Human mature endothelial cells modulate peripheral blood mononuclear cell differentiation toward an endothelial phenotype

Endothelial Dysfunction in Systemic Lupus Erythematosus and Systemic Sclerosis: A Common Trigger for Different Microvascular Diseases

This review describes the complex interplay between inflammation, vasculopathy and fibrosis that involve the heart and peripheral small vessels, leading to endothelial stiffness, vascular damage, and early aging in patients with systemic lupus erythematosus and systemic sclerosis, which represents two different models of vascular dysfunction among systemic autoimmune diseases. In fact, despite the fact that diagnostic methods and therapies have been significantly improved in the last years, affected patients show an excess of cardiovascular mortality if compared with the general population. In addition, we provide a complete overview on the new techniques which are used for the evaluation of endothelial dysfunction in a preclinical phase, which could represent a new approach in the assessment of cardiovascular risk in these patients.

Expression dynamics of vascular endothelial markers: endoglin and syndecan-1 in predicting dengue disease outcome

Plasma leakage is a hallmark process in dengue viral (DENV) infection that occurs due to the loss of vascular integrity in endothelial cells. Endoglin (ENG) and Syndecan-1 (SDC-1) are released by activated endothelial cells; however, the complete dynamics of its expression at the gene and protein levels during the course of DENV infection remains unknown. In the present study, we quantified the mRNA and soluble protein levels of ENG and SDC-1 in dengue cases during febrile, defervescence, and convalescence stages in Dengue without Warning Sign (DWOW-15), Dengue with Warning Sign (DWW-22), and Severe Dengue cases (SD-10) compared to nondengue Other Febrile Illness (OFI-10) and healthy control (HC-8). Respective protein and mRNA levels along with clinical characters were further analyzed for their efficacy in predicting disease outcomes using Support Vector Machine (SVM). We observed a steady and significant (P ≤ 0.01) increase in the levels of protein and mRNA of both the ENG and SDC-1 towards defervescence which is considered a critical phase in both severe and non-severe dengue cases. Importantly during the critical phase, the levels were significantly higher (P ≤ 0.001) in SD cases compared to DWW, DWOW, and OFI controls. However, at the time of admission (febrile), no such significant changes were observed within dengue, OFI, and healthy controls. SVM analysis revealed that the serum levels of ENG and SDC-1 along with other clinical symptoms could predict the disease severity with 100% accuracy. Based on the results we have proposed a mechanism on how ENG and SDC-1 could be involved in vascular dysfunction rather than just being a biomarker.

Endothelial cells and endothelial progenitor cells in the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive fibrosis, microvasculopathy, and autoimmunity. Endothelial cell (EC) injury and subsequent endothelial cell dysfunction is believed to be an initial event that eventually leads to a vicious pathogenic cycle. This process is further enhanced by defective angiogenesis and vasculogenesis, as the vascular repair machinery does not work properly. Endothelial progenitor cells (EPCs) are functionally and quantitatively insufficient to recover the endothelium in SSc patients. The dysfunctional ECs and EPCs not only trigger the formation of typical vascular lesions, such as progressive intimal fibrosis in small arteries and the loss of capillaries, but also promote a series of inflammatory and profibrotic processes, such as endothelial-mesenchymal transition and recruitment and accumulation of monocytic EPCs with profibrotic properties. These processes together contribute to the accumulation of extracellular matrix in the affected tissue. This review features current insights into the roles of ECs and EPCs in the pathogenesis of SSc.

Hematopoietic-to-mesenchymal transition of adipose tissue macrophages is regulated by integrin β1 and fabricated fibrin matrices

Some bona fide adult adipocytes arise de novo from a bone marrow-derived myeloid lineage. These studies further demonstrate that adipose tissue stroma contains a resident population of myeloid cells capable of adipocyte and multilineage mesenchymal differentiation. These resident myeloid cells lack hematopoietic markers and express mesenchymal and progenitor cell markers. Because bone marrow mesenchymal progenitor cells have not been shown to enter the circulation, we hypothesized that myeloid cells acquire mesenchymal differentiation capacity in adipose tissue. We fabricated a 3-dimensional fibrin matrix culture system to define the adipose differentiation potential of adipose tissue-resident myeloid subpopulations, including macrophages, granulocytes and dendritic cells. Our data show that multilineage mesenchymal potential was limited to adipose tissue macrophages, characterized by the acquisition of adipocyte, osteoblast, chondrocyte and skeletal muscle myocyte phenotypes. Fibrin hydrogel matrices stimulated macrophage loss of hematopoietic cell lineage determinants and the expression of mesenchymal and progenitor cell markers, including integrin β1. Ablation of integrin β1 in macrophages inhibited adipocyte specification. Therefore, some bona fide adipocytes are specifically derived from adipose tissue-resident macrophages via an integrin β1-dependent hematopoietic-to-mesenchymal transition, whereby they become capable of multipotent mesenchymal differentiation. The requirement for integrin β1 highlights this molecule as a potential target for controlling the production of marrow-derived adipocytes and their contribution to adipose tissue development and function.

Minocycline affects human neutrophil respiratory burst and transendothelial migration

OBJECTIVE

This study aimed at investigating the in vitro activity of minocycline and doxycycline on human polymorphonuclear (h-PMN) cell function.

METHODS

h-PMNs were isolated from whole venous blood of healthy subjects; PMN oxidative burst was measured by monitoring ROS-induced oxidation of luminol and transendothelial migration was studied by measuring PMN migration through a monolayer of human umbilical vein endothelial cells. Differences between multiple groups were determined by ANOVA followed by Tukey's multiple comparison test; Student's t test for unpaired data for two groups.

RESULTS

Minocycline (1-300 µM) concentration dependently and significantly inhibited oxidative burst of h-PMNs stimulated with 100 nM fMLP. Ten micromolar concentrations, which are superimposable to C _max following a standard oral dose of minocycline, promoted a 29.8 ± 4 % inhibition of respiratory burst (P < 0.001; n = 6). Doxycycline inhibited ROS production with a lesser extent and at higher concentrations. 10-100 µM minocycline impaired PMN transendothelial migration, with maximal effect at 100 µM (42.5 ± 7 %, inhibition, n = 5, P < 0.001).

CONCLUSIONS

These results added new insight into anti-inflammatory effects of minocycline exerted on innate immune h-PMN cell function.

Tissue engineering strategies for promoting vascularized bone regeneration

This review focuses on current tissue engineering strategies for promoting vascularized bone regeneration. We review the role of angiogenic growth factors in promoting vascularized bone regeneration and discuss the different therapeutic strategies for controlled/sustained growth factor delivery. Next, we address the therapeutic uses of stem cells in vascularized bone regeneration. Specifically, this review addresses the concept of co-culture using osteogenic and vasculogenic stem cells, and how adipose derived stem cells compare to bone marrow derived mesenchymal stem cells in the promotion of angiogenesis. We conclude this review with a discussion of a novel approach to bone regeneration through a cartilage intermediate, and discuss why it has the potential to be more effective than traditional bone grafting methods.

The role of integrin α2 in cell and matrix therapy that improves perfusion, viability and function of infarcted myocardium

Injectable delivery matrices hold promise in enhancing engraftment and the overall efficacy of cardiac cell therapies; however, the mechanisms responsible remain largely unknown. Here we studied the interaction of a collagen matrix with circulating angiogenic cells (CACs) in a mouse myocardial infarction model. CACs + matrix treatment enhanced CAC engraftment, and improved myocardial perfusion, viability and function compared to cells or matrix alone. Integrin-linked kinase (ILK) was up-regulated in matrix-cultured CACs. Integrin α2β1 blocking prevented ILK up-regulation, significantly reduced the adhesion, proliferation, and paracrine properties of matrix-cultured CACs, and negated the benefits of CACs + matrix therapy in vivo. Furthermore, integrin α5 was essential for the angiogenic potential of CACs on matrix. These findings indicate that the synergistic therapeutic effect of CACs + matrix therapy in MI requires the matrix to enhance CAC function via α2β1 and α5 integrin signaling mechanisms, rather than simply delivering the cells.

Peripheral blood stem cells: phenotypic diversity and potential clinical applications

A small proportion of cells in peripheral blood are actually pluripotent stem cells. These peripheral blood stem cells (PBSCs) are thought to be heterogeneous and could be exploited for a variety of clinical applications. The exact number of distinct populations is unknown. It is likely that individual PBSC populations detected by different experimental strategies are similar or overlapping but have been assigned different names. In this mini review, we divide PBSCs into seven groups: hematopoietic stem cells (HSCs), CD34- stem cells, CD14+ stem cells, mesenchymal stem cells (MSCs), very small embryonic-like (VSEL) stem cells, endothelial progenitor cells (EPCs), and other pluripotent stem cells. We review the major characteristics of these stem/progenitor cell populations and their potential applications in ophthalmology.

Phenotypic and functional changes in blood monocytes following adherence to endothelium

Objective

Blood monocytes are known to express endothelial-like genes during co-culture with endothelium. In this study, the time-dependent change in the phenotype pattern of primary blood monocytes after adhering to endothelium is reported using a novel HLA-A2 mistyped co-culture model.

Methods and Results

Freshly isolated human PBMCs were co-cultured with human umbilical vein endothelial cells or human coronary arterial endothelial cells of converse human leukocyte antigen A2 (HLA-A2) status. This allows the tracking of the PBMC-derived cells by HLA-A2 expression and assessment of their phenotype pattern over time. PBMCs that adhered to the endothelium at the start of the co-culture were predominantly CD11b+ blood monocytes. After 24 to 72 hours in co-culture, the endothelium-adherent monocytes acquired endothelial-like properties including the expression of endothelial nitric oxide synthase, CD105, CD144 and vascular endothelial growth factor receptor 2. The expression of monocyte/macrophage lineage antigens CD14, CD11b and CD36 were down regulated concomitantly. The adherent monocytes did not express CD115 after 1 day of co-culture. By day 6, the monocyte-derived cells expressed vascular cell adhesion molecule 1 in response to tumour necrosis factor alpha. Up to 10% of the PBMCs adhered to the endothelium. These monocyte-derived cells contributed up to 30% of the co-cultured cell layer and this was dose-dependent on the PBMC seeding density.

Conclusions

Human blood monocytes undergo rapid phenotype change to resemble endothelial cells after adhering to endothelium.

Dendritic cells the tumor microenvironment and the challenges for an effective antitumor vaccination

Many clinical trials have been carried out or are in progress to assess the therapeutic potential of dendritic-cell- (DC-) based vaccines on cancer patients, and recently the first DC-based vaccine for human cancer was approved by the FDA. Herewith, we describe the general characteristics of DCs and different strategies to generate effective antitumor DC vaccines. In recent years, the relevance of the tumor microenvironment in the progression of cancer has been highlighted. It has been shown that the tumor microenvironment is capable of inactivating various components of the immune system responsible for tumor clearance. In particular, the effect of the tumor microenvironment on antigen-presenting cells, such as DCs, does not only render these immune cells unable to induce specific immune responses, but also turns them into promoters of tumor growth. We also describe strategies likely to increase the efficacy of DC vaccines by reprogramming the immunosuppressive nature of the tumor microenvironment.

Characterization of circulating and monocyte-derived dendritic cells in obese and diabetic patients

Dendritic cells (DCs) are suspected to be involved in the development of atherogenesis, but their role is still unclear. The aim of this study was to characterize circulating DCs and monocyte-derived DCs (Mo-DCs) of obese and diabetic patients (T2D), and to study their interaction with human coronary smooth muscle cells (CASMCs). Obese post-menopausal women with or without insulin resistance were enrolled and were compared to age-matched healthy women. Myeloid circulating DCs significantly increased in obese T2D patients compared to healthy donors and a smaller increase was observed for plasmacytoid one. Mature Mo-DCs from obese T2D patients significantly decreased when compared to control, but they were significantly more capable of adhering to CASMCs compared to that from healthy controls and from not-T2D obese subjects. Altogether these data suggest that in conditions of insulin-resistance and obesity there is an up-regulation of myeloid DCs that might contribute to pathological vascular remodeling.

Human progenitor-derived endothelial cells vs. venous endothelial cells for vascular tissue engineering: an in vitro study

The isolation of endothelial progenitor cells from human peripheral blood generates a great hope in vascular tissue engineering because of particular benefit when compared with mature endothelial cells. We explored the capability of progenitor-derived endothelial cells (PDECs) to line fibrin and collagen scaffolds in comparison with human saphenous and umbilical cord vein endothelial cells (HSVECs and HUVECs): (a) in a static situation, allowing definition of the optimal cell culture conditions with different media and cell-seeding densities to check cell behaviour; (b) under shear stress conditions (flow chambers or tubular vascular constructs), allowing investigation of cell response and mRNA expression on both substrates by oligonucleotide microarray analysis and quantitative real-time PCR. Well characterized PDECs: (a) could not be expanded adequately with the usual mature ECs culture media; (b) were able to colonize and grow on fibrin glue; (c) exhibited higher resistance to oxidative stress than HSVECs and HUVECs; (d) withstood physiological shear stress when lining both substrates in flow chambers, and their gene expression was regulated; (e) colonized a collagen-impregnated vascular prosthesis and were able to sense mechanical forces. Our results provide an improved qualification of PDECs for vascular tissue engineering.

Enhanced angiogenic potency of monocytic endothelial progenitor cells in patients with systemic sclerosis

Introduction

Microvasculopathy is one of the characteristic features in patients with systemic sclerosis (SSc), but underlying mechanisms still remain uncertain. In this study, we evaluated the potential involvement of monocytic endothelial progenitor cells (EPCs) in pathogenic processes of SSc vasculopathy, by determining their number and contribution to blood vessel formation through angiogenesis and vasculogenesis.

Methods

Monocytic EPCs were enriched and enumerated using a culture of peripheral blood mononuclear cells and platelets on fibronectin in 23 patients with SSc, 22 patients with rheumatoid arthritis (RA), and 21 healthy controls. To assess the capacity of monocytic EPCs to promote vascular formation and the contribution of vasculogenesis to this process, we used an in vitro co-culture system with human umbilical vein endothelial cells (HUVECs) on Matrigel^® and an in vivo murine tumor neovascularization model.

Results

Monocytic EPCs were significantly increased in SSc patients than in RA patients or healthy controls (P = 0.01 for both comparisons). Monocytic EPCs derived from SSc patients promoted tubular formation in Matrigel^® cultures more than those from healthy controls (P = 0.007). Transplantation of monocytic EPCs into immunodeficient mice resulted in promotion of tumor growth and blood vessel formation, and these properties were more prominent in SSc than healthy monocytic EPCs (P = 0.03 for both comparisons). In contrast, incorporation of SSc monocytic EPCs into the tubular structure was less efficient in vitro and in vivo, compared with healthy monocytic EPCs.

Conclusions

SSc patients have high numbers of aberrant circulating monocytic EPCs that exert enhanced angiogenesis but are impaired in vasculogenesis. However, these cells apparently cannot overcome the anti-angiogenic environment that characterizes SSc-affected tissues.