[2] Repeated injuries, chronic inflammation and repair are susceptible to fibrosis, where an accidental excessive accumulation of extracellular matrix components, such as the collagen, is produced by fibroblasts, leading to the formation of a permanent fibrotic scar.

[4] Defined by the pathological accumulation of extracellular matrix (ECM) proteins, fibrosis results in scarring and thickening of the affected tissue — it is in essence a natural wound healing response which interferes with normal organ function.

[5] Fibrosis is similar to the process of scarring, in that both involve stimulated fibroblasts laying down connective tissue, including collagen and glycosaminoglycans.

The most well characterized pro-fibrotic mediator is TGF beta, which is released by macrophages as well as any damaged tissue between surfaces called interstitium.

However, several recent studies have demonstrated reversal in liver and lung tissue,[15][16][17] and in cases of renal,[18] myocardial,[19] and oral-submucosal fibrosis.