Photokinetic and ultrastructural studies on porphyrin photosensitization of HeLa cells.
Liposome-bound haematoporphyrin or haematoporphyrin dimethylester, as well as haematoporphyrin dissolved in phosphate-buffered saline, were added to HeLa cell monolayers at a dose of 1 microgram of porphyrin per 10(5) cells. After 2 min or 20 min incubation liposome-bound porphyrins were accumulated by cells in an about two-fold larger amount than the water-dissolved haematoporphyrin. This caused a more efficient photosensitization of HeLa cells by liposome-delivered porphyrins upon illumination with 366 nm light. Ultrastructural studies of HeLa cells, which had been incubated in a physiological medium for 24h after the end of irradiation, showed that liposomal porphyrins induce an early and extensive endocytoplasmic damage, leading to swelling of the mitochondria and vesiculation; changes of the permeability of the cytoplasmic membrane are also evident, especially in the case of haematoporphyrin dimethylester. On the other hand, water-dissolved haematoporphyrin predominantly photosensitizes damage of the plasma membrane. The different pattern of cell photodamage probably reflects a different subcellular distribution of the photosensitizing drugs.
Milanesi
C
C
Department of Biology, University of Padova, Italy.
Sorgato
F
F
Jori
G
G
D002470:Cell Survival / Q000187:drug effects*; D006367:HeLa Cells / Q000187:drug effects / Q000648:ultrastructure; D006415:Hematoporphyrins / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008027:Light; D008081:Liposomes
D006415:Hematoporphyrins; D008081:Liposomes