Basic fibroblast growth factor: an extracellular mechanotransducer in articular cartilage?

Mechanical stimuli are important signals in articular cartilage, but what mediates them is unknown. We have shown that extracellular-signal-regulated kinase was activated on cutting and loading articular cartilage, and deduced that this was due to the release of bFGF (basic fibroblast growth factor) from the tissue. bFGF was shown to be extracellular, and by immunohistochemistry, was present in the pericellular matrix of articular chondrocytes attached to the heparan sulphate proteoglycan perlecan. We propose a novel mechanotransduction model, whereby pericellular bFGF, a short distance from the cell surface, becomes available to the cell surface tyrosine kinase receptors when articular cartilage is loaded.