Glycocalyx Dimensions Research Articles

Persistent capillary rarefication in long COVID syndrome

BackgroundRecent studies have highlighted Coronavirus disease 2019 (COVID-19) as a multisystemic vascular disease. Up to 60% of the patients suffer from long-term sequelae and persistent symptoms even 6 months after the initial infection.MethodsThis prospective, observational study included 58 participants, 27 of whom were long COVID patients with persistent symptoms > 12 weeks after recovery from PCR-confirmed SARS-CoV-2 infection. Fifteen healthy volunteers and a historical cohort of critically ill COVID-19 patients (n = 16) served as controls. All participants underwent sublingual videomicroscopy using sidestream dark field imaging. A newly developed version of Glycocheck™ software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell velocity (VRBC) and the microvascular health score (MVHS™) in sublingual microvessels with diameters 4–25 µm.Measurements and main resultsAlthough dimensions of the glycocalyx were comparable to those of healthy controls, a µm-precise analysis showed a significant decrease of vascular density, that exclusively affected very small capillaries (D5: − 45.16%; D6: − 35.60%; D7: − 22.79%). Plotting VRBC of capillaries and feed vessels showed that the number of capillaries perfused in long COVID patients was comparable to that of critically ill COVID-19 patients and did not respond adequately to local variations of tissue metabolic demand. MVHS was markedly reduced in the long COVID cohort (healthy 3.87 vs. long COVID 2.72 points; p = 0.002).ConclusionsOur current data strongly suggest that COVID-19 leaves a persistent capillary rarefication even 18 months after infection. Whether, to what extent, and when the observed damage might be reversible remains unclear.

Microvascular and proteomic signatures overlap in COVID-19 and bacterial sepsis: the MICROCODE study

AimsAlthough coronavirus disease 2019 (COVID-19) and bacterial sepsis are distinct conditions, both are known to trigger endothelial dysfunction with corresponding microcirculatory impairment. The purpose of this study was to compare microvascular injury patterns and proteomic signatures in COVID-19 and bacterial sepsis patients.Methods and resultsThis multi-center, observational study included 22 hospitalized adult COVID-19 patients, 43 hospitalized bacterial sepsis patients, and 10 healthy controls from 4 hospitals. Microcirculation and glycocalyx dimensions were quantified via intravital sublingual microscopy. Plasma proteins were measured using targeted proteomics (Olink). Coregulation and cluster analysis of plasma proteins was performed using a training-set and confirmed in a test-set. An independent external cohort of 219 COVID-19 patients was used for validation and outcome analysis. Microcirculation and plasma proteome analysis found substantial overlap between COVID-19 and bacterial sepsis. Severity, but not disease entity explained most data variation. Unsupervised correlation analysis identified two main coregulated plasma protein signatures in both diseases that strictly counteract each other. They were associated with microvascular dysfunction and several established markers of clinical severity. The signatures were used to derive new composite biomarkers of microvascular injury that allow to predict 28-day mortality or/and intubation (area under the curve 0.90, p < 0.0001) in COVID-19.ConclusionOur data imply a common biological host response of microvascular injury in both bacterial sepsis and COVID-19. A distinct plasma signature correlates with endothelial health and improved outcomes, while a counteracting response is associated with glycocalyx breakdown and high mortality. Microvascular health biomarkers are powerful predictors of clinical outcomes.Graphical abstract

Heparanase Is a Putative Mediator of Endothelial Glycocalyx Damage in COVID-19 - A Proof-of-Concept Study.

Coronavirus disease 2019 (COVID-19) is a systemic disease associated with injury (thinning) of the endothelial glycocalyx (eGC), a protective layer on the vascular endothelium. The aim of this translational study was to investigate the role of the eGC-degrading enzyme heparanase (HPSE), which is known to play a central role in the destruction of the eGC in bacterial sepsis. Excess activity of HPSE in plasma from COVID-19 patients correlated with several markers of eGC damage and perfused boundary region (PBR, an inverse estimate of glycocalyx dimensions of vessels with a diameter 4-25 µm). In a series of translational experiments, we demonstrate that the changes in eGC thickness of cultured cells exposed to COVID-19 serum correlated closely with HPSE activity in concordant plasma samples (R = 0.82, P = 0.003). Inhibition of HPSE by a nonanticoagulant heparin fragment prevented eGC injury in response to COVID-19 serum, as shown by atomic force microscopy and immunofluorescence imaging. Our results suggest that the protective effect of heparin in COVID-19 may be due to an eGC-protective off-target effect.

380-P: Endothelial Glycocalyx Dimensions and Cardiovascular Risk Factors in Type 1 Diabetes

Background: The glycocalyx lines the inner surface of the capillary endothelium. Capillaroscopy enables visualization of the sublingual capillaries and measurement of the perfused boundary region (PBR) as an estimate of the glycocalyx. Novel software enables assessment of the PBR estimated at a fixed high flow level (PBR-hf) and the microvascularity by the MicroVascular Health Score (MVHS). Damaged glycocalyx may represent microvascular damage in diabetes and assessment of its dimension might improve early cardiovascular (CV) risk stratification. Aim: To assess the associations between PBR, PBR-hf and MVHS and CV risk factors in persons with type 1 diabetes (T1D); and to compare PBR, PBR-hf and MVHS in persons with T1D and healthy controls. Methods: Cross-sectional study including 161 persons with T1D stratified by stage of diabetic kidney disease according to level of albuminuria and 50 healthy controls without diabetes. The PBR, PBR-hf and MVHS were assessed by the GlucoCheck device (valid measurements were available in 136 (84.5%) with T1D and in all the controls). Higher PBR and PBR-hf indicate smaller glycocalyx width and lower MVHS represents a worse microvascular health. Results: There were no associations between PBR, PBR-hf or MVHS and the CV risk factors in persons with T1D, except for a higher PBR-hf and a lower MVHS in females (p = 0.01 for both). There was no difference in PBR, PBR-hf or MVHS in persons with normo-, micro- or macroalbuminuria (p ≥ 0.34). PBR was higher and MVHS was lower in persons with T1D as compared to the healthy controls (p ≤ 0.02). After adjustment for CV risk factors the difference in PBR remained significant (p = 0.001). Conclusions: The endothelial glycocalyx dimension was impaired in persons with T1D compared to healthy controls. We found no association between the endothelial glycocalyx dimension and the level of albuminuria or CV risk factors among persons with T1D. The use of the GlucoCheck device in T1D may not contribute to CV risk stratification. Disclosure E. Buur stougaard: Employee; Spouse/Partner; Novo Nordisk, Stock/Shareholder; Spouse/Partner; Novo Nordisk. S. Winther: None. H. Amadid: Stock/Shareholder; Self; Novo Nordisk A/S. M. Frimodt-moeller: None. F. Persson: Advisory Panel; Self; AstraZeneca, Bayer AG, Boehringer Ingelheim International GmbH, Mundipharma International, Novo Nordisk, Advisory Panel; Spouse/Partner; AstraZeneca, Bristol-Myers Squibb Company, Research Support; Self; Amgen Inc., AstraZeneca, Boehringer Ingelheim International GmbH, Novo Nordisk, Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Mundipharma International, Novo Nordisk. T. W. Hansen: Stock/Shareholder; Self; Novo Nordisk A/S. P. Rossing: Advisory Panel; Self; Astellas Pharma Inc., AstraZeneca, Bayer AG, Boehringer Ingelheim International GmbH, Gilead Sciences, Inc., Merck KGaA, Merck Sharp &amp; Dohme Corp., Novo Nordisk A/S, Sanofi, Vifor Pharma Management Ltd. Funding Novo Nordisk Foundation (NNF14SA0003)

Identification of novel sublingual parameters to analyze and diagnose microvascular dysfunction in sepsis: the NOSTRADAMUS study

BackgroundThe availability of handheld, noninvasive sublingual video-microscopes allows for visualization of the microcirculation in critically ill patients. Recent studies demonstrate that reduced numbers of blood-perfused microvessels and increased penetration of erythrocytes into the endothelial glycocalyx are essential components of microvascular dysfunction. The aim of this study was to identify novel microvascular variables to determine the level of microvascular dysfunction in sepsis and its relationship with clinical variables.MethodsThis observational, prospective, cross-sectional study included 51 participants, of which 34 critically ill sepsis patients were recruited from intensive care units of a university hospital. Seventeen healthy volunteers served as controls. All participants underwent sublingual videomicroscopy by sidestream darkfield imaging. A new developed version of the Glycocheck™ software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell (RBC) velocity, RBC content, and blood flow in sublingual microvessels with diameters between 4 and 25 µm.ResultsA detailed analysis of adjacent diameter classes (1 µm each) of vessels between 4 and 25 µm revealed a severe reduction of vascular density in very small capillaries (5–7 µm), which correlated with markers of sepsis severity. Analysis of RBC velocity (VRBC) revealed a strong dependency between capillary and feed vessel VRBC in sepsis patients (R2 = 0.63, p < 0.0001) but not in healthy controls (R2 = 0.04, p = 0.43), indicating impaired capillary (de-)recruitment in sepsis. This finding enabled the calculation of capillary recruitment and dynamic capillary blood volume (CBVdynamic). Moreover, adjustment of PBR to feed vessel VRBC further improved discrimination between sepsis patients and controls by about 50%. By combining these dynamic microvascular and glycocalyx variables, we developed the microvascular health score (MVHSdynamic™), which decreased from 7.4 [4.6–8.7] in controls to 1.8 [1.4–2.7] in sepsis patients (p < 0.0001) and correlated with sepsis severity.ConclusionWe introduce new important diameter-specific quantification and differentiated analysis of RBC kinetics, a key to understand microvascular dysfunction in sepsis. MVHSdynamic, which has a broad bandwidth to detect microvascular (dys-) function, might serve as a valuable tool to detect microvascular impairment in critically ill patients.

Microvascular dysfunction in COVID-19: the MYSTIC study

RationalePre-clinical and autopsy studies have fueled the hypothesis that a dysregulated vascular endothelium might play a central role in the pathogenesis of ARDS and multi-organ failure in COVID-19.ObjectivesTo comprehensively characterize and quantify microvascular alterations in patients with COVID-19.MethodsHospitalized adult patients with moderate-to-severe or critical COVID-19 (n = 23) were enrolled non-consecutively in this prospective, observational, cross-sectional, multi-center study. Fifteen healthy volunteers served as controls. All participants underwent intravital microscopy by sidestream dark field imaging to quantify vascular density, red blood cell velocity (VRBC), and glycocalyx dimensions (perfused boundary region, PBR) in sublingual microvessels. Circulating levels of endothelial and glycocalyx-associated markers were measured by multiplex proximity extension assay and enzyme-linked immunosorbent assay.Measurements and main resultsCOVID-19 patients showed an up to 90% reduction in vascular density, almost exclusively limited to small capillaries (diameter 4–6 µm), and also significant reductions of VRBC. Especially, patients on mechanical ventilation showed severe glycocalyx damage as indicated by higher PBR values (i.e., thinner glycocalyx) and increased blood levels of shed glycocalyx constituents. Several markers of endothelial dysfunction were increased and correlated with disease severity in COVID-19. PBR (AUC 0.75, p = 0.01), ADAMTS13 (von Willebrand factor-cleaving protease; AUC 0.74, p = 0.02), and vascular endothelial growth factor A (VEGF-A; AUC 0.73, p = 0.04) showed the best discriminatory ability to predict 60-day in-hospital mortality.ConclusionsOur data clearly show severe alterations of the microcirculation and the endothelial glycocalyx in patients with COVID-19. Future therapeutic approaches should consider the importance of systemic vascular involvement in COVID-19.

Sublingual microvasculature in diabetic patients

Diabetes is associated with micro- and macrovascular complications. The aim of the study was to investigate microvascular parameters (glycocalyx dimensions, perfused and total capillary density) in vivo in patients with type 1 and type 2 diabetes mellitus.In vivo sublingual videomicroscopy using sidestream darkfield - derived imaging was performed in 36 patients with diabetes mellitus (type 1: n = 20, type 2: n = 16) and compared to a control group of 36 healthy volunteers.Patients with HbA1c levels ≥ 8% had a significantly higher perfused boundary region (PBR; signifying the loss of glycocalyx dimensions) compared to patients with HbA1c levels < 8%, which was more pronounced in type 1 diabetes (2.08 μm [1.95–2.16 μm] vs.1.9 μm [1.66–1.94 μm], p = .029).Capillary density did not differ significantly between patients with diabetes and healthy controls. PBR was inversely related to RBC filling percentage and perfused capillary density in diabetic patients (r = −0.754, p < .001 and r = −0.505, p = .002, respectively) as well as in healthy volunteers (r = −0.701, p < .001 and r = −0.150, p = n.s.) signifying the association between glycocalyx dimensions and microvessel perfusion. Renal parameters were associated with microvascular perfusion in patients with type 2 diabetes (correlation between eGFR and perfused capillary density: r = 0. 568, p = .027/RBC filling percentage: r = 0.657, p = .008). In addition, the ratio of perfused/total capillary density correlated with CRP levels in type 2 diabetes (r = 0.682, p = .021).In conclusion, diabetes is associated with loss of glycocalyx density.

Microvascular Alterations During Cardiac Surgery Using a Heparin or Phosphorylcholine-Coated Circuit

Heparin biocompatible coating frequently is used to reduce inflammation and blood coagulation during cardiopulmonary bypass (CPB) in cardiac surgery. Whether heparin coating is protective or damaging to the vascular endothelium is unclear. The authors investigated whether heparin-coated (HC) circuits are associated with better preservation of microcirculatory perfusion and glycocalyx dimensions compared with nonheparin phosphorylcholine-coated (PC) circuits. Prospective, randomized blinded study. Tertiary university hospital. A total of 26 adults undergoing elective coronary artery bypass graft surgery with CPB. PC (n = 13) versus HC circuits (n = 13). Sublingual microcirculatory perfusion was measured before, during, and after CPB using sidestream dark field imaging and analyzed for perfused vessel density and perfused boundary region, an inverse parameter for glycocalyx dimensions. Onset of CPB was associated with an increase in perfused boundary region in the PC group that continued until the third postoperative day (2.0 ± 0.2 to 2.5 ± 0.2 µm; p = 0.018). This was paralleled by increased plasma syndecan-1 levels in the PC group. Contrastingly, both parameters remained unaltered in the HC group compared with baseline levels. CPB decreased perfused vessel density in both groups (CPB v pre-CPB: PC: 17 ± 2 to 13 ± 2 mm/mm2, p = 0.006; HC: 16 ± 2 to 11 ± 2 mm/mm2, p = 0.003) and remained equally altered in the first 3 postoperative days. The use of an HC circuit is associated with better preservation of the endothelial glycocalyx compared with PC circuits, whereas microcirculatory perfusion was disturbed equally in both groups. Hence, CPB-induced microcirculatory perfusion disturbances seem to be coating independent.

A Low Tacrolimus Concentration/Dose Ratio Increases the Risk for the Development of Acute Calcineurin Inhibitor-Induced Nephrotoxicity.

Fast tacrolimus metabolism is linked to inferior outcomes such as rejection and lower renal function after kidney transplantation. Renal calcineurin-inhibitor toxicity is a common adverse effect of tacrolimus therapy. The present contribution hypothesized that tacrolimus-induced nephrotoxicity is related to a low concentration/dose (C/D) ratio. We analyzed renal tubular epithelial cell cultures and 55 consecutive kidney transplant biopsy samples with tacrolimus-induced toxicity, the C/D ratio, C0, C2, and C4 Tac levels, pulse wave velocity analyses, and sublingual endothelial glycocalyx dimensions in the selected kidney transplant patients. A low C/D ratio (C/D ratio < 1.05 ng/mL×1/mg) was linked with higher C2 tacrolimus blood concentrations (19.2 ± 8.7 µg/L vs. 12.2 ± 5.2 µg/L respectively; p = 0.001) and higher degrees of nephrotoxicity despite comparable trough levels (6.3 ± 2.4 µg/L vs. 6.6 ± 2.2 µg/L respectively; p = 0.669). However, the tacrolimus metabolism rate did not affect the pulse wave velocity or glycocalyx in patients. In renal tubular epithelial cells exposed to tacrolimus according to a fast metabolism pharmacokinetic profile it led to reduced viability and increased Fn14 expression. We conclude from our data that the C/D ratio may be an appropriate tool for identifying patients at risk of developing calcineurin-inhibitor toxicity.

Red blood cell storage and adhesion to vascular endothelium under normal or stress conditions: An in vitro microfluidic study.

Observational studies have identified an association between duration of red blood cell (RBC) storage and adverse outcomes in trauma. Hemorrhagic shock (HS) leads to impaired tissue perfusion which is associated with endothelial cell glycocalyx (eGC) shedding. Adhesion of stored RBC to the vascular endothelium has been shown to lead to impaired perfusion in the microcirculation and contribute to organ failure and poor outcome. The role of either or both of the EC and RBC glycocalyx in this process is unknown and was studied in an in vitro model. Human umbilical vein endothelial cells were perfused in a microfluidic device with RBC solutions from fresh, less than 14-day or longer than 21-day storage. In some experiments, the HS microenvironment was simulated by hypoxia-reoxygenation (H/R) and epinephrine (Epi) in the perfusion experiments. Measurements obtained included endothelial cell (EC) and RBC glycocalyx and RBC adherence to human umbilical vein endothelial cell monolayers at variable shear rates. Endothelial cell glycocalyx and RBC glycocalyx dimensions were reduced by H/R and Epi and storage duration respectively. Red blood cell adherence to the endothelium was increased by H/R + Epi treatment and duration of RBC storage. Our data may help explain some of the remaining discrepancies regarding the impact of RBC storage duration on outcomes in the trauma population. Consideration of the integrity of the EC and RBC glycocalyx may guide future transfusion strategies in the trauma population. The microfluidic device system platform may offer a high throughput modality to study emerging therapies to mitigate adverse consequence of RBC storage duration on the perfused endothelium in the trauma setting.

Functional capillary impairment in patients with ventricular assist devices

The implantation of continuous – flow ventricular assist devices (VAD) is suggested to evoke angiodysplasia contributing to adverse events such as gastrointestinal bleeding. We evaluated in vivo capillary density and glycocalyx dimensions to investigate possible systemic microvascular changes in patients with chronic heart failure and VAD support vs. standard medical treatment. Forty-two patients with VAD support were compared to forty-one patients with ischemic and non-ischemic chronic heart failure (CHF) on standard pharmacotherapy and to a group of forty-two healthy subjects in a prospective cross-sectional study. Sublingual microcirculation was visualized using Sidestream Darkfield videomicroscopy and functional and perfused total capillary densities were quantified. Patients with VAD implantation were followed for one year and bleeding events were recorded. Median time after VAD implantation was 18 months. Patients were treated with centrifugal-flow devices (n = 31) or axial-flow devices (n = 11). Median functional capillary density was significantly lower in patients with VAD therapy as compared to CHF patients (196 vs. 255/mm2, p = 0.042, adjusted p-value). Functional and total capillary densities were 44% and 53% lower (both p < 0.001) in patients with VAD therapy when compared to healthy subjects. Cox regression analysis revealed loss of capillary density as a significant predictor of bleeding events during one -year follow-up of VAD patients (HR: 0.987, CI (95%): 0.977–0.998, p = 0.021 for functional and 0.992, CI (95%): 0.985–0.999, p = 0.03 for total capillary density). In conclusion, patients with VAD support exhibit capillary density rarefaction, which was associated with bleeding events. If confirmed independently, capillary impairment may be evaluated as novel marker of bleeding risk.

Dietary Interventions on Glycocalyx Dimensions in South Asian Patients With Diabetic Nephropathy.

Dietary Interventions on Glycocalyx Dimensions in South Asian Patients With Diabetic Nephropathy.

Oncotically Driven Control over Glycocalyx Dimension for Cell Surface Engineering and Protein Binding in the Longitudinal Direction

Here we present a simple technique for re-directing reactions on the cell surface to the outermost region of the glycocalyx. Macromolecular crowding with inert polymers was utilized to reversibly alter the accessibility of glycocalyx proteoglycans toward cell-surface reactive probes allowing for reactivity control in the longitudinal direction (‘z’-direction) on the glycocalyx. Studies in HUVECs demonstrated an oncotically driven collapse of the glycocalyx brush structure in the presence of crowders as the mechanism responsible for re-directing reactivity. This phenomenon is consistent across a variety of macromolecular agents including polymers, protein markers and antibodies which all displayed enhanced binding to the outermost surface of multiple cell types. We then demonstrated the biological significance of the technique by increasing the camouflage of red blood cell surface antigens via a crowding-enhanced attachment of voluminous polymers to the exterior of the glycocalyx. The accessibility to Rhesus D (RhD) and CD47 proteins on the cell surface was significantly decreased in crowding-assisted polymer grafting in comparison to non-crowded conditions. This strategy is expected to generate new tools for controlled glycocalyx engineering, probing the glycocalyx structure and function, and improving the development of cell based therapies.

Bedside analysis of the sublingual microvascular glycocalyx in the emergency room and intensive care unit \u2013 the GlycoNurse study

BackgroundDeterioration of the endothelial glycocalyx (eGC), a protective carbohydrate-rich layer lining the luminal surface of the endothelium, plays a key role in vascular barrier dysfunction and eventually organ-failure in systemic inflammatory response syndrome and sepsis. Early detection of glycocalyx damage could thus become an important goal in critical care. This study was designed to determine the feasibility and reproducibility of quantitative, real-time glycocalyx measurements performed at bedside in the emergency room (ER) and intensive care unit (ICU).MethodsThe observational study included 70 patients admitted to the ER or ICU of a university hospital. A physician and the nurse in charge of the patient performed sublingual microcirculatory measurements using sidestream dark field (SDF) imaging. A novel data acquisition and analysis software (GlycoCheck™) was used to analyze the perfused boundary region (PBR), an inverse parameter of endothelial glycocalyx dimensions in vessels with diameters of between 5 and 25 μm.ResultsThe method showed a good intra-observer reproducibility. Specifically, intraclass correlation coefficient analysis showed an excellent reproducibility between the physician’s measurements (0.77 [CI 95%: 0.52–0.89]). The bias between the two PBRs was − 0.077 ± 0.24 μm. Moreover, there were no significant differences in the PBR values obtained by the nurses when compared to those reported by the physician (regarded as the “gold standard” measurement). Intraclass correlation coefficient analysis showed excellent reproducibility between the nurses’ and physician’s PBRs (0.75 [95% CI: 0.52–0.87]). The mean difference between the two PBRs (i.e., the bias) was 0.007 ± 0.25 μm. The nurses’ PBR assessment had a 90% sensitivity (95% CI: 60–99%) and 90% specificity (95% CI: 80–93%) to identify a severely impaired glycocalyx.ConclusionGlycocalyx dimensions can be measured at patients’ bedside precisely by non-invasive assessment of the PBR. This assessment could become part of standard monitoring and contribute to clinical decision-making and resuscitation protocols in clinical trials and daily practice.

Sublingual functional capillary rarefaction in chronic heart failure.

Microcirculatory changes contribute to clinical symptoms and disease progression in chronic heart failure (CHF). A depression of coronary flow reserve is associated with a lower myocardial capillary density in biopsies. We hypothesized that changes in cardiac microcirculation might also be reflected by a systemic reduction in capillaries and visualized by sublingual videomicroscopy. The aim was to study invivo capillary density and glycocalyx dimensions in patients with CHF vs healthy controls. Fifty patients with ischaemic and nonischaemic CHF and standard treatment were compared to 35 healthy age-matched subjects in a prospective cross-sectional study. Sublingual microcirculation was visualized using a sidestream darkfield videomicroscope. Functional and perfused total capillary densities were compared between patients and controls. A reduced glycocalyx thickness was measured by an increased perfused boundary region (PBR). Median functional and total perfused capillary densities were 30% and 45% lower in patients with CHF (both P<.001). Intake of oral vitamin K antagonists was associated with significantly lower capillary densities (P<.05), but not independent of NT-proBNP. Dimensions of the glycocalyx were marginally lower in CHF patients than in healthy controls (<7% difference). However, PBR correlated significantly with inflammation markers (fibrinogen: r=.58; C-reactive protein: r=.42), platelet counts (r=.36) and inversely with measures of liver/renal function such as bilirubin (r=-.38) or estimated glomerular filtration rate (r=-.34) in CHF patients. CHF patients have got a markedly lower functional and total perfused capillary density in sublingual microvasculature when compared to controls, indicating a systemic decrease in microcirculation.

Side-by-Side Alterations in Glycocalyx Thickness and Perfused Microvascular Density During Acute Microcirculatory Alterations in Cardiac Surgery.

Endothelial glycocalyx injury causes microcirculatory perfusion disturbances in experimental studies, but the relevance in a clinical setting remains unknown. We investigated whether glycocalyx dimensions are reduced after onset of CPB and whether this is associated with alterations in microvascular perfusion. The current observational study included 36 patients undergoing cardiac surgery without or with CPB, using either nonpulsatile or pulsatile flow. Sublingual microcirculatory perfusion was assessed perioperatively and analyzed for perfused vessel density and PBR, an inverse parameter of endothelial glycocalyx dimensions. Perfused vessel density decreased after onset of CPB in parallel with an increase in PBR in both pulsatile and nonpulsatile groups. In the nonpulsatile CPB group, these alterations were still persistent in the ICU (PVD: T1 19.8 ± 2.8 mm/mm(2) vs. T3 15.3 ± 2.6 mm/mm(2) ; p = 0.004. PBR: T1 2.40 ± 0.35 μm vs. T3 2.60 ± 0.31 μm; p = 0.020). In the off-pump group, perfused vessel density remained unaltered. An inverse correlation between perfused vessel density and PBR was detected. This study shows that endothelial glycocalyx dimensions decrease after onset of CPB and are closely related to microvascular perfusion when assessed with a novel, noninvasive technique.

Microvascular Glycocalyx Dimension Estimated by Automated SDF Imaging is not Related to Cardiovascular Disease

The EG regulates vascular homeostasis and has anti-atherogenic properties. SDF imaging allows for noninvasive visualization of microvessels and automated estimation of EG dimensions. We aimed to assess whether microcirculatory EG dimension is related to cardiovascular disease. Sublingual EG dimension was estimated by SDF imaging in healthy volunteers and in patients visiting an outpatient clinic for vascular medicine of a university hospital in Amsterdam, the Netherlands. EG dimension was compared among healthy volunteers, patients with CVD, and patients at low (<10%) or high risk (≥ 10%) of CVD according to the Framingham algorithm. In total 120 patients and 30 healthy volunteers were included. Patients had a mean age of 59 ± 14 years, 71 (59%) were men and 24 (20%) were black. Healthy volunteers were on average 28 ± 4 years and 19 (63%) were men. EG dimension was similar in healthy volunteers (2.04 ± 0.23 μm), low-risk patients (2.05 ± 0.24 μm, n = 39), high-risk patients (2.05 ± 0.23 μm, n = 30) and in patients with CVD (2.09 ± 0.21 μm, n = 51, p = 0.79). EG dimension was not correlated with cardiovascular risk factors. Microcirculatory EG dimension, as estimated by automated SDF imaging, is not associated with CVD, suggesting that this technique may not contribute to cardiovascular risk stratification.

Regional specific adaptation of the endothelial glycocalyx dimension in tail-suspended rats.

Previous animal studies by using tail-suspended hindlimb-unloaded rat model have shown that simulated microgravity-induced vessel structural and functional remodeling may be anatomic region dependent. However, little care has been taken to assess the structural adaptation of the endothelial glycocalyx, the apical surface of the endothelium, the key mechanosensor mediating nitric oxide (NO) production, and the natural protective barrier of the vasculature. Therefore, the present study extended simulated microgravity-induced vessel remodeling to the endothelial glycocalyx level. The percents of bone mineral density (BMD) change from both control and tail-suspended (TS) rats were measured by micro-computed tomography (Micro-CT). Structural parameters such as the luminal diameter (D), the thickness of each layer, the ratio of intima to media (IMR), the cross-sectional areas of the intima (CSAI) and media (CSAM) of vessels from three different regions (the common carotid artery, abdominal aorta, and femoral artery) were assessed by hematoxylin and eosin staining. Dimensions of the glycocalyx above, below, and away from the endothelial cell nucleus were examined by fluorescein isothiocyanate-labeled wheat germ agglutinin (WGA-FITC) binding to the cryosection of vessels. Our results show that 3-week tail suspension of rats increases the thickness and CSA of the abdominal aortic endothelium by 23.7 and 21.1%, respectively, thickens the media layer of the common carotid artery by 34.0%, and increases the luminal diameter, the CSA of the intima and media of the femoral artery by 75.7, 93, and 61.2%, respectively. Correspondingly, the dimension of the glycocalyx away from the common carotid arterial and the abdominal aortic endothelial cell nucleus from tail-suspended rats shows a 1.66- and 1.64-fold increase respectively, while it shows a 0.79-fold reduction on the top of the femoral endothelial cells. These results suggest that simulated microgravity induces vascular endothelial glycocalyx remodeling in a regional-dependent manner. The perturbation of the endothelial glycocalyx at the lower body artery may be the first event of vascular remodeling initiating endothelial dysfunction, contributing to postspaceflight orthostatic intolerance.

1205 共焦点マイクロPIVと超解像度顕微鏡の組み合わせによる血管内皮細胞グリコカリックス層近傍の速度分布計測

1205 共焦点マイクロPIVと超解像度顕微鏡の組み合わせによる血管内皮細胞グリコカリックス層近傍の速度分布計測

The fate of large-diameter Dacron® vascular grafts in surgical practice: Are we really satisfied?

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