Selective killing of leukemic cells by merocyanine 540-mediated photosensitization

In vitro incubation of leukemic bone marrow with the lipophilic fluorescent dye merocyanine 540 and simultaneous exposure to light reduced the concentration of L1210 leukemia cells by about 5 orders of magnitude but spared enough normal pluripotent hematopoietic stem cells to allow hematopoietic reconstitution of lethally irradiated syngeneic mice. This simple and rapid procedure may find an application in the purging of tumor cells from autologous bone marrow grafts.