fibrocyter

Fibrocyter are circulating cells that originate from the bone marrow and contribute to connective tissue repair. They are considered distinct from resident fibroblasts and can migrate from the bloodstream to sites of tissue injury, where they participate in wound healing and scar formation.

In terms of markers, fibrocyter express both hematopoietic and mesenchymal characteristics. They commonly display CD34 and CD45 along with intracellular or secreted collagen I, and they may express other receptors such as CXCR4. Their identification often relies on a combination of surface markers and the presence of collagen I production, distinguishing them from mature leukocytes and resident stromal cells.

Fibrocyter are mobilized to injury sites in response to inflammatory and pro-fibrotic signals, including chemokines like CXCL12 (SDF-1) and transforming growth factor-beta (TGF-β). Once there, they can differentiate into fibroblast-like or myofibroblast-like cells, contributing to extracellular matrix production, including collagen and fibronectin, and to the remodeling of the damaged tissue. Through this activity, they help bridge the early inflammatory response and subsequent tissue repair, but excessive activity can promote fibrosis and scar formation.

Clinical relevance and research perspectives: fibrocyter have been studied in various fibrotic diseases, such as interstitial lung disease, liver fibrosis, kidney fibrosis, and systemic sclerosis. Their levels can be altered in disease states and they are investigated as potential biomarkers and therapeutic targets. The exact contribution of fibrocyter to different pathologies and their relative importance compared with resident fibroblasts remains an area of ongoing research.

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