Hypocrellin B Encapsulated in Triphenyl Phosphonium-Modified Cationic Liposomes for Photodynamic Treatment of Exudative Age-Related Macular Degeneration.

Verteporfin photodynamic therapy (PDT) has been approved for the treatment of exudative age-related macular degeneration (AMD) for over a decade. However, its extensive application has been impeded by inevitably collateral tissue damage and immediate induction of angiogenesis, in addition to the need of multiple treatments. In order to develop prospective photosensitizers for clinical use, a triphenyl phosphonium-modified cationic liposomal hypocrellin B (TPP cationic LHB) for angiogenic targeting and endothelial internalization was constructed. With optimal PDT parameters, TPP cationic LHB can lead to death of choroid-retinal vascular endothelial cells while cause negligible damage to collateral retinal pigment epithelium cells. This is likely due to the mitochondria targeting and effective intracellular singlet oxygen generation of TPP cationic LHB in vascular endothelial cells. Additionally, in vivo chick chorioallantoic membrane assay indicated the elevated neovessel-targeting ability and photo-induced anti-angiogenic activity of TPP cationic LHB. Furthermore, TPP cationic LHB PDT is able to maintain neovessel occlusion for an extended period of time compared with verteporfin PDT, without inducing significant increased expression of some angiogenic factors, such as vascular endothelial growth factor and integrin αvβ₃. This study describes a facile strategy that may be useful for developing new-generation photosensitizers to circumvent the limitations of PDT treatment of exudative AMD.