In-vitro evidence of autocrine secretion of vascular endothelial growth factor by endothelial cells from human placental blood vessels

Discovery and Development of Tumor Angiogenesis Assays

The angiogenesis process was described in its basic concepts in the works of the Scottish surgeon John Hunter and terminologically assessed in the early twentieth century. An aberrant angiogenesis is a prerequisite for cancer cells in solid tumors to grow and metastasize. The sprouting of new blood vessels is one of the major characteristics of cancer and represents a gateway for tumor cells to enter both the blood and lymphatic circulation systems. In vivo, ex vivo, and in vitro models of angiogenesis have provided essential tools for cancer research and antiangiogenic drug screening. Several in vivo studies have been performed to investigate the various steps of tumor angiogenesis and in vitro experiments contributed to dissecting the molecular bases of this phenomenon. Moreover, coculture of cancer and endothelial cells in 2D and 3D matrices have contributed to improve the recapitulation of the complex process of tumor angiogenesis, including the peculiar conditions of tumor microenvironment.

Gestational exposure to PCB-118 impairs placental angiogenesis and fetal growth

Maternal exposure to polychlorinated biphenyls (PCBs) results in adverse effects on fetal development. However, the underlying mechanism has not been sufficiently explored in respect to particular PCBs. Placental angiogenesis plays a crucial role in feto-maternal substances transportation and fetal development. The present study was conducted to investigate the effects of prenatal PCB118 exposure on placental angiogenesis and fetal growth. The pregnant dam received PCB118 at environmentally relevant doses (0, 20, or 100 μg/kg/day) intragastrically from gestational day (GD) 7.5-18.5 to establish an in vivo model. Compared with the control group, the fetal body and placental weights of the PCB118 (100 μg/kg/day) group were significantly decreased and the intrauterine growth retardation (IUGR) rates were increased both in the female and male fetus. Furthermore, we found that placental histology was significantly impaired and the number of blood vessels was decreased in the PCB118 group. Additionally, gestational exposure to PCB118 caused anomalous mRNA expression of the genes in the placenta regarding angiogenesis. These findings indicate that PCB118 may contribute to the occurrence of IUGR by provoking placental angiogenesis dysfunction. This study clarified the adverse effects and potential mechanism of prenatal PCBs exposure on fetal growth, providing a new theoretical and experimental basis for future treatment and prevention.

Mechanotransduction and Uterine Blood Flow in Preeclampsia: The Role of Mechanosensing Piezo 1 Ion Channels

There is a large increase in uterine arterial blood flow during normal pregnancy. Structural and cellular adjustments occur in the uterine vasculature during pregnancy to accommodate this increased blood flow through a complex adaptive process that is dependent on multiple coordinated and interactive influences and this process is known as "vascular remodeling." The etiology of preeclampsia involves aberrant placentation and vascular remodeling leading to reduced uteroplacental perfusion. The placental ischemia leads to development of hypertension and proteinuria in the mother, intrauterine growth restriction, and perinatal death in the fetus. However, the underlying source of the deficient vascular remodeling and the subsequent development of preeclampsia remain to be fully understood. Mechanoreceptors in the vascular system convert mechanical force (shear stress) to biochemical signals and feedback mechanisms. This review focuses on the Piezo 1 channel, a mechanosensitive channel that is sensitive to shear stress in the endothelium; it induces Ca2+ entry which is linked to endothelial nitric oxide synthase (eNOS) activation as the mechanoreceptor responsible for uterine vascular dilatation during pregnancy. Here we describe the downstream signaling pathways involved in this process and the possibility of a deficiency in expression of Piezo 1 in preeclampsia leading to the abnormal vascular dysfunction responsible for the pathophysiology of the disease. The Piezo 1 ion channel is expressed in the endothelium and vascular smooth muscle cells (VSMCs) of small-diameter arteries. It plays a role in the structural remodeling of arteries and is involved in mechanotransduction of hemodynamic shear stress by endothelial cells (ECs).

Vascular Endothelial Cell Behavior in Complex Mechanical Microenvironments

The vascular mechanical microenvironment consists of a mixture of spatially and temporally changing mechanical forces. This exposes vascular endothelial cells to both hemodynamic forces (fluid flow, cyclic stretching, lateral pressure) and vessel forces (basement membrane mechanical and topographical properties). The vascular mechanical microenvironment is "complex" because these forces are dynamic and interrelated. Endothelial cells sense these forces through mechanosensory structures and transduce them into functional responses via mechanotransduction pathways, culminating in behavior directly affecting vascular health. Recent in vitro studies have shown that endothelial cells respond in nuanced and unique ways to combinations of hemodynamic and vessel forces as compared to any single mechanical force. Understanding the interactive effects of the complex mechanical microenvironment on vascular endothelial behavior offers the opportunity to design future biomaterials and biomedical devices from the bottom-up by engineering for the cellular response. This review describes and defines (1) the blood vessel structure, (2) the complex mechanical microenvironment of the vascular endothelium, (3) the process in which vascular endothelial cells sense mechanical forces, and (4) the effect of mechanical forces on vascular endothelial cells with specific attention to recent works investigating the influence of combinations of mechanical forces. We conclude this review by providing our perspective on how the field can move forward to elucidate the effects of the complex mechanical microenvironment on vascular endothelial cell behavior.

Engineering tissues with a perfusable vessel-like network using endothelialized alginate hydrogel fiber and spheroid-enclosing microcapsules

Development of the technique for constructing an internal perfusable vascular network is a challenging issue in fabrication of dense three-dimensional tissues in vitro. Here, we report a method for realizing it. We assembled small tissue (about 200 μm in diameter)-enclosing hydrogel microcapsules and a single hydrogel fiber, both covered with human vascular endothelial cells in a collagen gel. The microcapsules and fiber were made from alginate and gelatin derivatives, and had cell adhesive surfaces. The endothelial cells on the hydrogel constructs sprouted and spontaneously formed a network connecting the hydrogel constructs with each other in the collagen gel. Perfusable vascular network-like structure formation after degrading the alginate-based hydrogel constructs by alginate lyase was confirmed by introducing solution containing tracer particles of about 3 μm in diameter into the lumen templated by the alginate hydrogel fiber. The introduced solution flowed into the spontaneously formed capillary branches and passed around the individual spherical tissues.

Mechanical stretch: physiological and pathological implications for human vascular endothelial cells

Vascular endothelial cells are subjected to hemodynamic forces such as mechanical stretch due to the pulsatile nature of blood flow. Mechanical stretch of different intensities is detected by mechanoreceptors on the cell surface which enables the conversion of external mechanical stimuli to biochemical signals in the cell, activating downstream signaling pathways. This activation may vary depending on whether the cell is exposed to physiological or pathological stretch intensities. Substantial stretch associated with normal physiological functioning is important in maintaining vascular homeostasis as it is involved in the regulation of cell structure, vascular angiogenesis, proliferation and control of vascular tone. However, the elevated pressure that occurs with hypertension exposes cells to excessive mechanical load, and this may lead to pathological consequences through the formation of reactive oxygen species, inflammation and/or apoptosis. These processes are activated by downstream signaling through various pathways that determine the fate of cells. Identification of the proteins involved in these processes may help elucidate novel mechanisms involved in vascular disease associated with pathological mechanical stretch and could provide new insight into therapeutic strategies aimed at countering the mechanisms’ negative effects.

VEGF 165 b in the developing vasculatures of the fetal human eye

VEGF(165) b is an anti-angiogenic form of VEGF(165) produced by alternative splicing. The localization of pro-angiogenic VEGF(165) and anti-angiogenic VEGF(165) b was investigated during development of the vasculatures in fetal human eyes from 7 to 21 weeks gestation (WG). The fetal vasculature of vitreous, which includes tunica vasculosa lentis (TVL), had moderate VEGF(165) immunoreactivity at 7WG and very little VEGF(165) b. Both forms were elevated at 12WG. VEGF(165) then decreased around 17WG when the TVL regresses but VEGF(165) b remained elevated. In choroid, VEGF(165) was present in forming choriocapillaris (CC) and retinal pigment epithelium (RPE) at 7WG while VEGF165b was present in CC and mesenchymal precursors within the choroidal stroma. By 21WG, both forms were elevated in RPE and choroidal blood vessels but VEGF(165) b was apical and VEGF(165) basal in RPE. Diffuse VEGF(165) immunoreactivity was prominent in 12WG innermost retina where blood vessels will form while VEGF(165) b was present in most CXCR4(+) progenitors in the inner neuroblastic layer and migrating angioblasts in the putative nerve fiber layer. By 21WG, VEGF(165) was present in nerve fibers and VEGF(165) b in the inner Muller cell process. The localization of VEGF(165) b was distinctly different from VEGF(165) both spatially and temporally and it was often associated with nucleus in progenitors.

Endothelial cell biology: role in the inflammatory response

Human endothelial cells are multifunctional cells that line blood vessels and are capable of secreting a variety of biologically active mediators. They normally maintain vascular hemostasis and prevent thrombotic complications. When affected by infection, stress, hypertension, dyslipidemia, or high homocysteine levels, endothelial cells undergo changes resulting in "dysfunction," characterized typically by decreased endothelial expression of nitric oxide, enhanced expression of cell adhesion molecules, and associated increased binding of circulating leukocytes to these cells. There is accompanying cytokine and chemokine elaboration, resulting in cellular recruitment and the orchestration of an acute inflammatory response that can culminate in chronic inflammation if reparative mechanisms are not operative. This review will address the basic biology of endothelial cells; the expression and regulation of endothelial-derived cytokines, chemokines, and growth factors; the transcriptional regulation of these genes in endothelial cells; and the role played by these fascinating cells in human disease.

Kisspeptin-10 inhibits angiogenesis in human placental vessels ex vivo and endothelial cells in vitro

Recent studies suggest that kisspeptin (a neuropeptide central to the regulation of gonadotrophin secretion) has diverse roles in human physiology, including a putative role in implantation and placental function. Kisspeptin and its receptor are present in human blood vessels, where they mediate vasoconstriction, and kisspeptin is known to inhibit tumor metastasis and trophoblast invasion, both processes involving angiogenesis. We hypothesized that kisspeptin contributes to the regulation of angiogenesis in the reproductive system. The presence of the kisspeptin receptor was confirmed in human placental blood vessels and human umbilical vein endothelial cells (HUVEC) using immunochemistry. The ability of kisspeptin-10 (KP-10) (a shorter biologically active processed peptide) to inhibit angiogenesis was tested in explanted human placental arteries and HUVEC using complementary ex vivo and in vitro assays. KP-10 inhibited new vessel sprouting from placental arteries embedded in Matrigel and tube-like structure formation by HUVEC, in a concentration-dependent manner. KP-10 had no effect on HUVEC viability or apoptosis but induced concentration-dependent inhibition of proliferation and migration. In conclusion, KP-10 has antiangiogenic effects and, given its high expression in the placenta, may contribute to the regulation of angiogenesis in this tissue.

Index to ring digit ratio in Saudi Arabia at Almadinah Almonawarah province: a direct and indirect measurement study

The digit ratio, or the relative lengths, of the 2nd and 4th digits (2D :4D) shows a sex difference, with males tending to have lower values in comparison with females. This sex differences arises early in the fetus and may result from the effects of prenatal testosterone and estrogen on the relative growth rate of the 2nd and 4th digits. This study aimed to estimate finger lengths and the 2D:4D ratios for the first time in Saudi Arabian subjects using direct and indirect measurements, and to evaluate the correlations between both indirect and direct 2D:4D with adult testosterone and various sexually dimorphic physical traits. The results revealed the following: (i) mean 2D:4D in Saudi Arabian samples varied from 0.96 to 0.99; (ii) mean 2D:4D was lower for indirect compared to direct 2D:4D; (iii) sex differences in indirect 2D:4D were higher than in direct 2D:4D measurements; (iv) there were no significant correlations between indirect or direct 2D:4D and testosterone level; (v) there were four significant correlations between direct 2D:4D and body size traits but no significant correlations between indirect 2D:4D and body size.

Endothelial membrane remodeling is obligate for anti-angiogenic radiosensitization during tumor radiosurgery

Background

While there is significant interest in combining anti-angiogenesis therapy with conventional anti-cancer treatment, clinical trials have as of yet yielded limited therapeutic gain, mainly because mechanisms of anti-angiogenic therapy remain to a large extent unknown. Currently, anti-angiogenic tumor therapy is conceptualized to either “normalize” dysfunctional tumor vasculature, or to prevent recruitment of circulating endothelial precursors into the tumor. An alternative biology, restricted to delivery of anti-angiogenics immediately prior to single dose radiotherapy (radiosurgery), is provided in the present study.

Methodology/Principal Findings

Genetic data indicate an acute wave of ceramide-mediated endothelial apoptosis, initiated by acid sphingomyelinase (ASMase), regulates tumor stem cell response to single dose radiotherapy, obligatory for tumor cure. Here we show VEGF prevented radiation-induced ASMase activation in cultured endothelium, occurring within minutes after radiation exposure, consequently repressing apoptosis, an event reversible with exogenous C₁₆-ceramide. Anti-VEGFR2 acts conversely, enhancing ceramide generation and apoptosis. In vivo, MCA/129 fibrosarcoma tumors were implanted in asmase^+/+ mice or asmase^−/− littermates and irradiated in the presence or absence of anti-VEGFR2 DC101 or anti-VEGF G6-31 antibodies. These anti-angiogenic agents, only if delivered immediately prior to single dose radiotherapy, de-repressed radiation-induced ASMase activation, synergistically increasing the endothelial apoptotic component of tumor response and tumor cure. Anti-angiogenic radiosensitization was abrogated in tumors implanted in asmase^−/− mice that provide apoptosis-resistant vasculature, or in wild-type littermates pre-treated with anti-ceramide antibody, indicating that ceramide is necessary for this effect.

Conclusions/Significance

These studies show that angiogenic factors fail to suppress apoptosis if ceramide remains elevated while anti-angiogenic therapies fail without ceramide elevation, defining a ceramide rheostat that determines outcome of single dose radiotherapy. Understanding the temporal sequencing of anti-angiogenic drugs and radiation enables optimized radiosensitization and design of innovative radiosurgery clinical trials.

Anti-HLA I antibodies induce VEGF production by endothelial cells, which increases proliferation and paracellular permeability

Anti-human leukocyte antigen class I (HLA I) antibodies were shown to activate several protein kinases in endothelial cells (ECs), which induces proliferation and cell survival. An important phenomenon in antibody-mediated rejection is the occurrence of interstitial edema. We investigated the effect of anti-HLA I antibodies on endothelial proliferation and permeability, as one possible underlying mechanism of edema formation. HLA I antibodies increased the permeability of cultured ECs isolated from umbilical veins. Anti-HLA I antibodies induced the production of vascular endothelial growth factor (VEGF) by ECs, which activated VEGF receptor 2 (VEGFR2) in an autocrine manner. Activated VEGFR2 led to a c-Src-dependent phosphorylation of vascular endothelial (VE)-cadherin and its degradation. Aberrant VE-cadherin expression resulted in impaired adherens junctions, which might lead to increased endothelial permeability. This effect was only observed after cross-linking of HLA I molecules by intact antibodies. Furthermore, our results suggest that increased endothelial proliferation following anti-HLA I treatment occurs via autocrine VEGFR2 activation. Our data indicate the ability of anti-HLA I to induce VEGF production in ECs. Transactivation of VEGFR2 leads to increased EC proliferation and paracellular permeability. The autocrine effect of VEGF on endothelial permeability might be an explanation for the formation of interstitial edema after transplantation.

Letrozole stimulates the growth of human endometrial explants cultured in three-dimensional fibrin matrix

OBJECTIVE

To investigate the effects of an aromatase inhibitor, letrozole, on the growth of human endometrium in a three-dimensional fibrin matrix model of endometriosis.

DESIGN

Experimental study of human endometrial biopsies in a three-dimensional fibrin matrix culture system.

SETTING

Academic research center.

PATIENT(S)

Eight normal women with benign gynecologic problems.

INTERVENTION(S)

Endometrial biopsy samples were washed, cut into small pieces, and placed between two layers of fibrin gel in the presence or absence of letrozole in the culture medium. Tissue changes were assessed by histological and immunohistochemical staining using an inverted microscope, image analysis, and a semiquantitative scoring system.

MAIN OUTCOME MEASURE(S)

Stromal and epithelial cell outgrowth into the fibrin matrix and angiogenesis comprising endothelial cell invasion of the matrix.

RESULT(S)

Letrozole (0.1 micromol/L, 1 micromol/L, and 10 micromol/L) exerted a significant growth stimulation effect on endometrial tissue in this model.

CONCLUSION(S)

In contrast to our expectations, letrozole stimulated growth of normal human endometrium in an in vitro model of endometriosis. Normal endometrium may respond differently than endometriotic lesions to therapeutic agents. Our findings should be kept in mind when considering future research to explore new clinical treatments for endometriosis.

In vitro antiangiogenic activity of selective somatostatin subtype-1 receptor agonists

BACKGROUND

Endothelial cells of human blood vessels (arteries and veins) show high levels of somatostatin subtype-1 receptor (sst(1)). The aim of the present study is to investigate the inhibitory effects of novel somatostatin analogs, highly selective for human sst(1), on in vitro angiogenesis and their modulation of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor-2 (VEGFR-2) expression.

MATERIALS AND METHODS

Somatostatin analogs BIM-23745 and BIM-23926 were tested for their ability to prevent proliferation and migration of human endothelial HMEC-1 cells, to modulate VEGF and VEGFR-2 expression and to inhibit sprouting of microvessels from cultured human placental vessel explants in fibrin matrix for 28 days.

RESULTS

The somatostatin sst(1 )receptor-selective agonists, BIM-23745 and BIM-23926 showed a suppression of endothelial proliferation (e.g. 10(-6) M BIM-23475, 40.0 +/- 2.1% vs. 100% of controls; 10(-7) M BIM-23926, 55.3 +/- 3.3% vs. 100% of controls), migration (e.g. 10(-7) M BIM-23475, 35.0 +/- 1.56% vs. 100% of controls; 10(-7) M BIM-23926, 53.7 +/- 1.77% vs. 100% of controls) and microvessel sprouting (e.g. 10(-8) M BIM-23475, 42.8 +/- 5.6% vs. 100% of controls; 10(-7) M BIM-23926, 17.2 +/- 11.8% vs. 100% of controls). A small but significant percentage of cells exposed to BIM-23745 and BIM-23926 for 24 h and for 72 h presented typical apoptotic morphology. Moreover, both the analogs significantly inhibit VEGF and VEGFR-2 gene expression in endothelial cells grown for 144 h in a fibrin matrix and the VEGF secretion in conditioned media.

CONCLUSIONS

The inhibition of endothelial activities suggests potential therapeutic utility for administration of somatostatin sst(1 )receptor-selective agonists in the proliferative diseases involving angiogenesis.

5-Aza-2'-deoxycytidine increases the expression of anti-angiogenic vascular endothelial growth factor 189b variant in human lung microvascular endothelial cells

Vascular endothelial growth factor (VEGF) is involved in angiogenesis, growth, and tumour cell metastasis. VEGF is expressed as alternative splice variants, which exhibit angiogenic and anti-angiogenic properties. We determined the effect of 5-Aza-2'-deoxycytidine (5-dAzaC) DNA methyltransferase (DNMTs) inhibitor on angiogenic and anti-angiogenic VEGF variants expression in immortalized human lung microvascular endothelial cells (HLMEC). Employing reverse transcription, real-time quantitative PCR (RQ-PCR), and Western blot analysis, we determined that 5-dAzaC decreased VEGF(121a) and VEGF(165a) angiogenic, and VEGF(121b) and VEGF(165b) anti-angiogenic variants expression in HLMEC. However, this DNMTs inhibitor significantly increases expression of VEGF(189b) anti-angiogenic variant transcript and protein in HLMEC. Our results suggest that the DNMTs activity may have an influence on the expression of angiogenic and anti-angiogenic VEGF variants in human lung microvascular endothelial cells.

Identification and analysis of in vitro cultured CD45-positive cells capable of multi-lineage differentiation

We report on a subset of cells that co-purify with CD45-positive/Lineage minus (CD45(pos)/Lin(minus)) hematopoietic cells that are capable of in vitro differentiation into multi-potential cells including cells with neuroectoderm properties. Although these cells are CD45 positive and have properties similar to CD45-negative mesenchymal progenitor cells (MPC) derived from bone marrow (BM), they are neither hematopoietic cells nor mesenchymal cells. These CD45(pos)/Lin(minus) cells can be expanded in vitro, express the stem cell genes Oct-4 and Nanog and can be induced to differentiate into endothelial cells, osteoblasts, muscle cells and neural cells at frequencies similar to those reported for bone marrow mesenchymal cells. Long-term culture of these cells followed by transplantation into NOD/SCID mice resulted in positive bone marrow stromal cell engraftment but not hematopoietic engraftment, suggesting that despite their CD45-positive status these cells do not have the same properties as hematopoietic stem cells. Clonal cell analysis determined that the culture period caused a broadening in the differentiation potential of the starting population.

Giant cell granuloma of the jawbones ? a proliferative vascular lesion? Immunohistochemical study with vascular endothelial growth factor and basic fibroblast growth factor

AIM

To estimate the angiogenic activity in central giant cell granuloma (CGCG) by immunohistochemical stains for vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). VEGF and bFGF immunoreactivity of the lesional mononuclear (MC) and giant (GC) cells was also investigated.

METHOD

The study consisted of 41 cases of CGCG. Vascularity was quantified by microvascular volume (MVV) as determined by point counting. In five cases of CGCG, regions at the surrounding border, which demonstrated reactive vascular-rich inflammatory areas, served as control. Immunoreactivity of the MC and GC was assessed as the percentage of VEGF- and bFGF-positive cells from the total number of the respective cell type.

RESULTS

Within CGCG lesions the extent of angiogenesis was low; MVV did not exceed 5% for either VEGF (88% of lesions) or bFGF (78% of lesions). The mean MVV of VEGF- and bFGF-positive blood vessels was 2.9% +/- 2.4% and 3.46% +/- 2.35%, respectively, significantly lower than in the control areas (27.5% +/- 7.3% and 28.08% +/- 5.5%, respectively) (P = 0.043). VEGF-positive and bFGF-positive MC and GC were found in nearly all lesions and in less than half of the lesions, respectively.

CONCLUSION

The low mean MVV of VEGF- and bFGF-positive blood vessels implies low angiogenic activity, which does not support the designation of CGCG as a true proliferative vascular lesion. MC and GC immunoreactivity for the angiogenic factors is assumed to play an important role in the osteoclastogenesis process, thus contributing to additional growth of the CGCG lesions.

Withdrawal: Pigment epithelium-derived factor inhibits angiogenesis via regulated intracellular proteolysis of vascular endothelial growth factor receptor 1

Pigment epithelium-derived factor (PEDF) has been identified as one of the most potent of endogenous negative regulators of blood vessel growth in the body. Here we report that PEDF is able to inhibit growth factor-induced angiogenesis in microvascular endothelial cells through a novel pathway requiring cleavage and intracellular translocation of the transmembrane domain of the VEGFR-1. Analysis of the subcellular distribution of VEGFR-1 revealed the appearance of an 80-kDa C-terminal domain in the cytosol of cells treated with VEGF and PEDF that correlated with a decrease of the full-length receptor in the nuclear and cytoskeletal fractions. This regulated intramembrane proteolysis is dependent on gamma-secretase because inhibition of gamma-secretase abolished the inhibitory effect of PEDF on VEGF-induced angiogenesis as well as VEGFR-1 cleavage. The addition of PEDF to microvascular endothelial cells significantly increases gamma-secretase activity even in the absence of VEGF, showing that VEGF binding to VEGF-R1 is essential for substrate availability. This increase in activity was associated with translocation of presenilin 1 from the perinuclear region to the cell membrane. PEDF was also able to inhibit VEGF-induced phosphorylation of VEGFR-1. Taken together we have identified two novel pathways by which PEDF inhibits VEGF-induced angiogenesis: regulated intramembrane proteolysis and inhibition of phosphorylation. This confirms the importance of PEDF and VEGFR-1 in the negative regulation of angiogenesis.

Antiangiogenic versus cytotoxic therapeutic approaches to human pancreas cancer: an experimental study with a vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor and gemcitabine

Pancreatic adenocarcinoma is a leading cause of cancer death in the United States and represents a challenging chemotherapeutic problem. The pharmacological control of angiogenesis might represent a novel approach to the management of pancreas cancer, since the pathological development of vascular supply is a critical step for tumor growth and may affect its prognosis. In order to test this hypothesis, SU5416 ([3-(3,5-dimethyl-1H-pyrrol-2-ylmethylene)-1,3-dihydro-indol-2-one]) a selective inhibitor of the vascular endothelial growth factor receptor-2 tyrosine kinase, and gemcitabine (2', 2'-difluorodeoxycytidine) were tested on endothelial (HUVEC) and pancreatic tumor cells (MIA PaCa-2) in vitro and in vivo alone and in simultaneous association. SU5416 inhibited HUVEC cells stimulated to proliferate by vascular endothelial growth factor but not MIA PaCa-2 cells; the drug concentration that decreased cell growth by 50% (IC50) was 0.14 microM. Furthermore, SU5416 reduced the development of microvessels from placental explants (IC50, 0.23 microM). Gemcitabine inhibited the growth of both HUVEC and MIA PaCa-2 cells with an IC50 of 0.08 and 0.1 microM, respectively. A synergistic effect (combination index <1 and dose reduction index >1) on anti-proliferative and pro-apoptotic activity was calculated with the simultaneous combination of the two drugs on endothelial cells. A marked in vivo antitumor effect on MIA PaCa-2 xenografts was observed with SU5416 at a protracted schedules, as well as with gemcitabine; furthermore, the combination between the two drugs resulted in an almost complete suppression of tumor growth and relapse. In conclusion, the present results provide the evidence of an effective anti-endothelial/antitumor activity of protracted administration of SU5416 on human pancreas cancer xenografts, which is comparable with the one obtained by gemcitabine; moreover, the synergistic combination between these drugs on endothelial cells and the promising association in pancreatic cancer xenografts could be used in future studies and translated into the clinical setting.

VEGF expression in the placenta from pregnancies complicated by hypertensive disorders

OBJECTIVE

To determine the expression of VEGF in the placental tissue from pregnancies complicated by hypertension disorders of different clinical severity.

DESIGN

Prospective cohort study.

SETTING

Polyclinic of Careggi, University of Florence, Italy.

SAMPLE

Placentas from women with gestational hypertension (n= 20), pre-eclampsia (n= 20) and pre-eclampsia with HELLP syndrome (n= 20) and from normotensive women (n= 20), as control group (gestational age comprised between 35 and 38 weeks).

METHODS

An immunohistochemical technique and a quantitative analysis to measure mRNA levels (RT-PCR) were employed.

MAIN OUTCOME MEASURES

Intensity of immunoreactivity and mRNA levels in the placental components. Differences between the data.

RESULTS

VEGF immunoreactivity was observable in all the placental components in the gestational hypertension cases as in the control ones. In the cases with pre-eclampsia and pre-eclampsia with HELLP syndrome, some placental components were not immunoreactive. However, the VEGF positive components of all the pathological groups showed a higher intensity of reactivity with respect to that of the control group. The levels of VEGF mRNA were higher in the gestational hypertension cases and lower in the cases of pre-eclampsia with HELLP syndrome with respect to the control ones; in the cases of pre-eclampsia, the levels were the same as the control ones.

CONCLUSION

The different expression of VEGF in the placenta of the pathological cases is probably related to haemodynamic changes that take place in these disorders, in order to attempt restoration of a normal uteroplacental flow.

Definition of the microvascular pattern of the normal human adult mammary gland

The present report provides a detailed description of microvascularization in the normal human mammary gland, and defines two novel morphometric parameters to be used as a reference when angiogenesis in breast carcinoma is evaluated. Microvascularization was analysed by histology, immunohistochemistry and computer-assisted analysis in a set of breast tissue samples taken from nine women, during the pre-ovulatory phase of the menstrual cycle. The two parameters designed for image analysis were: vascular density (VD): [microvessel number/(microvessel area + residual stromal area)] x 10 000; and vascular area ratio (VAR): [microvessel area/(microvessel area + residual stromal area)]. In the lobules VD (mean value +/- SE 2.48 +/- 0.14) and VAR (0.33 +/- 0.02) showed little variability and correlated significantly (P < 0.05). The areas occupied by microvessels, stroma and acini remained constant in all lobules (21.53 +/- 1.87%, 42.65 +/- 1.35% and 35.14 +/- 1.57%, respectively). Microvascularization of the lobules was of a sinusoidal type, with large S-shaped capillaries. In the ducts VD (2.95 +/- 0.16) and VAR (0.29 +/- 0.03) showed little variability but did not correlate significantly. Microvascularization of the ducts was of a classic type, with capillaries normal in size and shape. The expression of oestrogen (ER) and progesterone (PR) receptors was analysed by immunohistochemistry and compared with the morphometric results. ER expression levels were in the range 20-25% (24.3 +/- 2.1) and 14-18% (15.4 +/- 1.5) in lobules and ducts, respectively. PR expression levels were in the range 10-13% (11.1 +/- 1.6) and 14-17% (15.2 +/- 1.4), respectively. No correlation was found between ER/PR expression and vascularization parameters.

Production of Endothelin-1 and Big Endothelin-1 by Human Cardiac Myxoma Cells-Implications for the Origin of Myxomas-

BACKGROUND

Although the origin of cardiac myxomas is still controversial, the 2 main hypotheses are that the tumor cells originate either from multipotential mesenchymal cells or from endocardial neural tissue.

METHODS AND RESULTS

The production of various cytokines in 2 human cardiac myxoma cell lines was examined by enzyme-linked immunosorbent assay. After 7 days of culture, extremely high concentrations of interleukin-6 were detected in the culture media from both myxoma cell lines. Increased production of CXC chemokines, interleukin-8 and growth-related oncogene-alpha, were observed in both myxoma cell lines. Endothelin (ET)-1 and its precursor, big ET-1, were detected in the culture media from both myxoma cell lines. The production of both ET-1 and big ET-1 by myxoma cells was higher than by human umbilical vein endothelial cells. Similar to endothelial cells, myxoma cells did not produce stem cell factor, granulocyte colony-stimulating factor, hepatocyte growth factor, or ET-3.

CONCLUSIONS

The similarity of the cytokine production pattern between cardiac myxoma cells and endothelial cells supports the hypothesis that the tumor cells originate from mesenchymal cells capable of endothelial differentiation. Overproduction of CXC chemokines may explain, in part, the malignant potential of histologically benign myxomas.

Three-dimensional in vitro culture of endometrial explants mimics the early stages of endometriosis

OBJECTIVE

To reproduce the earliest phases of endometriosis using a new in vitro model in which cells from a cultured endometrial fragment can proliferate, invade, reconstitute new endometrial-like tissue, and generate blood vessels.

DESIGN

Experimental in vitro study.

SETTING

A hospital-based academic research institute.

PATIENT(S)

Five normal ovulating women undergoing surgery for various benign gynecological indications.

INTERVENTION(S)

Endometrial samples obtained from the fundus of the uterine cavity were placed in a three-dimensional fibrin matrix culture system.

MAIN OUTCOME MEASURE(S)

Degree of proliferation of stromal cells and invasion of the fibrin matrix, gland, and stroma formation, vessel sprouting, and immunohistochemical characterization of various cellular components.

RESULT(S)

During the first week of culture, an endometrial cell outgrowth was observed from the original fragments in 120 of 144 wells (83.3%). Subsequently, cell outgrowths could be quantified in 132 (91.6%), 129 (89.5%), and 127 (88.1%) of the wells after 15, 60, and 90 days, respectively. An invasion of the matrix by the human endometrial cells led to the formation of tubular structures that coalesced into tissue, architecturally resembling endometrium and in which the glands were immunohistochemically positive for cytokeratin. New capillaries, immunohistochemically positive for CD31 and vimentin, sprouted from the endometrial outgrowths at the beginning of the fifth week of culture.

CONCLUSION(S)

These data show that cells from endometrial explants can proliferate and invade a fibrin matrix in vitro generating new glands, stroma, and vessels consistent with endometriosis. The three-dimensional fibrin matrix used in the present study provides an opportunity to observe the earliest biological events of endometriosis in a quantifiable way.

Use of two replacements of serum during bovine embryo culture in vitro

This study evaluated the effect of two commercial serum replacements (Ultroser G and CPSR-3 on in vitro bovine embryo culture. In Experiment 1, zygotes were cultured in SOF+Ultroser G (2, 4 and 6%), SOF+CPSR-3 (2, 4 and 6%), and SOF+5% FCS (control). Blastocyst rates obtained after culturing with Ultroser G were lower than those with FCS. However, blastocyst rates for CPSR-3 were similar to those for serum. In addition, embryos produced in SOF+CPSR-3 had the same proportion inner cell mass number and total cell number as embryos cultured with FCS. In Experiment 2, a combination of serum replacements during different periods showed that treatment before the five-to eight-cell stages had no effect on further embryo development. However, treatments up to the morula stage affected blastocyst formation. The concentration of supplement and the timing of its inclusion in culture markedly affected embryo development. The serum replacement CPSR-3 can supplement embryo culture with blastocyst rates and quality similar to those for serum.