Homeostasis of Hemostasis: The Role of Endothelium

Endothelial Dysfunction in Patients Undergoing Cardiac Surgery: A Narrative Review and Clinical Implications

Cardiac surgery is one of the highest-risk procedures, usually involving cardiopulmonary bypass and commonly inducing endothelial injury that contributes to the development of perioperative and postoperative organ dysfunction. Substantial scientific efforts are being made to unravel the complex interaction of biomolecules involved in endothelial dysfunction to find new therapeutic targets and biomarkers and to develop therapeutic strategies to protect and restore the endothelium. This review highlights the current state-of-the-art knowledge on the structure and function of the endothelial glycocalyx and mechanisms of endothelial glycocalyx shedding in cardiac surgery. Particular emphasis is placed on potential strategies to protect and restore the endothelial glycocalyx in cardiac surgery. In addition, we have summarized and elaborated the latest evidence on conventional and potential biomarkers of endothelial dysfunction to provide a comprehensive synthesis of crucial mechanisms of endothelial dysfunction in patients undergoing cardiac surgery, and to highlight their clinical implications.

Tetrahedral Framework Nucleic Acids Connected with MicroRNA-126 Mimics for Applications in Vascular Inflammation, Remodeling, and Homeostasis

The repair of damaged endothelium is crucial for vascular homeostasis maintenance, which comprises the recovery of early stage impaired endothelial cells and migration of surrounding unimpaired endothelial cells. MicroRNAs (miRNAs) play an indispensable role in balancing gene expression in organisms. For vascular tissues, miR-126 is one of the most important regulators and might have substantial application potential in maintaining vascular homeostasis. In this study, a type of sticky-end-modified tetrahedral framework nucleic acids (tFNAs-SE) was employed to successfully link the miR-126 5p mimic duplex, which was termed tFNAs-miR-126 5p mimics (tFNAs-MMs). Existing vascular endothelial growth factors (VEGF), tFNAs-MMs can improve cell viability, resist apoptosis, and recover the state and functions of LPS-induced impaired human umbilical vein endothelial cells (HUVECs). The angiogenesis ability of impaired HUVECs was recovered by tFNAs-MMs in vitro and in vivo. The mechanisms underlying these phenomena were demonstrated to be related to the downregulation of caspase3 and negative regulators of VEGF (SPRED1 and PIK3R2). Moreover, tFNAs-MMs promoted the migration and proliferation of HUVECs. Briefly, the strategy of sticky-end-modified tFNAs connecting miRNA mimics is available for miRNA gain of function, while tFNAs-MMs might be a promising agent for repairing early stage vascular damage and maintaining vascular homeostasis.

Physicochemical Characterization of Fucoidans from Sargassum henslowianum C.Agardh and Their Antithrombotic Activity In Vitro

Sargassum fucoidan is a kind of sulfated heteropolysaccharide with a variety of biological activities. The aim of this study was to investigate the extraction, purification, physicochemical characterization and in vitro antithrombotic activity of fucoidan from Sargassum henslowianum C.Agardh. Hot-water-assisted ultrasound was used to extract fucoidan (F). Fucoidan was purified by DEAE cellulose 52 (F1), Vc-H2O2 (FD1) and Superdex 75 gel (FDS1). The physical and chemical properties of fucoidans were analyzed by chemical composition, monosaccharide composition, average molecular weight (Mw) and FTIR. The sulfate contents of F, F1, FD1 and FDS1 were 11.45%, 16.35% and 17.52%, 9.66%, respectively; the Mw was 5.677 × 105, 4.393 × 105, 2.176 × 104 and 6.166 × 103, respectively. The results of monosaccharide composition showed that the four fucoidans contained l-fucose, d-galactose, l-mannose, d-xylose, l-rhamnose and d-glucose, but the mass fraction ratio was different. The results of FTIR showed that fucoidan contained characteristic peaks of sugar and sulfate. In vitro, F1, FD1 and FDS1 could alleviate HUVEC damage induced by adrenaline (Adr). F1, FD1 and FDS1 decreased vWF and TF and increased the ratio of t-PA/PAI-1 in Adr-induced HUVEC.

Long-Term Passive Leg Stretch Improves Systemic Vascular Responsiveness as Much as Single-Leg Exercise Training

PURPOSE

The current study compared the local and systemic vascular responsiveness after small muscle mass endurance training or passive stretching training (PST).

METHODS

Thirty-six sex-matched healthy participants underwent 8-wk single-leg knee extension (SLKE) (n = 12) training or PST (n = 12), or no intervention (control, n = 12). Before and after the intervention, local and systemic vascular responsiveness was assessed by Doppler ultrasound at the femoral (local effect) and brachial artery (systemic effect) during single passive leg movement and brachial flow-mediated dilation (FMD) test, respectively.

RESULTS

After training, delta femoral blood flow (representing the local vascular responsiveness) increased after SLKE and PST by +54 (7)% (effect size, 2.72; P < 0.001) and +20 (2)% (effect size, 2.43; P < 0.001), respectively, albeit with a greater extent in SLKE (post-SLKE vs post-PST: +56 [8]% [effect size, 2.92; P < 0.001]). Interestingly, the %FMD (standing for the systemic effect) increased after SLKE and PST by +12 (2)% (effect size, 0.68; P < 0.001) and +11 (1)% (effect size, 0.83; P < 0.001), respectively, without any between-groups difference (P > 0.05). No changes occurred in control.

CONCLUSIONS

The present findings revealed that both active and passive training modalities induced similar improvements in the brachial artery dilatation capacity, whereas the former was more effective in improving femoral artery blood flow. Passive stretching could be used in people with limited mobility to improve vascular responsiveness both at the local and systemic level and in this latter case has similar effects as small muscle mass endurance training.

Targeting repair of the vascular endothelium and glycocalyx after traumatic injury with plasma and platelet resuscitation

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Endothelial glycocalyx shedding is a key instigator of the endotheliopathy of trauma.

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Plasma and platelet transfusions preserve vascular integrity in pre-clinical models.

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However, platelets may be less effective than plasma in preserving the glycocalyx.

Severely injured patients with hemorrhagic shock can develop endothelial dysfunction, systemic inflammation, and coagulation disturbances collectively known as the endotheliopathy of trauma (EOT). Shedding of the endothelial glycocalyx occurs early after injury, contributes to breakdown of the vascular barrier, and plays a critical role in the pathogenesis of multiple organ dysfunction, leading to poor outcomes in trauma patients. In this review we discuss (i) the pathophysiology of endothelial glycocalyx and vascular barrier breakdown following hemorrhagic shock and trauma, and (ii) the role of plasma and platelet transfusion in maintaining the glycocalyx and vascular endothelial integrity.

Recent Findings on Platelet Activation, vWF Multimers and Other Thrombotic Biomarkers Associated with Critical COVID-19

Mortality rate in patients with COVID-19 increases in those admitted to the ICU. Activation of the coagulation system is associated with the worse disease outcomes. The aim of this study was to evaluate platelet activation and thrombotic biomarkers in hospitalized patients with COVID-19 during the second and third infection waves of the pandemic during 2021, following a previous report that included patients from the first wave. Sixty five patients were recruited and classified according to disease outcome; 10 healthy donors were included as a control group. Among prothrombotic biomarkers, t-PA concentrations ( p < .0001), PAI-1 (0.0032) and D dimer ( p = .0011) were higher in patients who developed critical COVID-19. We also found platelet activation via αIIbβIII expression ( p < .0001) and higher presence of vWF-HMWM in severe COVID-19 ( p < .0001). Several prothrombotic biomarkers are found to be increased since hospital admission in patients which lately present a worse disease outcome (ICU admission/death), among these, platelet activation, vWF increased plasma concentration and presence of HMWM seem to be of special interest. New studies regarding the predictive value of thrombotic biomarkers are needed as SARS-CoV-2 variants continue to emerge.

Predictive Value of High ICAM-1 Level for Poor Treatment Response to Low-Dose Decitabine in Adult Corticosteroid Resistant ITP Patients

Primary immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease. Endothelial cell activation/injury has been found in some autoimmune diseases including SLE, systemic sclerosis, and rheumatoid arthritis, but its role in ITP pathogenesis remains unclear. This study attempted to elucidate the correlation between endothelial dysfunction and disease severity of ITP and find related markers to predict response to low-dose decitabine treatment. Compared with healthy volunteers, higher plasma levels of soluble intercellular adhesion molecule-1 (ICAM-1), vascular endothelial growth factor (VEGF), and Angiopoietin-2 were found in adult corticosteroid resistant ITP patients. Notably, ICAM-1 levels were negatively correlated with the platelet count, and positively associated with the bleeding score. Recently, we have reported the efficacy and safety of low-dose decitabine in adult patients with ITP who failed for the first line therapies. Here, we evaluated the correlation of plasma ICAM-1 level with the efficacy of low-dose decitabine therapy for corticosteroid resistant ITP. A total of 29 adult corticosteroid resistant ITP patients who received consecutive treatments of low-dose decitabine were enrolled in this study. Fourteen patients showed response (nine showed complete response and five showed partial response). The levels of ICAM-1 before and after treatment were significantly higher in the non-responsive ITP patients than in the responsive patients. As shown in the multivariable logistic regression model, the odds of developing no-response to low-dose decitabine increased by 36.8% for per 5 ng/ml increase in plasma ICAM-1 level [odds ratio (OR) 1.368, 95% confidence interval (CI): 1.060 to 1.764]. In summary, this was the first study to elucidate the relationship between endothelial dysfunction and corticosteroid resistant ITP and identify the potential predictive value of ICAM-1 level for response to low-dose decitabine.

Proteomics Analysis Reveals Diverse Molecular Characteristics between Endocardial and Aortic-Valvular Endothelium

The variations in the protein profile of aortic-valvular (AVE) and endocardial endothelial (EE) cells are currently unknown. The current study's objective is to identify differentially expressed proteins and associated pathways in both the endothelial cells. We used endothelial cells isolated from the porcine (Sus scrofa) aortic valve and endocardium for the profiling of proteins. Label-free proteomics was performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Our proteomics analysis revealed that 29 proteins were highly expressed, and 25 proteins were less expressed in the valve than the endocardial endothelium. The cell surface markers, such as CD63, ICAM1, PECAM1, PROCR, and TFRC, were highly expressed in EE. In contrast, CD44 was highly expressed in AVE. The pathway analysis showed that metabolic process-related proteins and extracellular matrix-related proteins were enriched in valves. Differential enrichment of signaling pathways was observed in the endocardium. The hemostasis function-related proteins were increased in both endothelial cells. The proteins and pathways enriched in aortic-valvular and endocardial endothelial cells revealed the distinct phenotype of these two closely related cells.

The Notch Pathway: A Link Between COVID-19 Pathophysiology and Its Cardiovascular Complications

COVID-19 is associated with a large number of cardiovascular sequelae, including dysrhythmias, myocardial injury, myocarditis and thrombosis. The Notch pathway is one likely culprit leading to these complications due to its direct role in viral entry, inflammation and coagulation processes, all shown to be key parts of COVID-19 pathogenesis. This review highlights links between the pathophysiology of SARS-CoV2 and the Notch signaling pathway that serve as primary drivers of the cardiovascular complications seen in COVID-19 patients.

Endothelium as a Source and Target of H2S to Improve Its Trophism and Function

The vascular endothelium consists of a single layer of squamous endothelial cells (ECs) lining the inner surface of blood vessels. Nowadays, it is no longer considered as a simple barrier between the blood and vessel wall, but a central hub to control blood flow homeostasis and fulfill tissue metabolic demands by furnishing oxygen and nutrients. The endothelium regulates the proper functioning of vessels and microcirculation, in terms of tone control, blood fluidity, and fine tuning of inflammatory and redox reactions within the vessel wall and in surrounding tissues. This multiplicity of effects is due to the ability of ECs to produce, process, and release key modulators. Among these, gasotransmitters such as nitric oxide (NO) and hydrogen sulfide (H₂S) are very active molecules constitutively produced by endotheliocytes for the maintenance and control of vascular physiological functions, while their impairment is responsible for endothelial dysfunction and cardiovascular disorders such as hypertension, atherosclerosis, and impaired wound healing and vascularization due to diabetes, infections, and ischemia. Upregulation of H₂S producing enzymes and administration of H₂S donors can be considered as innovative therapeutic approaches to improve EC biology and function, to revert endothelial dysfunction or to prevent cardiovascular disease progression. This review will focus on the beneficial autocrine/paracrine properties of H₂S on ECs and the state of the art on H₂S potentiating drugs and tools.

COVID-19 patients with hypertension are at potential risk of worsened organ injury

In less than 6 months, COVID-19 spread rapidly around the world and became a global health concern. Hypertension is the most common chronic disease in COVID-19 patients, but its impact on these patients has not been well described. In this retrospective study, 82 patients diagnosed with COVID-19 were enrolled, and epidemiological, demographic, clinical, laboratory, radiological and therapy-related data were analyzed and compared between COVID-19 patients with (29 cases) or without (53 cases) hypertension. The median age of the included patients was 60.5 years, and the cohort included 49 women (59.8%) and 33 (40.2%) men. Hypertension (31 [28.2%]) was the most common chronic illness, followed by diabetes (16 [19.5%]) and cardiovascular disease (15 [18.3%]). The most common symptoms were fatigue (55 [67.1%]), dry cough (46 [56.1%]) and fever ≥ 37.3 °C (46 [56.1%]). The median time from illness onset to positive RT-PCR test was 13.0 days (range 3–25 days). There were 6 deaths (20.7%) in the hypertension group and 5 deaths (9.4%) in the nonhypertension group, and more hypertensive patients with COVID-19 (8 [27.6%]) than nonhypertensive patients (2 [3.8%]) (P = 0.002) had at least one comorbid disease. Compared with nonhypertensive patients, hypertensive patients exhibited higher neutrophil counts, serum amyloid A, C-reactive protein, and NT-proBNP and lower lymphocyte counts and eGFR. Dynamic observations indicated more severe disease and poorer outcomes after hospital admission in the hypertension group. COVID-19 patients with hypertension have increased risks of severe inflammatory reactions, serious internal organ injury, and disease progression and deterioration.

Correlation analysis of coagulation dysfunction and liver damage in patients with novel coronavirus pneumonia: a single-center, retrospective, observational study

BACKGROUND

The novel coronavirus disease 2019 (COVID-19) is currently breaking out worldwide. COVID-19 patients may have different degrees of coagulopathy, but the mechanism is not yet clear. We aimed to analyse the relationship between coagulation dysfunction and liver damage in patients with COVID-19.

METHODS

A retrospective analysis of 74 patients with COVID-19 admitted to the First People's Hospital of Yueyang from 1 January to 30 March 2020 was carried out. According to the coagulation function, 27 cases entered the coagulopathy group and 47 cases entered the control group. A case control study was conducted to analyse the correlation between the occurrence of coagulation dysfunction and liver damage in COVID-19 patients.

RESULTS

Alanine aminotransferase (ALT) and aspartate aminotransferase (AST), markers of liver damage, were positively correlated with coagulopathy (p = 0.039, OR 2.960, 95% CI 1.055-8.304; and p = 0.028, OR 3.352, 95% CI 1.137-9.187). Alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT), and total bilirubin (TBIL) were not statistically correlated with coagulopathy. According to the diagnosis and treatment plan, the included cases were classified into mild, moderate, severe, and critical. The results showed that the occurrence of coagulation dysfunction had no statistical correlation with the severity of COVID-19.

CONCLUSION

Coagulation dysfunction in patients with COVID-19 is closely related to liver damage. A longer course of the disease may cause a vicious circle of coagulopathy and liver damage. Clinicians need to closely monitor coagulation and liver function tests and to give prophylactic or supportive therapy when needed.

Fundamental Basis of COVID-19 Pathogenesis

At the end of 2019, a new coronavirus infection occurred in the People’s Republic of China with an epicentre in the city of Wuhan. On February 11th, 2020, the World Health Organization assigned the official name of the infection caused by the new coronavirus – COVID-19. COVID-19 has affected people from all over the world given that the infection was noted in 200 countries resulting in annunciation of the pandemic situation. Human corona viruses cause mild to moderate respiratory infections. At the end of 2002, a new coronavirus appeared (SARS-CoV), the causal agent of atypical pneumonia, which caused acute respiratory distress syndrome (ARDS). The initial stage of COVID-19 infection is the penetration of SARS-CoV-2 into target cells that have angiotensin converting enzyme type II receptors. The virus enters the body through the respiratory tract and interacts primarily with toll-like receptors (TLRs). The events in SARS-Cov-2 induced infection follow the next scenario: epithelial cells via TLRs recognize and identify SARS-Cov-2, and after that the information is transmitted to the transcriptional NF-κB, which causes expression of the corresponding genes. Activated in this way, the epithelial cells begin to synthesize various biologically active molecules. The results obtained on preclinical material indicate that ROS generation increases and the antioxidant protection decreases, which plays a major role in the pathogenesis of SARS-CoV, as well as in the progression and severity of this respiratory disease.

Hypertension, Thrombosis, Kidney Failure, and Diabetes: Is COVID-19 an Endothelial Disease? A Comprehensive Evaluation of Clinical and Basic Evidence

The symptoms most commonly reported by patients affected by coronavirus disease (COVID-19) include cough, fever, and shortness of breath. However, other major events usually observed in COVID-19 patients (e.g., high blood pressure, arterial and venous thromboembolism, kidney disease, neurologic disorders, and diabetes mellitus) indicate that the virus is targeting the endothelium, one of the largest organs in the human body. Herein, we report a systematic and comprehensive evaluation of both clinical and preclinical evidence supporting the hypothesis that the endothelium is a key target organ in COVID-19, providing a mechanistic rationale behind its systemic manifestations.

Hemostatic Testing in Critically Ill Infants and Children

Children with critical illness frequently manifest imbalances in hemostasis with risk of consequent bleeding or pathologic thrombosis. Traditionally, plasma-based tests measuring clot formation by time to fibrin clot generation have been the "gold standard" in hemostasis testing. However, these tests are not sensitive to abnormalities in fibrinolysis or in conditions of enhanced clot formation that may lead to thrombosis. Additionally, they do not measure the critical roles played by platelets and endothelial cells. An added factor in the evaluation of these plasma-based tests is that in infants and young children plasma levels of many procoagulant and anticoagulant proteins are lower than in older children and adults resulting in prolonged clot generation times in spite of maintaining a normal hemostatic "balance." Consequently, newer assays directly measuring thrombin generation in plasma and others assessing the stages hemostasis including clot initiation, propagation, and fibrinolysis in whole blood by viscoelastic methods are now available and may allow for a global measurement of the hemostatic system. In this manuscript, we will review the processes by which clots are formed and by which hemostasis is regulated, and the rationale and limitations for the more commonly utilized tests. We will also discuss selected newer tests available for the assessment of hemostasis, their "pros" and "cons," and how they compare to the traditional tests of coagulation in the assessment and management of critically ill children.

Evidence of Improved Vascular Function in the Arteries of Trained but Not Untrained Limbs After Isolated Knee-Extension Training

Vascular endothelial function is a strong marker of cardiovascular health and it refers to the ability of the body to maintain the homeostasis of vascular tone. The endothelial cells react to mechanical and chemical stimuli modulating the smooth muscle cells relaxation. The extent of the induced vasodilation depends on the magnitude of the stimulus. During exercise, the peripheral circulation is mostly controlled by the endothelial cells response that increases the peripheral blood flow in body districts involved but also not involved with exercise. However, whether vascular adaptations occur also in the brachial artery as a result of isolated leg extension muscles (KE) training is still an open question. Repetitive changes in blood flow occurring during exercise may act as vascular training for vessels supplying the active muscle bed as well as for the vessels of body districts not directly involved with exercise. This study sought to evaluate whether small muscle mass (KE) training would induce improvements in endothelial function not only in the vasculature of the lower limb (measured at the femoral artery level in the limb directly involved with training), but also in the upper limb (measured at the brachial artery level in the limb not directly involved with training) as an effect of repetitive increments in the peripheral blood flow during training sessions. Ten young healthy participants (five females, and five males; age: 23 ± 3 years; stature: 1.70 ± 0.11 m; body mass: 66 ± 11 kg; BMI: 23 ± 1 kg ⋅ m^-2) underwent an 8-week KE training study. Maximum work rate (MWR), vascular function and peripheral blood flow were assessed pre- and post-KE training by KE ergometer, flow mediated dilatation (FMD) in the brachial artery (non-trained limb), and by passive limb movement (PLM) in femoral artery (trained limb), respectively. After 8 weeks of KE training, MWR and PLM increased by 44% (p = 0.015) and 153% (p = 0.003), respectively. Despite acute increase in brachial artery blood flow during exercise occurred (+25%; p < 0.001), endothelial function did not change after training. Eight weeks of KE training improved endothelial cells response only in the lower limb (measured at the femoral artery level) directly involved with training, likely without affecting the endothelial response of the upper limb (measured at the brachial artery level) not involved with training.

Comparison of endothelial promoter efficiency and specificity in mice reveals a subset of Pdgfb-positive hematopoietic cells

Essentials To reliably study the respective roles of blood and endothelial cells in hemostasis, mouse models with a strong and specific endothelial expression of the Cre recombinase are needed. Using mT/mG reporter mice and conditional JAK2V617F/WT mice, we compared Pdgfb-iCreERT2 and Cdh5(PAC)-CreERT2 with well-characterized Tie2-Cre mice. Comparison of recombination efficiency and specificity towards blood lineage reveals major differences between endothelial transgenic mice. Cre-mediated recombination occurs in a small number of adult hematopoietic stem cells in Pdgfb-iCreERT2;JAK2V617F/WT transgenic mice. SUMMARY: Background The vessel wall, and particularly blood endothelial cells (BECs), are intensively studied to better understand hemostasis and target thrombosis. To understand the specific role of BECs, it is important to have mouse models that allow specific and homogeneous expression of genes of interest in all BEC beds without concomitant expression in blood cells. Inducible Pdgfb-iCreERT2 and Cdh5(PAC)-CreERT2 transgenic mice are widely used for BEC targeting. However, issues remain in terms of recombination efficiency and specificity regarding hematopoietic cells. Objectives To determine which mouse model to choose when strong expression of a transgene is required in adult BECs from various organs, without concomitant expression in hematopoietic cells. Methods Using mT/mG reporter mice to measure recombination efficiency and conditional JAK2V617F/WT mice to assess specificity regarding hematopoietic cells, we compared Pdgfb-iCreERT2 and Cdh5(PAC)-CreERT2 with well-characterized Tie2-Cre mice. Results Adult Cdh5(PAC)-CreERT2 mice are endothelial specific but require a dose of 10 mg of tamoxifen to allow constant Cre expression. Pdgfb-iCreERT2 mice injected with 5 mg of tamoxifen are appropriate for most endothelial research fields except liver studies, as hepatic sinusoid ECs are not recombined. Surprisingly, 2 months after induction of Cre-mediated recombination, all Pdgfb-iCreERT2;JAK2V617F/WT mice developed a myeloproliferative neoplasm that is related to the presence of JAK2V617F in hematopoietic cells, showing for the first time that Cre-mediated recombination occurs in a small number of adult hematopoietic stem cells in Pdgfb-iCreERT2 transgenic mice. Conclusion This study provides useful guidelines for choosing the best mouse line to study the role of BECs in hemostasis and thrombosis.

Ascorbic acid improves thrombotic function of platelets during living donor liver transplantation by modulating the function of the E3 ubiquitin ligases c-Cbl and Cbl-b

OBJECTIVE

To investigate the effect of ascorbic acid (AA) on hemostatic function during living donor liver transplantation (LDLT).

METHODS

Blood samples from 21 LDLT recipients were taken within 30 minutes after induction and at 120 minutes after reperfusion. Rotational thromboelastography (TEG) and western blot analysis were used to analyze for fibrinolysis and functional changes in c-Cbl and Cbl-b, respectively. TEG test samples were prepared as one of three groups: C group (0.36 mL of blood), N group (0.324 mL of blood + 0.036 mL of 0.9% normal saline), and A group (0.324 mL of blood + 0.036 mL of 200 µmol/L-AA dissolved in 0.9% normal saline).

RESULTS

AA decreased fibrinolysis and increased clot rigidity at baseline and 120 minutes after reperfusion. Cbl-b expression was significantly increased at baseline and 120 minutes after reperfusion in the A group compared with the C and N groups. However, c-Cbl phosphorylation was most significantly decreased in the A group at baseline and 120 minutes after reperfusion.

CONCLUSION

AA can significantly decrease fibrinolysis and improve clot rigidity in LT recipients during LDLT, and functional changes in Cbl-b and c-Cbl might represent the underlying mechanism. AA may be considered for use during LDLT to decrease hyperfibrinolysis.

Protective effect of Xin-Ji-Er-Kang on cardiovascular remodeling in high salt-induced hypertensive mice

The aim of the present study was to investigate the effects of Xin-Ji-Er-Kang (XJEK) on high salt-induced hypertensive mice. Mice with high-salt diet-induced hypertension were divided into four groups: Control (standard diet alone for 8 weeks), model (diet containing 8% NaCl for 8 weeks and intragastric administration of distilled water for the last 4 weeks), XJEK + high-salt-treated (diet containing 8% NaCl for 8 weeks and intragastric administration of XJEK for the last 4 weeks) and irbesartan + high-salt-treated (diet containing 8% NaCl for 8 weeks with intragastric administration of irbesartan for the last 4 weeks). The hemodynamic index and cardiac pathological changes in the hypertensive mice were then examined. An aortic ring apparatus was used to detect acetylcholine-dependent endothelium relaxation function. Colorimetric analysis was applied to determine serum nitric oxide (NO), superoxide dismutase activity and malondialdehyde content; ELISA was employed to measure brain natriuretic peptide, serum angiotensin II (Ang II), endothelin-1 content and aldosterone; and immunohistochemistry was used to detect the expression of endothelial nitric oxide synthase (eNOS), interleukin (IL)-1β, IL-10 and tumor necrosis factor (TNF)-α in cardiac tissues. XJEK improved the heart systolic and diastolic function, ameliorated hemodynamic parameters and cardiovascular remodeling indices, blunted the cardiac pathological changes and improved endothelial dysfunction (ED) via boosting eNOS activity, promoting NO bioavailability and decreasing serum Ang II content. Furthermore, treatment with XJEK inhibited the increase of IL-1β and TNF-α expression and the decrease of IL-10 expression in cardiac tissues, and ameliorated oxidative stress status. Therefore, XJEK exerted protective effects against high salt-induced hypertension and cardiovascular remodeling in mice via improving ED, restoring pro- and anti-inflammatory factor balance and decreasing oxidative stress.

An increased tendency in fibrinogen activity and its association with a hypo-fibrinolytic state in early stages after injury in patients without acute traumatic coagulopathy (ATC)

Acute traumatic coagulopathy (ATC) diagnosed by prolongation of APTT and/or PT/INR involves alterations in platelet activity, coagulation and fibrinolysis. However, data showing the haemostatic situation in injured patients without ATC are scarce. To assess whether haemostatic impairment is also present in injured patients without ATC, ten injured patients without ATC and ten normal individuals were examined. The patients were sampled on arrival at the emergency department 0, 2, 12 h after surgical or other intervention. Thrombin generation, fibrin formation and fibrin proteolysis were determined via several laboratory methods, using tissue factor as the coagulation trigger. Thrombograms demonstrated that trauma accelerated both thrombin generation and decay. In the presence of unaffected peak thrombin levels, these two contradictory effects cancelled each other out, leading to the global endogenous thrombin potential (ETP) remaining normal. Under the mediation of normal ETP, fibrin network permeability (Ks) kept the reference levels in the two groups of subjects. Fibrinogen (FBG) activity (Clauss) rose with time from 0 to 2 h and 12 h, which significantly slowed down Clot Lysis Potential as determined by an in vitro method with exogenous t-PA. Summary: the main haemostatic impairment in the present patients concerned an increased tendency in FBG activity. Since an increase in FBG is a biomarker of acute inflammation and also predicts greater fibrin production which down-regulates fibrinolysis, we suggest that during early stages after injury, patients without ATC may suffer from worsening inflammation and confront enhancement of thrombosis risk due to dysfunction of fibrinolysis.

Shear stress: An essential driver of endothelial progenitor cells

The blood flow through vessels produces a tangential, or shear, stress sensed by their innermost layer (i.e., endothelium) and representing a major hemodynamic force. In humans, endothelial repair and blood vessel formation are mainly performed by circulating endothelial progenitor cells (EPCs) characterized by a considerable expression of vascular endothelial growth factor receptor 2 (VEGFR2), CD34, and CD133, pronounced tube formation activity in vitro, and strong reendothelialization or neovascularization capacity in vivo. EPCs have been proposed as a promising agent to induce reendothelialization of injured arteries, neovascularization of ischemic tissues, and endothelialization or vascularization of bioartificial constructs. A number of preconditioning approaches have been suggested to improve the regenerative potential of EPCs, including the use of biophysical stimuli such as shear stress. However, in spite of well-defined influence of shear stress on mature endothelial cells (ECs), articles summarizing how it affects EPCs are lacking. Here we discuss the impact of shear stress on homing, paracrine effects, and differentiation of EPCs. Unidirectional laminar shear stress significantly promotes homing of circulating EPCs to endothelial injury sites, induces anti-thrombotic and anti-atherosclerotic phenotype of EPCs, increases their capability to form capillary-like tubes in vitro, and enhances differentiation of EPCs into mature ECs in a dose-dependent manner. These effects are mediated by VEGFR2, Tie2, Notch, and β1/3 integrin signaling and can be abrogated by means of complementary siRNA/shRNA or selective pharmacological inhibitors of the respective proteins. Although the testing of sheared EPCs for vascular tissue engineering or regenerative medicine applications is still an unaccomplished task, favorable effects of unidirectional laminar shear stress on EPCs suggest its usefulness for their preconditioning.

Panax notoginseng saponins reduce high-risk factors for thrombosis through peroxisome proliferator-activated receptor -γ pathway

The classic Virchow theory suggests that blood stasis, hypercoagulability and endothelial dysfunction are three major factors that cause venous thrombosis (VT). It is a complicated biological process involved multi-factors. Platelet plays a central role and participates in multiple links of this process. Panax notoginseng saponins (PNS), the principal constituents derived from panax notoginseng, has been widely described for its anti-platelet activity. However, its potential mechanism against platelet aggregation has not been clarified. In this present study, we evaluated the anti-platelet effects of PNS on thrombin-induced platelet activation and its possible molecular mechanism of action, and further explored the therapeutic action of PNS on thrombin induced hypercoagulability in rat. Our results showed that PNS treatment inhibited platelet aggregation induced by thrombin, which was accompanied with over-expression of Peroxisome proliferator-activated receptor γ (PPAR-γ) protein, mRNA and upregulation of phosphatidylinositol 3 kinase (PI₃K)/ protein kinase B (Akt)/ endothelial nitric oxide synthase (eNOS) pathway in platelet, and this effect could be reversed by PPAR-γ inhibitor T0070907. In vivo, PNS significantly reversed thrombin-induced hypercoagulable state in rat which was accompanied by PPAR-γ protein and mRNA upregulation in rat lung. In conclusion, these data suggested that PNS could suppress thrombin-induced platelet aggregation in vitro and effectively improve hypercoagulable state in vivo and PNS-induced activation of PPAR-γ and its downstream PI₃K/Akt/eNOS pathway played the central role.

Sphingosine-1-phosphate improves endothelialization with reduction of thrombosis in recellularized human umbilical vein graft by inhibiting syndecan-1 shedding in vitro

Sphingosine-1-phosphate (S1P) has been known to promote endothelial cell (EC) proliferation and protect Syndecan-1 (SDC1) from shedding, thereby maintaining this antithrombotic signal. In the present study, we investigated the effect of S1P in the construction of a functional tissue-engineered blood vessel by using human endothelial cells and decellularized human umbilical vein (DHUV) scaffolds. Both human umbilical vein endothelial cells (HUVEC) and human cord blood derived endothelial progenitor cells (EPC) were seeded onto the scaffold with or without the S1P treatment. The efficacy of re-cellularization was determined by using the fluorescent marker CellTracker CMFDA and anti-CD31 immunostaining. The antithrombotic effect of S1P was examined by the anti-aggregation tests measuring platelet adherence and clotting time. Finally, we altered the expression of SDC1, a major glycocalyx protein on the endothelial cell surface, using MMP-7 digestion to explore its role using platelet adhesion tests in vitro. The result showed that S1P enhanced the attachment of HUVEC and EPC. Based on the anti-aggregation tests, S1P-treated HUVEC recellularized vessels when grafted showed reduced thrombus formation compared to controls. Our results also identified reduced SDC1 shedding from HUVEC responsible for inhibition of platelet adherence. However, no significant antithrombogenic effect of S1P was observed on EPC. In conclusion, S1P is an effective agent capable of decreasing thrombotic risk in engineered blood vessel grafts.

STATEMENT OF SIGNIFICANCE

Sphingosine-1phosphate (S1P) is a low molecular-weight phospholipid mediator that regulates diverse biological activities of endothelial cell, including survival, proliferation, cell barrier integrity, and also influences the development of the vascular system. Based on these characters, we the first time to use it as an additive during the process of a small caliber blood vessel construction by decellularized human umbilical vein and endothelial cell/endothelial progenitor. We further explored the function and mechanism of S1P in promoting revascularization and protection against thrombosis in this tissue engineered vascular grafts. The results showed that S1P could not only accelerate the generation but also reduce thrombus formation of small caliber blood vessel.

Understanding the Causes and Implications of Endothelial Metabolic Variation in Cardiovascular Disease through Genome-Scale Metabolic Modeling

High-throughput biochemical profiling has led to a requirement for advanced data interpretation techniques capable of integrating the analysis of gene, protein, and metabolic profiles to shed light on genotype-phenotype relationships. Herein, we consider the current state of knowledge of endothelial cell (EC) metabolism and its connections to cardiovascular disease (CVD) and explore the use of genome-scale metabolic models (GEMs) for integrating metabolic and genomic data. GEMs combine gene expression and metabolic data acting as frameworks for their analysis and, ultimately, afford mechanistic understanding of how genetic variation impacts metabolism. We demonstrate how GEMs can be used to investigate CVD-related genetic variation, drug resistance mechanisms, and novel metabolic pathways in ECs. The application of GEMs in personalized medicine is also highlighted. Particularly, we focus on the potential of GEMs to identify metabolic biomarkers of endothelial dysfunction and to discover methods of stratifying treatments for CVDs based on individual genetic markers. Recent advances in systems biology methodology, and how these methodologies can be applied to understand EC metabolism in both health and disease, are thus highlighted.

Why Do Patients Bleed?

Patients undergoing surgical procedures can bleed for a variety of reasons. Assuming that the surgical procedure has progressed well and that the surgeon can exclude surgical reasons for the unexpected bleeding, then the bleeding may be due to structural (anatomical) anomalies or disorders, recent drug intake, or disorders of hemostasis, which may be acquired or congenital. The current review aims to provide an overview of reasons that patients bleed in the perioperative setting, and it also provides guidance on how to screen for these conditions, through consideration of appropriate patient history and examination prior to surgical intervention, as well as guidance on investigating and managing the cause of unexpected bleeding.

Molecular engineering of high affinity single-chain antibody fragment for endothelial targeting of proteins and nanocarriers in rodents and humans

Endothelial cells (EC) represent an important target for pharmacologic intervention, given their central role in a wide variety of human pathophysiologic processes. Studies in lab animal species have established that conjugation of drugs and carriers with antibodies directed to surface targets like the Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1, a highly expressed endothelial transmembrane protein) help to achieve specific therapeutic interventions in ECs. To translate such "vascular immunotargeting" to clinical practice, it is necessary to replace antibodies by advanced ligands that are more amenable to use in humans. We report the molecular design of a single chain variable antibody fragment (scFv) that binds with high affinity to human PECAM-1 and cross-reacts with its counterpart in rats and other animal species, allowing parallel testing in vivo and in human endothelial cells in microfluidic model. Site-specific modification of the scFv allows conjugation of protein cargo and liposomes, enabling their endothelial targeting in these models. This study provides a template for molecular engineering of ligands, enabling studies of drug targeting in animal species and subsequent use in humans.