Use of the 10-Day-Old Chick Embryo Model for Studying Angiogenesis

The development of new vessels plays a critical role in a number of physiological and pathological events such as embryonic development, wound healing, arthritis, and tumor growth and metastasis (1–4). One area that has received considerable attention is determining the role that integrins play in angiogenesis. Recently, we demonstrated that integrin αvβ3 was highly expressed on angiogenic blood vessels associated with a variety of solid tumors and during granulation tissue formation (5,6). Importantly, little if any αvβ3 was detected on quiescent vessels (5,6). In addition, antagonists of αvβ3 were shown to specifically inhibit angiogenesis in vivo. These findings suggest an important role for integrin αvβ3 during neovascularization. Thus, a great deal of attention has been focused on understanding the cellular and molecular mechanisms by which integrins regulate angiogenesis. Angiogenesis can be defined as the process by which new blood vessels form from pre-existing vessels. This process is similar to, but not identical with vasculogenesis, in which new blood vessels arise from blood islands and precursor cells called angioblasts (1–3). Thus, an in-depth understanding of the molecules that regulate this complex biological process is of fundamental importance in both basic and clinical research. In fact, recent advances in our understanding of the molecular and biochemical events that facilitate angiogenesis have provided insight into cellular invasion in general as well as the development of novel strategies for the treatment of neovascular diseases (5,7–11).