Mechanism of photodynamic occlusion using liposomal Zn(II)-phtalocyanine.
OBJECTIVE
To evaluate the potential of liposomal Zinc(II)-phthalocyanine (ZnPc) to selectively target subretinal vasculature.


METHODS
Photodynamic therapy (PDT) with liposomal Zinc(II)-phtalocyanine was used to induce choroidal occlusion in eyes of pigmented rabbits. Drug doses of 0.16, 0.24, 0.32, and 0.4 mg/kg body weight were administered. Photosensitization was performed at a wavelength of 671 nm and an irradiance of 100 mW/cm2 applying fluences of 5, 10, 20, and 50 J/cm2.


RESULTS
Using liposomal ZnPc, occlusion of choroidal vessels was achieved without damage to the overlying neurosensory retina. A tight dose correlation was found with a drug dose of 0.32 mg/kg and a light dose of 10 J/cm2 inducing a selective thrombosis of the subretinal capillary layer. Histology revealed a selective intravascular alteration of the endothelial cells.


CONCLUSIONS
PDT using liposomal ZnPc allows occlusion of subretinal vasculature with maintenance of neuroretina and RPE. The destructive effect on choroidal vascular endothelium is intensive.
Schmidt-Erfurth
Ursula
U
Universitaetsklinik für Augenheilkunde und Optometrie, Vienna, Austria. schmidt-erfurth@meduniwien.ac.at
Michels
Stephan
S
Indorf
Lars
L
Eggers
Reinhard
R
Birngruber
Reginald
R
D000818:Animals; D001808:Blood Vessels / Q000187:drug effects* / Q000648:ultrastructure; D002199:Capillary Permeability / Q000187:drug effects; D002829:Choroid / Q000098:blood supply* / Q000648:ultrastructure; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005451:Fluorescein Angiography; D007211:Indoles / Q000494:pharmacology*; D054833:Isoindoles; D008081:Liposomes; D009942:Organometallic Compounds / Q000494:pharmacology*; D010778:Photochemotherapy; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects; D017319:Photosensitizing Agents / Q000494:pharmacology*; D010865:Pilot Projects; D011817:Rabbits; D012171:Retinal Vessels / Q000187:drug effects / Q000648:ultrastructure; D017967:Zinc Compounds
D007211:Indoles; D054833:Isoindoles; D008081:Liposomes; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D017967:Zinc Compounds; C052159:Zn(II)-phthalocyanine