Although numerous studies have demonstrated that circulating endothelial progenitors may be involved to a greater or lesser extent in vessel formation in the adult, few have unequivocally demonstrated their necessity in this process. Mice with reduced gene dosages of the Id transcription factors are unable to support neoangiogenesis in tumors. Rafii and colleagues demonstrated that bone marrow transplantation with wild-type marrow could reconstitute tumor angiogenesis in Idl+/~M3~/~ mice. Not only were these studies the first to imply that marrow-derived cells are involved in new vessel formation in the adult, but they also demonstrated that these cells are critical for this process of new vessel formation. In this work, approximately 90 percent of the tumor vessels were found to contain cells derived from the donor bone marrow.
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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.