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14 p.-6 fig., Background: The circulating form of human endoglin (sEng) is a cleavage product of membrane-bound endoglin present on endothelial cells. Because sEng encompasses an RGD motif involved in integrin binding, we hypothesized that sEng would be able to bind integrin αIIbβ3, thereby compromising platelet binding to fibrinogen and thrombus stability., Methods: In vitro human platelet aggregation, thrombus retraction, and secretion-competition assays were performed in the presence of sEng. Surface plasmon resonance (SPR) binding and computational (docking) analyses were carried out to evaluate protein-protein interactions. A transgenic mouse overexpressing human sEng (hsEng+) was used to measure bleeding/rebleeding, prothrombin time (PT), blood stream, and embolus formation after FeCl3-induced injury of the carotid artery., Results: Under flow conditions, supplementation of human whole blood with sEng led to a smaller thrombus size. sEng inhibited platelet aggregation and thrombus retraction, interfering with fibrinogen binding, but did not affect platelet activation. SPR binding studies demonstrated that the specific interaction between αIIbβ3 and sEng and molecular modeling showed a good fitting between αIIbβ3 and sEng structures involving the endoglin RGD motif, suggesting the possible formation of a highly stable αIIbβ3/sEng. hsEng+ mice showed increased bleeding time and number of rebleedings compared to wild-type mice. No differences in PT were denoted between genotypes. After FeCl3 injury, the number of released emboli in hsEng+ mice was higher and the occlusion was slower compared to controls., Conclusions: Our results demonstrate that sEng interferes with thrombus formation and stabilization, likely via its binding to platelet αIIbβ3, suggesting its involvement in primary hemostasis control., Promex Stiftung für die Forschung Foundation Consejo Superior de Investigaciones Científicas; Grant/Award Number: 201920E022 Spanish Ministry of Science, Innovation & Universities; Grant/Award Number: RTI2018-102242-B-I00 Comunidad de Madrid; Grant/Award Number: S2022/BMD-7278

Background: Angiogenesis is a process by which new vessels are formed from pre-existing ones when the physiological conditions of the vascular endothelium are altered. Heartworm disease (Dirofilaria immitis) causes changes in the vascular endothelium of the pulmonary arteries due to obstruction, friction and hypoxia. The aim of this study was to analyze whether the excretory/secretory antigen of adult worms interacts and modulates the angiogenic mechanism, viable cell number and cell migration, as well as the formation of pseudo-capillaries. Methods: Cultures of human vascular endothelial cells (HUVECs) stimulated with excretory/secretory antigens (DiES), surface-associated antigens (Cut) from D. immitis adult worms, VEGF, as well as DiES+VEGF and Cut+VEGF were used. The production of VEGF-A and other proangiogenic [soluble VEGFR-2 (sVEGFR-2), membrane Endoglin (mEndoglin)] and antiangiogenic [VEGFR-1/soluble Flt (sFlt), soluble Endoglin (sEndoglin)] molecules was assessed using commercial ELISA kits. Cell viability was analyzed by live cell count and cytotoxicity assays by a commercial kit. In addition, viable cell number by MTT-based assay, cell migration by wound-healing assay carrying out scratched wounds, and the capacity of pseudo-capillary formation to analyze cell connections and cell groups in Matrigel cell cultures, were evaluated. In all cases, non‑stimulated cultures were used as controls. Results: DiES+VEGF and Cut+VEGF significantly increased the production of VEGF and VEGFR2, and only Cut+VEGF significantly increased the production of VEGFR1/sFlt compared to other groups and non-stimulated cultures. Moreover, only DiES+VEGF produced a significant increase in viable cell number and cell migration, as well as in the organization and number of cell connections. Conclusions: Excretory/secretory and surface-associated antigens of adult D. immitis activated the angiogenic mechanism by mainly stimulating the synthesis of proangiogenic factors, and only excretory/secretory antigens increased viable cell number, activated cell migration and the formation of pseudo-capillaries. These processes could lead to vascular endothelial remodeling of the infected host and favor the long-term survival of the parasite.

Background: Surgery on varicose veins (crossectomy and stripping) may lead to recurrence, with clinical and socioeconomic repercussions. The etiopathogenesis of varicose veins has yet to be fully understood. Objective: Study the expression of endoglin and other molecules involved in the neovascularisation process in patients suffering from this disease. Methods: Total of 43 patients that have undergone surgery for varicose veins (24 primary and 19 recurrent). Endoglin and other molecules were identified on the venous wall (proximal -saphenofemoral junction- and distal), via real-time RT-PCR, and in serum, via ELISA: endoglin (Eng), vascular endothelial growth factor (VEGF-A), its receptors 1 and 2 (VEGFR1 or FLT1), (VEGFR2 or FLK), and the hypoxia-inducible factor (HIF-1A). All the patients signed a consent form. Results: The recurrent group recorded a higher expression of Eng, VEGF-A, VEGFR1, and VEGFR2 at the level of proximal venous wall compared to the primary group. HIF-1A did not record any differences. As regards the determination of the distal venous wall, no markers recorded differences between the groups. Among the serum determinations, only sFLT1 recorded a significant drop among the patients with recurrent varicose veins. Conclusions: Patients with recurrent varicose veins record a higher expression of endoglin and other markers of angiogenesis in proximal veins. Endoglin in the blood (sEng) serves no apparent purpose in recurrent varicose veins.

Background: Surgery on varicose veins (crossectomy and stripping) leads to recurrence and has clinical and socio-economic repercussions. Their etiopathogenesis has yet to fully under-stood. Objective: Study the expression of endoglin and other molecules involved in the neovascu-larisation process in patients suffering from this disease. Methods: 43 patients that have undergone surgery for varicose veins (24 primary and 19 recurrent). They were identified on the venous wall (proximal -saphenofemoral junction- and distal), via real-time RT-PCR, and in serum, via ELISA: Endoglin (Eng), Vascular Endothelial Growth Factor (VEGF-A), its receptors 1 and 2 (VEGFR1 or FLT1), (VEGFR2 or FLK), and the Hypoxia-Inducible Factor (HIF-1A). All the patients signed a con-sent form. Results: The recurrent group recorded a higher expression of Eng, VEGF-A, VEGFR1 and VEGFR2 at the level of proximal venous wall compared to the primary group. HIF-1A did not record any differences. As regards the determination of the distal venous wall, no markers recorded differ-ences between the groups. Among the serum determinations, only sFLT1 recorded a significant drop among the patients with recurrent varicose veins. Conclusions: Patients with recurrent vari-cose veins record a higher expression of endoglin and other markers of angiogenesis in proximal veins. Endoglin in the blood (sEng) has not proven to be of any use in recurrent varicose veins.

Simple Summary The modulation of tumor blood vessels is a great opportunity for improving cancer therapies. Understanding the cellular and molecular players that regulate the biology of tumor blood vessels and tumor angiogenesis is necessary for the development of new anti-tumor strategies. Bone morphogenetic protein 9 (BMP9) is a circulating factor with multiple effects in vascular biology through its receptor activin receptor-like kinase 1 (ALK1). In this review, we give an overview of the possible benefits of modulating BMP9–ALK1 functions for cancer therapy improvement. Abstract The improvement of cancer therapy efficacy, the extension of patient survival and the reduction of adverse side effects are major challenges in cancer research. Targeting blood vessels has been considered a promising strategy in cancer therapy. Since the tumor vasculature is disorganized, leaky and triggers immunosuppression and tumor hypoxia, several strategies have been studied to modify tumor vasculature for cancer therapy improvement. Anti-angiogenesis was first described as a mechanism to prevent the formation of new blood vessels and prevent the oxygen supply to tumor cells, showing numerous limitations. Vascular normalization using low doses of anti-angiogenic drugs was purposed to overcome the limitations of anti-angiogenic therapies. Other strategies such as vascular promotion or the induction of high endothelial venules are being studied now to improve cancer therapy. Bone morphogenetic protein 9 (BMP9) exerts a dual effect through the activin receptor-like kinase 1 (ALK1) receptor in blood vessel maturation or activation phase of angiogenesis. Thus, it is an interesting pathway to target in combination with chemotherapies or immunotherapies. This review manuscript explores the effect of the BMP9–ALK1 pathway in tumor angiogenesis and the possible usefulness of targeting this pathway in anti-angiogenesis, vascular normalization or vascular promotion therapies.

Endoglin (Eng) is an endothelial cell (EC) transmembrane glycoprotein involved in adhesion and angiogenesis. Eng mutations result in vessel abnormalities as observed in hereditary hemorrhagic telangiectasia of type 1. The role of Eng was investigated in endothelial functions and permeability under inflammatory conditions, focusing on the actin dynamic signaling pathway. Endothelial Colony-Forming Cells (ECFC) from human cord blood and mouse lung/aortic EC (MLEC, MAEC) from Eng+/+ and Eng+/− mice were used. ECFC silenced for Eng with Eng-siRNA and ctr-siRNA were used to test tubulogenesis and permeability +/− TNFα and +/− LIM kinase inhibitors (LIMKi). In silico modeling of TNFα–Eng interactions was carried out from PDB IDs 5HZW and 5HZV. Calcium ions (Ca2+) flux was studied by Oregon Green 488 in epifluorescence microscopy. Levels of cofilin phosphorylation and tubulin post-translational modifications were evaluated by Western blot. F-actin and actin–tubulin distribution/co-localization were evaluated in cells by confocal microscopy. Eng silencing in ECFCs resulted in a decrease of cell sprouting by 50 ± 15% (p &lt, 0.05) and an increase in pseudo-tube width (41 ± 4.5%, p &lt, 0.001) compared to control. Upon TNFα stimulation, ECFC Eng–siRNA displayed a significant higher permeability compared to ctr-siRNA (p &lt, 0.01), which is associated to a higher Ca2+ mobilization (p &lt, 0.01). Computational analysis suggested that Eng mitigated TNFα activity. F-actin polymerization was significantly increased in ECFC Eng-siRNA, MAEC+/−, and MLEC+/− compared to controls (p &lt, 0.001, p &lt, 0.01, and p &lt, 0.01, respectively) as well as actin/tubulin distribution (p &lt, 0.01). Furthermore, the inactive form of cofilin (P-cofilin at Ser3) was significantly decreased by 36.7 ± 4.8% in ECFC Eng-siRNA compared to ctr-siRNA (p &lt, 0.001). Interestingly, LIMKi reproduced the absence of Eng on TNFα-induced ECFC-increased permeability. Our data suggest that Eng plays a critical role in the homeostasis regulation of endothelial cells under inflammatory conditions (TNFα), and loss of Eng influences ECFC-related permeability through the LIMK/cofilin/actin rearrangement-signaling pathway.

Simple Summary The prognosis and response to immunotherapy depends largely on the composition of the tumor microenvironment (TME). So-called cold tumors are rich in cells and molecules that inhibit the antitumor response and, therefore, are associated with a worse prognosis. In contrast, hot tumors are rich in antitumor cells and respond well to immunotherapy. The creation of one type of TME or another is highly dependent on angiogenesis, inflammation, and cancer-associated fibroblast (CAF) accumulation. Endoglin (CD105) is a protein involved in these three processes, making it a possible target for the conversion of cold tumors into hot tumors. In this review we summarize the role of endoglin in these processes and present the anti-endoglin therapies already under study that could be applied for vascular normalization. Abstract Tumors are complex masses formed by malignant but also by normal cells. The interaction between these cells via cytokines, chemokines, growth factors, and enzymes that remodel the extracellular matrix (ECM) constitutes the tumor microenvironment (TME). This TME can be determinant in the prognosis and the response to some treatments such as immunotherapy. Depending on their TME, two types of tumors can be defined: hot tumors, characterized by an immunosupportive TME and a good response to immunotherapy; and cold tumors, which respond poorly to this therapy and are characterized by an immunosuppressive TME. A therapeutic strategy that has been shown to be useful for the conversion of cold tumors into hot tumors is vascular normalization. In this review we propose that endoglin (CD105) may be a useful target of this strategy since it is involved in the three main processes involved in the generation of the TME: angiogenesis, inflammation, and cancer-associated fibroblast (CAF) accumulation. Moreover, the analysis of endoglin expression in tumors, which is already used in the clinic to study the microvascular density and that is associated with worse prognosis, could be used to predict a patient’s response to immunotherapy.

Preeclampsia is a pregnancy-specific disease of high prevalence characterized by the onset of hypertension, among other maternal or fetal signs. Its etiopathogenesis remains elusive, but it is widely accepted that abnormal placentation results in the release of soluble factors that cause the clinical manifestations of the disease. An increased level of soluble endoglin (sEng) in plasma has been proposed to be an early diagnostic and prognostic biomarker of this disease. A pathogenic function of sEng involving hypertension has also been reported in several animal models with high levels of plasma sEng not directly dependent on pregnancy. The aim of this work was to study the functional effect of high plasma levels of sEng in the pathophysiology of preeclampsia in a model of pregnant mice, in which the levels of sEng in the maternal blood during pregnancy replicate the conditions of human preeclampsia. Our results show that wild type pregnant mice carrying human sEng-expressing transgenic fetuses (fWT(hsEng+)) present high plasma levels of sEng with a timing profile similar to that of human preeclampsia. High plasma levels of human sEng (hsEng) are associated with hypertension, proteinuria, fetal growth restriction, and the release of soluble factors to maternal plasma. In addition, fWT(hsEng+) mice also present placental alterations comparable to those caused by the poor remodeling of the spiral arteries characteristic of preeclampsia. In vitro and ex vivo experiments, performed in a human trophoblast cell line and human placental explants, show that sEng interferes with trophoblast invasion and the associated pseudovasculogenesis, a process by which cytotrophoblasts switch from an epithelial to an endothelial phenotype, both events being related to remodeling of the spiral arteries. Our findings provide a novel and useful animal model for future research in preeclampsia and reveal a much more relevant role of sEng in preeclampsia than initially proposed., This research was funded by the Ministerio de Economía y Competitividad of Spain (SAF2010-15881 and SAF2013-45784-R to J.M.L.-N.), the Junta de Castilla y León (GR100 to J.M.L.-N.), the Fundación Renal Iñigo Álvarez de Toledo, the Kidney Research Network REDINREN (RD06/0016/0013, RD12/0021/0032, and RD016/0009/0025 to J.M.L.-N.), the Instituto de Salud Carlos III (PI16/00460 and PI19/01630 to M.P., co-funded by FEDER), and Consejo Superior de Investigaciones Científicas of Spain (CSIC, grant 201920E022 to C.B.).

Nonalcoholic steatohepatitis (NASH) is characterized by hepatic steatosis with inflammation and fibrosis. Membrane endoglin (Eng) expression is shown to participate in fibrosis, and plasma concentrations of soluble endoglin (sEng) are increased in patients with hypercholesterolemia and type 2 diabetes mellitus. We hypothesize that NASH increases both hepatic Eng expression and sEng in blood and that high levels of sEng modulate cholesterol and bile acid (BA) metabolism and affect NASH progression. Three-month-old transgenic male mice overexpressing human sEng and their wild type littermates are fed for six months with either a high-saturated fat, high-fructose high-cholesterol (FFC) diet or a chow diet. Evaluation of NASH, Liquid chromatography&ndash, mass spectrometry (LC/MS) analysis of BA, hepatic expression of Eng, inflammation, fibrosis markers, enzymes and transporters involved in hepatic cholesterol and BA metabolism are assessed using Real-Time Quantitative Reverse Transcription Polymerase Chain reaction (qRT-PCR) and Western blot. The FFC diet significantly increases mouse sEng levels and increases hepatic expression of Eng. High levels of human sEng results in increased hepatic deposition of cholesterol due to reduced conversion into BA, as well as redirects the metabolism of triglycerides (TAG) to its accumulation in the liver, via reduced TAG elimination by &beta, oxidation combined with reduced hepatic efflux. We propose that sEng might be a biomarker of NASH development, and the presence of high levels of sEng might support NASH aggravation by impairing the essential defensive mechanism protecting NASH liver against excessive TAG and cholesterol accumulation, suggesting the importance of high sEng levels in patients prone to develop NASH.

Simultaneous administration of certain antihypertensive (renin-angiotensin system inhibitors and diuretics) and nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with a renal toxicity syndrome known as "triple whammy" acute kidney injury (TW-AKI), yet poorly characterized at the pathophysiological level, as no specific experimental model exists on which to conduct preclinical research. Herein, we generated and characterized a rat model of TW-AKI (0.7 mg/kg/day trandolapril +400 mg/kg/day ibuprofen +20 mg/kg/day furosemide). Double treatments involving the NSAID caused a subclinical acute kidney injury, as they reduced glomerular filtration rate to a significant but not sufficient extent to increase Cr

16 p.-7 fig. Rossi. E. et al., Complex interactions between platelets and activated endothelium occur during the thrombo-inflammatory reaction at sites of vascular injuries and during vascular hemostasis. The endothelial receptor endoglin is involved in inflammation through integrin-mediated leukocyte adhesion and transmigration; and heterozygous mutations in the endoglin gene cause hereditary hemorrhagic telangiectasia type 1. This vascular disease is characterized by a bleeding tendency that is postulated to be a consequence of telangiectasia fragility rather than a platelet defect, since platelets display normal functions in vitro in this condition. Here, we hypothesize that endoglin may act as an adhesion molecule involved in the interaction between endothelial cells and platelets through integrin recognition. We find that the extracellular domain of human endoglin promotes specific platelet adhesion under static conditions and confers resistance of adherent platelets to detachment upon exposure to flow. Also, platelets adhere to confluent endothelial cells in an endoglin-mediated process. Remarkably, Chinese hamster ovary cells ectopically expressing the human αIIbβ3 integrin acquire the capacity to adhere to myoblast transfectants expressing human endoglin, whereas platelets from Glanzmann’s thrombasthenia patients lacking the αIIbβ3 integrin are defective for endoglin-dependent adhesion to endothelial cells. Furthermore, the bleeding time, but not the prothrombin time, is significantly prolonged in endoglin-haplodeficient (Eng+/−) mice compared to Eng+/+ animals. These results suggest a new role for endoglin in αIIbβ3 integrin-mediated adhesion of platelets to the endothelium, and may provide a better understanding on the basic cellular mechanisms involved in hemostasis and thrombo-inflammatory events., This work was supported by Grants from Ministerio de Economia y Competitividad of Spain (SAF2013-43421-R to C. B., SAF2013-45784-R to J. M. L.-N., and BFU2010-15237 to C. G.-M.), Centro de Investigacion Biomedica en Red de Enfermedades Raras (CIBERER; ISCIII-CB06/07/0038 and ER16PIAC707 to C. B.), Red de Investigacion Cooperativa en Enfermedades Renales (REDINREN to J. M. L.-N.), The Conny-Maeva Charitable Foundation (to D. M. S.), and Fundación Renal Iñigo Alvarez de Toledo to J. M. L.-N. CIBERER and REDINREN are initiatives of the Instituto de Salud Carlos III (ISCIII) of Spain supported by FEDER funds.

Alterations in the process of angiogenesis, either by excess or by defect, are present in different common pathologies. For this reason, great efforts are being made toward the development of pro- and anti-angiogenic therapies. Since endoglin levels are enhanced in tissues undergoing angiogenesis, and changes in its expression lead to alterations in vessel formation, endoglin has become an ideal target for these types of therapies. Areas covered: In this review, the role of endoglin in angiogenesis is summarized. In addition, the authors review pro- and anti-angiogenic therapies that are currently being used and new approaches that target endoglin. The article includes therapies that are both in preclinical and clinical development. Expert opinion: Endoglin is a very good target for anti-angiogenic therapy, as demonstrated by the positive results obtained with anti-endoglin antibodies. However, although endoglin in pro-angiogenic therapies has been successful in vitro, its use has not yet reached clinical settings. Moreover, the authors believe that establishing the exact role of endoglin in angiogenesis is essential and that this should be the next step in this field in the coming years.

A soluble form of endoglin (sEng) released into the circulation was suggested to be a direct inducer of endothelial dysfunction, inflammation and contributed to the development of hypertension by interfering with TGF-β signaling in cardiovascular pathologies. In the present study, we assessed the hypothesis that high sEng level-induced hypertension via a possible sEng interference with TGF-β signaling pathways may result in inflammatory, structural or fibrotic changes in hearts of Sol-Eng+ mice (mice with high levels of soluble endoglin) fed either chow or high-fat diet. Female Sol-Eng+ mice and their age matched littermates with low plasma levels of sEng were fed either chow or high-fat diet (HFD). Heart samples were subsequently analyzed by histology, qRT-PCR and Western blot analysis. In this study, no differences in myocardial morphology/hypertrophy and possible fibrotic changes between Sol-Eng+ mice and control mice were detected on both chow and HFD. The presence of sEng did not significantly affect the expression of selected members of TGF-β signaling (membrane endoglin, TGFβRII, ALK-5, ALK-1, Id-1, PAI-1 and activated Smad proteins-pSmad 1,5 and pSmad 2,3), inflammation, heart remodeling (PDGFb, Col1A1) and endothelial dysfunction (VCAM-1, ICAM-1) in the hearts of Sol-Eng+ mice compared to control mice on both chow and high-fat diet. High levels of soluble endoglin did not affect microscopic structure (profibrotic and degenerative cardiomyocyte changes), and specific parts of TGF-β signaling, endothelial function and inflammation in the heart of Sol-Eng+ mice fed both chow diet or HFD. However, we cannot rule out a possibility that a long-term chronic exposure (9 months and more) to soluble endoglin alone or combined with other cardiovascular risk factors may contribute to alterations of heart function and structure in Sol-Eng+ mice, which is the topic in our lab in ongoing experiments.

Endoglin (CD105) is an auxiliary receptor for members of the TFG-β superfamily. Whereas it has been demonstrated that the deficiency of endoglin leads to minor and defective angiogenesis, little is known about the effect of its increased expression, characteristic of several types of cancer. Angiogenesis is essential for tumor growth, so high levels of proangiogenic molecules, such as endoglin, are supposed to be related to greater tumor growth leading to a poor cancer prognosis. However, we demonstrate here that endoglin overexpression do not stimulate sprouting or vascularization in several in vitro and in vivo models. Instead, steady endoglin overexpression keep endothelial cells in an active phenotype that results in an impairment of the correct stabilization of the endothelium and the recruitment of mural cells. In a context of continuous enhanced angiogenesis, such as in tumors, endoglin overexpression gives rise to altered vessels with an incomplete mural coverage that permit the extravasation of blood. Moreover, these alterations allow the intravasation of tumor cells, the subsequent development of metastases and, thus, a worse cancer prognosis., This work was supported by the Ministerio de Economía y Competitividad of Spain (SAF2010-15881 AND SAF2013-45784-R), the Junta de Castilla y León (GR100), the Fundación Renal Iñigo Álvarez de Toledo, the Kidney Research Network REDINREN (RD06/0016/0013, RD12/0021/0032 and RD016/0009/0025) and the Instituto de Salud Carlos III (PI16/00460 and co-funded by FEDER). Furthermore, CO-I and EN-G are supported by a contract from the Ministerio de Economía y Competitividad of Spain, and CE-T is supported by a fellowship from the Fundación Miguel Casado San José.

Cardiopulmonary dirofilariosis caused by Dirofilaria immitis produces inflammation, blood vessel obstruction and hypoxia, which are required conditions for the beginning of the process of neovascularization. Since D. immitis harbours intracellular symbiotic Wolbachia bacterium, the global understanding of the angiogenic process requires the analysis of the effect of the parasite molecules, but also that of Wolbachia. Canine primary lung microvascular endothelial cells were treated with the recombinant Wolbachia surface protein (rWSP) and the expression of angiogenic factors like Vascular Endothelial Growth Factor-A (VEGF-A), sFlt, membrane Endoglin (mEndoglin) and soluble Endoglin (sEndoglin), as well as the in vitro formation of pseudocapillaries, were measured. The analyses showed a significant increase in the expression of pro-angiogenic VEGF-A and anti-angiogenic sEndoglin, together with a significant decrease in both pro-angiogenic mEndoglin and pseudocapillary formation, compared to untreated controls. Due to the complexity of the angiogenic process and its relationship with other physiological processes like inflammation and fibrinolysis, these results might suggest that rWSP participate in various mechanisms related to each other and its effects might depend either on the balance between them or on the moment of their occurrence.

Angiogenesis is a complex process essential for tumor growth. For this reason, high levels of pro-angiogenic molecules, such as endoglin (CD105), are supposed to be related to greater tumor growth that lead to a poor cancer prognosis. However, we demonstrate here that defects in angiogenesis that can be attributed to high levels of endoglin, lead to development and worsening of cancer disease. Steady endoglin overexpression disrupts the correct stabilization of the endothelium and the recruitment of mural cells. In consequence, endoglin overexpression gives rise to altered vessels that promote the intravasation of tumor cells, the subsequent development of metastases and, thus, a worse cancer prognosis.

This protocol include two part. First we explain how quantify tumor circulating cells that are released from a primary tumor generated by subcutaneous injection of fluorescent tumor cells. This protocol was adapted from the following article: Wyckoff, J. B. et al. Direct Visualization of Macrophage-Assisted Tumor Cell Intravasation in Mammary Tumors. Cancer Res. 67, 2649–2656 (2007). In the second part, how to analyze lung metastasis in the same tumor model is explained.

Protocol for study the migration and ECM invasion in vitro using transwells.

Protocol for surgery ofmouse hindlimb ischemia. Adapted from Limbourg et al. Evaluation of postnatal arteriogenesis and angiogenesis in a mouse model of hind-limb ischemia. Nat Protoc 4: 1737–1746 (2009).

Protocol to create and quantify the co-culture of endothelial cells and pericytes in Matrigel®.

Protocol for retina disection and vessel immunofluorescence. Adapted from Tual-Chalot et al. Whole mount immunofluorescent staining of the neonatal mouse retina to investigate angiogenesis in vivo. J Vis Exp. 2013 Jul 9;(77):e50546 (2013).

Protocol to create and quantify the capillary-like structures in Matrigel® that characteristically form endothelial cells.

Protocol to evaluate pericyte adhesion to endothelial cells in vitro.

Standard protocol for western blot

Protocol to prepare the cultured cells to be analyzed by flow cytometry.

Protocol for Mouse Lung Endothelial Cells (MLECs) isolation. Adapted from Oblander, S. A. et al. Distinctive functions of membrane type 1 matrixmetalloprotease (MT1‐MMP or MMP‐14) in lung and submandibular gland development are independent of its role in pro‐MMP‐2 activation. Dev. Biol. 277, 255–269 (2005)

The amount of hemoglobin has been used by some authors to estimate the vasculature density of the organs (more hemoglobin, more vascularized). In most cases it is represented as mg hemoglobin / g tissue. In our case, in the tumors we relate the amount of hemoglobin with the amount of DNA, since there may be edema that contributes weight, but that really is not a tumor mass.

Preparation and implantation of Plugs of Matrigel.

Protocol for assess cell motility by the wound healing or scratch assay.

Culture and analysis of mouse aortic rings.

Protocol for direct count of the number of cells to evaluate cell proliferation.