Review of Pericytes in Tumor Biology

Abstract

Pericytes are contractile cells that surround the endothelium of capillaries and venules throughout the body. Pericytes were once thought to have a limited role in blood pressure control and angiogenesis. Today, knowledge about pericytes and other perivascular stem cells has vastly expanded. The understanding of the biologic significance of pericytes was most changed by the recognition of the perivascular identity of mesenchymal stem cells. The following review article will summarize the known functions and importance of pericytes in particular relevance to tumor biology. These roles include: 1) pericytes as the potential cell of origin for multiple soft tissue tumors, 2) the role of pericyte in regulating tumor cell vascular invasion, and 3) angiotropism or ‘pericytic mimicry’ as a mechanism of malignant tumor spread. Although not discussed, the role of pericytes in pathophysiology far exceeds the realms of tumor biology, including cardiovascular atherosclerotic disease, chronic kidney disease, fibrotic repair processes, and fibroproliferative diseases. In summary, the known roles of pericytes in tumor formation, growth, and invasion have greatly expanded. These include pericytic differentiation in soft tissue tumors, regulation of vascular invasion in solid tumors, and extravascular migratory migration of common malignancies.