Uptake of the components of hematoporphyrin derivative by cells and tumours

Abstract

The porphyrin content of cells labelled with hematoporphyrin derivative (Hpd) and tumors of mice injected with Hpd was analysed by means of high pressure liquid chromatography (HPLC). The components of Hpd may be classified in 3 groups: (A) Components with a high fluorescence quantum yield and with sharp peaks in the HPLC chromatogram. These are monomers. (B) Components with a lower fluorescence quantum yield and with sharp peaks in the HPLC chromatogram. These are probably dimers or oligomers. (C) Components with a low fluorescence quantum yield, with a short retention time on a P-10 column and with a broad and unresolved peak in the HPLC chromatogram. These are probably large aggregates. Components of group A are rapidly accumulated by cells but are easily removed by washing the cells with medium containing serum. Porphyrins of group B are significantly more concentrated by cells in vitro than porphyrins of group A and B and accumulate over a time interval of about 18 h. Porphyrins of group B gradually migrate to sites in the cells where they are more strongly retained. Tumors in mice behave differently from tumor cells in vitro since they mainly contain porphyrins of group C after an i.p. injection of Hpd in the mice.