Angiogenesis in Inflammatory Bowel Disease

Figure 1

Stages of angiogenesis process. (a) Normal, quiescent intestinal vessel: endothelial cells (ECs) with smooth basal membrane and regular extracellular matrix (ECM) are seen. (b) After angiogenic stimulation, activated EC secretes various proangiogenic and proinflammatory molecules. Then, increased permeability, vasodilatation, and extravasation of leucocytes occur. Basal membrane and ECM are degraded by metalloproteinases and proteases. ECs proliferate and migrate from this degraded area. After sprouting, ECs adhere to the matrix. (c) Tubulogenesis, lumen formation, and beginning of stabilization. (d) Remodeling and maturation: angiogenesis is completed in this stage by migration of pericytes and vascular smooth muscle cells to this area. If maturation of this new vessel is not completed, angiogenesis continues as pathogenic angiogenesis.