Showing papers on "Angiogenesis published in 1982"

Protamine is an inhibitor of angiogenesis

Abstract: Protamine is shown to be a specific inhibitor of angiogenesis. The compound inhibits the capillary proliferation observed in embryogenesis, inflammation, certain immune reactions and the growth of solid tumours.

Role of Prostaglandin E1 and Copper in Angiogenesis

Abstract: The interstitial fluid of MTW9A and Walker carcinomas and their ethanol extract induced strong angiogenic response in the rabbit (New Zealand White) corneal test. The fluid collected in vivo was rich in E-type prostaglandins, and prostaglandin E1 (PGE1) in particular was strongly angiogenic at the lowest dose as compared with the angiogenic responses of prostaglandins E2, I2, and F2 alpha. Neoplastic fibroblasts also induced a strong angiogenic response, but in indomethacin-treated rabbits neovascularization failed to occur. Copper was concentrated in the cornea during PGE1-induced neovascularization, and copper-deficient rabbits were unable to mount an angiogenic response in the corneal test. Ceruloplasmin, the copper carrier of plasma, was found to be angiogenic at high doses. In indomethacin-treated rabbits, however, ceruloplasmin at the same high doses failed to induce angiogenesis. The experiments are interpreted to indicate that angiogenesis is the end result of a sequence of events, two of which are PGE1 production and copper mobilization in the tissue where neovascularization occurs.

Angiogenesis: initiation and control.

Abstract: From in vivo experiments using new methods such as the rabbit cornea, it is now becoming clear that the growth of a capillary involves an ordered sequence of events that includes lysis of the basement membrane of a parent venule, directional migration of capillary endothelial cells toward the angiogenic stimulus, lumen formation, development of branches, and anastomosis of the tip of one tube with another to form a loop. It is also clear that diffusible angiogenic stimuli can be released not only from most solid tumors, but also from at least three non-neoplastic cells. These include activated macrophages, sensitized lymphocytes, and adipocytes. Other normal tissues can also stimulate angiogenesis, but the type of cell giving rise to the angiogenic stimulus is unknown, and the period of angiogenic stimulation is brief. With the recent ability to clone capillary endothelial cells and to carry them in long-term culture, it has been possible to further delineate the mechanism of capillary growth. In vitro studies have shown that the mast cell seems to behave as a helper cell for capillary endothelial cells, in some way speeding up their rate of directional migration. At this writing, heparin appears to be the principal mast cell factor responsible for this effect on capillary endothelial cells. One theoretical possibility is that mast cells may prepare the matrix, perhaps by slow release of heparin, so that capillary sprouts can more easily move through it toward their angiogenic target. While the study of angiogenesis as a phenomenon is still in an early phase, it has become possible, by using a combination of in vitro and in vivo techniques, to more thoroughly understand the initiation and control of capillary growth.

Role of platelets and fibrin in the healing sequence: an in vivo study of angiogenesis and collagen synthesis.

Abstract: The signals that initiate repair are poorly characterized. These studies investigate the capacity of platelets and fibrin to initiate angiogenesis, fibroplasia, collagen synthesis and monocyte migration in the rabbit cornea assay. Methods: Autologous platelets and platelet-free fibrin were isolated from rabbit blood. Released and control platelet preparations and autologous and commercial fibrin were implanted in rabbit corneas. Results: Thrombin-released platelets produced angiogenesis and opacification. Histology showed fibroplasia, corneal thickening, and neovascularization. Collagen synthesis was elevated to twice control levels in thrombin-activated platelet preparations. Various control platelet preparations produced no angiogenesis, no opacification, and no histologic change. All fibrin injections elicited a cellular exudate from the limbal vessels, followed by angiogenesis and corneal opacification. Histology showed a mononuclear infiltrate with neovascularization and fibroplasia. Control injections of rabbit skin collagen and fibroblasts produced no response.

Isolation of a nonmitogenic angiogenesis factor from wound fluid

Abstract: Angiogenesis, or new capillary growth, is essential to normal growth and wound healing. It is also active in several pathologic states, including the growth of malignant tumors. An extracellular, nonneoplastic angiogenesis factor has been isolated from cell-free rabbit wound fluid by pore-limit dialysis and chromatography on a size-exclusion HPLC column. The isolated angiogenesis factor was purified 9,600-fold with a yield of 81% and has a molecular weight between 2,000 and 14,000. Wound fluid angiogenesis factor was completely separated from the mitogenic activity of wound fluid; it did not increase the number of capillary endothelial cells in vitro or stimulate [3H]thymidine uptake by these cells. The isolated angiogenesis factor stimulated endothelial cell migration in vitro, and less than 200 ng of the factor stimulated angiogenesis in vivo in the corneal implant assay.

Tumor-Induced Neovascularization in the Mouse Eye

Abstract: Tumor fragments implanted in the mouse cornea induce a neovascular reaction characterized by the penetration of new blood vessels into the avascular cornea that ultimately reach the tumor to permit its further rapid growth. A method to achieve angiogenesis in the mouse cornea was studied, as well as the histologic and gross manifestations of the neovascular reaction and the effect of tumor cells or host irradiation on the observed angiogenic response. Sequential stages of tumor-induced neovascularization are described and documented for sarcoma 180- and C755 mammary adenocarcinoma-induced angiogenesis. A number of distinct processes of the angiogenesis response to tumors are discussed which suggest that several families of angiogenesis-inducing factors may mediate each of these processes. The importance of the development of a mouse model for the study of angiogenesis is stressed.

Fibronectin is produced by blood vessels in response to injury.

Abstract: During the time of tissue repair that ensues subsequent to tissue injury, blood vessel wall fibronectin increases concomitantly with endothelial proliferation and angiogenesis. However, the source of this blood vessel fibronectin had not been delineated. In this report we have demonstrated that microvascular fibronectin is produced in situ by the proliferating vessels surrounding excisional wounds. This finding was established by extirpating 3 mm of skin from the center of a well-healed rat xenograph on the flanks of immunosuppressed mice, harvesting the injured skin sites at various stages during the healing process, and staining the specimens with reciprocal species-specific anti-fibronectin. The proliferating donor vessels that surrounded the wounded graft had increased fluorescence staining with FITC conjugated mouse anti-rat fibronectin and no staining with rat anti-mouse fibronectin. This finding was taken as direct evidence that the fibronectin was produced in situ by the rat vessels and not derived from circulating mouse plasma.

Histotypic angiogenesis in vitro: Light microscopic, ultrastructural, and radioautographic studies

Abstract: A model for the study of angiogenesis in vitro is described. Rat aortas, cultured in a tridimensional matrix of clotted chick plasma, gave rise to luxuriant outgrowth of vascular channels. We studied this process with light microscopic, radioautographic, and ultrastructural techniques. On the 2nd d of culture, endothelial cells sprouted from the intima of the aorta and its collateral branches into the surrounding clot, forming solid cellular cords. A complex vascular network was established within the 1st wk by spindly, poorly differentiated endothelial cells. At this stage cells were migrating, branching, and proliferating in a longitudinal fashion (labeling index: 67.4% ± 7.7). Lumens, when present, appeared as slitlike spaces enclosed with junctional complexes. By the end of the 2nd wk the migratory activity decreased and proliferation occurred mostly in a cross-sectional plane, with formation of large patent lumens (labeling index: 48% ± 3.1). Vascular channels were lined by prominent endothelial cells rich in rough endoplasmic reticulum, polysomes, mitochondria, Golgi apparatuses, and coated vesicles. Cells were enveloped with a ruthenium red positive layer, particularly abundant on the luminal surface and in the interendothelial space. A discontinuous basal lamina was present along the abluminal side. At 28 d the labeling index was reduced to 2.25% ± 0.9. The still viable endothelium exhibited numerous microfilaments and microtubules, decreased cytoplasmic organelles, and increased pinocytotic activity. This experimental model, histophysiologic gradient culture, provides us with a new tool for the study of vascular morphogenesis, angiogenesis dependent growth of tumors, and neoplastic intravasation.

Angiogenesis induced by "normal" human breast tissue: a probable marker for precancer.

Abstract: Normal human breast lobules, freshly isolated by precision microdissection of tissue stained with methylene blue chloride, were assayed for their ability to induce neovascularization (angiogenesis) in rabbit irises. Histologically, normal lobules from cancerous breast induced angiogenesis twice as often as lobules from noncancerous breasts, suggesting that preneoplastic transformation is diffuse.

Differentiation-dependent stimulation of neovascularization and endothelial cell chemotaxis by 3T3 adipocytes.

Abstract: 3T3 cells that have undergone adipose differentiation in vitro secrete factor(s) that stimulate angiogenesis (neovascularization) in vivo. When medium containing 0.5% fetal calf serum was conditioned by 3T3-F442A adipocytes, it stimulated angiogenesis when placed on the chicken chorioallantoic membrane. Control medium or medium conditioned by preadipocytes did not stimulate angiogenesis, even at much higher doses. Thus, the production of the angiogenic activity is strongly dependent upon differentiation of the adipocytes. The degree of the angiogenic response to adipocyte-conditioned medium was potentiated by heparin; heparin added to unconditioned medium or to preadipocyte-conditioned medium was not angiogenic. The adipocyte-conditioned medium also strongly stimulated, in a differentiation-dependent fashion, the motility of aortic and capillary endothelial cells in a modified Boyden chamber assay. Checkerboard analysis cells indicated that 75% of the motility-stimulating activity was chemotactic in nature. The chemotactic activity has an apparent specificity for endothelial cells, in that chemotaxis of smooth muscle cells and fibroblasts was stimulated to a much lesser extent. These results, in conjunction with our previous demonstration of an endothelial cell mitogen produced by 3T3 adipocytes [Castellot, J. J., Jr., Karnovsky, M. J. & Spiegelman, B. M. (1980) Proc. Natl. Acad. Sci. USA 77, 6007-6011] indicate that the differentiation of these cells is closely linked to the production of factors that stimulate angiogenesis in vivo and growth and chemotaxis of endothelial cells in vitro.

Angiogenesis and Neoplastic Progression In Vitro

Abstract: In vivo cell populations at high risk of neoplastic transformation have been shown to acquire the ability to induce new formation of vessels. The present experiments tested whether the same change occurred during neoplastic transformation in vitro. In four cell populations (human HBL 100 mammary epithelium, BALB/c fibroblasts, C57BL-MG epithelium, and Syrian golden hamster embryo cells), angiogenic capacity appeared during their cultivation in vitro and was evident long before a neoplastic transformation could be recognized. The data were interpreted to support the hypothesis that acquisition of angiogenic capacity by a cell population normally devoid of this capacity indicates an increased risk of neoplastic transformation.

Stimulation of wound healing, using brain extract with fibroblast growth factor (FGF) activity. II. Histological and morphometric examination of cells and capillaries.

Abstract: Summary Reported in this paper are studies by which evidence was produced to increased formation of granulation tissue in rats, aged two and six months, seven days after repeated localised administration of brain extract from cattle with FGF activity (fibroblast growth factor). Such increased formation of granulation tissue was attributable to the formation in the same granulation tissue of larger amounts of capillaries, which actually provided conditions for better blood supply. The above increase was associated with stimulation of the synthetic function of fibroblasts and myofibroblasts in the granulation tissue. Comprehensive morphometric tests, including differential counting, appeared to show that additional effects had to be assumed, in particular on macrophages and lymphocytes. Such increase in angiogenesis seemed to suggest that in the in vivo model studied FGF proved to be, first of all, a factor of angiogenesis rather than a factor of fibroblast growth. The above results, as obtained from rats which differed in age, exhibited a certain variation in response to FGF. This seems to underline the importance of age-dependent examination also in the context of pharmacological studies.

A low-molecular-weight angiogenic factor in cat retina.

Abstract: A low-molecular-weight angiogenic factor has been isolated from healthy adult cat retinas. The factor, which has been purified by diethylaminoethyl (DEAE) cellulose chromatography and affinity chromatography, stimulates neovascularisation of the chick chorioallantoic membrane and has a number of properties similar to those previously described for a tumour factor. The finding of an angiogenic factor in healthy retina and its relationship to previously described inhibitors of angiogenesis is discussed.

Modulation of synthesis of specific proteins in endothelial cells by copper, cadmium, and disulfiram: An early response to an angiogenic inducer of cell migration

Abstract: Copper, cadmium, and disulfiram (an ionophore for copper) modulate the synthesis of several polypeptides in two clonal lines of bovine aortal endothelial cells. After treatment of Type 1 endothelial cells with 10(-3) M CuSO4 or 10(-5) M CdCl2 four cell-associated polypeptides (Mr = 28,000, 32,000, 73,000, and 83,000 daltons) were induced. In contrast, in Type 2 endothelial cells, which have cultural characteristics distinct from Type 1, only one new cell-associated protein (Mr = 32,000 daltons) was induced by CuSO4 or CdCl2. The same four polypeptides, described above, were induced by disulfiram (10(-7) M) in Type 1 endothelial cells. In contrast when Type 2 endothelial cells were treated with disulfiram the synthesis of only two new cell-associated proteins (Mr = 32,000 and 40,000 daltons) was induced. Other differences are revealed by analyses of proteins secreted into the growth medium. In particular low levels of only CuSO4 (10(-6) M) enhanced the synthesis in Type 2 cells of a protein (Mr = 220,000 daltons) identified as fibronectin. Since only copper ions induced fibronectin, we propose that the mechanism of induction of fibronectin synthesis, in contrast to the induction of cell-associated polypeptides, does not involve a sulphydryl-containing receptor molecule. It is suggested that the specific enhancement of fibronectin synthesis by copper ions may be a controlling event in the stimulation by copper ions of endothelial cell migration and angiogenesis.

An assay measuring the stimulation of several types of bovine endothelial cells by growth factor(s) derived from cultured human tumor cells

Abstract: Endothelial cell growth factor(s) from several previously untested human tumor cell lines (i.e., SK-HEP-1, MG63, A375, TE671-C1, RD) were detected using a low cell inoculum growth assay. The final cell density in the 2-cm2 wells was determined by a highly sensitive DNA content measurement performed directly in the tissue culture plates. The sensitivity of the assay to human tumor cell growth factors depended critically on the low cell inocula, 2,000 to 5,000 cells/well. Most of the bovine endothelial cells used were cloned from primary cultures; all the cell lines obtained from various fetal and nonfetal sources responded to the growth factor(s) (up to a 16× stimulation) as well as to endothelial cell growth supplement. Dose response curves showing the cell specific response of bovine endothelial cells were obtained. The growth stimulatory activity and the in vivo chick embryo chorioallantoic membrane assay responses correlated sufficiently to imply that the assay is detecting tumor angiogenesis factor or some closely related activity. This in vitro assay should prove useful in the identification and purification of tumor-derived factors and in the elucidation of the role of these factors in the events comprising angiogenesis.

Ultrastructure of vascular neoplasms. A transmission and scanning electron microscopical study based upon 42 cases.

Abstract: Summary The vascular tumors are morphologically recognized by their ability to configurate complete or atypical angiomatous structures. Based on our personal experience of 42 cases of benign and malignant angiomatous tumors, we discussed several aspects of their histogenesis and its morphology when studied with transmission and scanning electron microscopy. Therefore, a survey of the normal histology was developed based not only on normal adult histological structures but also on reparative tissues, as in chronic inflammatory reactions of the gingival mucosa, regenerative tissue of wounds and in chronic osteomyelitis. Supported by morphological arguments, we postulate the existence of several endothelial cell subpopulations, which are involved through several ways in tumoral angiogenesis. This fact is clearly seen in benign capillary angioma, in pseudopyogenic granuloma of the skin and in cellular angioma of infancy. Among the malignant vascular tumors, the hemangiopericytoma shows a large cell heterogeneity, dilating from well developed pericytes to fusocellular and anaplastic ones; well differentiated hemangiopericytoma keeps an epithelial-like appearance and its cells surrounded by basement membranes. It seems possible to distinguish an hemangioendothelioma from an angiosarcoma (hemangiocarcoma). Both are angiogenic neoplasms of malignant nature, but the first is mainly composed by transformed endothelial cells of a mesenchymal nature, similar to those seen in embryonic angiogenesis. The second tumor type possesses not only endothelial cells but also mesenchymal angioblasts from which other cells derivatives are conformed as atypical pericytes. Furthermore, in some cases angiosarcoma displays embryonic metaplastic hematopoiesis (erythropoiesis) inside the neoformed stroma. Histogeneis of Kaposi sarcoma of the skin remains a matter of controversy. The histiocytic endothelial cells could be considered as the primitive endothelial cell subpopulation from which this tumor group could be originated. Bone vascular tumors adopt a more specific texture. Particular emphasis is given to the angiogenic variant of Ewing's sarcoma, from which three cases have been isolated among the 219 neoplasms reviewed.