[Inhibition of neovascularization and tumor growth by dexamethasone]

It has been proposed that angiogenesis inhibitors should be used for the treatment of diseases accompanied by an uncontrolled angiogenic response, particularly such disease occurring during progressive growth of solid tumors. In this study, the antiangiogenic effect of dexamethasone (DEX) was studied in a system using chorioallantoic membranes (CAM) of fertilized eggs and rabbit corneas. First, DEX was examined for its effect on embryonic angiogenesis using 4, 5 day old CAMs of chick embryos. After the shell and shell membrane was removed, an EV pellet with or without DEX was placed within a silicon ring. Two days later, the antiangiogenic response was evaluated by measuring the avascular zone of the CAM beneath the pellet. When the CAM showed an avascular zone of 3 mm or more in diameter, the response was scored as positive. DEX showed potent antiangiogenic activity and produced an avascular zone in 100% of CAMs at the highest dose tested. (250 ng/egg). Next, inhibitory effect of vascularization and tumor growth by local implant of DEX was observed in a rabbit cornea assay. An intra-corneal pocket extending to within 1 mm of the limbus was used to house a 1-mm3 piece of glioma. In the treatment group, DEX-containing EV pellet was inserted between the limbus and glioma. Ten days after the implantation of glioma and EV pellet, vascular response and tumor growth was evaluated. For morphologic studies, the excised corneas were fixed with formaldehyde fixative and sectioned for light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)