Surface markers: An identity card of endothelial cells.

All endothelial cells have the common characteristic that they line the vessels of the blood circulatory system. However, endothelial cells display a large degree of heterogeneity in the function of their location in the vascular tree. In this article, we have summarized the expression patterns of a number of well-accepted endothelial surface markers present in normal microvascular endothelial cells, arterial and venous endothelial cells, lymphatic endothelial cells, tumor endothelial cells, and endothelial precursor cells.

RNAscope dual ISH-IHC technology to study angiogenesis in diffuse large B-cell lymphomas.

Diffuse large B-cell lymphomas (DLBCLs) are the most common types of Non-Hodgkin's lymphomas and are highly heterogeneous in terms of phenotype and treatment response. The natural course of DLBCLs tumor progression is featured by a flow of events leading to the enhancement of proliferative and invasive capabilities and, therefore, towards the establishment of a more aggressive phenotype. Angiogenesis is a constant hallmark of DLBCLs progression, has prognostic potential and promote DLBCLs dissemination. The study of DLBCLs angiogenesis mechanisms, and the tumor endothelium characterization, will allow us to identify new prognostic/predictive biomarkers to proper patient selection to antiangiogenic treatment. In our previous work, by RNAscope technology, we have demonstrated that Janus kinase (Jak) and signal transducer activator of transcription pathway (STAT) is one of the proangiogenic pathways activated in DLBCLs and it drives neoangiogenesis occurred by vasculogenesis mechanism. Here, we describe a detailed protocol to perform RNAscope technology alone and in combination with immunohistochemistry (called dual RNAscope ISH-IHC) in DLBCLs formalin-fixed, paraffin-embedded sections. We propose dual ISH-IHC as an extremely powerful method to study angiogenesis in DLBCLs, because it allows one to answer important biological questions that are difficult to address using other single methods.

Morphometric analysis of the branching of the vascular tree in the chick embryo area vasculosa.

The chick embryo includes the area vasculosa is subdivided into 2 concentric zones, the inner transparent area pellucida vasculosa and the surrounding less transparent area opaca vasculosa, peripherally limited by the sinus terminalis. In this study, we have analyzed by a modern morphometric approach the total length of the vascular network, the number of vascular branches, of the branching points density, the modality of vessel ramification, and spatial arrangement of the vascular network in four consecutive stages of development of the area vasculosa. The results have shown that there is a significant 15% increase in the total length of the vascular network associated with a progressive increase of the number of vascular branches and of the branching points density. Moreover, the results indicated that vascular spatial disorder significantly decreased during development in area vasculosa, suggesting a more uniform occupancy of the tissue by the vascular pattern. Finally, a more regular pattern of branching was observed, as indicated by the significant decrease of topological disorder of the vascular tree.

Erythropoietin in tumor angiogenesis.

Erythropoietin (EPO) is a moonlighting protein since is ability to work as hormone, cytokine and growth factor. Its cardinal function is to regulate erythropoiesis in the bone marrow. However, EPO with his receptor EPOR are expressed also in non-hematopoietic tissues such as endothelium where they exert a protective function. Moreover, it is known EPO-EPOR pathway contribute to neovascularization in the angiogenic switch of tumor, but the mechanism is not completely established. In this article, after a brief introduction on tumor angiogenesis and description of classical and non-classical pro-angiogenic factors, we review the role of EPO in tumor angiogenesis highlighting the different mechanisms activated by it to promote tumor growth and progression. Finally, we analyze the controversy between the beneficial and the harmful effects of EPO. We suppose that the accurate characterization of EPO variants and their downstream pathways will allow to develop specific inhibition strategies to block only EPOR expressed by tumor cells without inducing signalling in hematopoietic cells to avoid side effects.

Vascular Wall as Source of Stem Cells Able to Differentiate into Endothelial Cells.

The traditional view of the vascular biology is changed by the discovery of vascular progenitor cells in bone marrow or peripheral blood Further complexity is due to the findings that the vessel walls harbor progenitor and stem cells, called vascular wall-resident vascular stem cells (VW-VSCs), able to differentiate to mature vascular wall cells. These immature stem/progenitor cell populations and multipotent mesenchymal lineage participate in postnatal neovascularization and vascular wall remodeling. Further studies are necessary to deepen the knowledge on characterization and biology of VW-VSCs, in particular of endothelial progenitor cells (EPCs) in order to improve their use in clinical settings for regenerative approaches.

Inflammatory cells infiltrate and angiogenesis in locally advanced and metastatic cholangiocarcinoma.

BACKGROUND: Cholangiocarcinoma (CCA) is the second most common subtype of primary hepatobiliary cancer and one of the most aggressive characterized by an extremely poor prognosis with limited treatment options. Inflammatory cells in tumour microenvironment support tumour growth in term of progression, angiogenesis and metastatic capacity. A link between inflammation and biliary carcinogenesis has been previously observed but the mechanisms involved remain to be determined. METHODS: We investigated the microvascular density (MVD) and inflammatory cells in tissue samples from 40 patients with CCA with locally advanced CCA and metastatic CCA by means of immunohistochemical analysis of macrophages, mast cells, B and T lymphocytes and we correlated inflammatory infiltrate with MVD. RESULTS: We observed significant decrease in the levels of CD31 positive vessels, and CD8, CD4, CD68 and tryptase-positive cells in metastatic lesions as compared to the localized ones. A negative correlation between CD31 and CD8 and CD31 and CD4 in localized CCA samples was found as assessed by Spearman correlation analysis. CONCLUSIONS: In locally advanced CCA patients, there is a significant increase of immune cell infiltrate constituted by CD8+ and CD4+ lymphocytes, macrophages and mast cells as compared to the metastatic ones. This alteration in the tumour microenvironment infiltrate is related to a significant increased MVD in localized CCA lesions compared with the metastatic ones. Moreover, we observed a negative correlation between MVD and CD8+ , CD4+ cells in localized CCA patients.

PTX3 Modulates Neovascularization and Immune Inflammatory Infiltrate in a Murine Model of Fibrosarcoma.

Fibrosarcoma is an aggressive subtype of soft tissue sarcoma categorized in infantile/congenital-type and adult-type. Fibrosarcoma cells and its surrounding immune inflammatory infiltrates overexpress or induce the expression of fibroblast growth factor-2 (FGF-2) that have a crucial role in tumor progression and angiogenesis. The inflammation-associated long pentraxin 3 (PTX3) was found to reduce FGF-2-mediated angiogenesis, but its role on fibrosarcoma immune inflammatory infiltrate is still unknown. In this study, we have evaluated the PTX3 activity on immune infiltrating mast cells, macrophages and T-lymphocytes by immunohistochemistry on murine MC-TGS17-51 fibrosarcoma cells and on transgenic TgN(Tie2-hPTX3) mouse. In these fibrosarcoma models we found a reduced neovascularization and a significant decrease of inflammatory infiltrate. Indeed, we show that PTX3 reduces the level of complement 3 (C3) deposition reducing fibrosarcoma progression. In conclusion, we hypothesize that targeting fibrosarcoma microenvironment by FGF/FGFR inhibitors may improve treatment outcome.

Dp71 Expression in Human Glioblastoma.

BACKGROUND: Dp71 is the most abundant dystrophin (DMD) gene product in the nervous system. Mutation in the Dp71 coding region is associated with cognitive disturbances in Duchenne muscular dystrophy (DMD) patients, but the function of dystrophin Dp71 in tumor progression remains to be established. This study investigated Dp71 expression in glioblastoma, the most common and aggressive primary tumor of the central nervous system (CNS). METHODS: Dp71 expression was analyzed by immunofluorescence, immunohistochemistry, RT-PCR, and immunoblotting in glioblastoma cell lines and cells isolated from human glioblastoma multiforme (GBM) bioptic specimens. RESULTS: Dp71 isoform was expressed in normal human astrocytes (NHA) cell lines and decreased in glioblastoma cell lines and cells isolated from human glioblastoma multiforme bioptic specimens. Moreover, Dp71 was localized in the nucleus in normal cells, while it was localized into the cytoplasm of glioblastoma cells organized in clusters. We have shown, by double labeling, that Dp71 colocalizes with lamin B in normal astrocytes cells, confirming the roles of Dp71 and lamin B in maintaining nuclear architecture. Finally, we demonstrated that decreased Dp71 protein in cells isolated from human bioptic specimens was inversely correlated with the Ki-67 tumor proliferative index. CONCLUSION: A decreased Dp71 expression is associated with cancer proliferation and poor prognosis in glioblastoma.

Mast cells and primary systemic vasculitides.

Vasculitides are characterized by inflammation and necrosis of blood vessels leading to vessel occlusion and ischemic damages of tissues. Among the inflammatory cells involved in vasculitides, neutrophils, T cells, and macrophages have been identified as the predominant cell type. This review article is focused on the role of mast cells in these chronic inflammatory processes. Mast cells are characterized by their complex plasticity. Increasing evidences document that mast cells exert both pro- and anti-inflammatory functions depending on the cell types and the microenvironment they reside in. In this context, mast cell mediators able to modulate progression of vasculitides at different levels and the anatomic localization of mast cells in different vasculitides will be described. Finally, therapeutic approach including inhibition of recruitment of mast cells to the inflammatory infiltrate and blockade of their proinflammatory effects and proangiogenic functions as potential new targets for the treatment of these diseases will be discussed.

Rhu-Epo down-regulates pro-tumorigenic activity of cancer-associated fibroblasts in multiple myeloma.

We have previously demonstrated that recombinant human erythropoietin (rHuEpo) is involved in the regulation of the angiogenic response in multiple myeloma (MM) through a direct effect on macrophages and endothelial cells isolated from the bone marrow of patients with MM. The aim of the present study was designed to determine the effects of rHuEpo on cancer-associated fibroblasts (CAFs) from monoclonal gammopathy of undetermined significance (MGUS) and MM patients by means of in vitro and in vivo assays. rHuEpo treatment reduces the expression of mRNA levels of fibroblast activation markers, namely alpha smooth actin (αSMA) and fibroblast activation protein (FAP) in MGUS and MM CAFs, and of pro-inflammatory and pro-angiogenic cytokines, including interleukin (IL)-6 and IL-8, vascular endothelial growth factor-A (VEGF-A), fibroblast growth factor-2 (FGF-2), and hepatocyte growth factor (HGF) in MM CAFs. Moreover, rHuEpo inhibits the proliferative activity of MM CAFs and increased the apoptosis of MGUS and MM CAFs. Overall, these data suggest that rHu-Epo down-regulates CAFs pro-tumorigenic activity. Moreover, these results are not suggestive for a pro-angiogenic activity of rHuEpo on CAFs. In fact, rHuEpo pre-treatment induces a low angiogenic response in vivo in the chorioallantoic membrane (CAM) assay of MGUS and MM CAFs conditioned medium, not comparable to that of a well-known angiogenic cytokine, VEGF-A, tested in the same assay.

Spatial distribution of mast cells and macrophages around tumor glands in human breast ductal carcinoma.

Macrophages and mast cells are usually present in the tumor microenvironment and play an important role as regulators of inflammation, immunological response and angiogenesis in the tumor microenvironment. In this study, we have evaluated macrophage, mast cell, and microvessel density in a selected group of different grade of invasive breast carcinoma tumor specimens. Furthermore, we have investigated the pattern of distribution of CD68-positive macrophages and tryptase-positive mast cells around tumor glands. Results have shown that: A) Macrophages are more numerous in G2 and G3 breast cancer stages respect to controls, the per cent of macrophages in G1 samples was comparable to the controls, and the spatial relationship between macrophages and glands (as indicated by the mean cell-to-gland distance) correlated with CD31-positive vessels. B) Mast cells in G2 and G3 tumor specimens show a significant increase in their number as compared to control samples, and their spatial distribution around the glands did not show any significant difference among groups. Overall, the results of this study confirm the important role of macrophages and mast cells in tumor progression and angiogenesis in human ductal breast cancer, and pointed out the spatial relationship between tumor macrophages and glands, and its correlation with microvascular density.

Isolation and characterization of neural stem cells from dystrophic mdx mouse.

The blood-brain barrier (BBB) is altered in mdx mouse, an animal model to study Duchenne muscular dystrophy (DMD). Our previous work demonstrated that perivascular glial endfeet control the selective exchanges between blood and neuropil as well as the BBB development and integrity; the alterations of dystrophin and dystrophin-associated protein complex (DAPs) in the glial cells of mdx mouse, parallel damages of the BBB and increase in vascular permeability. The aim of this study was to improve our knowledge about brain cellular components in the mdx mouse through the isolation, for the first time, of the adult neural stem cells (ANSCs). We characterized them by FACS, electron microscopy, confocal immunofluorescence microscopy, Real Time-PCR and western blotting, and we studied the expression of the DAPs aquaporin-4 (AQP4), potassium channel Kir4.1, α- and ß-dystroglycan (αDG, ßDG), α-syntrophin (αSyn), and short dystrophin isoform Dp71 proteins. The results showed that the mdx ANSCs expressed CD133 and Nestin receptor as the control ones, but showed a reduction in Notch receptor and altered cell proliferation with an increment in the apoptotic nuclei. Ultrastructurally, they appeared 50% size reduced compared to control ones, with a few cytoplasmic organelles. Moreover, the mdx ANSCs are devoid in full length dystrophin 427, and they expressed post-transcriptional reduction in the Dp71 in parallel with the ubiquitin proteasome activation, and decrement of DAPs proteins which appeared diffused in the cytoplasm and not polarized on the stem cells plasmamembrane, as prevalently observed in the controls. Overall, these results indicate that structural and molecular alterations affect the neural stem cells in the dystrophic brain, whose increased apoptosis and reduced Dp71 and DAPs proteins expression, together with loss in Dp427 dystrophin, could be responsible of the altered mdx glial maintenance and differentiation and consequent failure in the vessels barrier control occurring in the adult dystrophic brain.

Angiogenic activity in vivo of the particulate matter (PM10).

BACKGROUND: Particulate matter (PM) is the most efficient vehicle for the inhalation and absorption of toxic substances into the body. METHOD: The present study was aimed at testing the hypothesis that PM10 samples collected on quartz filters exert an angiogenic activity in vivo in the chick embryo chorioallantoic membrane (CAM) assay. RESULTS: When the low, medium, and high PM10 concentrations filters were tested in the CAM assay, an increasing number of microvessels was detectable after 4 days of applications of the filters. Moreover, at histological level, numerous microvessels and a dense inflammatory infiltrate were recognizable in the CAM mesenchyme. CONCLUSION: Our data show a clear dose-response relationship between the dose variable (PM10 and Bap) and the outcome variable. So far, the PM10 target value is determined on the basis of regulatory agreements and is not health-based. In addition, the mere gravimetric measure of PM10 cannot be considered a fully reliable surrogate of the overall toxicity of the mixture.

A fractal analysis of the spatial distribution of tumoral mast cells in lymph nodes and bone marrow.

The spatial distribution of mast cells inside the tumor stroma has been little investigated. In this study, we have evaluated tumor mast cells distribution through the analysis of the morphological features of the spatial patterns generated by these cells, including size, shape, and architecture of the cell pattern. We have compared diffuse large B cells lymphoma (DLBCL) and systemic mastocytosis in two different anatomical localizations (lymph nodes for DLBCL and, respectively, bone marrow for mastocytosis). Results have indicated that, despite the high difference in size exhibited by the mast cells patterns in the two conditions, the spatial relationship between the mast cells forming the aggregates resulted similar, characterized by a significant tendency of the mast cells to self-organize in clusters.

Myeloma cells act as tolerogenic antigen-presenting cells and induce regulatory T cells in vitro.

Regulatory T cells (Tregs) are essential for maintenance of self-tolerance; however, tumor cells can exploit the tolerance to escape the immune system. We investigated the Tregs frequency in patients with multiple myeloma (MM) and in those with monoclonal gammopathy of undetermined significance (MGUS), and found that CD4(+) FoxP3(+) and CD8(+) FoxP3(+) Tregs were significantly increased in patients with MM and correlated with the active phase. Both Tregs subsets were expanded in cocultures of CD3(+) lymphocytes and fresh CD138(+) MM plasma cells or RPMI8226 and U266 cell lines and functioned as natural (n) and inducible (i) Tregs insofar as they inhibited the proliferation of stimulated CD3 lymphocytes via contact-dependent and contact-independent pathways. Induction of Tregs by MM plasma cells required a contact-dependent pathway, implying antigen recognition by T cells. MM plasma cells acted as immature and tolerogenic antigen-presenting cells (APCs), in that they displayed low CD80/CD86 expression associated with a phagocytic activity. By acting as immature APCs, MM plasma cells plausibly expand (n)Tregs and (i)Tregs both through conversion of CD3(+) FoxP3(-) into CD3(+) FoxP3(+) T cells and proliferation of CD3(+) FoxP3(+) T cells, which may suppress the anti-MM immune response.

Effects of prednisolone on the dystrophin-associated proteins in the blood-brain barrier and skeletal muscle of dystrophic mdx mice.

The mdx mouse, the most widely used animal model of Duchenne muscular dystrophy (DMD), develops a seriously impaired blood-brain barrier (BBB). As glucocorticoids are used clinically to delay the progression of DMD, we evaluated the effects of chronic treatment with α-methyl-prednisolone (PDN) on the expression of structural proteins and markers in the brain and skeletal muscle of the mdx mouse. We analyzed the immunocytochemical and biochemical expression of four BBB markers, including endothelial ZO-1 and occludin, desmin in pericytes, and glial fibrillary acidic protein (GFAP) in glial cells, and the expression of the short dystrophin isoform Dp 71, the dystrophin-associated proteins (DAPs), and aquaporin-4 (AQP4) and α-ß dystroglycan (DG) in the brain. We evaluated the BBB integrity of mdx and PDN-treated mdx mice by means of intravascular injection of horseradish peroxidase (HRP). The expression of DAPs was also assessed in gastrocnemius muscles and correlated with utrophin expression, and laminin content was measured in the muscle and brain. PDN treatment induced a significant increase in the mRNA and protein content of the BBB markers; a reduction in the phosphorylation of occludin in the brain and of AQP4/ß DG in both tissues; an increase of Dp71 protein content; and an increase of both mRNA and protein levels of the AQP4/α-ß DG complex. The latter was associated with enhanced laminin and utrophin in the muscle. The HRP assay demonstrated functional restoration of the BBB in the PDN-treated mdx mice. Specifically, mdx mice showed extensive perivascular labeling due to escape of the marker, while HRP was exclusively intravascular in the PDN-treated mice and the controls. These data illustrate for the first time that PDN reverses the BBB alterations in the mdx mouse and re-establishes the proper expression and phosphorylation of ß-DG in both the BBB and skeletal muscle. Further, PDN partially protects against muscle damage. The reduction in AQP4 and occludin phosphorylation, coupled with their anchoring to glial and endothelial membranes in PDN-treated mice, suggests that the drug may target the glial and endothelial cells. Our results suggest a novel mechanism for PDN action on cerebral and muscular function, restoring the link between DAPs and the extracellular matrix, most likely through protein kinase inactivation.

Erythropoietin is involved in the angiogenic potential of bone marrow macrophages in multiple myeloma.

Erythropoietin (Epo) is the crucial cytokine regulator of red blood cell production, and recombinant human erythropoietin (rHuEpo) is widely used in clinical practice for the treatment of anemia, primarily in kidney disease and in cancer. Increasing evidence suggests several biological roles for Epo and its receptor, Epo-R, unrelated to erythropoiesis, including angiogenesis. Epo-R has been found expressed in various non-haematopoietic cells and tissues, and in cancer cells. Here, we detected the expression of Epo-R in bone marrow-derived macrophages (BMMAs) from multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS) patients and assessed whether Epo/Epo-R axis plays a role in MM macrophage-mediated angiogenesis. We found that Epo-R is over-expressed in BMMAs from MM patients with active disease compared to MGUS patients. The treatment of BMMAs with rHuEpo significantly increased the expression and secretion of key pro-angiogenic mediators, such as vascular endothelial growth factor, hepatocyte growth factor and monocyte chemotactic protein (MCP-1/CCL-2), through activation of JAK2/STAT5 and PI3 K/Akt pathways. In addition, the conditioned media harvested from rHuEpo-treated BMMAs enhanced bone marrow-derived endothelial cell migration and capillary morphogenesis in vitro, and induced angiogenesis in the chorioallantoic membrane of chick embryos in vivo. Furthermore, we found an increase in the circulating levels of several pro-angiogenic cytokines in serum of MM patients with anemia under treatment with Epo. Our findings highlight the direct effect of rHuEpo on macrophage-mediated production of pro-angiogenic factors, suggesting that Epo/Epo-R pathway may be involved in the regulation of angiogenic response occurring in MM.

Evidences for insulator activity of the 5'UTR of the Drosophila melanogaster LTR-retrotransposon ZAM.

Insulators or chromatin boundary are DNA elements that organize the genome into discrete regulatory domains by limiting the actions of enhancers and silencers through a "positional-blocking mechanism". The role of these sequences, both in modulation of the enhancers range of action (enhancer-promoter selectivity) and in the organization of the chromatin in functional domains, is emerging strongly in these last years. There is a great interest in identifying new insulators because deeper knowledge of these elements can help understand how cis-regulatory elements coordinate the expression of the target genes. However, while insulators are critical in gene regulation and genome functioning, only a few have been reported so far. Here, we describe a new insulator sequence that is located in the 5'UTR of the Drosophila retrotransposon ZAM. We have used an "enhancer-blocking assay" to test its effects on the activity of the enhancer in transiently transfected Drosophila S2R(+) cell line. Moreover, we show that the new insulator is able to affect significantly the enhancer-promoter interaction in the human cell line HEK293. These results suggest the possibility of employing the ZAM insulator in gene transfer protocols from insects to mammals in order to counteract the transgene positional and genotoxic effects.

STAT3, tumor microenvironment, and microvessel density in diffuse large B cell lymphomas.

Constitutively activated STAT3 is correlated with more advanced clinical stage and overall poor survival of diffuse large B-cell lymphoma (DLBCL). The aim of this study was to evaluate STAT3 and Ki67 tumor cell expression, inflammatory cell infiltration, microvascular density in DLBCL bioptic specimens. RNA-scope showed that activated B cell (ABC) tissue samples contained a significant higher number of STAT3+ cells as compared to germinal center B (GCB) tissue samples. Immunohistochemical analysis showed a significant increased levels of CD3, CD8, CD68, CD163, CD34, and Ki67 positive cells in ABC patients. A positive correlation between STAT3 and CD3, CD8, CD68, and CD163 was evidenced in ABC group. In ABC group, we found also a positive correlation between CD8 and CD34 and a positive correlation between Ki67 and, CD68, and CD163. These data indicate that in ABC-as compared to GCB-DLBCL, a higher STAT3 expression is associated with a higher CD163+ TAM and CD8+ cell infiltration which induces a strong angiogenic response.