Differential susceptibility of primary cultured human skin cells to hypericin PDT in an in vitro model

Intracellular ROS levels measured in Fb at 3 μM HYP-PDT, displayed a significant 3.8 fold (p < 0.05) increase in ROS, but no significant difference in ROS levels occurred in Mc or Kc. Furthermore, 64% (p < 0.005) early apoptotic Fb and 20% (p < 0.05) early apoptotic Mc were evident; using fluorescence activated cell sorting (FACS), 24 h post 3 μM HYP-PDT. These results depict a differential response to HYP-PDT by different human skin cells thus highlighting the efficacy and indeed, the potential bystander effect of if administered in vivo. This study contributes toward our knowledge of the cellular response of the epidermis to photodynamic therapies and will possibly enhance the efficacy of future photobiological treatments.