Trombose arterial recorrente em paciente com doença de Fabry: relato de caso / Recurrent arterial thrombosis in a patient with Fabry disease: case report

Resumo A doença de Fabry é definida como uma doença rara de depósito lisossomal ligada ao cromossomo X que apresenta sintomas multissistêmicos, incluindo comprometimento vascular com eventos trombóticos. Paciente do sexo feminino, 57 anos, com diagnóstico de doença de Fabry há 11 anos, apresentava hiperidrose, hipoacusia e angioqueratoma nas mãos. Na história patológica pregressa, relatou episódio de acidente vascular encefálico isquêmico prévio aos 40 anos de idade e trombose arterial crônica agudizada em membro inferior direito há 1 ano, a qual foi tratada por meio de angioplastia com uso de stent, apresentando melhora temporária e recente recidiva do quadro. Os eventos trombóticos se enquadram nos sintomas típicos da doença de Fabry, e são resultantes do depósito de globotriaosilceramida no endotélio vascular, implicando em um estado pró-trombótico, justificando a reincidência dos sintomas e da trombose arterial em membro inferior.

Abstract Fabry disease is a rare disease, defined as an X-linked lysosomal deposition disease that presents with multisystemic symptoms, including vascular impairment with thrombotic events. A 57-year-old female patient diagnosed with Fabry disease 11 years previously, presented with hyperhidrosis, hypoacusis, and angiokeratoma on the hands. Her previous pathological history included an episode of ischemic stroke before the age of 40 years and chronic acute thrombosis in the right lower limb, 1 year previously, which had been treated with stent angioplasty, with temporary improvement followed by recent relapse of the condition. Thrombotic events fit the typical symptoms of Fabry disease and are caused by deposition of globotriaosylceramide in the vascular endothelium, constituting a prothrombotic state and explaining the recurrence of symptoms and arterial thrombosis in the lower limb.

A Tie2 kinase mutation causing venous malformations increases phosphorylation rates and enhances cooperativity.

The endothelial receptor tyrosine kinase Tie2 plays an important role in vascular formation and maintenance. Mutations in Tie2 lead to vascular malformations, which are painful vascular lesions that cause disfigurement, bleeding, and thrombosis. R849W Tie2 is the most common mutation implicated in an inherited form of vascular malformations and has been shown to be activating, though little is known about the kinetic features of catalysis. Here we undertake a steady-state kinetic analysis of heterologously expressed and purified wild type (WT) and R849W Tie2. While the catalytic efficiencies of the two forms are not significantly different, the observed maximal rate of phosphorylation, kcat,obs, is > 3-fold higher for R849W Tie2 compared to WT. Notably, steady-state catalysis by R849W Tie2 has more striking sigmoidal features compared to WT, suggesting enhanced positive cooperativity. We propose that activating catalytic features are one important consequence of the R849W mutation, though likely other factors such as increased protein binding affinity also contribute to the phenotypes observed in patients.

Cardiovascular development and survival require Mef2c function in the myocardial but not the endothelial lineage.

MEF2C is a member of the highly conserved MEF2 family of transcription factors and is a key regulator of cardiovascular development. In mice, Mef2c is expressed in the developing heart and vasculature, including the endothelium. Loss of Mef2c function in germline knockout mice leads to early embryonic demise and profound developmental abnormalities in the cardiovascular system. Previous attempts to uncover the cause of embryonic lethality by specifically disrupting Mef2c function in the heart or vasculature failed to recapitulate the global Mef2c knockout phenotype and instead resulted in relatively minor defects that did not compromise viability or result in significant cardiovascular defects. However, previous studies examined the requirement of Mef2c in the myocardial and endothelial lineages using Cre lines that begin to be expressed after the expression of Mef2c has already commenced. Here, we tested the requirement of Mef2c in the myocardial and endothelial lineages using conditional knockout approaches in mice with Cre lines that deleted Mef2c prior to onset of its expression in embryonic development. We found that deletion of Mef2c in the early myocardial lineage using Nkx2-5Cre resulted in cardiac and vascular abnormalities that were indistinguishable from the defects in the global Mef2c knockout. In contrast, early deletion of Mef2c in the vascular endothelium using an Etv2::Cre line active prior to the onset of Mef2c expression resulted in viable offspring that were indistinguishable from wild type controls with no overt defects in vascular development, despite nearly complete early deletion of Mef2c in the vascular endothelium. Thus, these studies support the idea that the requirement of MEF2C for vascular development is secondary to its requirement in the heart and suggest that the observed failure in vascular remodeling in Mef2c knockout mice results from defective heart function.

Fisiopatología de la enfermedad de Fabry / The pathophysiology of Fabry disease

La enfermedad de Fabry es una entidad lisosomal de expresión clínica sistémica, causada por el depósito tisular de globotriaosilceramida, debido a un déficit en su degradación. Como en la mayoría de las enfermedades lisosomales, la existencia de una mutación en un gen no explica las alteraciones fisiopatológicas que presentan los pacientes. Se realiza una revisión exhaustiva de los mecanismos patogénicos que acontecen en la enfermedad de Fabry (AU)

Fabry disease is a lysosomal condition with systemic clinical expression, caused by the tissue deposit of globotriaosylceramide, due to a deficit in its degradation. As with most lysosomal diseases, the presence of a mutation in a gene does not explain the pathophysiological disorders shown by patients. We conducted a comprehensive review of the pathogenic mechanisms that occur in Fabry disease (AU)

Testicular Hypoplasia Is Driven by Defective Vascular Formation.

OBJECTIVE: To determine if vanishing testis could result from a fault in embryological development as a result of an arrest in endothelial cell migration rather than secondary to just a random physical torsion/twist. A testicular nubbin or vanishing testis is considered to be secondary to a neonatal torsion and is usually associated with a hemosiderin deposit. MATERIALS AND METHODS: Cases of vanishing testis excision were compared with age-matched controls from cadaveric testes without known genitourinary pathology. To assess the testis microvasculature, we performed immunohistochemistry using an automated staining platform with controlled and standardized conditions and positive and negative controls. We used cluster of differentiation (CD) 34 to stain blood vessel endothelium, stem cells, and interstitium; CD31 (all endothelium); and D2-40 for lymphatic endothelium. Morphometric analysis was carried out, % of the total tissue with CD31 and CD34 positive stain was assessed, and the number of the lymphatic vessels (D2-40) per mm2 was counted. RESULTS: Of the 10 cases, 7 had evidence of hemosiderin deposit and calcification. The % distribution of CD34 in controls was higher, 13.4 ± 3.1 (mean ± standard deviation), compared to nubbin cases, 4.5 ± 2.9 (P ≤ .001). The % distribution of CD31 was 2.8 ± 0.83 in controls compared to 1.31 ± 0.60 in cases (P ≤ .001). The lymphatic distribution was similar in both groups, cases (6.4 ± 4.3 n/mm2) and controls (6.4 ± 1.7 n/mm2) (P = .99) CONCLUSION: This histopathological study suggests that disturbances in endothelial development may be a contributing factor leading to testicular hypoplasia and a resultant nubbin testis, independent of a physical torsion event.

Pulp Obliteration in a Patient with Sclerodermatous Chronic Graft-versus-Host Disease.

Dental pulp calcification is a common finding associated with localized dental trauma, genetic disorders, and systemic inflammatory diseases. Chronic graft-versus-host disease (cGVHD) is a frequent complication after allogeneic hematopoietic cell transplantation (allo-HCT) characterized by immune-mediated injury to the skin, mouth, eyes, liver, and other tissues, resulting in significant disability and reduced quality of life. We report a patient with sclerodermatous cGVHD who presented with general pulp calcification in all teeth 5 years after allo-HCT. A review of full mouth dental radiographs obtained just before allo-HCT revealed normal-appearing pulp chambers. Based on prior reports of generalized pulp calcification associated with progressive systemic sclerosis, we hypothesized that the etiology was likely related to the presence of cGVHD with associated vascular and fibrotic tissue changes within the pulp vasculature. Clinicians should consider cGVHD in the differential diagnosis of generalized pulp calcification.

Associação entre periodontite e disfunção endotelial: parâmetros clínicos periodontais e níveis dos marcadores inflamatórios IL-1ß, TNF-α, MMP2 e óxido nítrico / Association between periodontitis and Endothelial dysfunction: periodontal clinical parameters and levels of inflammatory markers IL-1ß, TNF-α, MMP2 and nitric oxide

Objetivos: A periodontite aumenta o risco das doenças cardiovasculares ateroscleróticas (DCA) e ambas doenças apresentam mecanismos fisiopatológicos semelhantes. A disfunção endotelial (DE) é um parâmetro precoce das DCA e sua associação com a periodontite foi pouco investigada até o presente momento. Neste contexto o objetivo geral deste estudo foi avaliar a associação entre a periodontite e a disfunção endotelial por meio de parâmetros clínicos periodontais e a presença dos marcadores inflamatórios IL-1ß, TNF-α, MMP2/TIMP2 e óxido nítrico. Métodos: A amostra foi constituída por 47 indivíduos de ambos os gêneros, sem alterações sistêmicas conhecidas, divididos em dois grupos: um grupo com 24 indivíduos com periodontite crônica e outro com 23 indivíduos sem periodontite crônica. Foram realizados exames periodontais de sangramento a sondagem (SS), profundidade de sondagem (PS), nível de inserção clínica (NIC) e avaliada a DE por meio da dilatação mediada por fluxo (DMF) da artéria braquial. A concentração dos mediadores inflamatórios IL-1ß, TNF-α, MMP2/TIMP2 foi avaliada pelo método ELISA e o óxido nítrico (ON) pela reação de Griess na saliva. Resultados: Os indivíduos com periodontite apresentaram significativamente maior DE quando comparados com indivíduos sem periodontite (p= 0,034 após hiperemia reativa e p= 0,049 após nitrato sublingual). Em relação aos mediadores inflamatórios avaliados, houve uma associação significativa entre a produção de MMP2/TIMP2 com a presença de periodontite (p=0,008) além de uma correlação positiva com todos parâmetros clínicos de gravidade da inflamação periodontal avaliados (PS, NIC, SS). Para os demais marcadores (IL-1ß, TNF-α e ON) os grupos com e sem periodontite apresentaram resultados similares. Foi identificada também uma correlação positiva significativa entre a produção de ON e uma menor DE (após hiperemia reativa p= 0,027 e após nitrato sublingual p=0,016). . Conclusão: Indivíduos com periodontite apresentaram maior DE, expressa por menor % de DMF da artéria braquial e maiores níveis de MMP2/TIMP2 que indivíduos sem periodontite. O ON foi significativamente associado com uma menor DE

Background: The periodontitis and atherosclerotic cardiovascular diseases (ACD) are chronic diseases which have a large number of risk factors and inflammatory mediators in common. The ACD has endothelial dysfunction (ED) with an important role in the initiation and progression of atherosclerosis. However, few investigations were conducted on a possible association between periodontitis and higher ED. In this context the general aim of this study is to evaluate the association between the endothelial function and the periodontitis using periodontal clinical parameters and the presence of inflammatory markers IL-1ß, TNF-α, MMP2 and nitric oxide. Methods: This study consisted of 47 subjects of both genders, systemically healthy divided into two groups: a group with 24 subjects with chronic periodontitis and another with 23 subjects without chronic periodontitis. Were done complete periodontal examination and evaluated ED by the flow-mediated dilatation (FMD) of the brachial artery and measured the levels of systemic inflammation mediators IL1ß, TNF-α, MMP2 and the nitric oxide (NO) in the saliva. Results: The subjects with periodontitis showed % DMF significantly worse when compared with subjects without periodontitis (p= 0.034 after reactive hyperemia and p= 0.049 after sublingual nitrate), thus subjects with periodontitis showed significantly higher ED. In relation to inflammatory mediators evaluated, there was a significant association between MMP2 with the presence of periodontitis (p=0.008) and a positive correlation with all clinical parameters of periodontal variation. For the other markers (IL-1ß, TNF-α, and nitric oxide) the groups with and without periodontitis showed similar results. It was also identified a significant positive correlation between the nitric oxide and a better endothelial function. Conclusion: subjects with periodontitis showed higher ED, expressed by smaller % of DMF brachial artery and higher levels of MMP2 that subjects without periodontitis

MST kinases in development and disease.

The mammalian MST kinase family, which is related to the Hippo kinase in Drosophila melanogaster, includes five related proteins: MST1 (also called STK4), MST2 (also called STK3), MST3 (also called STK24), MST4, and YSK1 (also called STK25 or SOK1). MST kinases are emerging as key signaling molecules that influence cell proliferation, organ size, cell migration, and cell polarity. Here we review the regulation and function of these kinases in normal physiology and pathologies, including cancer, endothelial malformations, and autoimmune disease.

Nuevas perspectivas en el tratamiento de enfermedades retinianas con aflibercept / No disponible

No disponible

Flt-1 (vascular endothelial growth factor receptor-1) is essential for the vascular endothelial growth factor-Notch feedback loop during angiogenesis.

OBJECTIVE: Vascular endothelial growth factor (VEGF) signaling induces Notch signaling during angiogenesis. Flt-1/VEGF receptor-1 negatively modulates VEGF signaling. Therefore, we tested the hypothesis that disrupted Flt-1 regulation of VEGF signaling causes Notch pathway defects that contribute to dysmorphogenesis of Flt-1 mutant vessels. APPROACH AND RESULTS: Wild-type and flt-1(-/-) mouse embryonic stem cell-derived vessels were exposed to pharmacological and protein-based Notch inhibitors with and without added VEGF. Vessel morphology, endothelial cell proliferation, and Notch target gene expression levels were assessed. Similar pathway manipulations were performed in developing vessels of zebrafish embryos. Notch inhibition reduced flt-1(-/-) embryonic stem cell-derived vessel branching dysmorphogenesis and endothelial hyperproliferation, and rescue of flt-1(-/-) vessels was accompanied by a reduction in elevated Notch targets. Surprisingly, wild-type vessel morphogenesis and proliferation were unaffected by Notch suppression, Notch targets in wild-type endothelium were unchanged, and Notch suppression perturbed zebrafish intersegmental vessels but not caudal vein plexuses. In contrast, exogenous VEGF caused wild-type embryonic stem cell-derived vessel and zebrafish intersegmental vessel dysmorphogenesis that was rescued by Notch blockade. CONCLUSIONS: Elevated Notch signaling downstream of perturbed VEGF signaling contributes to aberrant flt-1(-/-) blood vessel formation. Notch signaling may be dispensable for blood vessel formation when VEGF signaling is below a critical threshold.

Resolution of defective dorsal aortae patterning in Sema3E-deficient mice occurs via angiogenic remodeling.

BACKGROUND: Neuronal guidance cues influence endothelial cell (EC) behavior to shape the embryonic vascular system. The repulsive neuronal guidance cue, Semaphorin 3E (Sema3E), is critical for creating avascular zones that instruct and subsequently pattern the first embryonic vessels, the paired dorsal aortae (DA). Sema3E(-) (/) (-) embryos develop highly branched plexus-like vessels during vasculogenesis, instead of smooth paired vessels. Unexpectedly, despite these severe DA patterning defects, mutant mice are viable throughout adulthood. RESULTS: Examination of Sema3E(-) (/) (-) mice reveals that the plexus-like DA resolve into single, unbranched vessels between embryonic day (E) E8.25 and E8.75. Although fusion of Sema3E(-) (/) (-) DA occurs slightly earlier than in heterozygotes, the DA are otherwise indistinguishable, suggesting a complete "rescue" in their development. Resolution of the DA null plexuses occurs by remodeling rather than by means of changes in cell proliferation or death. CONCLUSIONS: Normalization of Sema3E(-) (/) (-) DA patterning defects demonstrates resilience of embryonic vascular patterning programs. Additional repulsive guidance cues within the lateral plate mesoderm likely re-establish avascular zones lost in Sema3E(-) (/) (-) embryos and guide resolution of mutant plexus into branchless, parallel aortae. Our observations explain how Sema3E(-) (/) (-) mice survive throughout development and into adulthood, despite severe initial vascular defects.

Disfunción endotelial y diabetes mellitus / Endothelial dysfunction and diabetes mellitus

Introducción: la disfunción endotelial se presenta con frecuencia en los individuos con diabetes mellitus, debido a que las alteraciones vasculares que aparecen en esta enfermedad y que son provocadas por la hiperglucemia crónica, facilitan su aparición, a lo cual puede contribuir también la hipertensión arterial y la dislipidemia que se presentan en los diabéticos. Objetivo: describir algunos eventos implicados en la aparición de la disfunción endotelial en la diabetes mellitus, y aspectos relacionados con su diagnóstico y tratamiento. Desarrollo: entre los marcadores más importantes de disfunción endotelial en la diabetes mellitus se encuentran, la elevación de las moléculas de adhesión celular y de marcadores de inflamación, la microalbuminuria, la hiperhomocisteinemia, y el incremento de la hemoglobina glucosilada, de la endotelina-1 y del estrés oxidativo. Para el diagnóstico de disfunción endotelial se utilizan la medición de sustancias reguladoras de biofunciones sintetizadas por el endotelio y de otras reconocidas como marcadores de disfunción endotelial, y pruebas indirectas, algunas de las cuales son invasivas; y para su tratamiento, disímiles medidas terapéuticas medicamentosas o no. Conclusiones: es importante identificar la disfunción endotelial tempranamente en los diabéticos y tratarla, en caso de estar presente(AU)

Introduction: endothelial dysfunction frequently appears in individuals with diabetes mellitus, because vascular alterations derived from chronic hyperglycemia facilitate the occurrence of the disease, to which blood hypertension and dislipidemia of diabetics also contribute. Objective: to describe some events involved in the onset of endothelial dysfunction in diabetes mellitus and several aspects related to diagnosis and treatment. Development: among the most important markers of endothelial dysfunction in diabetes mellitus are the rises of cell adhesion molecules and inflammation markers, microalbuminuria, hyperhomocysteinemia and the increase of glycated hemoglobin, of endothelin-1 and of oxidative stress. For the diagnosis, one uses the measurement of regulating substances of biofunctions synthesized by the endothelium and by others recognized as endothelial dysfunction markers, and indirect tests some of which are invasive. For the treatment, various therapeutic methods, either drug-based or not, are used. Conclusions: it is important to early identify endothelial dysfunction in diabetics and treat it as appropriate(AU)

Lack of endothelial diaphragms in fenestrae and caveolae of mutant Plvap-deficient mice.

Plasmalemmal vesicle-associated protein (PLVAP, PV-1) is specifically expressed in endothelial cells in which it localizes to diaphragms of fenestrae, caveolae, and transendothelial channels. To learn about its function, we generated mutant mice that lack PLVAP. In a C57BL/6N genetic background, homozygous Plvap-deficient embryos die before birth and suffer from subcutaneous edema, hemorrhages, and defects in the vascular wall of subcutaneous capillaries. In addition, hearts of Plvap(-/-) embryos show ventricular septal defects and thinner ventricular walls. In wild-type embryos, PLVAP and caveolae with a stomatal diaphragm are present in endothelial cells of subcutaneous capillaries and endocardium, while a diaphragm is missing in caveolae of Plvap(-/-) littermates. Plvap(-/-) mice in a mixed C57BL/6N/FVB-N genetic background are born and survive at the most for 4 weeks. Capillaries of exocrine and endocrine pancreas and of kidney peritubular interstitium were investigated in more detail as examples of fenestrated capillaries. In these vascular beds, Plvap(-/-) mice show a complete absence of diaphragms in fenestrae, caveolae, and transendothelial channels, findings which are associated with a substantial decrease in the number of endothelial fenestrae. The changes in the capillary phenotype correlate with a considerable retardation of postnatal growth and anemia. Plvap(-/-) mice provide an animal model to clarify the specific functional role of endothelial fenestrae and their contribution to passage of water and solutes in different organs.

Sulfotransferase Ndst1 is needed for mandibular and TMJ development.

Heparan sulfate proteoglycans (HS-PGs) regulate several developmental processes, but their possible roles in mandibular and TMJ formation are largely unclear. To uncover such roles, we generated mice lacking Golgi-associated N-sulfotransferase 1 (Ndst1) that catalyzes sulfation of HS-PG glycosaminoglycan chains. Ndst1-null mouse embryos exhibited different degrees of phenotypic penetrance. Severely affected mutants lacked the temporomandibular joint and condyle, but had a mandibular remnant that displayed abnormal tooth germs, substandard angiogenesis, and enhanced apoptosis. In mildly affected mutants, the condylar growth plate was dysfunctional and exhibited thicker superficial and polymorphic cell zones, a much wider distribution of Indian hedgehog signaling activity, and ectopic ossification along its lateral border. Interestingly, mildly affected mutants also exhibited facial asymmetry resembling that seen in individuals with hemifacial microsomia. Our findings indicate that Ndst1-dependent HS sulfation is critical for mandibular and TMJ development and allows HS-PGs to exert their roles via regulation of Ihh signaling topography and action.

Early vascular phenotypes in the genesis of hypertension.

Cardiovascular complications occurring in adults find their roots in risk factors operating early in life. Among the factors influencing cardiovascular risk, blood pressure values in children represent an important measurable marker of the level of potential cardiovascular risk later in life because the levels are both the cause and the consequence of early vascular alterations. Early vascular phenotypes represent a field of great interest, and they can be studied through indirect assessment using non-invasive techniques. Estimations of blood pressure components, pulse wave velocity, and reflecting waves provide valuable information that can be easily recorded and repeated overtime. A direct assessment, carried out by examining the umbilical vessels, can add further valuable information. In this review, we discuss the potential application of surrogate markers of early vascular alterations and describe the information provided by umbilical cord vessels.

A influência dos ácidos graxos trans na disfunção da célula endotelial e o possível efeito terapêutico do exercício sobre o tecido endotelial como forma de prevenção ou regressão da aterosclerose / Influence of trans fatty acids on endothelial cell dysfunction and possible therapeutic effects of physical activity on endothelial tissue for prevention or regression of atherosclerosis

O endotélio atua ativamente na regulação do tônus vascular, sintetizando e liberando substâncias vasoativas. A inflamação e os fatores de risco cardiovasculares alteram a homeostase vascular, levando à disfunção endotelial e possível formação de placas de ateroma. O aumento das concentrações plasmáticas de ácidos graxos livres pode causar lipotoxicidade vascular, disfunção do endotélio e, finalmente, aterosclerose. Dieta rica em lipídeos contendo ácidos graxos trans tem correlação positiva com a progressão de doenças cardiovasculares. Mudanças no estilo de vida, na adoção de dieta balanceada e atividade física são estratégias para a prevenção de doenças cardiovasculares e a reabilitação de pacientes. Nesta revisão, discutimos a influência benéfica do exercício físico em aspectos importantes da disfunção endotelial causados pelos ácidos graxos trans, incluindo evidências recentes e/ou ainda não exploradas. Discutimos também quais seriam os mecanismos envolvidos no comprometimento funcional da célula endotelial frente ao aumento de ácidos graxos trans na circulação.

The endothelium actively participates in the regulation of vascular tone through the synthesis and release of vasoactive mediators. Inflammation and cardiovascular risk factors affect vascular homeostasis, causing endothelial dysfunction and atheromatous plaque formation. Increased free fatty acid concentrations may result in vascular lipotoxicity, endothelium dysfunction and, ultimately, atherosclerosis. A lipid-rich diet including trans fatty acids has a positive correlation with the progression of cardiovascular diseases. Lifestyle changes, such as eating a well-balanced diet and participating in regular physical activity, have been proposed to prevent cardiovascular diseases and improve rehabilitation. In this review, we discuss the beneficial effects of regular exercise on important aspects of endothelial dysfunction caused by trans fatty acids, including recent and/or yet-to-be-described evidence. The discussion also comprehends the mechanisms involved in endothelial cell dysfunction due to increased trans fatty acid concentrations.

Malachite green induces cardiovascular defects in developing zebrafish (Danio rerio) embryos by blocking VEGFR-2 signaling.

Malachite green (MG) is a triphenyl methane dye used in various fields that demonstrates high toxicity to bacteria and mammalian cells. When bud stage zebrafish embryos were treated with MG at 125, 150, and 175ppb for 14h, the development of trunk including intersomitic vessels was inhibited in MG-treated flk-1-GFP transgenic embyos. MG clearly induced whole growth retardation. MG induced severe cell death in trunk intersomite region of zebrafish embryos and in human vascular endothelial cells in a dose-dependent manner. MG inhibited heart rates and cardiac looping. MG attenuated whole blood formation and inhibited vascular endothelial growth factor (VEGF)-induced receptor (R)-2 phosphorylation in vascular endothelial cells. In conclusion, MG significantly alters the cardiovascular development causing growth retardation in zebrafish through the blocking VEGFR-2 activation in early cardiovascular development. It suggests that MG may be an environmental toxic agent with the potential to induce embryonic cardiovascular defects in vertebrates.

Understanding tumor endothelial cell abnormalities to develop ideal anti-angiogenic therapies.

Tumor angiogenesis is necessary for solid tumor progression and metastasis. Tumor blood vessels have been shown to differ from their normal counterparts, for example, by changes in morphology. An important concept in tumor angiogenesis is that tumor endothelial cells are assumed to be genetically normal, even though these endothelial cells are structurally and functionally abnormal. To date, many anti-angiogenic drugs have been developed, but, their therapeutic efficacy is not dramatic and they have also been reported to cause toxic side effects. To develop ideal antiangiogenic therapies, understanding tumor endothelial cell abnormalities is important. We have isolated tumor endothelial cells from mouse tumor xenografts and have shown that tumor-associated endothelial cells are abnormal. Tumor-associated endothelial cells upregulate many genes, such as epidermal growth factor receptor (EGFR). Tumor-associated endothelial cells are also more sensitive to EGF. They also have relatively large, heterogeneous nuclei. Unexpectedly, tumor endothelial cells are cytogenetically abnormal. Fluorescence in situ hybridization (FISH) analysis showed that freshly isolated uncultured tumor endothelial cells were aneuploid and had abnormal multiple centrosomes. The degree of aneuploidy was exacerbated by passage in culture. In marked contrast, freshly isolated normal skin and adipose endothelial cells were diploid. They had normal centrosomes and remained cytogenetically stable in culture even up to 20 passages. We conclude that tumor endothelial cells can acquire cytogenetic abnormalities while in the tumor microenvironment. Questions as to whether or not tumor endothelial cells become resistant to antiangiogenic drugs are thus raised. Our preliminary data show that tumor endothelial cells are more resistant to certain chemotherapeutic drugs. Studies to evaluate the mechanism for cytogenetic abnormalities in tumor endothelial cells are underway. It is becoming quite clear that the tumor vasculature is much more complex and unpredictable than initially perceived. Here, we provide an overview of the current studies on tumor endothelial cell abnormalities.

EGFL7 regulates the collective migration of endothelial cells by restricting their spatial distribution.

During sprouting angiogenesis, groups of endothelial cells (ECs) migrate together in units called sprouts. In this study, we demonstrate that the vascular-specific secreted factor EGFL7 regulates the proper spatial organization of ECs within each sprout and influences their collective movement. In the homozygous Egfl7-knockout mice, vascular development is delayed in many organs despite normal EC proliferation, and 50% of the knockout embryos die in utero. ECs in the mutant vasculatures form abnormal aggregates and the vascular basement membrane marker collagen IV is mislocalized, suggesting that ECs fail to recognize the proper spatial position of their neighbors. Although the migratory ability of individual ECs in isolation is not affected by the loss of EGFL7, the aberrant spatial organization of ECs in the mutant tissues decreases their collective movement. Using in vitro and in vivo analyses, we showed that EGFL7 is a component of the interstitial extracellular matrix deposited on the basal sides of sprouts, a location suitable for conveying positional information to neighboring ECs. Taken together, we propose that EGFL7 defines the optimal path of EC movement by assuring the correct positioning of each EC in a nascent sprout.