Extent Of Angiogenesis Research Articles

Novel Gliosarcoma Cell Line Expressing Green Fluorescent Protein: A Model for Quantitative Assessment of Angiogenesis

Angiogenesis is essential for tumor proliferation and metastasis. The extent of angiogenesis is measured by microvessel density (MVD) which has been identified as an independent prognostic factor for relapse-free survival in cancer patients. Existing methods of MVD assessment measure the microvessel count in the most active area of neovascularization (“hot spots”) using antibodies against vascular endothelial antigens. This may produce unreliable results because of tissue volume loss and misshapening during the fixation and dehydration procedures. We report here a genetically engineered 9L cell line constitutively expressing green fluorescent protein that can be visualized using fluorescence microscopy without additional histological staining. The model developed in this study allows for the performance of simple and easy MVD counting, assuming that nonfluorescent “black spots” visible by fluorescence microscopy within the borders of the tumor tissue represent blood vessels. This assumption was confirmed by a comparative study utilizing conventional histological methods, anti-CD31 immunohistology, and Hoechst 33258 dye exclusion. This model is also useful for delineation of the true borders between tumor and normal brain tissue, including microscopic tumor extensions, without multiple histological staining. The suggested model allows quantification of tumor angiogenesis in tissue specimens, thus providing independent prognostic information about tumor growth and regression. It is expected to be most valuable in evaluating the efficacy of anti-angiogenic therapy.

Human lymphoblastoid cells produce extracellular matrix-degrading enzymes and induce endothelial cell proliferation, migration, morphogenesis, and angiogenesis.

Human lymphoproliferative diseases can be hypothesized to invade locally and to metastatize via mechanisms similar to those developed by a variety of solid tumors, i.e., the secretion of extracellular matrix-degrading enzymes and stimulation of angiogenesis. To assess this hypothesis, Namalwa, Raji, and Daudi cell lines (Burkitt's lymphoma), LIK and SB cell lines (B-cell lymphoblastic leukemia), CEM and Jurkat cell lines (T-cell lymphoblastic leukemia), and U266 cell line (multiple myeloma) were evaluated for their capacity to produce matrix metalloproteinase-2 and -9, and urokinase-type plasminogen activator. These cell lines were also assessed for their ability: (1) to produce the angiogenic basic fibroblast growth factor and vascular endothelial growth factor; (2) to induce an angiogenic phenotype in cultured endothelial cells, represented by cell proliferation, chemotaxis, and morphogenesis; (3) to stimulate angiogenesis in different in vivo experimental models. All cell lines expressed the mRNA for one or both metalloproteinases. Namalwa, Raji, LIK, SB, and U266 cells secreted the active form of both metalloproteinases, while Daudi, CEM, and Jurkat cells produced metalloproteinase-2 but not-9. In contrast, urokinase-type plasminogen activator was secreted only by SB cells. While Raji, LIK, SB, CEM, and Jurkat cells secreted both basic fibroblast growth factor and vascular endothelial growth factor, Daudi and U266 cells produced only the former, and Namalwa cells only the latter. Accordingly, the conditioned medium of all cell lines stimulated cell proliferation and/or chemotaxis in cultured endothelial cells, with the exception of that of Namalwa cells which was ineffective. The conditioned medium of CEM and Jurkat cells induced morphogenesis in cultured endothelial cells grown on a reconstituted basement membrane (Matrigel). Lastly, Namalwa, Raji, LIK, SB, U266, CEM, and Jurkat cells induced angiogenesis and mononuclear cell recruitment in the murine Matrigel sponge model and in a chick embryo chorioallantoic membrane assay. The extent of angiogenesis in both models was strictly correlated with the density of the mononuclear cell infiltrate. The results indicate that human lymphoproliferative disease cells possess both local and remote invasive ability via the secretion of matrix-degrading enzymes and the induction of angiogenesis which is fostered by host inflammatory cells and by an intervening ensemble of angiogenic factors.

Development of angiogenesis inhibitors for cancer therapy.

Abundant literature exists demonstrating that tumors are dependent on angiogenesis for both tumor growth and invasion. The extent of angiogenesis in primary tumors has been demonstrated to be associated with a negative prognosis in several tumors including non-small cell lung carcinoma, prostate cancer, and in node-negative breast cancer, where angiogenesis is an independent negative prognostic factor. These data demonstrate the significance of angiogenesis in tumor biology and indicate that it can be utilized as a target for novel therapeutic strategies. The recent expansion of knowledge into the specific pathways of tumor angiogenesis has provided reagents which can now be utilized to provide markers of efficacy of antiangiogenic agents in cancer patients. A critical part of the development of angiogenesis inhibitors for cancer therapy is the clinical trial strategy. Since these agents are primarily thought to be cytostatic, carefully designed trials must be conducted which focus on appropriate endpoints and integrate relevant biologic markers to support efficacy.

An Intradermal Assay for Quantification and Kinetics Studies of Tumor Angiogenesis in Mice

A method is reported for the study of early phases of neovascularization in syngeneic murine tumors and human tumor xenografts in nude mice. Using this method, the effect of irradiation of tumor cells or tumor bed on tumor angiogenesis was studied. Tumor cells were injected intradermally in the abdominal skin flap, which was reopened at 2-day intervals to quantify newly formed blood vessels at the site of tumor cell injection. Both tumor cell injection and blood vessel counting were performed under a dissecting microscope. Using three syngeneic murine tumors and two clones of a human colonic adenocarcinoma, it was observed that new blood vessels started appearing within a few days after tumor cell injection and that this event preceded measurable tumor growth. The number of blood vessels increased exponentially for several days but then their further growth slowed. The extent of angiogenesis depended on the tumor type and the number of tumor cells injected. The exposure of the skin flap to ionizing radiation prior to tumor cell injection reduced neovascularization. We further observed that heavily irradiated tumor cells retained their ability to induce angiogenic response and that lymphoid cells (peritoneal exudate and spleen cells) could also elicit an angiogenic response, although it is weaker than the response elicited by tumor cells. Thus this method is suitable for quantification and kinetics of early phases of tumor angiogenesis in individual mice bearing transplants of syngeneic tumors or human tumor xenografts, and it can be useful for investigating various regulators of tumor angiogenesis.

Effects of Cimetidine and Omeprazole on Angiogenesis in Granulation Tissue of Acetic Acid-Induced Gastric Ulcers in Rats

We investigated the effects of cimetidine and omeprazole on angiogenesis in granulation tissue and on the healing of gastric ulcers induced by acetic acid in rats. Either cimetidine (50 or 100 mg/kg) or omeprazole (10 or 20 mg/kg) was orally administered once daily for 9 consecutive days from the day following ulcer production. The ulcer index on the 10th and 30th days after ulcer production, and the extent of angiogenesis on the 10th day were examined. Cimetidine dose-dependently decreased the extent of angiogenesis on the 10th day, whereas the ulcer index on the 10th days was not significantly different between cimetidine-treated and control rats. The ulcer index of the groups treated with cimetidine during the initial 9-day period was increased compared with the control group on the 30th day. In contrast, oral omeprazole did not affect angiogenesis on the 10th day and decreased the ulcer index on both the 10th and 30th days. These results suggest that oral cimetidine may inhibit angiogenesis in ulcer granulation tissue possibly via the blocking of histamine H2 receptors and this may be one cause of delayed ulcer healing.