[Studies on purging leukemic cells by photosensitizer PSD-007 laser photoradiation in vitro]

The sensitivity to photosensitization mediated by the hematoporphyrin photosensitizer PSD-007 of acute promyelocytic leukemic cell line (HL-60) was compared with normal human hemopoietic progenitor cells. The results showed that the leukemic cells were more sensitive. After being treated with 10 micrograms.ml-1 PSD-007 followed by 2J.cm-2 copper vapor laser light irradiation, the clonogenic leukemic (HL-60) cells were reduced 98%, but the survival rate of human granulocyte-macrophage colony-forming units (CFU-GM) was 40 +/- 8%. Mixing of normal human marrow cells with leukemic (HL-60) cells (ratio 100:1) did not interfere with elimination of tumor cells. The ultrastructure changes of HL-60 cells treated by laser photoradiation was observed under the trans-electronic microscope. The mitochondria, endoplasmic reticulum and cell membrane were involved. This means that the cell biomembrane is the main target to be attacked. It is considered that PSD-007-laser photoradiation therapy is efficient for killing leukemic cells.