Hematopoietic Derived Fibrocytes: Emerging Effector Cells in Fibrotic Disorders

Abstract

Fibrocytes constitute a unique population of mesenchymal progenitor cells from hematopoietic origin. They display a unique spectrum of immune and molecular characteristics such as the simultaneous expression of mesenchymal (collagen types I and III, fibronectin), leukocyte (CD45), monocyte (CD14), and hematopoietic stem cell (CD34) markers. Fibrocytes were initially described in the context of wound repair and since their original description in 1994, our understanding and knowledge of this novel cell population has grown considerably. They have the potential to differentiate into fibroblasts and myofibroblasts among other mesenchymal cells such adipocytes, osteoblasts, and chondrocytes. Fibrocytes are a rich source of inflammatory cytokines, growth factors, and chemokines that provide important intercellular signals within the local tissue microenvironment. Moreover, fibrocytes possess the immunological features typical of an antigen-presenting cell (APC), and they have the capacity for the presentation of antigens to naive T-cells.