The effects of growth factors and conditioned media on the proliferation of human corneal epithelial cells and keratocytes

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Abstract
• Background: As growth factors play an important role in epithelial wound repair, we evaluated the effect of exogenous growth factors in the presence and absence of corneal epithelial and keratocyte conditioned medium on human corneal epithelial cell and keratocyte proliferation. • Methods: Preconfluent cultures of human corneal epithelial cells or stromal keratocytes were exposed to varying concentrations of EGF, TGF-β or bFGF in the presence or absence of human corneal epithelial or stromal keratocyte conditioned medium. Cell numbers were determined after 48 h incubation. RIA and ELISA were used to quantify the levels of EGF, TGF-β and bFGF in conditioned media. • Results: EGF and bFGF increased, while TGF-β decreased, the proliferation of both cell types in a dosedependent manner. Epithelial cell conditioned medium inhibited, and keratocyte conditioned medium stimulated, the proliferation of both cell types. The proliferative effects of EGF, TGF-β and bFGF in the presence of keratocyte conditioned medium were additive for both cell types. By contrast, the addition of exogenous growth factors was unable to overcome the inhibitory potential of epithelial conditioned medium. Both conditioned media contained significant levels of bFGF, but TGF-β levels in epithelial conditioned medium were up to 5 times greater than that in keratocyte conditioned medium. • Conclusions: The results indicate that corneal cells maintain tissue homeostasis and modulate the wound healing response via paracrine/autocrine pathways.