Abstract
Purpose: :
To study the anti-apoptotic effect of riboflavin on ex vivo cultivated limbal epithelial cells exposed to ultraviolet-A irradiation.
Methods: :
Ex vivo cultured limbal epithelial cells on denuded amniotic membrane were exposed to UV-A radiation was used in corneal collagen cross-linking in the presence and absence of photo-sensitizer riboflavin. These cells were then used for extraction of RNA, cDNA conversion or used for staining. Quantitative PCR and immunoflourscence staining were done for evaluating the apoptotic state of the cells in different treated and untreated conditions. The statistical analysis was finally done using Student-T test.
Results: :
It was noted that anti-apoptotic genes such as Bcl-2 was down-regulated whereas Bax, a pro-apoptotic gene was up-regulated. Significant up-regulation was detected in the levels of active caspase in cells exposed to UV-A in comparison to untreated cells as detected using FLICA staining.
Conclusions: :
The results indicate that exposure of LECs to the UV-A dosage used in C3R procedure enhances the apoptotic genes as well as caspase activity. In the presence of riboflavin the damage caused by UV-A is marginalized but not totally abrogated. Apoptosis could be detected both in ABCG2 positive and negative population. This study results emphasize the importance of a long term follow up of the patients undergone UV-A based collagen cross-linking therapy. A long term health of limbal epithelial cell population in these patients is critical as depletion of this population would have deleterious effects on the general regenerative potential of limbal cells in this group of patients.
Keywords: keratoconus • gene/expression • apoptosis/cell death