Maspin overexpression correlates with increased expression of vascular endothelial growth factors A, C, and D in human ovarian carcinoma

The vascular endothelial growth factor (VEGF) family, including VEGFA, VEGFC, and VEGFD, plays an essential role in the angiogenesis of both pathologic and nonpathologic conditions. Maspin belongs to the serpin superfamily and has been identified as a tumor suppressor because it inhibits motility, invasion, and angiogenesis. Few studies have compared maspin with VEGF in ovarian carcinoma. Therefore, we investigated the expression and correlation of maspin, VEGFA, VEGFC, and VEGFD with the tumorigenesis of the ovary and clinicopathologic variables.

Using immunohistochemistry, we examined maspin, VEGFA, VEGFC, and VEGFD expression in 60 ovarian carcinoma tissues (35 serous papillary carcinomas, 18 endometrioid carcinomas, and 7 primary ovarian mucinous carcinomas). Staining of cells was scored as +2 if more than 50% of the cells were positive, as +1 if less than 50% of the cells were positive, and as negative if none of the cells stained positive.

Overexpression of maspin, VEGFC, and VEGFD was significantly associated with high tumor grade (P<.001, P=.004, P<.001, respectively), clinical stage (P=.002, .01, and .001, respectively), the presence of ascites (P<.001, P=.03, and P=.001, respectively), and the presence of metastatic lymph nodes (P=.002, P<.001, and P<.001, respectively). Maspin was correlated with VEGFA (P=.01), VEGFC (P<.001), and VEGFD (P<.001). The VEGFA score was positively correlated with high tumor grade (P=.04), lymphovascular space invasion (LVSI) (P<.001), International Federation of Gynecology and Obstetrics (FIGO) stage (P=.009), maspin, VEGFC (P=.003), and VEGFD (P=.003), but it was not correlated with the presence of ascites and metastatic lymph nodes.

Maspin, VEGFC, and VEGFD are expressed in ovarian tumors with a poor prognostic parameters, and seem to play a role in ovarian cancer angiogenesis, progression, and lymph node metastases. Our results indicate that in contrast to most other carcinomas, maspin expression is directly associated with the biological aggressiveness of ovarian carcinoma. These results may offer new insights regarding the role of maspin in ovarian cancer and might also affect the diagnosis and treatment strategies.     

Comparison of molecular determinants of angiogenesis and lymphangiogenesis in lymph node metastases and in primary tumours of patients with breast cancer

Angiogenesis and lymphangiogenesis are complex processes, driven by multiple factors. In primary breast tumours (PTs), VEGFA, -C and -D are the most important (lymph)angiogenic factors. The induction of lymphangiogenesis in axillary lymph node (LN) metastases of patients with breast cancer was described recently. To compare the molecular determinants of (lymph)angiogenesis in LN metastases and PTs of breast cancer patients, RNA was isolated from formalin-fixed, paraffin-embedded tissue sections of a metastatically involved and uninvolved LN and the PT from 26 lymph node-positive patients. The expression of 12 (lymph)angiogenic markers was measured by qRT-PCR. Expression was correlated with tumour cell proliferation, angiogenesis and lymphangiogenesis, quantified by tumour cell proliferation fraction (TCP%) and (lymphatic) endothelial cell proliferation fraction [(L)ECP%]. TCP%, ECP% and LECP% were assessed on immunohistochemical double stains for CD34/Ki-67 and D2-40/Ki-67, respectively. In involved LNs, the relative gene expression levels of PROX1 (p < 0.001) and FGF2 (p = 0.008) were decreased and the expression levels of VEGFA (p = 0.01) and PDGFB (p = 0.002) were increased compared to uninvolved LNs. The expression of most markers was increased in PTs compared to involved LNs. In metastatically involved LNs, the expression of VEGFA correlated with ECP% (r = 0.54, p = 0.009) and LECP% (r = 0.76, p < 0.001). In PTs, VEGFA correlated only with ECP% (r = 0.74, p < 0.001). VEGFD correlated with peritumoural LECP% (r = 0.61, p = 0.001) and with VEGFC (r = 0.78, p < 0.001). Linear regression analysis confirmed the expression of VEGFA as an independent predictor of ECP% in both PTs and LN metastases and of LECP% in LN metastases. The expression of VEGFD, but not of VEGFA, independently predicted peritumoural LECP% in PTs. Our results confirm existing data that, in PTs, angiogenesis and lymphangiogenesis are respectively driven by VEGFA and VEGFD. In contrast, in LN metastases, both processes seem to be driven by VEGFA. Lymphangiogenesis in PTs and in LN metastases might thus be driven by different factors.     

Multiplexed analysis of angiogenesis and lymphangiogenesis factors predicts outcome for non-small cell lung cancer patients

Angiogenesis and lymphangiogenesis are key components of non-small cell lung cancer (NSCLC) tumor growth and metastatic spread; however, the prognostic and predictive role of angiogenic and lymphangiogenic biomarkers remains controversial for NSCLC patients. We assessed VEGF, VEGFC, VEGFD, VEGFR3 protein expression, tumor microvessel, and lymphatic vessel (LmVD) density by immunohistochemistry in 103 NSCLC; biomarkers were analyzed individually as well as multiplexed with each other. No correlations were identified between VEGF, VEGFC, VEGFD, or LmVD and clinical characteristics. VEGFR3 was correlated with VEGFC (p = 0.03), VEGFD (p < 0.0001), and intratumor LmVD (p = 0.03). Tumors that did not express VEGFR3 had a worse prognosis (log rank p = 0.03). VEGF was significantly correlated with survival in adenocarcinomas (log rank p = 0.014) but not in squamous cell carcinomas (log rank p = 0.5). Multivariate Cox regression analysis confirmed the independent prognostic potential of VEGFR3 (hazard ratio (HR) = 0.05; 95% confidence intervals (CI) = 0.008–0.32, p = 0.002) for all patients and VEGF (HR = 8.69, 95% CI = 1.4–53.69, p = 0.02) for adenocarcinomas. When biomarkers were multiplexed, only stage and VEGFC expression were independent predictors of survival for all patients. Weighted expression of VEGFC, VEGFR3, and stage was used to build a prognostic classifier for stage I–IIIA patients; patients in the low risk group had prolonged survival compared with high risk patients (log rank p = 0.02). There was no association between biomarkers and early recurrence or response to treatment. Angiogenic and lymphangiogenic biomarkers studied define subgroups of patients at high risk and may be useful for prognostic stratification of NSCLC patients especially those with early stage disease.     

血管内皮生长因子C及其受体3在非小细胞肺癌组织中的表达及意义

目的　探讨血管内皮生长因子C(VEGF C)和受体 (VEGFR) 3在人非小细胞肺癌(NSCLC)组织中的表达及其与微血管、微淋巴管形成、淋巴转移、预后之间的关系。方法　对 76例人NSCLC及相应癌旁组织行VEGF C、VEGFR 3及CD34免疫组织化学染色链霉素抗生物素蛋白 过氧化物酶 (SP)法检测 ,进行淋巴管密度计数、微血管密度 (MVD)计数 ,并结合临床和病理资料进行分析。结果　NSCLC中 ,VEGF C的表达与肺癌分化程度负相关 (P =0 0 0 9)。VEGF C和VEGFR 3的表达水平与淋巴结转移呈正相关 (分别P =0 0 0 8,P =0 0 13) ,与淋巴浸润呈正相关 (分别P =0 0 2 7,P =0 0 2 0 )。VEGF C的表达与VEGFR 3在肺癌细胞中的表达呈正相关 (P =0 0 0 9)。VEGF C与淋巴管密度 (P =0 0 0 6 )、MVD(P =0 0 4 6 )呈正相关。淋巴管密度与淋巴结转移 (P =0 0 10 )、淋巴浸润 (P =0 0 19)、TNM分期 (P =0 0 15 )呈正相关 ,MVD与血行转移 (P <0 0 0 1)、TNM分期 (P <0 0 0 1)呈正相关。VEGF C阳性表达与生存时间、5年生存率呈负相关 (P <0 0 0 1)。结论　NSCLC中 ,VEGF C通过自分泌方式作用于受体VEGFR 3,促进肺癌组织生长 ,抑制分化。VEGF C促使肺癌内淋巴管形成 ,促进肺癌淋巴结转移。VEGF C和VEGFR 3表达增高、淋巴管密度增加     

Vascular endothelial growth factor ligands and receptors that regulate human cytotrophoblast survival are dysregulated in severe preeclampsia and hemolysis, elevated liver enzymes, and low platelets syndrome

Human placental development combines elements of tumorigenesis and vasculogenesis. The organ's specialized epithelial cells, termed cytotrophoblasts, invade the uterus where they reside in the interstitial compartment. They also line uterine arteries and veins. During invasion, ectodermally derived cytotrophoblasts undergo pseudovasculogenesis, switching their adhesion molecule repertoire to mimic that of vascular cells. Failures in this transformation accompany the pregnancy complication preeclampsia. Here, we used a combination of in situ and in vitro analyses to characterize the cell's expression of vascular endothelial growth factor (VEGF) family ligands and receptors, key regulators of conventional vasculogenesis and angiogenesis. Cytotrophoblast differentiation and invasion during the first and second trimesters of pregnancy were associated with down-regulation of VEGF receptor (VEGFR)-2. Invasive cytotrophoblasts in early gestation expressed VEGF-A, VEGF-C, placental growth factor (PlGF), VEGFR-1, and VEGFR-3 and, at term, VEGF-A, PlGF, and VEGFR-1. In vitro the cells incorporated VEGF-A into the surrounding extracellular matrix; PlGF was secreted. We also found that cytotrophoblasts responded to the VEGF ligands they produced. Blocking ligand binding significantly decreased their expression of integrin alpha1, an adhesion molecule highly expressed by endovascular cytotrophoblasts, and increased apoptosis. In severe preeclampsia and hemolysis, elevated liver enzymes, and low platelets syndrome, immunolocalization on tissue sections showed that cytotrophoblast VEGF-A and VEGFR-1 staining decreased; staining for PlGF was unaffected. Cytotrophoblast secretion of the soluble form of VEGFR-1 in vitro also increased. Together, the results of this study showed that VEGF family members regulate cytotrophoblast survival and that expression of a subset of family members is dysregulated in severe forms of preeclampsia.     

PlGF expression in pre‐invasive and invasive lesions of uterine cervix is associated with angiogenesis and lymphangiogenesis

Most vascular endothelial growth factors (VEGF) have been shown to be associated with lymphangiogenesis and angiogenesis in various cancers. However, whether placental growth factor (PlGF), a rarely mentioned VEGF member, is involved in the pathogenesis of uterine cervical lesions remains unclear. To address this issue, we examined the relationship between PlGF expression and clinicopathologic variables in patients with pre‐invasive and invasive lesions of uterine cervix. Sixty‐two cervical specimens were immunostained with PlGF polyclonal antibody to define PlGF expression, and monoclonal antibodies D2‐40 and CD34 to evaluate the lymphatic vessel density (LVD) and blood vessel density (BVD) of the lesions. PlGF mRNA level was detected by RT‐PCR in all lesions from fresh tissues. We found that the levels of PlGF protein and mRNA expression were related to clinical stages (p < 0.05), but not to other clinicopathologic variables. No significant difference in PlGF expression was observed between squamous carcinoma and adenocarcinoma. Increased LVD and BVD were all associated with advanced stages (p < 0.001). Although LVD was strongly correlated with BVD, only high LVD was associated with pelvic lymphatic metastasis. Moreover, the level of PlGF expression was associated with both BVD(r = 0.715, p < 0.001) and LVD(r = 0.321, p < 0.05). Together, our study suggests that PlGF may participate in both tumor‐associated angiogenesis and lymphangiogenesis of cervical carcinogenesis.     

Human/mouse cross-reactive anti-VEGF receptor 2 recombinant antibodies selected from an immune b9 allotype rabbit antibody library

Vascular endothelial growth factor (VEGF) and its receptors have been implicated in promoting solid tumor growth and metastasis via stimulating tumor-associated angiogenesis. Models of murine tumor angiogenesis and receptor-specific antibodies are required to evaluate roles of VEGF receptors in mouse models of human cancer. Human VEGFR2 (also known as KDR) and murine VEGFR2 (or Flk-1) share 85% amino acid sequence identity in their extracellular domain. We describe here the development of antibodies that cross-react with mouse and human VEGFR2. High-affinity, species cross-reactive, Fabs specific for KDR/Flk-1 were selected from an antibody phage display library generated from an immunized rabbit of b9 allotype. The selected chimeric rabbit/human Fabs were found to bind to purified KDR and Flk-1 with nanomolar affinity. Three of the selected Fabs detected KDR expression on human endothelial cells as well as Flk-1 on murine endothelial cells. The availability of anti-VEGFR2 Fab with species cross-reactivity will help to decipher the functional role of KDR/Flk-1 in tumor biology as well as facilitate the preclinical evaluation of the suitability of KDR/Flk-1 for drug targeting. This report underscores our earlier finding that b9 rabbits are excellent sources for high-affinity cross-reactive antibodies with therapeutic potential.     

血管内皮生长因子-C促进淋巴管内皮细胞的增殖、迁移和F-肌动蛋白重组

目的 研究血管内皮生长因子-C(VEGF-C)对于淋巴管内皮细胞增殖和迁移的作用，探讨VEGF-C促进淋巴管新生的机制。方法 从狗的胸导管分离和培养淋巴管内皮细胞。标记内皮细胞的VEGFR-3和F-肌动蛋白，在荧光显微镜和共聚焦激光扫描显微镜下观察。用VEGF-C刺激后，计数增殖细胞和迁移细胞，测量细胞迁移距离，并与bFGF和VEGF的作用进行比较。结果 淋巴管内皮细胞表达VEGFR-3，静脉内皮细胞为阴性。bFGF和VEGF-C促进淋巴管内皮细胞的增殖，VEGF-C的作用比bFGF强。与对照组相比，bFGF、VEGF和VEGF-C组引起迁移细胞的数目增多和迁移距离增大，VEGF-C的作用最强。在VEGF-C组的迁移细胞，F-肌动蛋白和应力纤维明显增多。结论 淋巴管内皮细胞特异性表达VEGFR-3，VEGF-C促进淋巴管内皮细胞的增殖和迁移，引起F-肌动蛋白的重组和应力纤维形成。     

Angiopoietins and angiopoietin-like proteins in angiogenesis.

Vascular network formation requires several endothelial cell growth factors. These factors have a potent angiogenic effect, and their precise coordination is essential for vascular development. Among them, angiopoietins function through the Tie2 receptor, whose signaling is critical to regulate vascular stabilization and remodeling. It has been reported that the angiopoietin/Tie2 signal is involved in survival and migration of endothelial cells and regulates vascular remodeling and maintenance of vascular integrity. More recent studies demonstrate that angiopoietin/Tie2 signaling is also required for lymphangiogenesis. The authors and several other groups have identified six angiopoietin-like proteins (Angptls) containing a coiled-coil domain and a fibrinogen-like domain, both of which are characteristic of angiopoietins. Interestingly, Angptls also function in angiogenesis through regulating survival and migration of endothelial cells, although Angptls do not bind the angiopoietin receptor Tie2. Currently, Angptls are orphan ligands, but they have been reported to have pleiotropic effects not only on vascular cells but also on metabolism and tumor biology. Here, the authors review current findings relating to the roles of angiopoietins and Angptls in vascular biology and discuss molecular mechanisms relevant to these factors and angiogenesis.     

Triptolide Suppresses Alkali Burn‐Induced Corneal Angiogenesis Along with a Downregulation of VEGFA and VEGFC Expression

Triptolide (TPL) is an active compound extracted from a Chinese herbal medicine tripterygium wilfordii Hook. f. (Celastraceae), which has been used as an anti‐inflammatory drug for years. It also inhibits the growth and proliferation of different types of cancer cells. The inhibitory effect of TPL on angiogenesis after chemical‐induced corneal inflammation was studied in vivo. The effects of TPL on the proliferation, apoptosis, migration, and tube formation of rat aortic endothelial cells (RAECs) were studied in vitro. Cell proliferation and apoptosis were measured by MTT assay and flow cytometry, respectively. Migration was analyzed using the scratch wound healing assay and transwell assay. Tube formation assay was used to examine angiogenesis. Real‐time PCR and Western blot were used to determine the expression of vascular endothelial growth factor A (VEGFA) and VEGFC. To study the in vivo effects of TPL, the mouse model of alkali burn‐induced corneal angiogenesis was used. The angiogenesis was analyzed by determining the density of the newly generated blood vessels in corneas. We found that TPL induced apoptosis and inhibited the proliferation of RAECs in a dose‐dependent manner. TPL inhibited migration and tube formation of RAECs and decreased the expression of VEGFA and VEGFC in vitro. Furthermore, TPL suppressed alkali burn‐induced corneal angiogenesis and inhibited the expression of VEGFA and VEGFC in corneas in vivo. In conclusion, topical TPL as a pharmacological agent has the ability to reduce angiogenesis in cornea and may have clinical indications for the treatment of corneal angiogenesis diseases which have to be further explored. Anat Rec, 300:1348–1355, 2017. © 2017 Wiley Periodicals, Inc.     

Integrin α4 Induces Lymphangiogenesis and Metastasis via Upregulation of VEGF‐C in Human Colon Cancer

Vascular endothelial growth factor‐C (VEGF‐C) is a key regulator in lymphangiogenesis, and is overexpressed in various malignancies. Integrin α4β1, a new member of the VEGF‐C/VEGF receptor pathway, was found to be overexpressed in melanoma tumors. However, little is known regarding the potential role of integrin α4β1 in lymphangiogenesis and other solid tumors. The aim of this study was to investigate the expression patterns of integrin α4 and VEGF‐C in relation to lymphangiogenesis and clinicopathological parameters in human colon cancer. The expression of integrin α4, VEGF‐C, and VEGFR‐3 was assessed in 71 human colon cancer tissues and 30 paracancerous normal tissues by immunohistochemical staining. Lymphatic microvessel density (LMVD) was measured after D2‐40‐labeling, and the correlations among different factors were statistically analyzed. The expression of integrin α4, VEGF‐C, VEGFR‐3, and LMVD was higher in colon cancer tissues compared with the normal paracancerous colon tissues. There was a positive correlation between the expression of integrin α4 and VEGF‐C. Integrin α4 and VEGF‐C were significantly associated with the clinicopathological parameters (LMVD, Duke's stage, and lymph node metastasis). Kaplan–Meier analyses indicated that patients with high integrin α4 or VEGF‐C expression had significantly shorter overall survival and tumor‐free survival time. Multivariate analyses suggested that integrin α4 and VEGF‐C may serve as independent prognostic factors for human colon cancer. Both integrin α4 and VEGF‐C are involved in lymphangiogenesis and lymphatic metastasis. Our results demonstrated that integrin α4 is a novel prognostic indicator for human colon cancer. Anat Rec, 299:741–747, 2016. © 2016 Wiley Periodicals, Inc.     

Xanthatin,a novel potent inhibitor of VEGFR2 signaling,inhibits angiogenesis and tumor growth in breast cancer cells

Anti-angiogenesis targeting vascular endothelial growth factor receptor 2 (VEGFR2) has emerged as an important tool for cancer treatment. In this study, we described a novel VEGFR2 inhibitor, xanthatin, which inhibits tumor angiogenesis and growth. The biochemical profiles of xanthatin were investigated using kinase assay, migration assay, tube formation, Matrigel plug assay, western blot, immunofluorescence and human tumor xenograft model. Xanthatin significantly inhibited growth, migration and tube formation of human umbilical vascular endothelial cell as well as inhibited vascular endothelial growth factor (VEGF)-stimulated angiogenesis. In addition, it inhibited VEGF-induced phosphorylation of VEGFR2 and its downstream signaling regulator. Moreover, xanthatin directly inhibit proliferation of breast cancer cells MDA-MB-231. Oral administration of xanthatin could markedly inhibit human tumor xenograft growth and decreased microvessel densities (MVD) in tumor sections. Taken together, these preclinical evaluations suggest that xanthatin inhibits angiogenesis and may be a promising anticancer drug candidate.     

VEGF‐D deficiency in mice does not affect embryonic or postnatal lymphangiogenesis but reduces lymphatic metastasis

Vascular endothelial growth factor‐D (VEGF‐D) is one of the two ligands of the VEGFR‐3 receptor on lymphatic endothelial cells. Gene‐silencing studies in mice and Xenopus tadpoles recently showed that the role of endogenous VEGF‐D in lymphatic development is moderate. By contrast, exogenous VEGF‐D is capable of stimulating lymphangiogenesis. Nonetheless, its endogenous role in pathological conditions remains largely unknown. Hence, we reassessed its role in disease, using Vegf‐d^null mice. Vegf‐d^null mice were generated that, under physiological conditions, displayed normal embryonic and postnatal lymphangiogenesis and lymphatic remodelling, efficient lymphatic functioning and normal health. Vegf‐d^null mice also reponded normally in models of skin wound healing and healing of infarcted myocardium, despite enhanced expression of VEGF‐D in these models in wild‐type mice. In contrast, Vegf‐d^null mice displayed reduced peritumoral lymphangiogenesis and lymph node metastasis in an orthotopic pancreatic tumour model. Together, our data indicate that endogenous VEGF‐D in mice is dispensible for lymphangiogenesis during development, in postnatal and adult physiology and in several pathological conditions, but significantly contributes to lymphatic metastasis. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Signaling pathways induced by vascular endothelial growth factor (review)

Vasculogenesis and angiogenesis are the mechanisms responsible for the development of the blood vessels. Angiogenesis refers to the formation of capillaries from pre-existing vessels in the embryo and adult organism, while vasculogenesis is the development of new blood vessels from the differentiation of endothelial precursors (angioblasts) in situ. Vascular endothelial growth factor (VEGF) family members are major mediators of vasculogenesis and angiogenesis both during development and in pathological conditions. VEGF has a variety of effects on vascular endothelium, including the ability to promote endothelial cell viability, mitogenesis, chemotaxis, and vascular permeability. It mediates its activity mainly via two tyrosine kinase receptors, VEGFR-1 (flt-1) and VEGFR-2 (flk-1/KDR), although other receptors, such as neuropilin-1 and -2, can also bind VEGF. Another tyrosine kinase receptor, VEGFR-3 (flt-4) binds VEGF-C and VEGF-D and is more important in the development of lymphatic vessels. While the functional effects of VEGF on endothelial cells has been well studied, not as much is known about VEGF signaling. This review summarizes the different pathways known to be involved in VEGF signal transduction and the biological responses triggered by the VEGF signaling cascade.     

Inhibition of ocular angiogenesis by siRNA targeting vascular endothelial growth factor pathway genes: therapeutic strategy for herpetic stromal keratitis

Ocular neovascularization often results in vision impairment. Frequently vascular endothelial cell growth factors (VEGFs) are mainly responsible for the pathological neovascularization as in the case in neovascularization induced by CpG oligodeoxynucleotides and herpes simplex virus infection in this report. siRNAs targeting either VEGFA, VEGFR1, VEGFR2, or a mix of the three were shown to significantly inhibit neovascularization induced by CpG when given locally or systemically. The efficacy of systemic administration was facilitated by the use of a polymer delivery vehicle. Additional experiments showed a significant inhibitory effect of the siRNAs mix when given either locally or systemically in vehicle against herpes simplex virus-induced angiogenesis as well as against lesions of stromal keratitis. These results indicate that the use of VEGF pathway-specific siRNAs represents a useful therapy against neovascularization-related eye diseases.     

Design of a variant of vascular endothelial growth factor-A (VEGF-A) antagonizing KDR/Flk-1 and Flt-1

Because of its central role in pathological angiogenesis, vascular endothelial growth factor (VEGF) has become a major target for anti-angiogenic therapies. We report here the construction of a heterodimeric antagonistic VEGF variant (HD-VEGF). In this antagonist, binding domains for the VEGF-receptors KDR/Flk-1 and Flt-1 are present at one pole of the dimer, whereas the other pole carries domain swap mutations, which prevent binding to either receptor. As HD-VEGF can only bind to monomeric receptors, it does not lead to signal transduction. Moreover, it antagonizes VEGF and possibly other members of the VEGF family, which are KDR/Flk-1 and Flt-1 ligands. We show here that HD-VEGF is a potent inhibitor of VEGF-mediated proliferation and tissue factor induction in endothelial cell cultures, requiring only a 20-fold and a 4-fold excess, respectively, to block the activity of wtVEGF completely. A 4-fold excess of HD-VEGF over wtVEGF was also sufficient to abrogate vascular permeability as determined in the Miles assay in vivo. Furthermore, HD-VEGF inhibited fetal bone angiogenesis in an ex vivo assay. Thus, HD-VEGF blocks KDR- and Flt-1-mediated VEGF activities that are crucial in the angiogenic process and is therefore a promising, multipotent compound in the treatment of angiogenesis-related diseases.     

Localisation of Placenta Growth Factor (PlGF) in Human Term Placenta

Abstract

Placenta growth factor (PlGF) is a growth factor which belongs to the vascular endothelial growth factor (VEGF) family and is known to bind to the fms-like tyrosine kinase receptor (flt-1). Using Western blot analysis a 50 kDa band was identified in placental protein extract which corresponded to PlGF homodimer. Immunoreactive PlGF was localised to the vasculosyncytial membrane and in the media of large blood vessels of the placental villi, while staining within the mesenchyme was weak and diffuse. There was moderate staining for PlGF in discrete cells in the chorion and no staining in the epithelial layer of the amnion. The maternal decidual cells showed strong staining for PlGF immunoreactive protein. PlGF mRNA was predominantly expressed by the vasculosyncytial membrane of villous trophoblast, whilst there was no apparent expression of PlGF mRNA within the villous mesenchyme. These results suggest that PlGF may be an important paracrine factor for vascular endothelial cells in placental angiogenesis and an autocrine mediator of trophoblast function.     

Neuropilin-1 Participates in Wound Angiogenesis

Angiogenesis, the formation of new capillaries from existing vasculature, plays an essential role in tissue repair. The rapid onset and predominance of proangiogenic factors optimizes healing in damaged tissues. One factor that directly mediates wound vessel angiogenesis is vascular endothelial growth factor (VEGF). Although much is known about the biology of VEGF and its cognate receptors, VEGFR1 and VEGFR2, the role of a recently identified co-receptor for VEGF, neuropilin-1, is not well understood. Using a murine model of dermal wound repair, we found that neuropilin-1 was abundantly expressed on new vasculature in healing wounds. Moreover, mice treated with anti-neuropilin-1 antibodies exhibited a significant decrease in vascular density within these wounds (67% decrease, P = 0.0132). In in vitro assays, VEGF induced formation of endothelial cord-like structures on collagen gel and endothelial cell migration toward VEGF was inhibited by antibodies directed against neuropilin-1. These results provide both in vitro and in vivo evidence for a critical role of neuropilin-1 in wound angiogenesis.