Vitronectin or fibronectin is required for corneal fibroblast-seeded collagen gel contraction

The wound healing process in the corneal stroma involves the activation of corneal keratocytes and the expression of associated phenotypes (fibroblasts and myofibroblasts). One of these phenotypes, the myofibroblasts, synthesizes alpha-smooth muscle actin in order to affect wound closure by contracting the surrounding matrix. Excessive contraction results in the formation of unresolvable scars that are undesirable in the corneal stroma. The authors tested the effect of vitronectin and fibronectin on the contraction process associated with corneal wound healing.

Collagen gels were prepared and were exposed to different treatments of fetal calf serum (FCS). The FCS used was either depleted of fibronectin and vitronectin or contained a known concentration of fibronectin, vitronectin, or both at 50 microg/ml. Contraction was measured using image analysis and cross sections of contracted gels were examined for alpha-smooth muscle actin expression using laser confocal microscopy.

Fibroblasts seeded in collagen gels paralleled the morphologic characteristics and cell distribution of keratocytes in unwounded cornea. Matrix contraction was dependent on the presence of fibronectin and/or vitronectin where myofibroblasts were present. The cell-mediated contraction process was maximal at 0.5 x 10(5) fibroblasts/ml.

These studies showed that vitronectin or fibronectin is required for the myofibroblast-associated contraction to occur in this in vitro model of stromal wound healing. This model system shows a distinct potential for further studies relating to the corneal wound healing process.