IN-VIVO UPTAKE OF LIPOSOMAL BENZOPORPHYRIN DERIVATIVE AND PHOTOTHROMBOSIS IN EXPERIMENTAL CORNEAL NEOVASCULARIZATION

Background and Objective: Photodynamic therapy (PDT) has been used suc cessfully to occlude neovascularizations experimentally. We evaluated the vasoocclusive potential of benzoporphyrin derivative (BPD), a new photosensitizer currently in clinical trials. Since liposomally formul ated BPD strongly binds to endogenous low density lipoproteins (LDL) a fter i.v. injection, LDL act as carrier to deliver BPD preferentially 60 proliferating endothelial cells. Study Design/Materials and Methods : Corneal neovascularizations in rabbits were used as model. Time-depe ndent uptake and retention of liposomal BPD were measured in vivo by m onitoring the laser-induced fluorescence (LIF). Photothrombosis was in duced using a dye laser emitting at 692 nm. Results: A maximal BPD con centration was measured at 60-90 minutes postinjection determining the optimal time interval for treatment. Exposures as low as 10 J/cm(2) a llowed complete and irreversible neovascular occlusion as documented a ngiographically. Histology revealed selective endothelial damage, adja cent corneal stroma, or iris vessels, remained intact. Identical resul ts were obtained using BPD directly complexed with LDL suggesting use of a LDL-mediated pathway. Conclusion: We suggest BPD-PDT for a select ive treatment of neovascular diseases. (C) 1995 Wiley-Liss, Inc.