R. Di Stefano

Endothelial targeting with C1-inhibitor reduces complement activation in vitro and during ex vivo reperfusion of pig liver

Tissue damage during cold storage and reperfusion remains a major obstacle to wider use of transplantation. Vascular endothelial cells and complement activation are thought to be involved in the inflammatory reactions following reperfusion, so endothelial targeting of complement inhibitors is of great interest. Using an in vitro model of human umbilical vein endothelial cells (HUVEC) cold storage and an animal model of ex vivo liver reperfusion after cold ischaemia, we assessed the effect of C1‐INH on cell functions and liver damage. We found that in vitro C1‐INH bound to HUVEC in a manner depending on the duration of cold storage. Cell‐bound C1‐INH was functionally active since retained the ability to inhibit exogenous C1s. To assess the ability of cell‐bound C1‐INH to prevent complement activation during organ reperfusion, we added C1‐INH to the preservation solution in an animal model of extracorporeal liver reperfusion. Ex vivo liver reperfusion after 8 h of cold ischaemia resulted in plasma C3 activation and reduction of total serum haemolytic activity, and at tissue level deposition of C3 associated with variable level of inflammatory cell infiltration and tissue damage. These findings were reduced when livers were stored in preservation solution containing C1‐INH. Immunohistochemical analysis of C1‐INH‐treated livers showed immunoreactivity localized on the sinusoidal pole of the liver trabeculae, linked to sinusoidal endothelium, so it is likely that the protective effect was due to C1‐INH retained by the livers. These results suggest that adding C1‐INH to the preservation solution may be useful to reduce complement activation and tissue injury during the reperfusion of an ischaemic liver.

Fibrin acts as biomimetic niche inducing both differentiation and stem cell marker expression of early human endothelial progenitor cells

Objectives:  Transplantation of endothelial progenitor cells (EPCs) is a promising approach for revascularization of tissue. We have used a natural and biocompatible biopolymer, fibrin, to induce cell population growth, differentiation and functional activity of EPCs.

High production of endothelin after foam sclerotherapy: a new pathogenetic hypothesis for neurological and visual disturbances after sclerotherapy

Background Visual and neurological disturbances have always been reported following liquid sclerotherapy (LS) for venous insufficiency. In 1993 Cabrera introduced foam sclerotherapy (FS) using a detergent sclerosant as Lauromacrogol 400 or sodium tetradecyl sulphate. Several authors have reported with FS an increased incidence of such transient visual disturbances and neurological complications. This has been associated with gas or air used to generate the sclerosing foam. The frequent association of the presence of a patent foramen ovale, a common condition in normal population, and such complications has led several authors to consider neurological and visual disturbances as paradoxical gas embolism. Objective We are introducing a new pathogenetic hypothesis for sclerotherapy complications. Medical literature shows evidence of a clear relationship among cerebral and retinal vasospasm, migraine and intimal irritation. We think that the irritating sclerosant agent may stimulate a significant release of vasoactive substances from the venous wall, specifically endothelin 1 (ET-1), the most powerful vasoconstricting agent. Method We have studied systemic ET-1 levels after LS and FS with Lauromacrogol 400 in a group of 13 rats at one and five minutes after injection. Results While ET-1 levels did not change significantly in control and in the LS group, a significant increase was detected after FS at one and five minutes. Conclusion We conclude that should the same results be found in patients treated using sclerosing foam (SF), ET-1 levels may closely correlate to the onset of visual or cerebral complications. Due to the bronchoconstrictor activity of ET-1, a relationship with post-treatment cough can be also postulated.

Rare combination of left ventricular noncompaction, bicuspid aortic valve and myocardial bridging. Rare case or common genetic mutations?

Left ventricular noncompaction is a relatively common genetic cardiomyopathy. In most cases, noncompaction is an isolated disease confined to the left ventricular myocardium, characterized by prominent trabeculations with deep intertrabecular recesses. It may be present also in various types of congenital heart diseases [1–20]. We present the case of a 36-year-old man, who came under our observation for stable angina pectoris. He has a history of severe arterial hypertension controlled pharmacologically and a known aortic bicuspid valve with normal flow. Echocardiographic evaluation confirms bicuspid aorta (Fig. 1A) with normal flow, associated with a mild trabecular apical hypertrophy (Fig. 1B). The apexwas also ipokynetic. Coronaric arteriography showed the absence of coronaric lesions (Fig. 1C andD) and the presence of a myocardial bridging (Fig. 2A and B). Ventriculography showed that the contrast mediumwas inserted in small intertrabecular recesses (Fig. 2C), suggesting the existence of a minor form of noncompacted myocardium [21–33]. This findingmade us suspect that different congenital heart diseases could have the same genetical background. In conclusion,we cannot ascertain from this single case the existence of a common genetic background for this association of congenital heart diseases (myocardial noncompaction, bicuspid aortic valve and myocardial bridging). However, the identification of further cases could identify a potentially

Endothelial progenitor cell homing in human myocardium in patients with coronary artery disease

Endothelialprogenitorcells(EPCs)aremobilizedfrombonemarrowinto peripheral blood, contributing to the revascularization of ischemicareas, to endothelial repair and to the physiological maintenance ofvascularization. EPC mobilization and homing have been primarilylinked to ischemia and inflammation presence [1]. EPCs are directlycorrelated with endothelial function and inversely correlated withcardiovascular risk factors and atherosclerosis progression [2].EPClevelshavealsobeencorrelatedtoprognosisevaluationincardiovascu-lar disease [3].Regarding EPC correlation with coronary artery disease (CAD)presence and severity, an inverse relationship with CAD severity, inde-pendent of traditional risk factors, was demonstrated by EPC colonycounting [4],whileahighnumberofEPCsassociatedwithCADandcorre-latedwithstenosisseveritywereshownby flowcytometry [5].Recentlyanew protocol, adapted from the standardized ISHAGE protocol for hema-topoieticstemcells,hasbeendevelopedforEPClevelevaluationtoenablecomparison of clinical and laboratory data [6].While thepresence of circulatingEPCshasbeenwidely evaluated indifferent diseases, few studies tried to evaluate the presence of EPCs inhuman vital myocardium.TheaimofourstudywastoinvestigateEPClevelsbothinperipheralbloodand inmyocardium in thesame patients atthesame time, evalu-atingthecorrelationwith CADpresence. In bothsampleswequantifiedCD34

Renal denervation rapidly restores circulating proangiogenic hematopoietic cells in patients affected by drug-resistant hypertension

Poor control of blood pressure (BP) is the most common attributable risk of death worldwide. Renal sympathetic denervation (RSD) has been recently proposed for the treatment of drugresistant hypertension (R-HTN) [1]. RSD can effectively reduce elevated blood pressure in R-HTN [2–4], also in particular cases [5], probably due to the effects of sympathoinhibitory accompaniment. Circulating proangiogenic hematopoietic cells (PHCs), including their largest cell population CD34+ cells, are multipotent circulating cells derived from bone marrow that have been proven capable of angiogenic and reparative properties in vivo [6]. PHCs are a heterogeneous population of cells in different states of maturation with the ability to differentiate into cell types of different organs and systems, including cardiomyocytes, smooth muscle cells, and endothelial progenitor cells [7]. Although it is to date not clear if they are able to give rise to mature endothelial cells in vivo, and they are different from endothelial forming colony cells, it is currently accepted that PHCs can work as proangiogenic support cells, maintaining their importance in terms of regenerative/reparative potential and their prognostic value [6,8]. PHCs, in fact, have been shown to contribute to postnatal vasculogenesis and vascular damage repair either directly or via paracrine effects [6], participating in healthy and damaged endothelial turnover and angiogenesis and are negatively affected by risk factors for cardiovascular disease (CVD) and positively by changes in lifestyle [9]. Much of the regenerative/reparative potential of PHCs may be attributed to CD34+ cells (including also their subsets, multiple positive phenotypes

Role of circulating endothelial progenitor cells in the reparative mechanisms of stable ischemic myocardium

BACKGROUND Mobilization of endothelial progenitor cells (EPCs) into circulation from bone marrow in patients with acute myocardial infarction has strong scientific evidence; less is known about EPC mobilization in patients with stable coronary artery disease (CAD). The aim of this study was to investigate the association of stable ischemic heart disease with EPC levels in tissue and blood. METHODS Fifty-five consecutive patients admitted to a single treatment center for valve or coronary artery bypass grafting (CABG) surgeries were included in the study. Blood samples were collected in the morning before surgery and analyzed by flow-cytometry to determine peripheral EPC levels (EPC/ml). Tissue EPC (CD34+VEGFR2+) levels were assessed on a right atrial appendage segment. RESULTS Mean age was 76±5years, 48% were men, and 53% had CAD The number of CD34+ VEGFR2+ cells in the tissue of patients with CAD was significantly higher (p<0.005) and circulating EPC showed a tendency to be reduced by approximately 20% in peripheral blood of patients with CAD when compared to those without CAD. CONCLUSION Patients with stable CAD had higher EPC density values (EPC/mm2) and were more likely to have lower EPC blood levels when compare with normal controls.

Endothelial Activation in Xenografts’ Rejection: Evaluation of the Role of Heparan-Sulphate

Endothelial activation plays an important role in discordant xenogenic rejection. The process is thought to be initiated by antigen-antibody recognition and complement cascade that lead to activation and damage of endothelium as the main target of rejection. One aspect of endothelial activation is the loss and release of a proteoglycan like heparan-sulphate (HS) from cellular surface. The anticoagulant and fibrinolytic activity of heparan-sulphate is well documented but other properties of HS need further investigation.