Bone marrow angiogenesis in patients with active multiple myeloma

Factor VIII-related antigen (FVIII-RA)-positive microvessel areas were measured by both immunohistochemistry and computerized image analysis in patients with active multiple myeloma (MM), nonactive MM, and monoclonal gammopathies of undetermined significance (MGUS). A five-to sixfold larger area was found in patients with active MM compared to the other two groups. Aquaporin 1 (AQP1)-positive microvessel areas, measured with the same techniques on adjacent tissue sections, were also increased in active MM, and tended to be larger than and closely correlated with the FVIII-RA areas. Numerous mast cells were found in the bone marrow of active MM patients, and counts were strictly correlated with the microvessel density. The conditioned medium (CM) of bone marrow plasma cells from active MM patients stimulated endothelial cell proliferation and chemotaxis, monocyte chemotaxis, and angiogenesis in vivo (assessed by the chick embryo chorioallantoic membrane [CAM] system) more strongly and frequently than the CM of patients with nonactive MM and MGUS. Immunoassay of plasma cell lysates gave significantly higher levels of fibroblast growth factor-2 (FGF-2) in patients with active MM than in the other two groups, and a neutralizing anti-FGF-2 antibody inhibited by 46% to 68% the biological activity exerted by the CM in vitro and in the CAM. In situ hybridization of bone marrow plasma cells and zymography of CM showed that patients with active MM express higher levels of matrix metalloproteinase-2 (MMP-2) mRNA and protein than those with nonactive MM and MGUS, whereas MMP-9 expression and secretion overlapped in all groups. Overall data indicate that patients with active MM represent the vascular phase of plasma cell tumors that is induced, at least partly, through FGF-2 and MMP-2. Mast cells possibly contribute to the vascular phase via angiogenic factors in their secretory granules. Both angiogenesis and MMP-2 secretion can account for intramedullary and extramedullary spreading of plasma cells in patients with active MM.

In vivo absence of synergism between fibroblast growth factor-2 and vascular endothelial growth factor

Fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF) are potent angiogenesis inducers in vivo and in vitro and may act in synergy. This possibility has been investigated by their simultaneous administration in the chick embryo chorioallantoic membrane (CAM) assay. Macroscopic and microscopic quantification of the angiogenic response 4 days after administration clearly demonstrated the absence of synergism. When FGF-2 or VEGF concentration was fixed at 0.25 microg/embryo, the simultaneous addition of increasing concentration (0.25, 0.50, 1.0 microg/embryo) of VEGF or FGF-2 did not stimulate a synergistic dose-dependent angiogenic response. In both conditions, the angiogenic response overlapped that induced by the two growth factors administered alone. It is suggested that exogenous administration of FGF-2 and VEGF in the CAM assay may induce an activation of endogenous angiogenic factors, such as FGF-2, and endogenous inhibitors of angiogenesis, such as nitric oxide, normally expressed in the CAM during the development of its vascular tree. Thus, in an in vivo system, evaluation of synergistic action between two cytokines and discrimination of their specific activity are more difficult than in an in vitro assay.

Chorioallantoic membrane capillary bed: a useful target for studying angiogenesis and anti-angiogenesis in vivo

The chick embryo chorioallantoic membrane (CAM) is an extraembryonic membrane that is commonly used in vivo to study both angiogenesis and anti-angiogenesis. This review 1) summarizes the current knowledge about the structure of the CAM's capillary bed; 2) discusses the controversy about the existence of a single blood sinus or a capillary plexus underlying the chorionic epithelium; 3) describes a new model of the CAM vascular growth, namely the intussusceptive mode; 4) reports findings regarding the role played by endogenous fibroblast growth factor-2 in CAM vascularization; and 5) addresses the use and limitations of the CAM as a model for studying angiogenesis and anti-angiogenesis.

Inhibition of neuroblastoma-induced angiogenesis by fenretinide

Retinoids are a class of natural or synthetic compounds that participate in the control of cell proliferation, differentiation and fetal development. The synthetic retinoid fenretinide (HPR) inhibits carcinogenesis in various animal models. Retinoids have also been suggested to be effective inhibitors of angiogenesis. The effects of HPR on certain endothelial cell functions were investigated in vitro, and its effects on angiogenesis was studied in vivo, by using the chorioallantoic membrane (CAM) assay. HPR inhibited vascular endothelial growth factor- (VEGF-) and fibroblast growth factor-2- (FGF-2)-induced endothelial cell proliferation without affecting endothelial motility; moreover, HPR inhibited growth factor-induced angiogenesis in the CAM assay. Furthermore, a significant antiangiogenic potential of HPR has also been observed in neuroblastoma (NB) biopsy-induced angiogenesis in vivo. We previously demonstrated that supernatants derived from NB cell lines stimulated endothelial cell proliferation. In the present study, we found that this effect was abolished when NB cells were incubated in the presence of HPR. VEGF- and FGF-2-specific ELISA assays, performed on both NB cells derived from conditioned medium and cellular extracts, indicated no consistent effect of HPR on the level of these angiogenic cytokines. Moreover, RT-PCR analysis of VEGF and FGF-2 gene expression confirmed the above lack of effect. HPR was also able to significantly repress the spontaneous growth of endothelial cells, requiring at least 48-72 hr of treatment with HPR, followed by a progressive accumulation of cells in G(1) at subsequent time points. Finally, immunohistochemistry experiments performed in the CAM assay demonstrated that endothelial staining of both VEGF receptor 2 and FGF-2 receptor-2 was reduced after implantation of HPR-loaded sponges, as compared to control CAMs. These data suggest that HPR exerts its antiangiogenic activity through both a direct effect on endothelial cell proliferative activity and an inhibitory effect on the responsivity of the endothelial cells to the proliferative stimuli mediated by angiogenic growth factors.

Angiogenesis, angiogenic factor expression and hematological malignancies

Solid tumor growth consists of an avascular and a subsequent vascular phase. Several studies have now shown that, as in solid tumors, angiogenesis also plays a critical role in the progression of hematological malignancies. Monoclonal gammopathy of undetermined significance (MGUS) and non-active to active multiple myeloma (MM) progress when plasma cells induce angiogenesis and this in turn promotes progression. The increased bone marrow neovascularization, increased angiogenic and proteolytic potential of plasma cells may explain the frequent occurrence of extramedullary localization in MM. As observed in active MM, enhanced bone marrow neovascularization is apparent in acute untreated lymphoblastic leukemia. In B-cell non-Hodgkin's lymphomas, angiogenesis is significantly enhanced in relation to progression. Angiostatic molecules, such as thalidomide, could also be considered for the clinical management of hematological tumors.

Angiogenic activity of leptin in the chick embryo chorioallantoic membrane is in part mediated by endogenous fibroblast growth factor-2

Recently, it has been demonstrated that leptin, the product of the ob gene, playing a key role in the regulation of body weight, is angiogenic in vitro and in vivo. In this study we investigated the angiogenic potential of human leptin in vivo by using the chick embryo chorioallantoic membrane (CAM) assay, with the aim to establish whether this angiogenic activity is partly dependent on endogenous fibroblast growth factor-2 (FGF-2), which is normally expressed during CAM development. Results showed that leptin is able to stimulate angiogenesis and that the angiogenic response is similar to that obtained with FGF-2. The stimulating property of leptin is specific, as the application of anti-leptin antibodies onto the CAM significantly inhibits the angiogenic response. Moreover, this angiogenic activity is in part due to the activation of endogenous FGF-2. The application of anti-FGF-2 antibodies reduces the angiogenic response to leptin by 40%. Our study confirms that leptin is angiogenic in vivo and suggests that, at least in the chick CAM, its activity is in part mediated by the activation of endogenous FGF-2.

alpha(v)beta(3) integrin engagement modulates cell adhesion, proliferation, and protease secretion in human lymphoid tumor cells

OBJECTIVE

The mechanisms used by human lymphoproliferative diseases to invade locally and metastasize are thought to be similar to those developed by solid tumors, including cell proliferation and secretion of extracellular matrix-degrading enzymes following adhesion to extracellular matrix proteins. Hence, the ability of Namalwa (Burkitt's lymphoma), U266 (multiple myeloma), and CEM (T-cell lymphoblastic leukemia) cells to interact with the extracellular matrix components vitronectin and fibronectin was determined. Fresh bone marrow plasma cells from patients with multiple myeloma also were studied.

MATERIALS AND METHODS

Engagement of alpha(v)beta(3) integrin, formation and protein composition of focal adhesion contacts on the cell surface, phosphorylation of several signal transduction proteins in the contacts, cell proliferation, and enzyme secretion were studied following adhesion to vitronectin and fibronectin.

RESULTS

All three lines adhered to immobilized vitronectin and fibronectin. Adhesion was fully prevented by neutralizing monoclonal anti-alpha(v)beta(3) integrin antibody. Integrin engagement caused the formation of phosphorylated pp60(src)/focal adhesion kinase complexes and the aggregation of focal adhesion plaques containing the beta(3) integrin subunit, the cytoskeletal proteins vinculin, cortactin, and paxillin, the tyrosine kinases focal adhesion kinase and pp60(src), the adapter protein Grb-2, and the mitogen-activated protein kinase ERK-2. Free and immobilized vitronectin and fibronectin stimulated the proliferation of cells under serum-free conditions and the production and release of urokinase-type plasminogen activator, and increased the release of the activated forms of matrix metalloproteinase-2 and matrix metalloproteinase-9 in an alpha(v)beta(3) integrin-dependent manner. Similar results were obtained in myeloma plasma cells.

CONCLUSIONS

The demonstrated ability of lymphoid tumor cells to interact with the extracellular matrix components vitronectin and fibronectin via alpha(v)beta(3) integrin can be interpreted as evidence of a novel mechanism for their invasion and spreading. This interaction allows them to adhere to the substratum and enhances their proliferation and protease secretion.

Cell-mediated delivery of fibroblast growth factor-2 and vascular endothelial growth factor onto the chick chorioallantoic membrane: endothelial fenestration and angiogenesis

Fibroblast growth factor-2 (FGF2) and vascular endothelial growth factor (VEGF) exert their angiogenic activity by interacting with endothelial cells in a distinct manner. In this study, we investigated the morphological features of endothelial cells of the chick embryo chorioallantoic membrane (CAM) microvasculature after stimulation with FGF2 or VEGF. In order to provide a continuous delivery of the growth factor, we utilized a recently developed gelatin sponge/CAM assay in which a limited number of FGF2- or VEGF-transfected cells were adsorbed onto gelatin sponges and applied on the top of the CAM on day 8 of development. Their angiogenic activity was compared to that exerted by a single bolus of the corresponding growth factor. All the angiogenic stimuli induced a comparable vasoproliferative response, as demonstrated by the appearance of similar numbers of immature blood vessels within the sponge on day 12. No angiogenic response was observed in CAMs implanted with the corresponding parental cell lines or vehicle. Electron microscopy demonstrated that VEGF-overexpressing cells modified the phenotype of the endothelium of the blood vessels at the boundary between the implant and the surrounding CAM mesenchyme. The endothelial lining of 30% of these vessels showed segmental attenuations, was frequently interrupted and became fenestrated, mimicking what is observed in tumor vasculature. In contrast, the vessels consisted of continuous endothelium sealed by tight junctions in all the other experimental conditions. These results indicate that FGF2 and VEGF interact with endothelial cells of the CAM in a distinct manner. Both growth factors induce a potent angiogenic response, but only VEGF delivered in a continuous manner by its transfectants can modify the phenotype of the otherwise quiescent endothelium of CAM blood microvessels. The gelatin sponge/CAM assay may constitute a new model to study the mechanisms leading to endothelial fenestration in tumor growth.

Beryllium(II) Complexes of the Kläui Tripodal Ligand Cyclopentadienyltris(diethylphosphito-P)cobaltate(−)

The interactions of the beryllium(II) ion with the cyclopentadienyltris(diethylphosphito-P)cobaltate monoanion, L(-), have been investigated, in aqueous solution, by synthetic methods, potentiometry, ESMS, and (1)H, (31)P, and (9)Be NMR spectroscopy. L(-) has been found able to displace either two or three water molecules in the beryllium(II) coordination sphere, to form mononuclear, dinuclear, and trinuclear derivatives, in which the metal ion is pseudotetrahedrally coordinated. The species [BeL(H(2)O)](+) and [Be(2)L(2)(mu-OH)](+) have been identified in solution while complexes of formula BeL(2) and [Be(3)L(4)](ClO(4))(2) have been isolated as solid materials. The species [BeL(OPPh(2))](+), closely related to [BeL(H(2)O)](+), has been characterized in acetone solution and isolated as tetraphenylborate salt. The structure of the unusual trimeric complex [Be(3)L(4)](2+) has been elucidated by an unprecedented 2D (9)Be-(31)P NMR correlation spectrum showing the presence of a single central beryllium nucleus and two equivalent terminal beryllium nuclei. The three beryllium centers are held together by four cobaltate ligands, which display two different bonding modes: two ligands are terminally linked with all the three oxygen donors to one terminal beryllium, and the other two bridge two metal centers, sharing the oxygen donors between central and terminal beryllium atoms.

Microvessel overexpression of aquaporin 1 parallels bone marrow angiogenesis in patients with active multiple myeloma

The erythrocyte water channel aquaporin 1 (AQP1) is expressed in multiple absorptive and secretory epithelia including the capillary endothelia. Immunoblot analysis showed that bone marrow biopsies of patients with active multiple myeloma (MM) display significantly higher levels of AQP1 than those from patients with non-active MM, whose values are higher, but to a lesser extent, than those of patients with monoclonal gammopathies of undetermined significance (MGUS). Values of MGUS overlapped those of patients with anaemia as a result of iron or vitamin B12 deficiencies (called 'benign anaemias'). Immunohistochemistry and computerized image analysis of AQP1 highlighted bone marrow microvessels whose area per microscopic field was significantly greater in patients with active MM, and always larger than and closely correlated with the microvessel area when assessed with factor VIII-related antigen/von Willebrand's factor (FVIII-VWF). The intensity of AQP1 expression by microvessels evaluated using image analysis was significantly greater in active than non-active MM and in the latter over MGUS or benign anaemias. It is suggested that, among plasma cell tumours, AQP1 expression is preferentially associated with microvessels of MM and that the highest degree of expression occurs in active MM in step with enhanced angiogenesis, in which AQP1 recognizes more immature neovessels than FVIII-VWF. It may, perhaps, favour angiogenesis in a positive loop and, hence, MM progression, and thus be applied for therapeutic vascular targeting.

A syndrome characterized by psychiatric disorders, recurrent mucosal infections and natural immunity deficits: clinical approach

The authors summarize their own previous work on the identification of a subset of patients characterized by psychiatric disorders, recurrency of mucosal infections and impaired natural immunity. The diagnostic approach to these patients based on the close collaboration between infectivologists, immunologists and psychiatrists is described with the aim to find out combined treatments for the amelioration of clinical manifestations.

Vascular endothelial growth factor and vascular endothelial growth factor receptor-2 expression in the chick embryo area vasculosa

Vascular endothelial growth factor is an angiogenic factor in vivo and in vitro that plays a crucial role in the control of blood vessel development and in pathological angiogenesis. The vascularized extraembryonic membranes of the chick embryo include the area vasculosa and the chorioallantoic membrane. In this study, we investigated the expression of vascular endothelial growth factor and of its receptor-2, specifically expressed by the endothelial cells, in the chick area vasculosa at days 6, 10 and 14 of incubation. Our results indicate that, in all the three developmental stages examined, vascular endothelial growth factor is clearly expressed in the endodermal cells immediately adjacent to the mesodermal endothelial cells which, in turn, expressed vascular endothelial growth factor receptor-2. These observations suggest that during the development of the vascular system, endodermal cells, expressing vascular endothelial growth factor, initiate angiogenesis by stimulating directly mesodermal cells, which express vascular endothelial growth factor receptor-2. Moreover, our data demonstrate that vascular endothelial growth factor receptor-2 expression is also maintained by endothelial cells in the later stages of development, until day 14 of incubation. In accord with other literature data, this suggests that vascular endothelial growth factor is required not only for proliferation, but also for the survival of endothelial cells.

Operative vaginal delivery: clinical appraisal of a new vacuum extraction device

The efficacy of a new vacuum extraction device, the Kiwi OmniCup, and its effects on mothers and infants were tested in a study of 18 non-rotational and 32 rotational vacuum assisted deliveries. Forty-nine (98%) of the extractions resulted in successful vaginal births. Autorotation of the fetal head when the occiput was transverse or posterior was achieved in 31 (97%) of the 32 vacuum procedures. The high success rates recorded for both vaginal delivery and autorotation of the fetal head were largely attributable to the fact that flexing cup applications were achieved in 90 % of the vacuum attempts. There were no cases of serious maternal trauma or clinically significant neonatal injuries. Two infants had cephalohaematomas and one infant developed a small subgaleal haemorrhage following a difficult delivery, which resolved rapidly without complications. It was concluded that the Kiwi OmniCup is an efficient and safe vacuum device for assisted vaginal delivery, provided it is used correctly and appropriately.

The thymus at the crossroad of neuroimmune interactions

The numerous relationships existing between the nervous and the immune systems suggest that the neural networks present in the intrathymic microenvironment may influence T-cell development. We previously reported that thymic neural-crest-derived stromal cells are involved in a neural differentiation pathway and are able to produce neurotrophic factors and neurokines that are in turn able to increase and/or modulate thymic-stromal cell neuronal phenotype. We also showed that EGF promotes a neural phenotype in thymic epithelial cells by enhancing the expression of neuronal-specific markers, neurotransmitters, and neuropoietic cytokines, such as IL-6 and CNTF. More recently we showed that the effect of EGF in directing thymic epithelial cells toward a neural-oriented cell fate is mediated by modulating the expression of genes directly involved in neurotypic differentiation (i.e., thrombospondin-1). EGF-induced regulation of stromal cells may also affect T-cell differentiation, as we observed that an EGF-pretreatment reduces the ability of thymic epithelial cells to sustain thymocyte differentiation in vitro. Finally, we demonstrated that a complex network involving the neurotrophin BDNF and its specific receptors may have a role in sustaining thymocyte precursor survival and supporting the thymocyte differentiation process. All together, our results suggest that the thymus may be the site of integration of different neuroimmune networks that are potentially involved in the regulation of thymocyte survival and/or differentiation.

Monocyte-macrophage system and polymorphonuclear leukocytes in workers exposed to low levels of metallic mercury

Our previous research (Soleo L, Vacca A, Vimercati L et al. Occup Environ Med 1997;54:437-442) showed a reduction in tumor necrosis factor-alpha (TNF-alpha) serum levels in workers with prolonged exposure to low doses of inorganic mercury, suggesting an in vivo functional defect of the monocyte-macrophage system. On this basis, here we wondered whether workers exposed to lower doses of metallic mercury displayed possible changes in the monocyte-macrophage system. In this particular cohort of workers, we also sought for the effects of the exposure on the polymorphonuclear leukocytes (PMNL) chemotaxis. The monocyte-macrophage system and the natural killer (NK) cells were examined in 19 exposed workers and in 25 unexposed workers, as the control group (controls). Specifically, the circulating monocyte-macrophage cells and their CD13, CD15 and CD33 subsets, serum cytokines (IL-8, GM-CSF and TNF-alpha) and the NK cells were analyzed. In seven exposed and seven controls randomly chosen workers the PMNL chemotaxis was also assessed. The selected indicator of mercury exposure were the levels of mercury in the urine (U-Hg), that was significantly higher in exposed workers than the controls (9.7 +/- 5.5 microg/l and 2.4 +/- 1.2 microg/l, respectively). None of the exposed workers had shown signs of either acute or chronic inorganic mercury toxicity or any form of hypersensitivity. Several immunological variables tested, monocyte-macrophage cells and their subsets, NK cells and serum cytokines overlapped between the exposed and the control workers. When the workers were considered as a whole (exposed plus controls), no correlation was found between current U-Hg and all immunological parameters. However, when exposed workers were studied separately, an inverse correlation was disclosed between cumulative U-Hg and cells (as percentage) expressing the CD13 (r = -0.599; P = 0.007) and CD15 (r = -0.614; P = 0.005) molecules, and NK cells (r = -0.455; P = 0.05). Moreover, a significant impairment in the PMNL chemotaxis (t = 3.70; P = 0.003) was observed in the exposed workers. The results of our study suggest that the exposure to very low levels of metallic mercury led to subtle impairment of circulating monocyte and NK cells (as percentages) according to the increase in U-Hg levels, as well as of the PMNL chemotactic function in this particular group of workers, even though they remain clinically asymptomatic. Therefore, we suggest that impairment of these parameters provide a sensitive indicator of metallic mercury and other chemical contaminants present in the environment.

Coordinate immunoreactivity to vascular endothelial growth factor receptor-2 and its ligand suggests a paracrine regulation during the development of the vascular system in the chick embryo bursa of Fabricius

The bursa of Fabricius is a lymphoid organ of the chick which plays an important role in the development of the immune system. The role of angiogenic factors in the development of the vascular system of this organ has been poorly investigated. Vascular endothelial growth factor (VEGF) is a major regulator of endothelial cell proliferation, angiogenesis and vascular permeability, and its activities are mediated by two receptors, VEGFR-1 and VEGFR-2. In this study we have investigated by immunohistochemistry the VEGF and VEGFR-2 immunoreactivity in developing bursa of Fabricius. Starting from day 10 of incubation, the endodermal epithelium reacts with VEGF and gives rise to the lymphoid follicles, while the vascular endothelium reacts with VEGFR-2. These data support the view that VEGF acts as a paracrine stimulator of angiogenesis in the avian embryo and confirm the requirement of the endodermal layer for the normal formation of blood vessels by mesodermal cells.

Postnatal vasculogenesis

It is generally accepted that vasculogenesis is limited to early embryogenesis and is believed not to occur in adult, whereas angiogenesis occurs in both the developing embryo and postnatal life. However, the distinction between them is not absolute, because both require endothelial cell proliferation and migration and three-dimensional reorganization of newly formed blood vessels, nor are they mutually exclusive, inasmuch as angioblasts can be incorporated into expanding pre-existing blood vessels. Recent observations indicate that vasculogenesis may not be restricted to early embryogenesis, but may also have a physiological role or contribute to the pathology of vascular diseases in adults. The major evidence in favor of this new view comes from: (i) demonstration of the presence of circulating endothelial cells and endothelial precursor cells; (ii) newly described mechanisms of blood vessel formation in tumor growth. The potential biomedical applications of endothelial precursor cells and the new opportunities for the development of new forms of tumor-targeted treatments are discussed.

Angiogenesis extent and expression of matrix metalloproteinase-2 and -9 correlate with progression in human neuroblastoma

In human tumors changes in angiogenesis and expression of extracellular matrix-degrading enzymes occur simultaneously during invasion and metastasis. Tissues from 20 biopsies of human neuroblastoma (NB) were investigated immunohistochemically by using an antibody against factor VIII to determine their microvessel number, and by in situ hybridisation to determine the expression of mRNA of the matrix metalloproteinase-2 (MMP-2) and MMP-9. The extent of angiogenesis and the expression of the MMP-2 and MMP-9 mRNA were upregulated in advancing stages. These in situ data suggest that angiogenesis and degradation of extracellular matrix occur simultaneously with NB tumor progression.

The discovery of angiogenic factors: a historical review

Angiogenesis is a biological process by which new capillaries are formed and it occurs in many physiological and pathological conditions. It is controlled by the net balance between molecules that have positive and negative regulatory activity and this concept had led to the notion of the "angiogenic switch," depending on an increased production of one or more of the positive regulators of angiogenesis. Numerous inducers of angiogenesis have been identified and this review offers a historical account of the relevant literature concerning the discovery of the best-characterized angiogenic factors.