in healthy patients and those with CVD. Importantly, we used an easy-to-use handheld device that can be easily translated to clinical settings. Our results indicate that baseline microvascular impairments in structure and function can be detected using the CytoCam technology, although reactivity to acetylcholine may be maintained even during disease in the peripheral microcirculation.

Sweat as a source of non-invasive biomarkers for clinical diagnosis: An overview

Sweat has excellent potential as one of the sources of non-invasive biomarkers for clinical diagnosis. It is relatively easy to collect and process and may contain different disease-specific markers and drug metabolites, making it ideal for various clinical applications. This article discusses the anatomy of sweat glands and their role in sweat production, as well as the history and development of multiple sweat sample collection and analysis techniques. Another primary focus of this article is the application of sweat detection in clinical disease diagnosis and other life scenarios. Finally, the limitations and prospects of sweat analysis are discussed.

State of the field: cellular and exosomal therapeutic approaches in vascular regeneration

Pathologies of the vasculature including the microvasculature are often complex in nature, leading to loss of physiological homeostatic regulation of patency and adequate perfusion to match tissue metabolic demands. Microvascular dysfunction is a key underlying element in the majority of pathologies of failing organs and tissues. Contributing pathological factors to this dysfunction include oxidative stress, mitochondrial dysfunction, endoplasmic reticular (ER) stress, endothelial dysfunction, loss of angiogenic potential and vascular density, and greater senescence and apoptosis. In many clinical settings, current pharmacologic strategies use a single or narrow targeted approach to address symptoms of pathology rather than a comprehensive and multifaceted approach to address their root cause. To address this, efforts have been heavily focused on cellular therapies and cell-free therapies (e.g., exosomes) that can tackle the multifaceted etiology of vascular and microvascular dysfunction. In this review, we discuss 1) the state of the field in terms of common therapeutic cell population isolation techniques, their unique characteristics, and their advantages and disadvantages, 2) common molecular mechanisms of cell therapies to restore vascularization and/or vascular function, 3) arguments for and against allogeneic versus autologous applications of cell therapies, 4) emerging strategies to optimize and enhance cell therapies through priming and preconditioning, and, finally, 5) emerging strategies to bolster therapeutic effect. Relevant and recent clinical and animal studies using cellular therapies to restore vascular function or pathologic tissue health by way of improved vascularization are highlighted throughout these sections.

[Assessment of the structural and functional state of blood vessels in patients with hypertrophic cardiomyopathy]

Aim      To evaluate the structural and functional condition of the vasculature using fingertip photoplethysmography and computerized videocapillaroscopy in patients with hypertrophic cardiomyopathy (HCMP).Material and methods  The study included patients with HCMP (n=48; 28 (57 %) men; age, 54.3±13.6 years) and healthy volunteers (control group, n=33, 15 (45 %) men; age, 58.2±8.8 years). Standard laboratory and instrumental examination (blood count and biochemistry, electrocardiography, echocardiography, Holter electrocardiogram monitoring) were performed for all HCMP patients. The condition of vascular wall at various levels of the vasculature was evaluated by fingertip photoplethysmography (apparatus Angioscan-01) and computerized nail-fold videocapillaroscopy (apparatus Capillaroscan-01). The photoplethysmography study analyzed structural parameters, including the arterial wall stiffness index (aSI) of large blood vessels and the resistance index (RI) of small muscular arteries. Endothelial dysfunction was evaluated by the occlusion index (OI) and phase shift (PS). The capillaroscopy study assessed structural parameters, including the resting capillary density (rCD) and the capillary density following venous occlusion (voCD), and functional parameters, including the percentage of perfused capillaries (PPC), the percentage of restored capillaries (PRC), and the capillary density after the reactive hyperemia test (rhCD).Results The study showed increases in aSI (8.8 [6.8; 12.2] and RI (32.5 [17.4; 47.9] in the HCMP group. The OI was significantly lower in the HCMP group (1.3 [1.1; 1.5]) than in the control group (1.8 [1.5; 2.7], р<0.001). Also, PS values were significantly decreased in the HCMP group (4.4 [2.3; 8.6]) compared to the control group (8.4 [5.1; 12.1]. p=0.018). Disorders of structural and functional capillary indexes were observed in HCMP patients compared to the control group; rCD and voCD were decreased in the HCMP group (60 [52.6; 68] and 88 [75; 90], respectively) compared to the control group (75.8 [60; 87] and 90 [73; 101]), however, no intergroup difference reached a statistical significance. The rhCD, PPC, and PRC values were decreased in the HCMP group (66.3 [55; 72], 86.7 [70.9; 104.2] and 1.7 [-6.95; 20.3], respectively) compared to the control group (86 [68.6; 100], 103 [96; 114] and 18.4 [8.1; 27.4], respectively); PPC and PRC values were significantly different (р<0.005 and p<0.004, respectively).Conclusion      In patients with HCMP, fingertip photoplethysmography and computerized videocapillaroscopy showed increased wall stiffness in both large blood vessels and microvasculature, pronounced endothelial dysfunction, and decreases in capillary density and percentage of restored capillaries following respective tests.