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Simple Summary: Angiogenesis is a synchronous mechanism of new blood vessel formation that is controlled by pro- and anti-angiogenic factors. Angiogenesis differs from tissue to tissue, especially in pathological conditions. The exact nature of the co-operation between angiogenic markers is still unknown. Herein, we describe the possible critical changes in VEGF-A, TGF-β1, ANG1, ANG2, and HIF-1α in ectopic endometriosis (with elevated pro-angiogenic factors in all studied fields), in ovarian endometrioid adenocarcinoma (showing typical upregulation on the TGF-β1 axis), and two different types of endometrial carcinoma (with an extreme pathological ANG2/ANG1 axis for mixed mesodermal tumors). Understanding the angiogenic mechanism within pathological tissues could help to improve angiogenic treatment strategies and lead to better prognoses. A characteristic feature of uterine pathologies is a specific change in cell metabolism, which predominantly manifests as a shift in the need for nutrients, thereby directing cells to engage in different angiogenic marker activities. Angiogenesis is one of the main signals supporting the survival and development of cells and tissues not only under physiological conditions. Therefore, it is necessary that we understand pathological hyperactivation in all uterine diseases, from endometriosis through ovarian endometrioid adenocarcinoma to malignant transformed cells of the uterine epithelium and body. This work presents the gene expression results of selected angiogenesis targets (VEGF-A, TGF-β1, ANG1/2, and HIF-1α), cell migration, and cell–cell interaction determined in vitro. Our results suggest that angiogenesis varies in the tested pathological conditions (ectopic endometriosis—12Z; ovarian endometrioid adenocarcinoma—A2780; tumors—SK-UT-1 and RL-95-2) compared to physiological angiogenesis (HME1). The differential expression of angiogenic factors may contribute (or is a contributing factor) to the observed differences to acknowledge an inherent variability in angiogenesis among cell lines. Determining the genomic phenomena responsible for processes associated with inadequate angiogenesis in the pelvic region could help us to develop individual treatment strategies and explain resistance to treatment. [ABSTRACT FROM AUTHOR]

Background: The angiopoietin/TIE system is one of the signalling pathways that regulate vascular development and remodelling during morphogenesis of the placental complex. Deregulation of the vascularization process is associated with primary placental insufficiency through destabilization of the maternal-fetal functional system. Disruption of expression of pro-angiogenic factors is associated with reduction of the microcirculatory bed and installation of circulatory dysfunction. The aim: Evaluation of Ang2 immunoexpression in early term compromised uterine pregnancies in the context of chorio-villous circulatory dysfunction in primary placental insufficiency. Material and methods: Abortion product from 67 patients with early term compromised pregnancies (stagnant pregnancies – 43 cases, early miscarriages – 11 cases, control batch that included 13 cases of pregnancies solved on social indications) were immunohistochemically evaluated with the marker for anti-Ang2 and anti-CD31. Results: The majority of sites analyzed were Ang2 negative, with the exception of syncytiotrophoblast, that reached the highest score (+3) in most cases. A maximum placental vascularisation index was achieved in the control group. The stagnant pregnacies batch has registered the lowest vascular density mean. Conclusions: The placentation period is characterized by a weak Ang2 cellular environment in the chorio-villous germinal site in the group of short-term compromised pregnancies, except a highly positive syncytiotrophoblast. The immunoexpression profile in vascular endothelium correlates statistically significantly with placental vascularization index and chorio-villous vascular density in stagnant pregnancies.

Nowadays; intravitreal anti-vascular endothelial growth factor (VEGF) drugs are considered the first-line therapeutic strategy for treating macular exudative diseases; including wet age-related macular degeneration (w-AMD) and diabetic macular edema (DME). Despite the important clinical achievements obtained by anti-VEGF drugs in the management of w-AMD and DME; some limits still remain; including high treatment burden; the presence of unsatisfactory results in a certain percentage of patients and long-term visual acuity decline due to complications such as macular atrophy and fibrosis. Targeting the angiopoietin/Tie (Ang/Tie) pathway beyond the VEGF pathway may be a possible therapeutic strategy; which may has the potential to solve some of the previous mentioned challenges. Faricimab is a new; bispecific antibody targeting both VEGF-A and the Ang-Tie/pathway. It was approved by FDA and; more recently; by EMA for treating w-AMD and DME. Results from phase III trials TENAYA and LUCERNE (w-AMD) and RHINE and YOSEMITE (DME) have shown the potential of faricimab to maintain clinical efficacy with more prolonged treatment regimens compared to aflibercept (12 or 16 weeks) with a a good safety profile. [ABSTRACT FROM AUTHOR]

Though survival rates for preterm infants are improving, the incidence of chronic lung disease of infancy, or bronchopulmonary dysplasia (BPD), remains high. Histologically, BPD is characterized by larger and fewer alveoli. Hypoxia-inducible factors (HIFs) may be protective in the context of hyperoxia-induced lung injury, but the cell-specific effects of HIF expression in neonatal lung injury remain unknown. Thus, we sought to determine whether HIF stabilization in SM22a-expressing cells can limit hyperoxiainduced neonatal lung injury. We generated SM22a-specific HIF-1a-stabilized mice (SM22a-PHD1/2/mice) by cross-breeding SM22a-promotor-driven Cre recombinase mice with prolyl hydroxylase PHD1flox/flox and PHD2flox/flox mice. Neonatal mice were randomized to 21% O2 (normoxia) or 80% O2 (hyperoxia) exposure for 14 days. For the hyperoxia recovery studies, neonatal mice were recovered from normoxia for an additional 10 wk. SM22a-specific HIF-1a stabilization mitigated hyperoxia-induced lung injury and preserved microvessel density compared with control mice for both neonates and adults. In SM22a-PHD1/2/mice, pulmonary artery endothelial cells (PAECs) were more proliferative and pulmonary arteries expressed more collagen IV compared with control mice, even under hyperoxic conditions. Angiopoietin-2 (Ang2) mRNA expression in pulmonary artery smooth muscle cells (PASMC) was greater in SM22a-PHD1/2/compared with control mice in both normoxia and hyperoxia. Pulmonary endothelial cells (PECs) cocultured with PASMC isolated from SM22a-PHD1/2/mice formed more tubes and branches with greater tube length compared with PEC cocultured with PASMC isolated from SM22a-PHD1/2þ/þ mice. Addition of Ang2 recombinant protein further augmented tube formation for both PHD1/2þ/þ and PHD1/2/PASMC. Cell-specific deletion of PHD1 and 2 selectively increases HIF-1a expression in SM22a-expressing cells and protects neonatal lung development despite prolonged hyperoxia exposure. HIF stabilization in SM22a-expressing cells preserved endothelial cell proliferation, microvascular density, increased angiopoietin-2 expression, and lung structure, suggesting a role for cell-specific HIF-1a stabilization to prevent neonatal lung injury. [ABSTRACT FROM AUTHOR]

Nowadays; intravitreal anti-vascular endothelial growth factor (VEGF) drugs are considered the first-line therapeutic strategy for treating macular exudative diseases; including wet age-related macular degeneration (w-AMD) and diabetic macular edema (DME). Despite the important clinical achievements obtained by anti-VEGF drugs in the management of w-AMD and DME; some limits still remain; including high treatment burden; the presence of unsatisfactory results in a certain percentage of patients and long-term visual acuity decline due to complications such as macular atrophy and fibrosis. Targeting the angiopoietin/Tie (Ang/Tie) pathway beyond the VEGF pathway may be a possible therapeutic strategy; which may has the potential to solve some of the previous mentioned challenges. Faricimab is a new; bispecific antibody targeting both VEGF-A and the Ang-Tie/pathway. It was approved by FDA and; more recently; by EMA for treating w-AMD and DME. Results from phase III trials TENAYA and LUCERNE (w-AMD) and RHINE and YOSEMITE (DME) have shown the potential of faricimab to maintain clinical efficacy with more prolonged treatment regimens compared to aflibercept (12 or 16 weeks) with a a good safety profile.

Abstract Background Proper oxygen balance in the dental pulp is essential for cell metabolism. Angiogenesis in the pulp is a constant process during the life of the tooth. Hypoxia indicators in a tissue, such as HIF-1α, as well as vascular destabilization markers, such as ANG2 and its receptor TIE2, are necessary for angiogenesis. Therefore the purpose of this study is to evaluate the expression of HIF-1α, ANG1, ANG2 and TIE2 in dental pulp as early angiogenesis indicators in teeth with complete and incomplete root development. Methods Forty human dental pulps were obtained from freshly extracted third molars divided into two groups: incomplete (n = 20) and complete (n = 20) root development. Dental pulps were stored at − 80 °C, defrosted in an ice bath and re-frozen with their respective thaws to disintegrate the tissue. Three sonication cycles were performed until the tissues were homogenized, then thaw were centrifuged and the supernatant was collected for the detection of the markers to be studied. The samples were processed for the ELISA test using the ELISA-sandwich principle. Student t and Mann–Whitney U tests were performed to determine statistically significant differences between groups. Results In the complete root development, HIF-1α, ANG1, ANG2 and TIE2 expressions were significantly higher than their expression in the incomplete root development group. Conclusions The angiogenic process seems to be a physiological process in the dental pulp. Angiogenic activity is higher in teeth with mature than immature apex teeth.

Macrophages play important roles in angiogenesis; however, previous studies on macrophage angiogenesis have focused on traditional 2D cultures. In this study, we established a 3D culture system for macrophages using collagen microcarriers and assessed the effect of 3D culture on their angiogenic capabilities. Macrophages grown in 3D culture displayed a significantly different morphology and arrangement under electron microscopy compared to those grown in 2D culture. Tube formation assays and chick embryo chorioallantoic membrane assays further revealed that 3D-cultured macrophages were less angiogenic than those in 2D culture. Whole-transcriptome sequencing showed that nearly 40% of genes were significantly differently expressed, including nine important angiogenic factors of which seven had been downregulated. In addition, the expression of almost all genes related to two important angiogenic pathways was decreased in 3D-cultured macrophages, including the two key angiogenic factors, VEGFA and ANG2. Together, the findings of our study improve our understanding of angiogenesis and 3D macrophage culture in tissues, and provide new avenues and methods for future research on macrophages. [ABSTRACT FROM AUTHOR]

Macrophages play important roles in angiogenesis; however, previous studies on macrophage angiogenesis have focused on traditional 2D cultures. In this study, we established a 3D culture system for macrophages using collagen microcarriers and assessed the effect of 3D culture on their angiogenic capabilities. Macrophages grown in 3D culture displayed a significantly different morphology and arrangement under electron microscopy compared to those grown in 2D culture. Tube formation assays and chick embryo chorioallantoic membrane assays further revealed that 3D-cultured macrophages were less angiogenic than those in 2D culture. Whole-transcriptome sequencing showed that nearly 40% of genes were significantly differently expressed, including nine important angiogenic factors of which seven had been downregulated. In addition, the expression of almost all genes related to two important angiogenic pathways was decreased in 3D-cultured macrophages, including the two key angiogenic factors, VEGFA and ANG2. Together, the findings of our study improve our understanding of angiogenesis and 3D macrophage culture in tissues, and provide new avenues and methods for future research on macrophages.

Background: Choroidal neovascularization (CNV) is a major cause of blindness in patients with age-related macular degeneration. CNV is characterized by new blood vessel growth and subretinal fluid accumulation, which results in mechanical pressure on retinal pigment epithelial (RPE) cells. The overexpression of RPE-derived angiogenic factors plays an important role in inducing CNV. In this work, we investigated the effect of mechanical stress on the expression of angiogenic factors in porcine RPE cells and determined the impact of conditioned medium on in-vitro angiogenesis. Results: The goal of this study was to determine whether low levels of acute mechanical stress during early CNV can induce the expression of angiogenic factors in RPE cells and accelerate angiogenesis. Using a novel device, acute mechanical stress was applied to primary porcine RPE cells and the resulting changes in the expression of major angiogenic factors, VEGF, ANG2, HIF-1α, IL6, IL8 and TNF-α, were examined using immunocytochemistry, qRT-PCR, and ELISA. An in vitro tube formation assay was used to determine the effect of secreted angiogenic proteins due to mechanical stress on endothelial tube formation by human umbilical vein endothelial cells (HUVECs). Our results showed an increase in the expression of VEGF, ANG2, IL-6 and IL-8 in response to mechanical stress, resulting in increased in vitro angiogenesis. Abnormal epithelial-mesenchymal transition (EMT) in RPE cells is also associated with CNV and further retinal degeneration. Our qRT-PCR results verified an increase in the expression of EMT genes, CDH2, VIM and FN1, in RPE cells. Conclusions: In conclusion, we showed that acute mechanical stress induces the expression of major angiogenic and EMT factors and promotes in vitro angiogenesis, suggesting that mechanical stress plays a role in promoting aberrant angiogenesis in AMD. [ABSTRACT FROM AUTHOR]

Aim: To quantify the expression of angiogenic growth factors (ANG2, VEGFA, TGFß1) and their corresponding receptors (VEGFR1, VGFR2, NRP1 and TGFßR1) in human dental pulps from extracted third molars with complete and incomplete root development. Methodology: Fifty‐six dental pulp samples obtained from freshly extracted human third molars were divided equally into two groups according to their stage of root development; 28 third molars with complete root development and 28 third molars with incomplete root development. All samples were processed and total RNA was extracted, cDNA was then synthetized for each sample and the target genes expression profiles for ANG2, VEGFA, VEGFR1, VEGFR2, NRP1, TGFß1 and TGFßR1 were obtained by RT2‐PCR. The data was analysed with a Student's t‐test to compare the replicate ∆∆Ct values for each gene. Results: Teeth with incomplete root development were associated with a significantly greater gene expression of TGFβR1 (P = 0.03), whereas in teeth with complete root development the genes that had significantly greater expression were VEGFA (P = 0.04). Conclusion: The angiogenic growth factors (ANG2, VEGFA, TGFβ1) and their receptors (NRP1, VEGFR1, VEGFR2 and TGFßR1) were expressed in pulps of teeth with complete and incomplete root development measured by RT2‐PCR, with TGFBR1 genes being significantly different in teeth with incomplete root development and VEGFA genes in teeth with complete root development. [ABSTRACT FROM AUTHOR]

Background/Aims: The pro-angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietins (Angs) play a prominent role in synovial angiogenesis, an early and critical event in the pathogenesis of rheumatoid arthritis (RA). Interleukin (IL)-35 is an anti-inflammatory cytokine that attenuates collagen-induced arthritis, however, the mechanisms involved are not fully understood. Methods: The effects of IL-35 on endothelial cell migration, adhesion, and tube formation were examined using human umbilical vein endothelial cells (HUVEC) in vitro. The effects of IL-35 on vessel formation in vivo were examined using a murine Matrigel plugs model. MMP2/MMP9 and IL-6/IL-8 secretion were assessed by zymography and ELISA, respectively. The crosstalk between IL-35, VEGF, and Ang2 in HUVECs and RA synovial tissue explants was investigated. Results: IL-35 inhibited basal and VEGF-induced HUVEC migration and adhesion in vitro as well as tube formation in vitro and in vivo. VEGF increased Ang2 secretion by HUVECs and RA synovial tissue explants, and exogenous Ang2 promoted HUVEC migration, adhesion, and tube formation with similar potency to VEGF. Blocking the Ang/Tie2 pathway with a Tie2 kinase antibody inhibited the proangiogenic effects of exogenous Ang2 and VEGF in HUVECs. IL-35 inhibited basal and VEGF-induced Ang2 secretion by HUVECs and RA synovial tissue explants; it also antagonized the proangiogenic effects of exogenous Ang2 in HUVECs. Moreover, IL-35 reduced basal and VEGF/Ang2-induced MMP2/MMP9 and IL-6/IL-8 secretion. Conclusion: These results suggested that IL-35 restrains RA angiogenesis and inflammation by downregulating basal and VEGF-induced Ang2 secretion as well as disrupting Ang2/Tie2 signal transduction. Our findings extend current understanding of mechanisms regulating RA angiogenesis and may support development of novel angiogenesis-targeting therapeutics for RA treatment.

Endothelial cells that form the inner layer of blood and lymphatic vessels are important regulators of vascular functions and centrally involved in the pathogenesis of vascular diseases. In addition to the vascular endothelial growth factor (VEGF) receptor pathway, the angiopoietin (Ang)–Tie system is a second endothelial cell specific ligand–receptor signalling system necessary for embryonic cardiovascular and lymphatic development. The Ang–Tie system also regulates postnatal angiogenesis, vessel remodelling, vascular permeability and inflammation to maintain vascular homoeostasis in adult physiology. This system is implicated in numerous diseases where the vasculature has an important contribution, such as cancer, sepsis, diabetes, atherosclerosis and ocular diseases. Furthermore, mutations in the TIE2 signalling pathway cause defects in vascular morphogenesis, resulting in venous malformations and primary congenital glaucoma. Here, we review recent advances in the understanding of the Ang–Tie signalling system, including cross-talk with the vascular endothelial protein tyrosine phosphatase (VE-PTP) and the integrin cell adhesion receptors, focusing on the Ang–Tie system in vascular development and pathogenesis of vascular diseases. [ABSTRACT FROM AUTHOR]

Almost all cancers show intrinsic and/or evasive resistance to vascular endothelial growth factor ( VEGF) inhibitors by multiple mechanisms. Serum angiopoietin-2 (Ang2) level has been proposed as a potential biomarker of VEGF inhibitor response in several cancers. From these clinical observations, the Ang2 and Tie2 (its receptor) axis has been focused on as a promising target. Here, we show a novel strategy to circumvent the resistance by combining multi-tyrosine kinase inhibitors lenvatinib ( VEGF receptor, fibroblast growth factor receptor, and RET inhibitor) and golvatinib (E7050; c-Met, Tie2, and EphB4 inhibitor). Tie2 identifies a highly pro-angiogenic macrophage subset, Tie2-expressing macrophages ( TEM). Angi-Tie2 and EphB4-EphrinB2 signaling plays critical roles in pericyte-mediated vessel stabilization. In vitro analyses suggested that golvatinib combined with lenvatinib inhibited pericyte-mediated vessel stabilization and TEM differentiation. In thyroid and endometrial cancer models, golvatinib and lenvatinib inhibited pericyte network development and TEM infiltration, resulting in severe perfusion disorder and massive apoptosis. Body weight loss was tolerable, and no macroscopic change was observed. These preclinical studies suggest that modulation of the tumor microenvironment by a strategic and well-tolerated combination of multi-targeting tyrosine kinase inhibitors may sensitize cancer to VEGF inhibitors. [ABSTRACT FROM AUTHOR]

Decidualization is accompanied by extensive angiogenesis, which is an essential step in the maturation of new blood vessels in mammalian pregnancy. The purpose of this study was to determine a distribution of uNK cells (CD56+ uNK or CD56bright cells) in human decidua of the first-trimester pregnancy, and investigate whether uNK cells in human decidua could express vascular endothelial growth factor (VEGF-A) and/or angiopoietin2 (Ang2). Our immunohistochemical staining results demonstrated that a great amount of uNK (CD56+) cells scattered throughout the decidual stroma and near endometrial gland and spiral vessels in human decidua. The protein expression of VEGF-A and Ang2 was detected in decidual stroma cells, capillary endothelial cells and glandular cells in tissue specimens. There was a positive correlation between microvessel density (MVD) and the number of the CD56-positive uNK cells in decidual stroma, and also between the number of the CD56-positive uNK cells and VEGF-A protein expression in the tissue. In addition, we found that uNK cells in human decidua could express VEGF-A mRNA, but not Ang2 mRNA, in isolated uNK cells in human decidua of the first-trimester gestation by combination of LCM and Nested-PCR. Our study indicated that uNK cells, through expressing VEGF-A, may play an important role in the angiogenic response at the time of human decidualization and early placenta development. [ABSTRACT FROM AUTHOR]

The present study demonstrated that the vessel number in bone marrow biopsies from acute myeloid leukaemia (AML) patients (n = 23) was significantly increased at diagnosis compared with normal bone marrow (P = 0·019) and was restored to normal levels after achieving complete remission (P = 0·03). The in vitro angiogenic potential of culture supernatant of AML cells was assessed using endothelial cell (EC) migration and proliferation assays. Increased EC migration and EC proliferation was induced in 7/20 and 19/20 AML supernatents respectively. The degree of in vivo neovascularization did not correlate with the ability of AML cells to stimulate in vitro endothelial cell migration and/or proliferation. This might be in part a result of the heterogeneous pattern of angiogenic factors produced by AML cells. The expression of different angiogenic factors was studied using reverse transcription polymerase chain reaction. Cells from 17/20 AML patients showed wide variation in spontaneous vascular endothelial growth factor (VEGF) expression, 4/19 expressed varied spontaneous blastic fibroblast growth factor mRNA levels and all patient samples showed spontaneous interleukin 8 mRNA expression. All AML samples expressed matrix metalloproteinase (MMP)-2 and/or MMP-9. VEGF mRNA expression correlated well with protein level (P = 0·006). A correlation was found between the degree of VEGF expression and neoangiogenesis (correlation coefficient = 0·448, P = 0·05). These results suggest that malignant cell proliferation, angiogenesis and VEGF expression are linked in AML and might contribute to the growth advantage of the malignant counterpart as a result of the paracrine production of growth factors produced by the surrounding endothelial cells. [ABSTRACT FROM AUTHOR]