The chick embryo chorioallantoic membrane as a model for studying of angiogenesis process

Abstract

Introduction: Cancer is the result of uncontrolled cell divisions, and angiogenesis processes are those that support and maintenance the tumor changes. Recently, the angiogenesis becomes one of the most studied physiological event due to the key role it plays in the pathogenesis of cancer as well because of its potential as a therapeutic target. To analyze the mechanisms underlying normal and pathological angiogenesis numerous angiogenic tests in vivo have been determined using different species of animals, including mammals, birds and fish. The range of biological studies in vivo of the angiogenesis allowed scientists to progress rapidly in highlighting of the action mechanism of multiple proangiogenic factors. The cost, simplicity, reproducibility, and credibility are the determinants that dictate the choice of method.

Discussion: Chick embryo chorioallantoic membrane (CAM) is a extremely vascularized extraembryonic membrane. It represents an accessible and inexpensive model in vivo, which is used long time in the reproductive biology as well in studying of angiogenesis. Due to lack of immune system in early development and the absence of rejection reactions, CAM becomes the preferred model for studying of cancer and its metastasis process. The test consists by implantation of a culture of cells on the chorioallantoic membrane of the chick embryo. The incubation period ranges from 1-3 days, depending of the substances, after which angiogenesis can be quantified by the image analysis or by colorimetric methods of detection. Quantification of the angiogenic response is performed using the vascular scale (0 to 4). At the site of implantation, is identifying the vascular density (intensity of newly formed blood vessels) and the vascular index (highlighting of branching points in relation with overlapped ring).

Conclusion: CAM allows the study of tumor growth, of anti-tumor therapies, and of pro-tumor molecular pathways in a biologically relevant system, which is also an accessible and inexpensive model. Thereby, CAM is an excellent model to obtain information on partial questions still unresolved.