| Popis: |
It has been well established that tumor growth depends on angiogenesis, the process of continued expansion of endothelial cells from preexisting blood vessels (1,2). Tumors in situ, which are smaller than 3 mm in diameter, exist in a prevascular state and are limited in their ability to grow without perfusion from the blood supply. Without such a neovascularization process, these dormant tumors remain microscopic in size and quiescent for years (1,3). The recruitment of new blood vessels increases the availability of oxygen and metabolites to the tumor and removes waste products. Moreover, this newly formed vasculature facilitates the escape of tumor cells to distant regions of the body, where they may form detectable metastases (4,5). Evidence suggests that new vessel growth from bone marrow-derived endothelial precursor cells also contributes to tumor blood vessel development (6,7). |
