Angiogenesis, the development of blood vessels from the preexisting vasculature, is recognized to play a central role in organismal development and pathologies such as tumor growth and metastasis. Two of the primary classes of molecular players in angiogenic regulation include growth factors and the extracellular matrix (ECM), the latter being the special focus of this review. The ECM scaffold that EC produce during capillary morphogenesis and in the differentiated microvasculature comprises 10 or more macromolecules, and many of these have been reported to exhibit pro- or antiangiogenic activities in their native or processed forms. Thus, at first glance, the literature presents a bewildering collection of information that appears difficult to integrate into a coherent model for the ECM regulation of angiogen-esis. However, results from numerous studies suggest that a simple way to categorize the ECM control of angiogenesis is in the form of a model, wherein the intact basement membrane that promotes quiescence and differentiation comprises the first phase, and that certain conditions stimulate the endothelium to degrade the basement membrane, and encounter the second phase, the stromal or provisional matrices, including fibrillar collagens and fibrin, that promote capillary tube morphogenesis (Figures 1 and 2). The focus of this chapter is on discussing this two-phase model of angiogenesis and on deciphering the role the ECM plays in controlling and modulating this morphogenic event. Finally, we will discuss how this information may be applied to ECM bioengineering, which may be used to influence angiogenesis in vivo.
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This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.