The regeneration of blood vessels is often triggered by ischemic conditions, physical injury, or the need to support growing tissues. The key initiators of this process are various growth factors such as Vascular Endothelial Growth Factor (VEGF) and Platelet-Derived Growth Factor (PDGF). These growth factors bind to receptors on endothelial cells, activating intracellular signaling pathways that prompt these cells to proliferate and migrate.