Transforming growth factor beta1 signalling, wound healing and repair: a multifunctional cytokine with clinical implications for wound repair, a delicate balance.

Transforming growth factor beta1 (TGFbeta1) is a multifunctional cytokine known to be involved in a number of human diseases. It is believed to play an important role in wound healing and repair, as it is a key regulator of the production and remodelling of the extracellular matrix through its effect on mesenchymal cells. Over the last few years, it has become evident that the signalling pathway of TGFbeta is complex with numerous receptor-ligand interactions, intracellular pathways and a number of mechanisms, which not only control the signalling but may also decide the response to the TGFbeta signal. This review focuses on TGFbeta1 signalling and the role that TGFbeta1 plays in wound healing, repair and scarring.

In vitro flexor tendon cell response to TGF-beta1: a gene expression study.

PURPOSE: Adhesion formation around zone II flexor tendon repairs remains an important clinical challenge. Tendon healing is complex, and when uncontrolled it may lead to adhesion formation. Transforming growth factor-beta1 (TGF-beta1) is a multipotent growth factor known to be involved in wound healing and scar formation. It has also been shown to have a role in both tendon healing and adhesion formation. METHODS: Uninjured rabbit flexor tendons were divided into endotenon, epitenon, and sheath cells and cultured separately. The in vitro effect of TGF-beta1 gene expression was determined on quiescent tendon cells using real-time polymerase chain reaction for collagen type 1, collagen type 3, fibronectin, plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator (t-PA). RESULTS: Endotenon-derived cells showed a statistically significant down-regulation of collagen type I gene expression in response to TGF-beta1 compared with untreated endotenon cells and with both epitenon and sheath cells at a number of time points. However, endotenon cells showed an increase in collagen type 3 gene expression compared with untreated cells and epitenon cells. All cells showed a statistically significant increase in fibronectin in the later time points compared with the untreated cells. Endotenon-derived cells showed an early increase in PAI-1, whereas sheath cells showed a later increase. CONCLUSIONS: We have shown that cells cultured from 3 separate parts of the flexor tendon-sheath complex respond in different ways when stimulated with TGF-beta1. The down-regulation of collagen types 1 and 3 in endotenon cells may give further insight into the effects of TGF-beta1 in tendon healing. Also, the upregulation of fibronectin and PAI-1, combined with a down-regulation of tissue plasminogen activator, could explain the association of TGF-beta1 with tendon adhesion formation. Treatments aimed at improving tendon healing and the prevention of adhesions may arise from modification of the effects of TGF-beta1.

The growth factors involved in flexor tendon repair and adhesion formation.

Flexor tendon injuries remain a significant clinical problem, owing to the formation of adhesions or tendon rupture. A number of strategies have been tried to improve outcomes, but as yet none are routinely used in clinical practice. Understanding the role that growth factors play in tendon repair should enable a more targeted approach to be developed to improve the results of flexor tendon repair. This review describes the main growth factors in tendon wound healing, and the role they play in both repair and adhesion formation.