Volume XXIV - Nr.1 - November 2009

The role of fibronectin in the healing of a skin wound

The healing process of a skin wound is an ideal model to study fibronectin functions.

New light was recently shed on the role of this glycoprotein in the sequence of events which enable reconstitution of a wounded tissue, skin in this case.

This further supports the dermopharmaceutic as well as cosmetic use of Dermonectin ® (Vevy codex 18.1926), as a fibronectin-stimulating factor. Fibronectin, one of the components of the clot which is formed in a wound, acts as chemotactical factor for monocytes.

These cells are attracted by fibronectin fragments containing the domains which can bind to cellular surface proteins. It is similar to the activity of collagen and elastin fragments, but also stimulating fibroblast and endothelial cell movements.

For its binding capacity, fibronectin probably coats the debris present in the wound, denaturated collagen molecules, DNA, fibrin and actin molecules, as well as bacteria, and enables phagocytosis by macrofages.

Though not directly acting as opsonin or being provided by a very weak direct opsonizing activity, it boosts the action of other systems, such as the monocyte phagocytosis process (activity which does not belong to collagen or elastin).

Fibronectin Mechanism: a Receptor. Fibronectin, by simultaneous interaction with cell surface and extracellular matrix components (such as collagen, heparin and fibrin) promotes migration of epidermal cells towards wound lips and fibroblasts and capillaries growth.

Its role should be to provide a proper support for cell movement. Finally, it is deemed that fibronectin constitutes a warp for matrix formation and an essential support for the activity of myofibroblasts which determine wound contraction.

The innumerable interactions between cells and fibronectin which take place during the healing of a wound prompted research on the receptors, located on the cell surface, which enable such interactions. One of them, with high affinity, was isolated, cloned and identified in many cell types.

This fibronectin receptor belongs to the large family of integrins, glycoproteins consisting of an a chain of 142-180 kD and of a b chain of 95-130 kD. Such a and b chains are always assembled in the pla­sma membrane and have a large extracellular and a smaller cytoplasmatic domain. Depending on the specific a and b cells contained, integrins can bind to fibronectin, as well as to numerous other cells, such as collagen, laminin and vitronectin.

The presence of fibronectin receptors was studied in the pig skin. Using specific antibodies for these receptors it was observed that, under normal circumstances, they are scarcely present in the epidermal basal cells, while they are more abundant at the level of hair follicle cells, of eccrine gland myoepithelial cells, of smooth muscle cells of hair erectors, of endothelial cells, of pericytes and vasal smooth muscle cells.

During the wound healing process, when the granulation tissues have for­med, fibronectin receptors can be identified in fibroblasts, and the interaction between these cells and the extracellular matrix fibronectin was confirmed by electron microscopy studies.

Dermonectin (Vevy codex 18.1926) The first effective oligomer precursor of fibronectin which, as such, really help in increasing skin firmness and resiliency

Subsequently, when the wound coarcts, this process is made possible by the complex which forms between fibronectin receptors and the fibrils of this protein, which, like a network, envelops fibroblasts and allows transmission of their contraction.

In addition, the fibronectin receptors of integrin b chain are present in the migrant, basal and suprabasal cells of the epidermis, and this phenomenon is not limited to the wound, but also extends beyond its edges.

Fibronectin and its Receptors: an Active Intervention. Then, after reconstitution of a normal basal membrane, both fibronectin and its receptors decrease considerably, and their disappearance determines and confirms the hypothesis of their active intervention in the wound healing process.

Concluding, even though the healing of a wound requires the coordinated occurrence of numerous and not yet completely discovered events, fibronectin and its receptors are likely to play the following two major roles:

  1. they allow migration of epidermal cells which might use fibronectin receptors to move on the extra­cellular matrix rich in this glycoprotein;
  2. they enable fibroblasts, through the network formed by the complex between fibronectin and its receptors on the surface of such cells, to cause contraction of wounded tissues.



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