Aims To investigate the therapeutic effects of nanophthalocyanine photosensitizers on an experimental rat choroidal neovescularization (CNV) model, as well as to evaluate the cytotoxicity of which on human retinal pigment epithelia (HRPE) and human retinal endothelial cells (HRECs).
Methods  Two types of photosensitizers, G₁-ZnPc(COOH)₈ and G₁-ZnPc(COOH)₈/m respectively, were administrated for photodynamic therapy (PDT) after a successful establishment of CNV model on Brown-Norway (BN) rats via fundus photocoagulation. The therapeutic effects of the two drugs were assessed through optical coherence tomography (OCT), fluorescein fundus angiography (FFA) and transmission electron microscopy (TEM). For cytotoxicity tests, cell counting kit-8 (CCK-8) assays and changes of mitochondrial transmembrane potential (△Ψm) were conducted on HRPE and HRECs after initial uptake of the two drugs.
Results  Both photosensitizers demonstrated an improvement of vascular leakage and closure of CNV 1 week after PDT as confirmed by fundus image, OCT, FFA and TEM. Two weeks after PDT, G₁-ZnPc(COOH)₈/m showed a better CNV closure effect versus G₁-ZnPc(COOH)₈ (p<0.05). A significant difference (P＜0.01) was found in uptake of the two drugs in HRPE and HRECs, with no difference between the drugs (P＞0.05). Both photosensitizers showed cytotoxicity on HRPE, but G₁-ZnPc(COOH)₈/m induced a lower cell viability.
Conclusions G₁-ZnPc(COOH)₈/m mediated PDT is better than G₁-ZnPc(COOH)₈ inCNV closure and also have the advantage of fast metabolism leading to less side effect.