Cytokine modulation of endothelial cell sensitivity to photodynamic therapy

The purpose of this study was to determine if recombinant angiogenic cytokines modulate the sensitivity of endothelial cells to the toxic effects of chloroaluminum sulphonated phthalocyanine (AlSPc) photodynamic therapy (PDT). Bovine pulmonary artery endothelial cells in 24-well tissue culture plates were pretreated for 24 hr with AlSPc and either acidic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), tumor necrosis factor-alpha (TNF), interleukin-1-alpha (IL-1), or transforming growth factor-beta (TGF) followed by argon-pumped dye laser. Endothelial cell damage was monitored with 51chromium release. FGF, TGF, and, to a lesser extent, IL-1, enhanced the PDT-mediated damage to endothelial cells, whereas PDGF and TNF did not significantly modulate toxicity. The enhanced endothelial cell damage was seemingly not related to rate of cell proliferation or amount of photoactive drug uptake by the EC. These results suggest that presence of tumor secreted cytokines may enhance PDT-mediated toxicity of tumor associated endothelial cells.