Bone marrow purging by photodynamic treatment in children with acute leukemia - Cytoprotective action of Amifostine

In order to evaluate the combined effect of Amifostine and Merocyanine 540 during photoirradiation in neoplastic cells, bone marrow cells from childre n with acute leukemia (AL), age-matched controls as well as HL-60 cell line were studied. Cell suspensions were incubated with Amifostine, then with M C 540 and they were subsequently exposed to different irradiation doses by Argon Laser 514 nm. Cell survival was estimated by trypan blue supravital s tain following a 24-h incubation. The leukemic cell line was studied in con tinuous liquid cell cultures for 4 weeks. The survival of normal bone marro w progenitors has been estimated by colony formation assay in methylcellulo se cultures. Our results showed that Amifostine enhances the photokilling e ffect of MC 540 on leukemic cells and significantly protects bone marrow nu cleated and committed progenitors (BFU-E and CFU-GM) from children with AL under chemotherapy. In conclusion, Amifostine seems to be a promising cytop rotective agent in the clinical use of purging with MC 540 mediated phototh erapy. (C) 2000 Elsevier Science Ltd. All rights reserved.