intravasate

Intravasate is a biological term referring to the entry of cells from surrounding tissue into a vessel, most commonly a blood or lymphatic vessel. In cancer biology, intravasation describes the step in the metastatic cascade where tumor cells breach the vessel wall to join the circulation, enabling them to spread to distant sites. The process can also pertain to certain physiological contexts in which cells move toward and enter the vascular system.

Mechanisms of intravasation involve multiple coordinated steps. Tumor cells migrate toward blood or lymphatic vessels and adhere to the endothelium via surface molecules. They often secrete proteolytic enzymes, such as matrix metalloproteinases, to degrade the basement membrane and surrounding extracellular matrix, facilitating traversal of the endothelial barrier. Endothelial cells may retract or form transient gaps, and cells can migrate through paracellular or transcellular routes. The tumor microenvironment, including tumor-associated macrophages and abnormal, leaky vasculature created by angiogenesis, can promote intravasation by increasing permeability and providing pro-migratory signals.

Clinical and research relevance extends from cancer metastasis to immune surveillance. In cancer, intravasation determines the number of circulating tumor cells and is linked to metastatic potential and prognosis. Circulating tumor cells serve as a biomarker in some cancers. Therapeutic approaches have targeted endothelial–tumor interactions, vascular permeability, and proteolytic activity to limit intravasation, though translating these strategies into durable clinical benefits has been challenging.

See also: metastasis, extravasation, diapedesis, circulating tumor cells.