title: Endostatin inhibits microvessel formation in the ex vivo rat aortic ring angiogenesis assay.
abstract: Endostatin has demonstrated potent antiangiogenic and antitumor activity in mouse models. We have investigated the ex vivo rat aortic ring assay and a human vein model to assess the biological activity of murine and human endostatin. Rat aortic rings were exposed to recombinant murine endostatin (Spodoptera frugipera; Calbiochem, San Diego, CA) or recombinant human endostatin (Pichia pastoris; EntreMed, Rockville, MD). After 5 days, murine endostatin (500 microgram/ml) demonstrated inhibition of microvessel outgrowth with dose-dependent effects (down to 16 microgram/ml). No significant inhibition was observed with human endostatin in the rat assay. Human endostatin at 250 and 500 microgram/ml inhibited outgrowths from human saphenous vein rings after a 14-day incubation. Electron microscopy assessed the formation of basal lamina, confirming that the microvessels were progenitors of patent vessels. Immunostaining for Factor VIII or CD34 demonstrated that the microvessel cells were endothelial. BrdU incorporation assays supported the presence of proliferating endothelial cells, correlating with neovascularization from the aortic wall. We conclude that the rat aortic ring assay confirms the antiangiogenic activity of murine but not human endostatin, suggesting that the model may have species specificity. However, the human form shows biological activity against human vascular tissue.
authors.affiliation: Medicine Branch, Division of Clinical Sciences (DCS), National Cancer Institute (NCI), Bethesda, Maryland, 20892, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Kruger
authors.forename: P H
authors.initials: PH
authors.lastname: Duray
authors.forename: M G
authors.initials: MG
authors.lastname: Tsokos
authors.forename: D J
authors.initials: DJ
authors.lastname: Venzon
authors.forename: S K
authors.initials: SK
authors.lastname: Libutti
authors.forename: S C
authors.initials: SC
authors.lastname: Dixon
authors.forename: M A
authors.initials: MA
authors.lastname: Rudek
authors.forename: J
authors.initials: J
authors.lastname: Pluda
authors.forename: C
authors.initials: C
authors.lastname: Allegra
authors.forename: W D
authors.initials: WD
authors.lastname: Figg
mesh_terms: D020533:Angiogenesis Inhibitors / Q000235:genetics / Q000494:pharmacology*; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D001013:Aorta, Thoracic / Q000187:drug effects*; D003094:Collagen / Q000235:genetics / Q000494:pharmacology*; D043169:Endostatins; D004730:Endothelium, Vascular / Q000187:drug effects / Q000276:immunology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008854:Microscopy, Electron; D018919:Neovascularization, Physiologic / Q000187:drug effects; D010446:Peptide Fragments / Q000235:genetics / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000235:genetics / Q000494:pharmacology; D012501:Saphenous Vein / Q000187:drug effects; D013045:Species Specificity
chemical_list: D020533:Angiogenesis Inhibitors; D018952:Antigens, CD34; D043169:Endostatins; D010446:Peptide Fragments; D011994:Recombinant Proteins; D003094:Collagen