Phenalen-1-one-mediated photodynamic therapy inhibits keloid graft progression by reducing vessel formation and promoting fibroblast apoptosis

Background Keloid is a unique refractory syndrome characterized by a proliferation disorder of the fibroblasts. Recently, photodynamic therapy (PDT) has become a promising technique to modulate fibroblasts. However, use of the photosensitizer Phenalen-1-one (Ph1) in PDT for keloid remains to be explored. Objectives This study investigated the efficacy of Ph1-PDT in the in vitro and in vivo models of keloid. Material and methods Cell viability was assessed with a Cell Counting Kit-8 (CCK-8) analysis in keloid fibroblasts. The migrated and invaded keloid fibroblasts after Ph1-PDT were detected using scratch and matrigel invasion assays in vitro. Flow cytometry measured the apoptosis changes. The protein concentrations and the mRNA expression of inflammatory modulators (interleukin 8 (IL-8) and IL-1β) were determined using enzyme-linked immunosorbent assay (ELISA) and real-time quantitative polymerase chain reaction (RT-qPCR) methods, respectively. Nude mice were used to perform the transplantation of keloid grafts. Western blot analysis measured the protein expression of CD31, CD34, tumor growth factor β1 (TGF-β1), and collagen 1 in keloid fibroblasts and grafts. Results Our results revealed that Ph1-PDT significantly suppressed cell viability, migration and invasion, and enhanced the rate of cell apoptosis and caspase-3 expression in keloid fibroblasts. Moreover, in the nude mice model, Ph1-PDT decreased the volume of the graft and attenuated the vessel density by inhibiting the expression of vessel density biomarkers (CD31 and CD34) in keloid grafts. Furthermore, Ph1-PDT significantly inactivated the inflammatory mediators in keloid grafts. In addition, Ph1-PDT considerably attenuated the development of keloids by inhibiting TGF-β1 and collagen 1 proteins in keloid fibroblasts and grafts. Conclusions Ph1-PDT may suppress keloid progression by reducing vessel formation and inflammation, and promoting fibroblast apoptosis, suggesting a potential therapy method for keloid.