Relative Sensitivity of Leukemic (CML) and Normal Progenitor Cells to Treatment with the Photosensitizer Benzoporphyrin Derivative and Light

Abstract

Normal bone marrow and peripheral blood committed progenitor cells were found to be significantly more resistant to treatment with the photosensitizer benzoporphyrin derivative (BPD) and white fluorescent light (11 J/cm2) than were clonogenic cells from two cell lines (K562 and EM2) derived from nonremission patients with myelogenous leukemias. Bone marrow and peripheral blood committed progenitor cells from normal donors were also found to be more resistant to this treatment than were equivalent cells from patients with chronic myelogenous leukemia (CML). Normal bone marrow mononuclear cells grown in long-term marrow culture (LTMC) following treatment with BPD and light showed that no differences in stem cell productivity existed between control and treated samples. When bone marrow from CML patients was treated in the same manner, the numbers of progenitors detected in the nonadherent population during culture were greatly reduced compared to control material. Two rounds of PCR using nested primers to detect BCR-ABL mRNA showed that while this treatment significantly decreased the numbers of stem cells bearing the Philadelphia chromosome, it did not eliminate them.