Role of TGFβ1 and WNT6 in FGF2 and BMP4-driven endothelial differentiation of murine embryonic stem cells

Embryonic stem cells (ES) are a valuable source of endothelial cells. By co-culturing ES cells with the stromal PA6 cells, the endothelial commitment can be achieved by adding exogenous FGF2 or BMP4. In this work, the molecular pathways that direct the differentiation of ES cells toward endothelium in response to FGF2 are evaluated and compared to those activated by BMP4. To this purpose the genes expression profiles of both ES/PA6 co-cultures and of pure cultures of PA6 cells were obtained by microarray technique at different time points. The bioinformatics processing of the data indicated TGFβ1 as the most represented upstream regulator in FGF2-induced endothelial commitment while WNT pathway as the most represented in BMP4-activated endothelial differentiation. Loss of function experiments were performed to validate the importance of TGFβ1 and WNT6 respectively in FGF2 and BMP4-induced endothelial differentiation. The loss of TGFβ1 expression significantly impaired the accomplishment of the endothelial commitment unless exogenous recombinant TGFβ1 was added to the culture medium. Similarly, silencing WNT6 expression partially affected the endothelial differentiation of the ES cells upon BMP4 stimulation. Such dysfunction was recovered by the addition of recombinant WNT6 to the culture medium. The ES/PA6 co-culture system recreates an in vitro complete microenvironment in which endothelial commitment is accomplished in response to alternative signals through different mechanisms. Given the importance of WNT and TGFβ1 in mediating the crosstalk between tumor and stromal cells this work adds new insights in the mechanism of tumor angiogenesis and of its possible inhibition.

     

Diagnosis of structural changes] of the brain in patients with coronary and asymptomatic carotid atherosclerosis

AIM: To compare echomorphostructure of atherosclerotic plaques and vascular stenosis degree with structural changes of the brain according to MR image in patients with combined atherosclerotic affection of coronary and carotid arteries in an asymptomatic course of carotid atherosclerosis. MATERIAL AND METHODS: MR imaging was made in 53 men aged 44 to 78 years with stenosing atherosclerotic affection of the internal carotid arteries. Vascular obstruction reached 30-80%. Neurological examination detected no signs of focal brain lesions. Hypertension, myocardial infarction, permanent atrial fibrillation were diagnosed in 19 (36%), 20 (38%) and 12 (23%) patients, respectively. RESULTS: Ultrasound investigation has established that carotid arteries contain more frequently spongy and heterogenic plaques than dense and calcinated. MRI registered structural alterations of cerebral tissue of various degree in 96% cases. CONCLUSION: Significant correlations were established between ischemic affection of the brain with myocardial infarction, arterial hypertension, cardiac fibrillation, type of atherosclerotic plaque.     

Abnormal cerebrovascular reactivity in patients with asymptomatic atherosclerosis of the carotid arteries

The study included 53 patients (males at the age of 44-78 years) with ischemic heart disease and arterial hypertension with asymptomatic unilateral atherosclerotic affection of carotid arteries (CA). Ultrasonic investigation registered 30-80% stenosis of carotid arteries in the absence of neurological deficit. Cerebrovascular reactivity was assessed by means of the hypercapnic hypoxic test (HHT) including breathing via additional "dead space" for 3 min. Initial and peak linear velocity of the blood flow in the middle cerebral artery was measured with ultrasonic transcranial dopplerography. By HHT results, three types of cerebral vascular reactions in patients with combined atherosclerosis of coronary and carotid arteries were identified: subnormal dilatation on the side of stenosed internal carotid artery, increased dilatation and paradoxical vasoconstriction on the affected side. Cerebrovascular reactivity and the type of atherosclerotic plaques did not collerate.     

Function of the brain venous system and a 24-h profile of arterial pressure in hypertensive patients

AIM: To study blood flow along the internal jugular veins (IJV) in the initial state and under the action of nitroglycerin in patients with essential arterial hypertension (EAH) with reference to characteristics of a 24-h profile of blood pressure. MATERIAL AND METHODS: A 24-h monitoring of blood pressure (MBP), duplex scanning of IJV, venous IJV outflow were studied in 26 patients with EAH stage 2 (mean age 39 +/- 5.0) before and after sublingual intake of nitroglycerin (0.5 mg). RESULTS: By 24-h MBP findings, two groups of patients were identified: with unaffected blood pressure profile (group 1) and affected profile (group 2). Nitroglycerin produced a unidirectional reaction of IJV (increased outflow) in group 1 and multidirectional changes of venous outflow along the IJV in patients of group 2. CONCLUSION: Nitroglycerin test showed different venous cerebral hemodynamics in EAH patients with different variants of 24-h MBP.     

Carotid atherosclerosis detectability in patients with coronary heart disease and arterial hypertension

AIM: To assess detectability of carotid atherosclerosis in patients with coronary heart disease (CHD) and arterial hypertension (AH) by the data of ultrasonic screening, to study location and detectability of atherosclerotic lesion of common carotid arteries, internal carotid arteries, external carotid arteries in correlation with basic disease. MATERIAL AND METHODS: Ultrasonic screening of brachyocephalic arteries was made in 469 patients: with CHD (n = 239), AH (n = 230) including patients with concomitant postinfarction cardiosclerosis (PICS) and moderate chronic cerebrovascular failure (CCVF). RESULTS: Ultrasonic angiography detected atherosclerotic carotid artery lesion in patients with CHD and PICS (81.6%) or CCVF (76.9%) or angina pectoris (64.2%). In hypertension subjects carotid artery atherosclerosis was encountered in 28.1%. CONCLUSION: It is justified to make ultrasonography of carotid arteries in all patients with CHD and AH irrespective of age, gender, underlying clinical diagnosis.     

Superparamagnetic iron oxide nanoparticles impair endothelial integrity and inhibit nitric oxide production

Superparamagnetic iron oxide nanoparticles (SPION) are widely used both clinically and experimentally for diverse in vivo applications, such as contrast enhancement in magnetic resonance imaging, hyperthermia and drug delivery. Biomedical applications require particles to have defined physical and chemical properties, and to be stable in biological media. Despite a suggested low cytotoxic action, adverse reactions of SPION in concentrations relevant for biomedical use have not yet been studied in sufficient detail. In the present work we employed Endorem®, dextran-stabilized SPION approved as an intravenous contrast agent, and compared its action to a set of other nanoparticles with potential for magnetic resonance imaging applications. SPION in concentrations relevant for in vivo applications were rapidly taken up by endothelial cells and exhibited no direct cytotoxicity. Electric cell impedance sensing measurements demonstrated that SPION, but not BaSO₄/Gd nanoparticles, impaired endothelial integrity, as was confirmed by increased intercellular gap formation in endothelial monolayers. These structural changes induced the subcellular translocation and inhibition of the cytoprotective and anti-atherosclerotic enzyme endothelial NO-synthase and reduced NO production. Lipopolysaccharide-induced inflammatory NO production of macrophages was not affected by SPION. In conclusion, our data suggest that SPION might substantially alter endothelial integrity and function at therapeutically relevant doses, which are not cytotoxic.     

Cerebral microcirculation and structural changes in the brain in essential hypertension

The purpose of the study was to examine cerebral microcirculatory and structural changes in 32 patients (20 males and 12 females whose age varied from 37 to 63 years) with moderate arterial hypertension (AH). All the patients underwent single-photon emission computed tomography of the brain, using (99m)Tc-hexamethylpropyleneaminoxylfor the evaluation of perfusion, as well as magnetic resonance imaging for the examination of cerebral structures. Cerebral structural changes and perfusion impairments were detected in patients with AH, even if they had no clinical signs of cerebrovascular insufficiency. Inadequate blood flow most frequently occurred in the parietal and temporal regions of the brain. There was a reduction in the cerebrovascular reserve in the frontal lobes in AH.