Biomedical subjects

D Ribatti

Publications and source records attributed to D Ribatti.

197 records · Page 11Linked to original sources

PubMedDate not supplied

Endothelin-1, a regulator of angiogenesis in the chick chorioallantoic membrane.

We investigated the angiogenic properties of endothelin-1 (ET-1) using a novel experimental approach involving the constant production and release of ET-1, which was achieved by grafting stably transfected Chinese hamster ovary (CHO) (CHO-ET-1) cell aggregates onto the chorioallantoic membrane (CAM) ectoderm. Macroscopic observation showed that CHO-ET-1 cell aggregates formed highly vascularized nodules surrounded by radially rearranged vessels, with a strong angiogenic response. 5-Bromo-2'-deoxy-uridine (BrdU) studies showed an increase in endothelial cell proliferation in the CAM vasculature around CHO-ET-1 nodules. An angiogenic response was also observed with gelatin sponges containing conditioned medium from CHO-ET-1 cells. The specific involvement of ET-1 in the angiogenic effect mediated by CHO-ET-1 was demonstrated by the reduction or abolition of neovascularized CHO-ET-1 nodules by (1) bosentan, a mixed antagonist of ET(A)/ET(B) receptors, (2) an ET(A) receptor antagonist (Ru69986) and (3) phosporamidon, an inhibitor of endothelin-converting enzyme-1 (ECE-1). We also demonstrated that VEGF was involved in CHO-ET-1-mediated angiogenesis, by using a specific inhibitor of VEGF tyrosine kinase receptor activity (PTK787/ZK 222584), which abolished CHO-ET-1 nodule formation and CAM neovascularization. Thus, our results show that exogenous ET-1 mediates angiogenesis in vivo.

Allantois↗

PubMedDate not supplied

New model for the study of angiogenesis and antiangiogenesis in the chick embryo chorioallantoic membrane: the gelatin sponge/chorioallantoic membrane assay.

Several methods for the in vivo study of angiogenesis are available, and each angiogenic assay presents distinct advantages and disadvantages. In this study, we present a new method for the quantitation of angiogenesis and antiangiogenesis in the chick embryo chorioallantoic membrane (CAM), based on the implantation of gelatin sponges on the top of growing CAM, on day 8 of incubation. After implantation, the sponges were treated with a stimulator (recombinant human basic fibroblast growth factor, FGF2) or an inhibitor (a rabbit polyclonal anti-FGF2 antibody) of blood vessel formation. Blood vessels growing vertically into the sponge and at the boundary between sponge and surrounding CAM mesenchyme were counted by a morphometric method on day 12. In addition, to assess whether the gelatin sponge is an appropriate vehicle to deliver cultured cells and evaluate their angiogenic potential, mouse aortic endothelial cells were cotransfected with human FGF2 and the Escherichia coli beta-galactosidase (beta-GAL) reporter gene. Stable transfectants were absorbed by the sponge, and evaluation of the angiogenic response was paralleled by beta-GAL staining to visualize implanted cells. This technique may facilitate the discovery and development of agonists or antagonists of angiogenesis.

Allantois↗

PubMedDate not supplied

Exogenous heparin induces an increase in glycosaminoglycans of the chick embryo chorioallantoic membrane: its possible role in the regulation of angiogenic processes.

In this study heparin (HE) was injected into the allantoic sac of chick embryo eggs at 5, 9, 14 days of incubation. 48 h after injection glycosaminoglycan (GAG) concentration was measured in the chorioallantoic membrane (CAM) in order to verify if HE-related CAM angiogenic activity previously demonstrated [Ribatti et al: Acta Anat 1987; 130:257-263] might be correlated with changes in GAG concentration. The results showed that HE inoculation induced an increase of 3H-glucosamine incorporation into total GAGs in comparison to control CAMs. Furthermore, HE altered the balance between the GAG classes, and in particular it produced a significant increase in the accumulation of hyaluronic acid and heparan sulfate between 7 and 11 days of incubation in comparison to control CAMs.

Allantois↗

PubMedDate not supplied

Pyogenic granuloma stimulates angiogenesis in the chick embryo chorioallantoic membrane.

Ten samples of pyogenic granuloma and 10 of normal skin from age- and sex-matched controls were grafted onto the chick embryo chorioallantoic membrane (CAM) to investigate their possible angiogenic activity. The angiogenic response in pathological and control implants was assessed on histologic sections by a planimetric point-count method 4 days after grafting. The CAM mast cells were also quantified. The vascular counts in the area underlying the pyogenic granuloma were four times higher than those of normal skin. A higher number of mucosa-like mast cells was detected in the intermediate mesenchyme of the CAM in pathological samples in comparison to controls. Pyogenic granuloma may promote angiogenesis leading to release of several angiogenic factors. The role played in angiogenic response by the inflammatory cells, mainly mast cells, forming the perilesional infiltrate was supported by this study.

Adolescent↗

PubMedDate not supplied

Human recombinant interferon alpha-2a inhibits angiogenesis of chick area vasculosa in shell-less culture.

In vivo suppression of neovascularization by in situ administration of human recombinant interferon alpha 2a (hrIFN-alpha 2a) was tested on the chick embryo area vasculosa (AV). Methylcellulose discs, each containing 5 IU of hrIFN-alpha 2a were implanted onto the AV at Hamburger-Hamilton (HH) stage 13, and inhibition of blood vessel growth was morphometrically evaluated between HH stages 20 and 27. Our results show: (i) a decreased extent of the AV; (ii) a decreased AV total vessel length; (iii) modified percent ratios of different classes of AV vessels having a definite length. The observed effects of treating with hrIFN-alpha 2a are likely attributable to inhibition of endothelial cell proliferation.

Animals↗

PubMedDate not supplied

Models for studying angiogenesis in vivo.

In vivo and in vitro techniques are available for research on the functions of endothelial cells during angiogenesis. In this review we describe and evaluate the methodology and specific features of some of the most frequently used in vivo assays.

Allantois↗

PubMedDate not supplied

[Thalidomide in treatment of connective diseases and vasculities].

Thalidomide is an immunomodulatory, anti-inflammatory and anti-angiogenic drug. Thalidomide exerts its effects by decreasing circulating CD4 positive T-cells and stimulating CD8 positive T-cells, by increasing the number of Natural Killer cells and T-helper 2 cells. Thalidomide also inhibits proliferation of stimulated T-cells and leukocyte chemotaxis. It modifies a number of integrin receptors and other leukocytic surface receptors and down-modulates cell-adhesion molecules involved in leukocyte migration. It has been demonstrated that thalidomide inhibits TNFalpha, IL-5, IL-6, IL-8, IL-12 production and increases production of IL-2, IL-10 and INFgamma. Moreover thalidomide plays an important role in inhibition of VEGF and FGF-2 mediated angiogenesis. Although the exact mechanism of action is not fully understood and only limited treatment opinions exist, thalidomide plays a role also in connective diseases and vasculities. Thalidomide has been seen efficacious in the treatment of cutaneous disorders in patients with systemic lupus erythematosus and in mucocutaneous disease in Behcet's disease with a not dose-dependent response, even if it should be restricted to selected patients because of its important side effects.

Administration, Oral↗

PubMedDate not supplied

[Angiogenesis and anti-angiogenesis in human neoplasms. Recent developments and the therapeutic prospects].

Angiogenesis entails new vessel formation from preexisting vessels. It follows vasculogenesis during embryo development. In post-natal life, it occurs both in physiological conditions (wound repair and cyclically in the female genital system) and pathological conditions such as tumors. Several sequential steps are involved, including basement membrane degradation by proteolytic enzymes secreted by the endothelial cells, chemotaxis toward the stimulus and proliferation of these cells, canalization, branching and formation of vascular loops, stabilization and functional maturation of neovessels following perivascular apposition of pericytes and smooth muscle cells, and neosynthesis of basement membrane constituents. Tumor angiogenesis is regulated by several factors, mainly growth factors for the endothelial cells secreted by both the tumor and host inflammatory cells, and mobilized from extracellular matrix stores by proteases secreted by tumor cells. Regulatory factors also include the extracellular matrix components and endothelial cell integrins, hypoxia, oncogenes and tumor suppressor genes. Angiogenesis is mandatory to the process of tumor progression (growth, invasion and metastasis), since it conveys oxygen and metabolites, whereas endothelial cells secrete growth factors for tumor cells and a variety of proteinases which facilitate invasion and increase opportunities for tumor cells to enter the circulation. We present our results concerning the relationship between angiogenesis and progression in patients with melanoma, multiple myeloma, B-cell non-Hodgkin's lymphomas and mycosis fungoides. Lastly, it is becoming increasingly evident that agents interfering with blood vessel formation also interfere with tumor progression. These include antagonists of angiogenic growth factors, angiogenic receptors, endothelial cell integrins, and proteolytic enzymes, as well as non-specific toxic agents for vessels and low-dose chemotherapeutic agents. Their recent applications in preclinical models and in neoplastic patients are reviewed.

Angiogenesis Inducing Agents↗

PubMedDate not supplied

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.

Angiogenesis Inducing Agents↗

PubMedDate not supplied

Angiogenesis induced by B-cell non-Hodgkin's lymphomas. Lack of correlation with tumor malignancy and immunologic phenotype.

Correlations of malignancy grade, immunologic phenotype and angiogenic capacity were studied in B-cell non-Hodgkin's lymphomas grafted onto chorioallantoic membranes of chicken embryos. The angiogenic response elicited by the tumors was significantly greater than the response to normal lymph nodes, but it did not correlate with either the malignancy grade or the immunologic phenotype of the tumors. The elevated angiogenic capacity of neoplastic tissues is confirmed. The results also suggest that the extensive vasoproliferative response required by a rapidly growing tumor is not only controlled by the neoplastic cell population but, probably, by the host-response as well.

Adult↗

PubMedDate not supplied

Angiogenesis under normal and pathological conditions.

Angiogenesis, i.e. the generation of new blood capillaries, occurs in utero (during embryonal and fetal development) and in both physiological and pathological situations during extrauterine life. Several angiogenic factors have now been isolated, including angiogenin, acidic and basic fibroblast growth factors, and alpha and beta transforming growth factors. Their amino acid sequences have been determined and their genes cloned. Other factors await complete characterisation. An account is given of techniques used in the investigation of angiogenesis, both in vivo (transparent chambers; corneal micropockets; implantation on chick chorioallantoic membrane; employment of polymers for the sustained release of angiogenesis factors) and in vitro (cloning and long-term culture of capillary endothelial cells). The angiogenesis induced by solid tumours differs from other forms in that it is not self-limited and continues indefinitely until eradication of the tumour or death of the host. Anti-angiogenic factors have also been identified, particularly a new class of nonglucocorticoid steroids. Their employment in tumour therapy is a possibility, since neoplastic expansion is essentially dependent on angiogenesis.

Angiogenesis Inducing Agents↗

PubMedDate not supplied

Ultrastructure and permeability of immature neural and extraneural blood vessels.

The ultrastructure and permeability to the marker horseradish peroxidase in the leptomeningeal and neural vessels of the optic lobes, and in the wing bud vessels, were compared, during early stages of chick embryo vasculogenesis, in order to ascertain whether young neural vessels, like mature ones, possess structural specificity preventing the free transport of molecules through their wall (blood-brain barrier). The results demonstrated that immature endothelia are always permeable to the tracer, since the marker passes the vessel wall through the interendothelial clefts (paracellular route) as well as by endo-exocytotic mechanisms (transcellular route). Nevertheless, the transport by vesicles is somewhat reduced in the neural vessels compared to that in the extraneural ones, suggesting that the former may be influenced by the surrounding neuropile to differentiate in a specific manner right from early development.

Animals↗

PubMedDate not supplied

[Corticosteroids and cerebral vessel permeability during embryonic development].

The effects of cortisol on the development of the blood-brain barrier (b.b.b.) were microscopically investigated in the chick embryo optic tectum using horseradish peroxidase (hrp) as marker of vascular permeability. Hrp was injected intracardially at the 15th and 21st incubation day (i.d.), i.e. 5 and 11 days after the last administration of the drug (10 micrograms/50 microliters saline solution at the 8th and 10th i.d.). This treatment caused damage to the maturation process of the b.b.b. to hrp. The intraneural blood vessel walls were not able to prevent the marker extravasation which was massive at the 15th i.d. and circumscribed to limited perivascular areas at the 21st i.d. A possible pathogenetic mechanism of this phenomenon is discussed.

Animals↗

PubMedDate not supplied

[Effects of carbaryl on the morphogenesis of the extremities in chick embryos].

Experimental studies have been carried out to evaluate the effects of carbaryl (l.-naphthyl-methyl-carbamate)- an anticholinesterase pesticide - on the morphogenesis and development of the chick embryo. A solution containing 0.5 mg of carbaryl has been injected in the allantoic sac of the embryos treated (n = 130), at the 5th or 6th incubation day. In comparison with a control group (= 70), some morphological alterations have been found in the embryos treated, at the expense of the skeleton apparatus, particularly in the most distal portions of the lower limbs, as tibial and metatarsal angulations, with their curtailment. Such effects might be related to an interference in the synthesis of NAD (nicotinamide-adenine-dinucleotide), as reported for other organophosphoric pesticides.

Abnormalities, Drug-Induced↗

PubMedDate not supplied

[Role of the vascular component in growth of solid tumors: a historical review].

Angiogenesis is a fundamental biological process by which new capillary blood vessels are formed. It is essential in many physiological conditions, such as embryonic development, ovulation and wound repair, and pathological ones, such as arthritis, diabetic retinopathy, and tumours. Solid tumours have angiogenesis capacity, and tumour growth and metastasis are angiogenesis-dependent. Neoplastic cell populations can grow to form a clinically evident tumour only if the host produces a vascular network sufficient to sustain tumour growth. Furthermore, the new blood vessels provide a gateway for tumour cells to enter the circulation and metastasize to distant sites. Tumour angiogenesis is essentially mediated by angiogenic molecules elaborated by tumour cells. We review here the most important literature on this topic and emphasize the crucial and paradigmatic role of this biological process and its relevance in a possible anti-angiogenic therapeutic approach to the treatment of solid tumours.

Animals↗

PubMedDate not supplied

[Apoptosis or programmed cell death: regulatory and pathophysiological mechanisms].

Apoptosis is an active death process genetically encoded to eliminate abnormal or unwanted cells. The phenomenon is induced by a cascade of molecular events leading to nucleolysis by endonucleases and involves a number of membrane receptors and cytoplasmic proteins. These structures (including Fas, müllerian inhibiting substance, p53 and the c-myc oncogene) contribute, by interactive regulatory mechanisms, to the promotion or inhibition of apoptosis, on the basis of both external stimulus and cell activation state. Since apoptosis is a selective process to suppress defective cells, deregulation of genes encoding for such apoptosis-related proteins could be relevant in the growth of several tumors. Remarkably, overexpression of the bcl-2 gene in a few experimental lymphomas has been associated with neoplastic proliferation because of its inhibitory effect on apoptosis. Conversely, early activation of Fas, an apoptosis-inducing gene on HIV-infected CD4+ lymphocytes, is thought to aggravate T cell lymphopenia in HIV infection by increasing the level of normal apoptosis. Genetic deregulation of apoptosis has also been postulated in the pathogenesis of several diseases. Indeed, while preliminary studies suggest that apoptosis plays a role in autoimmune disorders including systemic lupus erythematosus, the pathogenesis of a few degenerative neuropathies, such as Alzheimer's disease, could depend on a similar altered mechanism in apoptosis of neuronal cells. However, no studies are presently available to suggest that exploitation of molecular events of apoptosis would imply therapeutic progress.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Lymph node angiogenesis in lymphoproliferative disorders: type II Mixed cryoglobulinemia as a model.

OBJECTIVES: Lymph node biopsies from patients with mixed cryoglobulinemia (MC) were investigated for: a) the presence of the hepatitis C virus (HCV) peptides C22 and C100; b) the degree of angiogenesis and of inflammatory infiltrate (macrophages and neutrophils); c) the distribution of laminin and type IV collagen, the main components of the subendothelial basement membrane; and d) the ultrastructural characteristics of the microvessels. METHODS: Cryostat sections were stained by immunoperoxidase to highlight HCV peptides, endothelial cells, their basement membrane components, and inflammatory cells. Planimetric methods were applied to count the microvessels and inflammatory cells, and to evaluate the distribution pattern of the basement membrane components. Microvessels were also analysed at the ultrastructural level. RESULTS: HCV+ lymph nodes showed higher microvessel and inflammatory cell counts than the HCV- lymph nodes. Their laminin and type IV collagen distribution and ultrastructural findings also indicated immature capillaries. CONCLUSIONS: HCV could be introduced into the lymph nodes by infected mononuclear cells, and trigger inflammation and angiogenesis, thus contributing to the inflammatory process. Angiogenesis, in turn, could facilitate HCV dissemination and persistence in MC.

Biopsy↗