Origins of fibrosis: pericytes take centre stage.

Pericytes are ubiquitous perivascular cells that have recently attracted interest as potential myofibroblast precursors. In turn, myofibroblasts are the major source of extracellular matrix components that accumulate during tissue fibrosis. Given the worldwide burden of fibrotic disease and paucity of therapeutic options available to halt its progression, elucidating the origins of myofibroblasts is of prime importance. The advent of genetic strategies that permit fate-mapping of specific cell populations through permanent and heritable expression of reporter proteins has begun to shed light on the source of the fibrogenic myofibroblast. Here we discuss recent studies in multiple organs that highlight the central role of pericytes in the origins of fibrosis.