Angiogenesis is coming of age

Individual variability of vascularization of the anterior papillary muscle within the right ventricle of human heart

Background

To date there is scarce published evidence reporting the dual blood supply reaching anterior papillary muscle (APM), which descends from both major coronary arteries. Such a vascular configuration can prevent the dysfunction of right ventricular entire valvular system in case of the occlusion of proximal part of either right coronary artery (RCA) or left coronary artery (LCA). The aim of our study was to determine the vascular pattern of APM blood supply which originates from two main coronary arteries, in the context of the APM and septomarginal trabecula (SMT) topography.

Methods

The study was carried out using tissue obtained from 36 human hearts. The material was divided into four morphological types of SMT/APM arrangement. Vascularization and blood supply pattern of papillary muscle was investigated following the analysis of multiple tissue cross sections. The origin of APM arterial supply was traced back to both main coronary arteries. Cross-sectional area of the arteries was estimated at the base of APM and compared within mixed male-female population, aged 18–76.

Results

We noted that as much as 78% of entire APM material had a blood supply vasculature originating from both LCA and RCA branches. In contrast, 22% of cases APM was supplied by a single coronary artery, while in each case it proved to be LCA. We have never found APM arterial supply provided exclusively by RCA. In case of double AMP blood supply an average of total cross-section area of the arteries branching from LCA, was noted to be in excess of two and a half times bigger in type III and more than two times bigger in type IV, as compared with the arteries originating from RCA.

Conclusions

Our research confirm the possibility of double blood supply which vascularizes APM, but the finding does not necessarily apply in all cases. However, APM seems to be predominantly vascularized by arteries deriving from LCA, regardless of their morphological type.

Inflammation and vascular remodeling in the ventral hippocampus contributes to vulnerability to stress

During exposure to chronic stress, some individuals engage in active coping behaviors that promote resiliency to stress. Other individuals engage in passive coping that is associated with vulnerability to stress and with anxiety and depression. In an effort to identify novel molecular mechanisms that underlie vulnerability or resilience to stress, we used nonbiased analyses of microRNAs in the ventral hippocampus (vHPC) to identify those miRNAs differentially expressed in active (long-latency (LL)/resilient) or passive (short-latency (SL)/vulnerable) rats following chronic social defeat. In the vHPC of active coping rats, miR-455-3p level was increased, while miR-30e-3p level was increased in the vHPC of passive coping rats. Pathway analyses identified inflammatory and vascular remodeling pathways as enriched by genes targeted by these microRNAs. Utilizing several independent markers for blood vessels, inflammatory processes and neural activity in the vHPC, we found that SL/vulnerable rats exhibit increased neural activity, vascular remodeling and inflammatory processes that include both increased blood-brain barrier permeability and increased number of microglia in the vHPC relative to control and resilient rats. To test the relevance of these changes for the development of the vulnerable phenotype, we used pharmacological approaches to determine the contribution of inflammatory processes in mediating vulnerability and resiliency. Administration of the pro-inflammatory cytokine vascular endothelial growth factor-164 increased vulnerability to stress, while the non-steroidal anti-inflammatory drug meloxicam attenuated vulnerability. Collectively, these results show that vulnerability to stress is determined by a re-designed neurovascular unit characterized by increased neural activity, vascular remodeling and pro-inflammatory mechanisms in the vHPC. These results suggest that dampening inflammatory processes by administering anti-inflammatory agents reduces vulnerability to stress. These results have translational relevance as they suggest that administration of anti-inflammatory agents may reduce the impact of stress or trauma in vulnerable individuals.

Detection of pancreatic ductal adenocarcinoma in mice by ultrasound imaging of thymocyte differentiation antigen 1

BACKGROUND & AIMS

Early detection of pancreatic ductal adenocarcinoma (PDAC) allows for surgical resection and increases patient survival times. Imaging agents that bind and amplify the signal of neovascular proteins in neoplasms can be detected by ultrasound, enabling accurate detection of small lesions. We searched for new markers of neovasculature in PDAC and assessed their potential for tumor detection by ultrasound molecular imaging.

METHODS

Thymocyte differentiation antigen 1 (Thy1) was identified as a specific biomarker of PDAC neovasculature by proteomic analysis. Up-regulation in PDAC was validated by immunohistochemical analysis of pancreatic tissue samples from 28 healthy individuals, 15 with primary chronic pancreatitis tissues, and 196 with PDAC. Binding of Thy1-targeted contrast microbubbles was assessed in cultured cells, in mice with orthotopic PDAC xenograft tumors expressing human Thy1 on the neovasculature, and on the neovasculature of a genetic mouse model of PDAC.

RESULTS

Based on immunohistochemical analyses, levels of Thy1 were significantly higher in the vascular of human PDAC than chronic pancreatitis (P = .007) or normal tissue samples (P < .0001). In mice, ultrasound imaging accurately detected human Thy1-positive PDAC xenografts, as well as PDACs that express endogenous Thy1 in genetic mouse models of PDAC.

CONCLUSIONS

We have identified and validated Thy1 as a marker of PDAC that can be detected by ultrasound molecular imaging in mice. The development of a specific imaging agent and identification of Thy1 as a new biomarker could aid in the diagnosis of this cancer and management of patients.

Fractal analysis of extra-embryonic vascularization in Japanese quail embryos exposed to extremely low frequency magnetic fields

Magnetic fields (MF) can alter the dynamic behavior of vascular tissue and may have a stimulatory or inhibitory effect on blood vessel growth. Fractal geometry has been used in several studies as a tool to describe the development of blood vascular networks. Due to its self-similarity, irregularity, fractional dimension, and dependence on the scale of vessel dimensions, vascular networks can be taken as fractal objects. In this work, we calculated the fractal dimension by the methods of box counting (D(bc)) and information dimension (D(inf)) to evaluate the development of blood vessels of the yolk sac membrane (YSM) from quail embryos exposed to MF with a magnetic flux density of 1 mT and a frequency of 60 Hz. The obtained results showed that when the MF was applied to embryos aged between 48 and 72 h, in sessions of 2 h (6 h/day) and 3 h (9 h/day) with exposure intervals between 6 and 5 h, respectively, blood vascular formation was inhibited. Exposure sessions shorter than 2 h or longer than 3 h had no observable change on the vascular process. In contrast, the magnetic field had no observable change on the YSM vascular network for embryos aged between 72 and 96 h, irrespective of the exposure time. In conclusion, these results show a "window effect" regarding exposure time.

The feasibility of low mechanical index contrast enhanced ultrasound (CEUS) in distinguishing malignant from benign thoracic lesions

We proposed to assess the feasibility of low mechanical index (MI) contrast enhanced ultrasound (CEUS) in the characterisation of thoracic lesions. Fifty patients were prospectively examined by CEUS and images acquired on a low MI (0.17-0.24) setting following injection of SonoVue. From region-of-interest (ROI) generated signal intensity (SI) time curves, the maximum SI, bolus arrival time (BAT), time to peak intensity (TTP), wash-in slope and mean transit time (MTT) were calculated. Using the Wilcoxon rank test; parameters and threshold values for positive differentiation were determined. In addition, for the parameters that allowed positive differentiation between malignant and benign lesions receiver operator curves (ROC) were obtained. The wash-in slope, TTP and MTT (p = 0.0003, <0.0001, 0.02) allowed positive differentiation. The sensitivity and specificity was 93% and 78%, with 6.87 s(-1) threshold value for the wash-in slope, 78% and 89% with 11.84 s threshold for the TTP and 48% and 89% with 78.6 s threshold for the MTT. CEUS is a useful tool for differentiating malignant and benign thoracic lesions.

Recent advances in anti-angiogenic therapy of cancer

Since angiogenesis is critical for tumor growth and metastasis, anti-angiogenic treatment is a highly promising therapeutic approach. Thus, for over last couple of decades, there has been a robust activity aimed towards the discovery of angiogenesis inhibitors. More than forty anti-angiogenic drugs are being tested in clinical trials all over the world. This review discusses agents that have approved by the FDA and are currently in use for treating patients either as single-agents or in combination with other chemotherapeutic agents.

Stem cells and scaffolds for vascularizing engineered tissue constructs

The clinical impact of tissue engineering depends upon our ability to direct cells to form tissues with characteristic structural and mechanical properties from the molecular level up to organized tissue. Induction and creation of functional vascular networks has been one of the main goals of tissue engineering either in vitro, for the transplantation of prevascularized constructs, or in vivo, for cellular organization within the implantation site. In most cases, tissue engineering attempts to recapitulate certain aspects of normal development in order to stimulate cell differentiation and functional tissue assembly. The induction of tissue growth generally involves the use of biodegradable and bioactive materials designed, ideally, to provide a mechanical, physical, and biochemical template for tissue regeneration. Human embryonic stem cells (hESCs), derived from the inner cell mass of a developing blastocyst, are capable of differentiating into all cell types of the body. Specifically, hESCs have the capability to differentiate and form blood vessels de novo in a process called vasculogenesis. Human ESC-derived endothelial progenitor cells (EPCs) and endothelial cells have substantial potential for microvessel formation, in vitro and in vivo. Human adult EPCs are being isolated to understand the fundamental biology of how these cells are regulated as a population and to explore whether these cells can be differentiated and reimplanted as a cellular therapy in order to arrest or even reverse damaged vasculature. This chapter focuses on advances made toward the generation and engineering of functional vascular tissue, focusing on both the scaffolds - the synthetic and biopolymer materials - and the cell sources - hESCs and hEPCs.

The role of CXC chemokines in pulmonary fibrosis

The CXC chemokine family is a pleiotropic family of cytokines that are involved in promoting the trafficking of various leukocytes, in regulating angiogenesis and vascular remodeling, and in promoting the mobilization and trafficking of mesenchymal progenitor cells such as fibrocytes. These functions of CXC chemokines are important in the pathogenesis of pulmonary fibrosis and other fibroproliferative disorders. In this Review, we discuss the biology of CXC chemokine family members, specifically as it relates to their role in regulating vascular remodeling and trafficking of circulating mesenchymal progenitor cells (also known as fibrocytes) in pulmonary fibrosis.

In-vitro and in-vivo assays for angiogenesis-modulating drug discovery and development

In the past 35 years, significant findings have been made in relation to angiogenesis, and how this usually normal physiological function is converted into an abnormal state in cancer. To search for agents that can inhibit angiogenesis, and thereby prevent a tumour from proliferation and spread that is ultimately fatal to the patient, various in-vitro assays have been developed. In addition, older assays have been refined usually into high throughput screening formats, mainly by the biopharmaceutical industry in their attempts to develop novel therapeutic molecules and maintain a pipeline of lead candidates. The central aim is to extract more accurate data that would facilitate the birth of innovative mechanisms to defeat aberrant angiogenesis in-vivo. At the same time, better in-vivo models have been established, with the goal to mimic as close as possible the natural progression of various types of neoplasms in response to a good angiogenic response. More clinically relevant models are needed as anti-angiogenesis drug discovery and drug development companies fast track their lead molecules from preclinical investigations to phase I clinical trials.

Cancer CXC chemokine networks and tumour angiogenesis

Chemokines have pleiotropic effects in regulating immunity, angiogenesis, stem cell trafficking, and mediating organ-specific metastases of cancer. In the context of angiogenesis, the CXC chemokine family is a unique group of cytokines known for their ability to behave in a disparate manner in the regulation of angiogenesis. The glutamic acid-leucine-arginine (ELR+) CXC chemokines are potent promoters of angiogenesis, and mediate their angiogenic activity via signal-coupling of CXCR2 on endothelium. By contrast, members of the CXC chemokine family, such as platelet factor-4 (PF4; CXCL4) and interferon-inducible CXC chemokines are potent inhibitors of angiogenesis, and use CXCR3 on endothelium to mediate their angiostatic activity. This review will discuss the biology of CXC chemokines in the context of angiogenesis related to cancer.

CXC chemokines in angiogenesis

CXC chemokines display pleiotropic effects in immunity, regulating angiogenesis, and mediating organ-specific metastases of cancer. In the context of angiogenesis, CXC chemokines are a unique family of cytokines, known for their ability to behave in a disparate manner in the regulation of angiogenesis. Members that contain the 'ELR' motif are potent promoters of angiogenesis, and mediate their angiogenic activity via binding and activating CXCR2 on endothelium. In contrast, members, in general, those are inducible by interferons and lack the ELR motif (ELR-) are potent inhibitors of angiogenesis, and bind to CXCR3 on endothelium. This review will discuss the biology of these angiogenic and angiostatic CXC chemokines and discuss their disparate angiogenic activity in the context of a variety of disorders.

TGFβ/BMP activate the smooth muscle/bone differentiation programs in mesoangioblasts

Mesoangioblasts are vessel-derived stem cells that can be induced to differentiate into different cell types of the mesoderm such as muscle and bone. The gene expression profile of four clonal derived lines of mesoangioblasts was determined by DNA micro-array analysis: it was similar in the four lines but different from 10T1/2 embryonic fibroblasts, used as comparison. Many known genes expressed by mesoangioblasts belong to response pathways to developmental signalling molecules, such as Wnt or TGFβ/BMP. Interestingly, mesoangioblasts express receptors of the TGFβ/BMP family and several Smads and, accordingly, differentiate very efficiently into smooth muscle cells in response to TGFβ and into osteoblasts in response to BMP. In addition, insulin signalling promotes adipogenic differentiation, possibly through the activation of IGF-R. Several Wnts and Frizzled, Dishevelled and Tcfs are expressed, suggesting the existence of an autocrine loop for proliferation and indeed, forced expression of Frzb-1 inhibits cell division. Mesoangioblasts also express many neuro-ectodermal genes and yet undergo only abortive neurogenesis, even after forced expression of neurogenin 1 or 2, MASH or NeuroD. Finally, mesoangioblasts express several pro-inflammatory genes, cytokines and cytokine receptors, which may explain their ability to be recruited by tissue inflammation. Our data define a unique phenotype for mesoangioblasts, explain several of their biological features and set the basis for future functional studies on the role of these cells in tissue histogenesis and repair.

Case-control study of use of nonsteroidal antiinflammatory drugs and glioblastoma multiforme

Evidence from epidemiologic and experimental studies suggests that use of nonsteroidal antiinflammatory drugs (NSAIDs) reduces risk of colon and breast cancer. The association between use of aspirin and other NSAIDs and risk of adult glioblastoma multiforme (GBM) was evaluated among 236 incident GBM cases and 401 population-based controls frequency-matched on age, gender, and ethnicity from the San Francisco Bay Area Adult Glioma Study. Cases (or proxies) and controls were interviewed in person between May 1997 and August 2000. Cases with self-reported GBM reported less use of at least 600 pills of all types of NSAIDs combined during the 10-year prediagnostic period than did controls (odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.3, 0.8). Findings were consistent for aspirin (OR = 0.51, 95% CI: 0.3, 0.8), ibuprofen (OR = 0.41, 95% CI: 0.2, 0.8), and naproxen/other NSAIDs (OR = 0.34, 95% CI: 0.1, 0.8). GBM cases also reported less use of acetaminophen than did controls (OR = 0.51, 95% CI: 0.3, 1.0). Eliminating participants who initiated NSAID use within 2 years of diagnosis yielded similar results. These findings show an inverse association between NSAID use and GBM. Further studies are warranted to determine whether NSAIDs might be effective in the inhibition of GBM development or progression.

Del1 mediates VSMC adhesion, migration, and proliferation through interaction with integrin alpha(v)beta(3)

Del1 is a matrix protein transiently expressed by embryonic endothelial cells. It was recently demonstrated that vascular endothelial cells adhere and interact with Del1 through alpha(v)beta(3)- integrins, providing an autocrine angiogenic signaling pathway in this cell type. To determine whether Del1 might signal to other cell types in the vessel wall in a paracrine fashion, studies were conducted with vascular smooth muscle cells (VSMC). Del1 promoted adhesion and migration of VSMC in a dose-dependent fashion. These functions were mediated through alpha(v)beta(3)-integrins, as the vitronectin receptor inhibitory peptide containing penacillamine (PCN) arginine-glycine-aspartic acid (PCN-RGD) and an antibody specific for the alpha(v)beta(3)-integrin specifically blocked both adhesion and migration. Adhesion of VSMC to Del1 was associated with organization of actin filaments and formation of focal contacts enriched in vinculin and alpha(v)beta(3). Furthermore, Del1 supported VSMC proliferation at least in part by inhibiting these cells from undergoing apoptosis. These data, in conjunction with evidence that Del1 expression is reactivated in vascular injury, suggest that Del1 may have a paracrine role in vessel wall development and remodeling.

[The mechanisms of angiogenesis. Medical and therapeutic applications]

PURPOSE

Endothelial and smooth muscle cells interact with each other to form new blood vessels. In this review, the cellular and molecular mechanism underlying the formation of the primary vascular plexus (vasculogenesis), the sprouting of further blood vessels (angiogenesis) and their maturation via recruitment of smooth muscle cells (arteriogenesis) during physiological and pathological conditions are summarized.

CURRENT KNOWLEDGE AND KEY POINT

The concept of angiogenesis is studied in tumoral and cardiovascular pathology. Promoting the formation of new collateral vessels in ischemic tissues using angiogenic growth factors (therapeutic angiogenesis) is a promising approach in cardiovascular diseases. Conversely, inhibition of the action of key regulators of angiogenesis is a new pathway for the treatment of solid tumors and metastasis.

FUTURE PROSPECTS AND PROJECTS

These concepts are being tested now in clinical trials in the oncology or cardiovascular fields. Some trials are reported in this review with their potential adverse effects, limits and developments in the future.

Angiogenesis in the pathogenesis of inflammatory joint and lung diseases

This paper reviews hypotheses about roles of angiogenesis in the pathogenesis of inflammatory disease in two organs, the synovial joint and the lung. Neovascularisation is a fundamental process for growth and tissue repair after injury. Nevertheless, it may contribute to a variety of chronic inflammatory diseases, including rheumatoid arthritis, osteoarthritis, asthma, and pulmonary fibrosis. Inflammation can promote angiogenesis, and new vessels may enhance tissue inflammation. Angiogenesis in inflammatory disease may also contribute to tissue growth, disordered tissue perfusion, abnormal ossification, and enhanced responses to normal or pathological stimuli. Angiogenesis inhibitors may reduce inflammation and may also help to restore appropriate tissue structure and function.

Immunohistochemical localization of vascular endothelial growth factor, transforming growth factor alpha, and transforming growth factor beta1 in human corneas with neovascularization

PURPOSE

To analyze presence and distribution of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)alpha, and TGFbeta1 in human corneas with neovascularization due to different corneal diseases.

METHODS

Indirect immunohistochemistry for VEGF, TGFalpha, and TGFbeta1, was performed on paraffin-embedded corneas obtained by keratoplasty. Corneas from each of the four main groups of histopathologic diagnoses associated with corneal neovascularization were analyzed (scarring after keratitis, graft rejection/insufficiency, acute necrotizing keratitis, scarring after mechanical/chemical injury). Subclassification of inflammatory infiltrates was done using immunohistochemistry for CD3 (T-lymphocytes) and CD68 (macrophages).

RESULTS

The analyzed angiogenic factors were detectable in corneas from all four histopathologic groups in a similar distribution; capillary endothelial cells, stromal and intravascular inflammatory cells (T-lymphocytes, macrophages), and basal corneal epithelial cells stained positive for the tested angiogenic factors.

CONCLUSION

The angiogenic factors VEGF, TGFalpha, and TGFbeta1 are detectable in human corneas with neovascularization. Their distribution is quite uniform in different corneal diseases, resulting in corneal angiogenesis. An antiangiogenic therapy inhibiting corneal neovascularization by antagonizing angiogenic factors would have to counteract several angiogenic factors.

Mechanical signalling and angiogenesis. The integration of cell-extracellular matrix couplings

In vitro angiogenesis assays have shown that the couplings between fibrin gel and cell traction forces trigger biogel pre-patterning, consisting, in the formation of lacunae which evolve toward capillary-like structures (CLS) networks. Depending on the experimental conditions (number of seeded cells, gel elasticity,...), this pre-patterning can be enhanced or inhibited. A theoretical model based on a description of the cell-biogel biochemical and mechanical interactions is proposed as a basis for understanding how integrating these interactions can lead to the pre-patterning of the biogel. We showed that the critical parameter values corresponding to the bifurcation of the model solutions correspond to threshold values of the experimental variables. Furthermore, simulations of the mechanocellular model give rise to dynamic remodelling patterns of the biogel which are in good agreement both with the lacunae morphologies and with the time and space scales derived from the in vitro angiogenesis assays. Special attention has been paid in the simulations to cell proteolytic activity and to the amplitude of cell traction forces. We finally discussed how modelling guided experiments can be inferred from these results.

Increased blood vessel density in decidua parietalis is associated with spontaneous human first trimester abortion

Spontaneous pregnancy loss affects 15-18% of couples, and a number of potential causes are being discussed. The purpose of the present study was to assess if angiogenic disorders in the decidua of early human pregnancy could be related to spontaneous abortions. First trimester human decidua from elective terminations of normally progressing pregnancies and from missed abortions were investigated immunohistochemically. We quantified vessel density in decidua from normal pregnancies and from abortions by von Willebrand factor (vWF), platelet endothelial cell adhesion molecule (PECAM-1) and CD34 staining. Decidual blood vessel expression of alphavbeta3 integrin was also investigated. Significant increase (P < 0.02) in vessel density was observed in decidua parietalis of abortions, compared to decidua basalis. This increase was detected on slides stained for vWF and CD34, but not for PECAM-1. We observed a 15% increase analysing with vWF and a 77% increase with CD34 staining. alphavbeta3 integrin expression was not significantly different, neither in decidua parietalis from abortion, nor parietalis from normal pregnancies. Our data suggest that the increased vascularization in decidua parietalis from abortions could reflect complex disorders, such as specific cytokine expressions and hypoxia phenomena during the development of the decidua.

Is extravasation a Fas-regulated process?

The monolayer of endothelial cells that coats the luminal surface of the vessel wall has numerous physiological functions, including the prevention of coagulation, control of vascular permeability, maintenance of vascular tone and regulation of leukocyte extravasation. Recently, we detected functional Fas ligand (FasL) expression on the endothelial lining of blood vessels. FasL induces apoptotic cell death in the multitude of cell types that express its receptor, Fas. Here, we review the function of vascular endothelium in controlling leukocyte extravasation, and illustrate how the regulation of endothelial FasL expression might contribute to this process. We also describe the role of leukocyte extravasation in angiogenesis and atherosclerosis, and we suggest that FasL gene transfer might provide a means of treating diseases of the proliferative vessel wall, particularly those that result from the detrimental infiltration of inflammatory cells.