What are fibroblasts?
A fibroblast is the principal active cell of connective tissue. Irregularly shaped and adherent, these cells are known for producing large amounts of extracellular matrix (ECM) proteins such as collagen, glycosaminoglycans, and proteoglycans. This in itself makes them important components of many cell culture protocols; but it has become increasingly clear that the functions of fibroblasts stretch far beyond their ability to make ECM components.
It should be noted that the term fibroblast is often used interchangeably with fibrocyte. Technically, however, a fibrocyte is the inactive precursor of a fibroblast; in terms of maintenance and tissue metabolism. A fibroblast refers to the ‘activated’ cell that secretes ECM components. Although they are two different forms of the same cell type, they have several distinct features (Figure 1).