Purging efficacy of ZnPcH₁-based photodynamic therapy on chronic myeloid leukemia bone marrow.

INTRODUCTION

Ex vivo purging is an emerging technique for successful transplantation of autologous hematopoietic stem cells in the treatment of leukemia. Among them, photodynamic therapy (PDT) might be a promising modality. The objective of this study was to evaluate the purging efficacy of ex vivo PDT on chronic myeloid leukemia (CML).

METHODS

A new amphiphilic mono-α-substituted zinc (II) phthalocyanine (ZnPcH₁) was used as a PDT photosensitizer. Nest reverse transcription polymerase chain reaction (RT-PCR) and real-time quantitative PCR of BCR/ABL1 fusion gene remained positive were performed to determine the purging effects of ZnPcH₁-PDT on the mixture of CML cell line K562 cells and normal bone marrow mononuclear cells (MNC) and on the CML cells from the bone marrow of patients with CML who had achieved complete hematology remission but whose BCR/ABL1 fusion genes remained positive.

RESULTS

CML cells exhibited higher susceptibility to ZnPcH₁-PDT than normal granulocyte/macrophage progenitors. PDT could eliminate K562 cells from K562-normal MNC mixture and the residual BCR/ABL1 positive CML cells from the bone marrow of patients with CML.

CONCLUSION

Our data suggest that ZnPcH₁-PDT may be a useful modality for purging CML cells for autologous grafts.