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T.A. Young, M.B. Pantcheva, E.J. Connolly, M.S. Mandelcorn, C.I. Whiteside, C.L. Grosskreutz, E.S. Gragoudas, J.W. Miller; Apoptosis in Acute Photodynamic Therapy of Choroidal Neovascularization in the Rat Model . Invest. Ophthalmol. Vis. Sci. 2003;44(13):3932.
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Purpose: Photodynamic therapy (PDT) using verteporfin is an accepted therapy of choroidal neovascularization (CNV). Apoptosis has been postulated as a mechanism by which PDT is effective in tumors and other disease entities. We have previously shown that modulation of caspase and Bcl-2 family occurs after PDT of microvascular endothelial and retinal pigment epithelial cells in vitro. The purpose of this work was to investigate the role of apoptosis in vivo following verteporfin PDT of choroidal neovascularization in the rat. Methods: Laser burns were applied in a peripapillary fashion in 30 eyes of Brown-Norway rats and CNV was documented by angiographic leakage 3-4 weeks after laser. Verteporfin PDT was applied to leaking CNV using 6 mg/m2 verteporfin followed by laser irradiation using 600 mW/cm2 and 25 J/cm2 at 689 nm 15 minutes after drug injection. Eyes were enucleated at 1 h, 2h, 4 h, and 24 h after treatment. TUNEL staining performed on sections after paraformaldehyde fixation and paraffin embedding was performed to evaluate retinal apoptosis of treated lesions. Results: TUNEL positive cells were identified in PDT treated lesion sites at all time points of specimen sections. Positive stained cells were observed in the outer nuclear layer and endothelial cells comprising the CNV lesion, in only PDT treated eyes. CNV lesions which did not receive PDT did not show TUNEL posivitity. Conclusions: Apoptosis may play an important role in the mechanism of action of PDT treated CNV lesions. Signals for the occurrence of subsequent leaking vessel closure may be mediated by acute apoptotic activity post verteporfin PDT.
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