Francesca Felice

Angiogenesis as Risk Factor for Plaque Vulnerability

Atherosclerosis is now generally accepted as an inflammatory disease, characterized by degenerative changes and extracellular accumulation of lipid and cholesterol. The evolving inflammatory reaction plays an important role in the initiation of atherosclerotic plaques and their destabilization, converting a chronic process into an acute disorder with an ensuing thrombo-embolism. Neovascularization has been, also, recognized as an important process for the progression of atherosclerotic plaques. In fact, vulnerable atherosclerotic plaque prone to rupture are characterized by an enlarged necrotic core containing an increased number of vasa vasorum, apoptotic macrophages, and more frequent intraplaque haemorrhage. Various functional roles have been assigned to intimal microvessels. This network of immature blood vessels is a viable source of intraplaque haemorrhage providing erythrocyte-derived phospholipids and free cholesterol. However, it is still challenging and controversial the relationship between the very process of angiogenesis and its causal association with the progression and complication of atherosclerosis. The selective targeting of neoangiogenesis poses a possible approach for the elimination of pre-existing and new growth of microvessels. The identification of target lesions is a critical issue, because current technologies have yet to achieve the goal of characterizing plaque morphology to the degree necessary to correctly identify rupture-prone lesions according to pathologic criteria. However, few imaging techniques can be used to detect the neovascularization within the atherosclerotic plaque in vivo. This review discusses the potential role of intraplaque angiogenesis as risk factor for plaque vulnerability.

Fibrin as a scaffold for cardiac tissue engineering

Fibrin is a natural biopolymer with many interesting properties, such as biocompatibility, bioresorbability, ease of processing, ability to be tailored to modify the conditions of polymerization, and potential for incorporation of both cells and cell mediators. Moreover, the fibrin network has a nanometric fibrous structure, mimicking extracellular matrix, and it can also be used in autologous applications. Therefore, fibrin has found many applications in tissue engineering, combined with cells, growth factors, or drugs. Because a major limitation of cardiac cell therapy is low cell engraftment, the use of biodegradable scaffolds for specific homing and in situ cell retention is desirable. Thus, fibrin‐based injectable cardiac tissue engineering may enhance cell therapy efficacy. Fibrin‐based biomaterials can also be used for engineering heart valves or cardiac patches. The aim of this review is to show cardiac bioengineering uses of fibrin, both as a cell delivery vehicle and as an implantable biomaterial.

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.

Red grape skin and seeds polyphenols: Evidence of their protective effects on endothelial progenitor cells and improvement of their intestinal absorption.

SCOPE To evaluate the ability of grape skin and seeds to protect endothelial progenitor cells (EPC) from oxidative stress induced by hyperglycemia (HG) compared to red wine (RW) and prepare innovative pharmaceutical systems for the oral administration of red grape extract allowing the overcoming of its poor intestinal absorption. METHODS AND RESULTS Human EPC were characterized by expression of cell surface markers. Cells were incubated with different concentrations of total polyphenols from grape components or RW in the presence or absence of HG. Cell viability, migration, adhesion, and reactive oxygen species (ROS) production were assayed. Intestinal permeation of polyphenols was studied in the absence or presence of a quaternary ammonium-chitosan conjugate (N⁺(60)-Ch). Grape components and RW increased EPC viability, adhesion and migration, and prevented the HG effect (P < 0.01). ROS production induced by HG was significantly reduced only by grape seed extract and RW (P < 0.01). N⁺(60)-Ch acted as an effective enhancer of polyphenol permeability across the excised rat intestine. CONCLUSIONS Red grape components are a source of antioxidant compounds that ameliorate EPC viability and function, while preventing endothelial dysfunction. The use of polycationic chitosan derivatives can promote the absorption of polyphenols across intestinal epithelium, thus increasing their bioavailability and potential therapeutic value in atherosclerosis.

Oxidative stress in response to high glucose levels in endothelial cells and in endothelial progenitor cells: evidence for differential glutathione peroxidase-1 expression.

Endothelial cells and endothelial progenitor cells (EPCs) play a key role in the pathogenesis of vascular disease. Both cell types are affected by the oxidative stress but their susceptibility may be different. This study aimed to investigate the antioxidative enzymes activated in EPCs after high constant glucose exposure as compared to endothelial cells (HUVECs). Both cells were incubated in the presence of normal (5mM) and high constant (25mM) d-glucose, as well as l-glucose as osmotic control for 48 and 96h. After a 48-hour exposure to high d-glucose, cell viability was significantly decreased both in EPCs and HUVECs as compared with normal d-glucose (p<0.01). However, after 96h there was no difference between EPCs grown on normal or high d-glucose, while HUVEC viability was affected by high d-glucose at 96h too (p<0.001). High d-glucose exposure induced a significant increase in reactive oxygen species (ROS) production in both cell types at 48h; however, after 96h, a significant decrease in ROS production (p<0.01) and a parallel marked increase in glutathione peroxidase type 1 (GPx-1) expression (p<0.01) and activity (p<0.01) were observed in EPCs compared to HUVECs. These data suggest that EPCs have a well-adaptive response to oxidative stress induced by constant and sustained high glucose exposure. This resistance to high glucose levels might be due to increased expression and activity of glutathione peroxidase allowing better cell survival.

Mucoadhesive nanoparticles made of thiolated quaternary chitosan crosslinked with hyaluronan

Mucoadhesive polymeric nanoparticles intended for drug transport across the gastrointestinal mucosa were prepared from quaternary ammonium-chitosan conjugates synthesised from reduced-MW chitosan (32 kDa). Conjugates contained pendant moieties of 2-4 adjacent diethyl-dimethylene-ammonium groups substituted on repeating units (26-55%). Conjugates were thiolated via amide bonds with thioglycolic acid to yield products with thiol content in the 35-87 μmol/g range. Nanoparticles with mean size in the 270-370 nm range and positive zeta-potential (+3.7 to +12.5 mV) resulted from ionotropic gelation of the thiolated conjugates with de-polymerised hyaluronic acid (470 kDa). The nanoparticles were fairly stable in size and thiol content and showed a significant mucoadhesivity, matching and even exceeding that of the constituent polymers. Nanoparticles were internalised by endothelial progenitor cells in direct relation to their surface charge intensity. Nanoparticle uptake significantly improved cell viability and resistance to oxidation. The lyophilised nanoparticles were re-dispersible and could make a manageable formulation for oral use.

Smoking and Endothelial Progenitor Cells: A Revision of Literature

Accumulating evidence indicates that circulating endothelial progenitor cells (EPCs) derived from bone marrow contribute to reendothelialization of injuried vessels as well as neo-vascularization of ischemic lesions in either a direct or an indirect way. Moreover, the number and/or the functional activity of EPCs are inversely correlated with risk factors for cardiovascular disease. Among the different risk factors, cigarette smoking is a major cause of reducing the numbers and function of circulating EPCs. This review is a revision of recent literature on EPC alteration associated with smoking. In particular, we show the recent observation on the effects of active and second hand smoke (SHS) exposure on EPC number and functional activity. This review also considers the effects of nicotine and other smoke compounds on EPC number and activity, in in vitro and in vivo models.

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.

Delivery of natural polyphenols by polymeric nanoparticles improves the resistance of endothelial progenitor cells to oxidative stress

PURPOSE Bone marrow-derived endothelial progenitor cells (EPCs) circulate into peripheral blood and significantly contribute to neo-vascularisation and re-endothelialisation as part of the process of vascular repair. Several studies have reported decreased EPC number in the presence of oxidative stress. Aim of this study was to evaluate the validity of mucoadhesive polymeric nanoparticles as a delivery system of natural products able to protect EPCs from oxidative stress. METHODS The total polyphenol content and antioxidant capacity of red grape seed extract (GSE) either pre-veraison (p-GSE) or ripe (r-GSE) were measured. Cell viability was evaluated by WST-1 assay. Nanoparticles were prepared by ionotropic crosslinking of two structurally different thiolated quaternary ammonium-chitosan conjugates. A hyaluronic acid solution, containing p-GSE or r-GSE, was added to a stirred solution of each of the two chitosan derivatives to obtain p- or r-GSE loaded nanoparticles (NP) of two types. RESULTS Both GSE types demonstrated strong antioxidant capacity. p-GSE showed a higher content in total polyphenols compared to r-GSE. NP size was in the 310-340 nm range, with 24 h stability, and nearly 100% encapsulation efficiency for both GSE types. NP were internalized by cells to an extent related directly with their surface charge intensity. GSE-NP uptake significantly improved cell viability and resistance to oxidation. CONCLUSIONS Nanotechnology has a great potential in nutraceutical delivery. The present results suggest that NP is a highly promising polyphenol carrier system particularly useful to protect EPCs from oxidative stress, thus improving their survival.