In vitro photodynamic therapy of endothelial cells using hematoporphyrin monomethyl ether (Hemoporfin): Relevance to treatment of port wine stains

Hemoporfin (hematoporphyrin monomethyl ether, HMME) is a relatively new photosensitizer that has achieved success in mediating photodynamic therapy (PDT) of port wine stains in China. However, the exact mechanism of Hemoporfin PDT on endothelial cell proliferation and apoptosis is unclear. The present study investigated the mechanism of action of HMME-PDT on endothelial cells in vitro. Human umbilical vein endothelial cells (HUVECs) were cultured in vitro. HMME-PDT treated the cells and detected the phototoxicity by cell counting kit-8 (CCK-8) assay, apoptosis by Flow cytometry assay and quantification of the secreted VEGF-A levels using ELISA and different proteins expression by quantitative real-time PCR and Western blotting. Phototoxicity was caused in an HMME and light dose-dependent manner. Apoptosis was induced as shown by Annexin-V/propidium iodide staining and morphological changes. The Bax/Bcl-2 ratio was increased as shown by Western blot for protein and RT-qPCR for mRNA. VEGF-A expression was reduced and signaling molecules in the Akt/mTOR pathway were inhibited as shown by ELISA and immunofluorescence. Hemoporfin (hematoporphyrin monomethyl ether, HMME) has achieved success in mediating photodynamic therapy (PDT) of port wine stains. The clinical success of HMME-PDT with low recurrence rates can be explained by inhibition of endothelial cell proliferation through VEGF/Akt /mTOR pathway.