Chemotaxis of human keratocytes is increased by platelet-derived growth factor-BB, epidermal growth factor, transforming growth factor-alpha, acidic fibroblast growth factor, insulin-like growth factor-I, and transforming growth factor-beta

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Abstract
PURPOSE. Following corneal wounding, early migration of keratocytes into the wound area is of pivotal importance in the healing process, but the nature of this migration is not well understood. The influence of peptide growth factors on the chemotactic and chemokinetic migration of human corneal keratocytes was investigated, using the following growth factors: platelet derived growth factor-BB (PDGF-BB), epidermal growth factor (EGF), transforming growth factor-a (TGF-a), acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), insulin-like growth factor-I (IGF-I), and transforming growth factor-beta-1 (TGF-ß1). METHODS. The chemotactic stimulation was investigated in the Boyden blind-well chemotaxis chamber, and the chemokinetic effect of the growth factors determined by a modified checkerboard analysis. RESULTS. PDGF-BB, EGF and TGF-ß1 stimulated chemotaxis towards a peak value, with a subsequent decline at higher concentrations. PDGF-BB and EGF peaked at 1 ng/ml with a 2.0 and a 2.5-fold increase respectively in the number of keratocytes migrating, whereas TGF-ß1 reached a maximum response at 0.1 ng/ml, with a 1.7-fold increase. Chemotaxis reached an early plateau and remained constant at concentrations between 1 ng/ml and 100 ng/ml when stimulating with TGF-a (2.7-fold), bFGF (2.0-fold), aFGF (2.7-fold), and IGF-I (4.5-fold). Checkerboard analysis revealed that all growth factors were chemotactic agents for human keratocytes, except bFGF, which principally stimulated chemokinesis. CONCLUSION. These in vitro results demonstrate that PDGF-BB, EGF, TGF-a, aFGF, IGF-I, and TGF-ß1 increase keratocyte chemotaxis, and they may play an important role in the early recruitment of keratocytes to the corneal wound site in vivo.