Purpose: With increasing resistance of microorganisms to antibiotics, photodynamic inactivation (PDI) may be a potential treatment alternative for infectious keratitis. Growth factors have the function to regulate proliferation, apoptosis and motility of the cells, and thereby affect wound healing. The purpose of this study was to evaluate the possible impact of PDI on the secretion of keratinocyte growth factor (KGF), fibroblast growth factor beta (FGFb), vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and transforming growth factor β1 (TGFβ1) of human keratocytes, in vitro.
Methods: Primary human keratocytes were isolated by digestion in collagenase A (1.0 mg/ml) from human corneal buttons, and cultured in DMEM/Ham's F12 medium supplemented with 10% FCS. Keratocyte cell cultures underwent illumination using red (670 nm) light for 13 min following exposure to 100 nM concentration of the photosensitizer chlorin e6 (Ce6) in culture medium. Five hours and 24 hours after PDI, secretion of KGF, FGFb, VEGF, HGF and TGFβ1 was measured by enzyme-linked immunoabsorbent assay (ELISA).
Results: Compared to untreated controls, FGFb secretion of keratocytes increased (p < 0.0001) and HGF expression decreased (p < 0.01) significantly 5 hours after PDI, whereas KGF, VEGF, and TGFβ1 secretion remained unchanged. Twenty-four hours following PDI, KGF secretion decreased (p < 0.0001) significantly, while FGFb, HGF, VEGF and TGFβ1 concentrations did not differ markedly from untreated controls.
Conclusions: Photodynamic inactivation triggers FGFb and inhibits HGF secretion of keratocytes transiently (5 hours) and inhibits KGF secretion 24 hours following treatment. In the short term, PDI does not have an impact on VEGF and TGFβ1 secretion of keratocytes, in vitro.