A novel quantitative chick embryo assay as an angiogenesis model using digital image analysis.

A number of pathological events in humans such as solid tumour growth and metastasis have been found to be associated with angiogenesis, the formation of new blood vessels front pre-existing vasculature. A novel approach in cancer treatment consists of blocking or delaying the progression of neovascularisation to dysplastic cells in order to stop delivery of nutrients and oxygen. Thus, agents with antiangiogenic activity may be useful to treat cancer with potentially less systemic toxicity than conventional cytotoxic therapeutics. In this study we report the development and validation of a modified quantitative and objective in vivo chick embryo assay with Digital Image Analysis to screen compounds for antiangiogenic activity. The evaluation of vascular responses was optimised to less than one minute per sample in order to make this automatic method suitable for larger experimental series. Significant activity of the known antiangiogenic compounds thalidomide and captopril was determined, which resulted in approximately 50% inhibition of the vessel area compared to the control. The stability and release of thalidomide and captopril within 48 h after application to the extraembryonic vessel system was monitored by HPLC analysis. In conclusion, this multiple target test system will be complementary to existing angiogenesis assays and may be useful to quantify the antiangiogenic activity of compounds.