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C.A. Barden, H.L. Chandler, P. Lu, C.M. H. Colitz; The Effect of Grape Seed Extract on Canine Lens Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2541.
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© ARVO (1962-2015); The Authors (2016-present)
Cataract is one of the most prevalent causes of blindness in dogs and cataract surgery is the most common surgical procedure performed by veterinary ophthalmologists. Lens epithelial cells (LEC) exhibit epithelial–mesenchymal tranformation–like (EMT) changes characterized by pseudometaplasia, proliferation, and migration in response to oxidative stress, inflammation, and other causes of cataractogenesis and secondary cataract. We previously showed that pAkt and Cox–2 were up–regulated in cataractous LEC. Grape seed proanthocyanidin extract (GSE) has free radical scavenging activities, as well as anti–inflammatory and antioxidative properties. We hypothesize that the combined effects of GSE will slow or prevent the EMT changes seen in LEC via inhibition of Akt and/or Cox–2.
The LEC scratch model (wound healing model) with primary cultures of canine LEC was used in these assays. The DCF assay was used to test the efficacy of GSE’s free radical scavenging ability. LEC were treated with epidermal growth factor (EGF), GSE, and EGF+GSE while undergoing psuedometaplastic migration in response to a ‘scratch’. Cell migration was monitored using digital photography and a computerized cell migration evaluation instrument (ECIS 1600, Applied BioPhysics). Cox–2 and Akt were evaluated by Western blot analysis and quantitative RT–PCR.
GSE significantly reduced the production of reactive oxygen species. EGF stimulated cell migration while GSE decreased cell migration below the level of untreated cells. In the presence of EGF, GSE reduced cell migration to the level of untreated cells. EGF increased p–Akt expression while GSE decreased expression of p–Akt. GSE diminished the EGF–induced increased expression of pAkt. EGF and GSE did not change Cox–2 protein or mRNA expression or Akt mRNA.
These results confirm the free radical scavenging ability of GSE in canine LEC. Furthermore, GSE decreased several characteristics associated with EMT, i.e. increased LEC migration and p–Akt expression. It appears that GSE’s effects are mediated post–translationally but this requires more study. We are optimistic about our findings and propose that GSE may slow or prevent cataractogenesis and/or secondary cataract in vivo. In vivo studies are currently underway.
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