Tatiana Santoni

Circulating Endothelial Progenitor Cells Characterization, Function and Relationship with Cardiovascular Risk Factors

Since the first description of putative progenitor endothelial cells mobilized from bone marrow by stimuli like ischemia and cytokines, several studies in animals have confirmed their role in neovascularization of ischemic organs. In ischemic myocardium endothelial progenitor cells can prevent cardiomyocyte apoptosis, reduce remodeling and improve cardiac function. These observations led to the hypothesis of endothelial progenitor cells as possible cell-based therapy in patients by autologous transplantation in ischemic tissue or by improving peripheral circulating numbers with mobilization by cytokines. Early trials, including a randomized one, suggest that the intracoronary autologous bone marrow cell transfer after myocardial infarction exerts at least short term functional benefits. Since endothelial damage and dysfunction play a critical role in atherosclerosis disease, research interest was addressed to evaluate the role of progenitor endothelial cells in vascular endothelial layer maintenance. Opposing to local resident endothelial cells poor proliferation rate, progenitor endothelial cells regenerative capacity, homing and integration into blood vessels have been interpreted as a protective role of these cells in vascular homeostasis. Indeed, the number and function of endothelial progenitor cells relate with the progression of atherosclerosis; the accumulation of cardiovascular risk factors or an increased overall risk are inversely associated with endothelial progenitor cells number and function. Finally, recent studies have shown a role of progenitor cells numbers to predict cardiovascular events, raising endothelial progenitor cells to the podium of novel prognostic biomarker.

Cyclins of phases G1, S and G2/M are overexpressed in aneuploid mammary carcinomas.

Expression of cyclins A, B1 and D1 in human breast cancer was analyzed using dual-parameter flow cytometry with simultaneous evaluation of the DNA content. The asynchronous MCF-7 breast adenocarcinoma cells were used to implement flow cytometry analysis and to analyze the cell cycle distribution of cyclins. The patterns of the cyclin expression were also analyzed in vivo in fresh tissue specimens of human breast carcinomas. The combined measurement of DNA and cyclins showed a higher cyclin expression in aneuploid (11.5 +/- 2.0%, 4.3 +/- 1.1%, and 19.5 +/- 3.4% positive cells for cyclins A, B, and D1, respectively) than in diploid carcinomas (3.9 +/- 1.2%, 1.1 +/- 0.4%, and 5.0 +/- 1.2% positive cells for cyclins A, B, and D1, respectively). A positive relationship was also found between cyclin A and D1 expression and H(3)-thymidine labeling index. In the in vitro model, the asynchronous growing MCF-7 cells showed a variable number of cells expressing cyclins in an unscheduled way, unrelated to the phase at which these cyclins are expressed in normal cells. A similar condition was also observed in tumors. In conclusion, the data showed a deregulated expression of cyclins in a transformed adenocarcinoma cell line and in breast tumors. Furthermore, overexpression of these proteins is related to the aneuploid and high proliferative activity of human mammary carcinomas.

Significant endothelin release in patients treated with foam sclerotherapy

Background Foam sclerotherapy has been proven to be a safe and effective treatment for superficial venous insufficiency, but transient visual and neurologic disturbances continue to be reported. These side effects have been theorized to be related to the presence of air or gases in the sclerosing foam that results in “bubble” migration into the cerebral circulation. We present a differing hypothesis that significant amounts of endothelin are released from the treated veins, amounts capable of causing these complications. Material and Methods We tested the release of endothelin 1 (ET‐1) in 12 rats after sclerotherapy with sodium tetradecyl sulfate (STS) in liquid and foam preparations. In 11 human subjects, we measured ET‐1 in systemic circulation and in a draining vein after foam sclerotherapy with polidocanol. Results Rats treated with STS showed a significant increase in ET‐1 levels 1 and 5 minutes after foam sclerotherapy. Patients treated with foam sclerotherapy showed a marked increase in ET‐1 levels that correlated significantly with local ET‐1 levels. Conclusions Evidence of ET‐1 release represents a plausible relationship explaining neurologic and visual disturbances reported after sclerotherapy.

Effect of different chitosan derivatives on in vitro scratch wound assay: A comparative study

Different strategies have been developed to make the wound-healing process faster and less painful. Recently, numerous studies demonstrated the ability of chitosan to accelerate wound healing. Aim of the present study has been to evaluate the effect of different chitosan derivatives to improve wound healing process. Quaternary ammonium-chitosan conjugates with low or high molecular weight (MW) and their thiolated derivatives effect were studied on human skin fibroblasts in terms of viability and migration (scratch wound assay). Results were compared both with basal medium (untreated cells) and with a positive control (chitosan chlorhydrate). After 24h both high and low MW chitosan derivatives were non-toxic up to 10 μg/ml. The concentration of 10 μg/ml was used for wound healing experiments. High-MW quaternary ammonium-chitosan conjugates bearing thiol groups on their chains were more effective in promoting cell migration than the non-thiolated conjugates and the chitosan chlorhydrate. Moreover, they significantly improve wound healing process compared to untreated cells. According to the present in vitro preliminary results, high MW thiolated quaternary ammonium-chitosan conjugates can be considered good candidates for the management of wounds.

Different growth conditions for peripheral blood endothelial progenitors

PURPOSE To compare different growth conditions for endothelial progenitor cells (EPCs) from peripheral blood mononuclear cells (PBMNCs). METHODS AND MATERIALS PBMNCs of healthy volunteers were cultured on fibronectin as follows: M199 with VEGF, bFGF, IGF-I; the same medium with bovine retina-derived extract (RDE); freshly isolated or depleted of adherent cells PBMNCs in HUVEC conditioned medium; DiI-stained PBMNCs with HUVECs (1:4 ratio) in Ml99 with RDE. PBMNCs were analysed by FACS using mAbs for endothelial markers. EPCs migration was determined using a modified Boyden chamber assay and VEGF as chemoattractant. EPCs were seeded alone or with HUVECs on Matrigel to assess in vitro angiogenesis. RESULTS With growth factors, numerous cell clusters appeared within 1 week. Spindle-shaped and attached cells sprouted, differentiating in endothelial cell (EC)-like cells within 2 weeks and forming cobblestone-like monolayers within 3 weeks. With RDE, numerous large cell clusters appeared within 1 week, but the number of cells with an EC morphology decreased during culture. FACS confirmed the endothelial phenotype and attached cells were able to migrate in response to VEGF. When nonadherent cells were cultured in HUVEC conditioned medium, they proliferated readily and EPCs were induced while freshly isolated cells neither proliferated nor induced EPCs. FACS analysis of the cocultures showed the presence of double-labeled PBMNCs expressing endothelial antigens. Capillary-like structures were observed on Matrigel only from cocultures and PBMNCs were able to incorporate in these networks. CONCLUSIONS PBMNCs are able to differentiate in EPCs when stimulated with appropriate culture conditions (growth factors, HUVEC conditioned medium, HUVECs).

Human peripheral blood endothelial progenitor cells synthesize and express functionally active tissue factor

INTRODUCTION Endothelial progenitor cells are circulating cells able to home to sites of vascular damage and to contribute to the revascularization of ischemic areas. We evaluated whether endothelial progenitor cells synthesize tissue factor, a procoagulant protein also involved in angiogenesis. MATERIALS AND METHODS Endothelial progenitor cells were obtained from the peripheral blood mononuclear fraction of normal donors and cultured in endothelial medium supplemented with specific growth factors. The procoagulant activity expressed by cells disrupted by freeze-thaw cycles was assessed by a one stage clotting assay. Tissue factor mRNA expression was evaluated by RT-PCR. RESULTS Endothelial progenitor cells do not express procoagulant activity in baseline conditions. However, lipopolysaccharide induces the expression of procoagulant activity. The effect is dose-dependent and reaches statistical significance at 100 ng/mL lipopolysaccharide. Inhibition with an anti-tissue factor antibody and amplification of cDNA with primers based on the tissue factor sequence confirm the identity of this activity with tissue factor. The kinetics of tissue factor expression by endothelial progenitor cells is identical to that of human umbilical vein endothelial cells showing maximal activity within 4 hours, and then decreasing; in contrast, tissue factor expression by mononuclear cells lasts for longer times. Both 5,6-dichloro-beta D-ribofuranosyl-benzimidazole and cycloheximide prevented the expression of procoagulant activity. Stimulation of endothelial progenitor cells with tumor necrosis factor-alpha did not elicit any detectable procoagulant activity. CONCLUSIONS Endothelial progenitor cells can be stimulated by lipopolysaccharide to synthesize tissue factor. This protein might be involved in thrombotic phenomena and might contribute to endothelial progenitor cells related neovascularization.

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

Endothelial progenitor cell secretome delivered by novel polymeric nanoparticles in ischemic hindlimb

&NA; Endothelial progenitor cells (EPCs) contribute to ischemic tissue repair by paracrine secretion up‐regulated by hypoxia. In this study we use novel nanoparticles (NPs) as carriers for a controlled release of EPC secretome (CM) to improve their angiogenic properties. The in vivo effect in ischemic hindlimb rat model was evaluated, comparing hypoxic EPC‐CM‐NPs with hypoxic EPC‐CM alone. A proteomic characterization of hypoxic CM and the in vitro effect on endothelial cells (HUVECs) were also performed. Up to 647 protein, 17 of which with angiogenic properties, were upregulated by hypoxia. Moreover, hypoxic EPC‐CM significantly promoted capillary‐like structures on Matrigel. A significant increase of blood perfusion in ischemic limbs at 2 weeks with EPC‐CM‐loaded NPs as compared to both EPC‐CM and control and a significant increase of capillary formation were observed. The use of EPC‐CM‐NPs significantly improved neoangiogenesis in vivo, underlining the advantages of controlled release in regenerative medicine.

Effect of aminaphtone on in vitro vascular permeability and capillary-like maintenance:

Objectives Aminaphtone, a naphtohydrochinone used in the treatment of capillary disorders, may affect oedema in chronic venous insufficiency. Aim of study is to investigate the effect of aminaphtone on vascular endothelial permeability in vitro and its effects on three-dimensional capillary-like structures formed by human umbilical vein endothelial cells. Method Human umbilical vein endothelial cells were treated with 50 ng/ml VEGF for 2 h and aminaphtone for 6 h. Permeability assay, VE-cadherin expression and Matrigel assay were performed. Results VEGF-induced permeability was significantly decreased by aminaphtone in a range concentration of 1–20 µg/ml. Aminaphtone restored VE-cadherin expression. Finally, 6 h pre-treatment with aminaphtone significantly preserved capillary-like structures formed by human umbilical vein endothelial cells on Matrigel up to 48 h compared to untreated cells. Conclusions Aminaphtone significantly protects endothelium permeability and stabilises endothelial cells organised in capillary-like structures, modulating VE-cadherin expression. These data might explain the clinical benefit of aminaphtone on chronic venous insufficiency.

Endothelial progenitor cells recruitment correlate with coronary artery disease severity

Background: Despite many studies investigated the level and function of peripheral blood Endothelial Progenitor Cells (EPCs), less scientific evidence concerning the presence and the role of EPCs in human myocardium exists. Our study aimed to investigate EPC density in atrial appendage, a well known source of different stem cells, and EPC blood levels in patients (pts) with coronary artery disease (CAD) undergoing to bypass and in pts undergoing to Isolated Valve Surgery (IVS) with no CAD.