| Popis: |
Edema formation in ischemic and hypoxic tissues is mediated by the production of hypoxia-inducible factors such as the vascular endothelial growth factor (VEGF) (Marti et al. 2000 and Schoch et al. 2002). In this context, VEGF, although better known as the major angiogenesis-inducing factor, was first described as a vascular permeability-increasing factor (Senger et al. 1983). In addition, leakiness of blood vessels is a striking observation in many tumor vessels believed to be formed by ischemia-induced angiogenesis. This has led to the concept that vascular permeability is required for tumor angiogenesis (Dvorak et al. 1999). The possible link between angiogenesis and vascular permeability/edema formation is also of major clinical interest in respect to diseases other than tumors. Edema formation accompanies angiogenesis in many ischemic disorders such as myocardial infarction or stroke. Furthermore, therapeutic attempts to overcome ischemic conditions by application of angiogenic factors such as VEGF are hampered by severe edema formation (van Bruggen et al. 1999). It is a still unresolved question whether vascular permeability is an unavoidable feature of angiogenesis or only a side effect of it, which by mere coincidence occurs in parallel and, therefore, could be counteracted. |
