Effects of exogenous recombinant human bone morphogenic protein-7 on the corneal epithelial mesenchymal transition and fibrosis

AIM: To evaluate the effect of exogenous recombinant human bone morphogenic protein-7 (rhBMP-7) on transforming growth factor-alpha (TGF-beta)-induced epithelial mesenchymal cell transition (EMT) and assessed its antifibrotic effect via topical application. METHODS: The cytotoxic effect of rhBMP-7 was evaluated and the EMT of human corneal epithelial cells (HECEs) was induced by TGF-beta. HECEs were then cultured in the presence of rhBMP-7 and/or hyaluronic acid (HA). EMT markers, fibronectin, E-cadherin, alpha-smooth muscle actin (alpha-SMA), and matrix metaloproteinase-9 (MMP-9), were evaluated. The level of corneal fibrosis and the reepithelization rate were evaluated using a rabbit keratectomy model. Expression of alpha-SMA in keratocytes were quantified following treatment with different concentrations of rhBMP-7. RESULTS: Treatment with rhBMP-7 attenuated TGF-beta-induced EMT in HECEs. It significantly attenuated fibronectin secretion (31.6%; P<0.05), the alpha-SMA protein level (72.2%; P<0.01), and MMP-9 expression (23.6%, P<0.05) in HECEs compared with cells grown in the presence of TGF-6 alone. E-cadherin expression was significantly enhanced (289.7%; P<0.01) in the presence of rhBMP-7. Topical application of rhBMP-7 combined with 0.1% HA significantly reduced the amount of alpha-SMA(+) cells by 43.18% (P<0.05) at a concentration of 2.5 mu g/mL and by 47.73% (P<0.05) at 25 mu g/mL, compared with the control group, without disturbing corneal reepithelization. CONCLUSION: rhBMP-7 attenuates TGF-beta-induced EMT in vitro, and topical application of rhBMP-7 reduces keratocyte myodifferentiation during the early wound healing stages in vivo without hindering reepithelization. Topical rhBMP-7 application as biological eye drops seems to be feasible in diseases involving TGF-beta-related comeal fibrosis with corneal reepithelization disorders.