Studies on the effect of photodynamic therapy on in vitro cultured neoplastic cells

Photodynamic therapy (PDT) represents a therapeutic approach in which photosensitised neoplastic cells undergo destruction under the effect of light. In this study we have attempted to define effects of PDT on CHO cells, sensitised with protoporphyrin IX (PpIX). The photosensitised CHO cells were exposed to a visible light and development of apoptotic and necrotic lesions was followed in the cells, using the fluorescent staining with propidium iodide and Hoechst 33342. The experiments demonstrated that PpIX and light, acting in parallel, induce development of apoptotic and necrotic lesions in the cells. Intensity of the lesions was correlated with the concentration of the applied photosensibiliser and with the duration of exposure to light. The control experiments suggest that development of apoptosis in the applied model probably reflect mitochondrial damage, while processes developing close to the cell membrane are responsible for necrosis. In order to corroborate the obtained results, ultrastructural studies were performed on experimental groups in which evident apoptotic lesions were observed in the cells.