Evaluation of the effects of systemic photodynamic therapy in a rat model of acute myeloid leukemia

• SPDT was performed on blood from BNML rats during extracorporeal circulation.
• SPDT increased the survival time of BNML rats.
• BNML rats subjected to SPDT exhibited reduced numbers of leukemia cells.
• BNML rats subjected to SPDT exhibited reduced serum cytokine levels.

Systemic PDT (SPDT) approach is developed to treat a variety of hematological diseases, including cancers and blood-borne infections. We evaluated the efficacy of an SPDT method for treating leukemia using a Brown Norway myeloid leukemia (BNML) rat model with the LT12 cells engineered to express GFP. The survival times of animals receiving SPDT at 5 (early-SPDT) and 10 (mid-SPDT) days post-LT12 injection were prolonged by 2 days, the rats in the late-SPDT group (15 days) exhibited a 6-day increase in life span (p < 0.05). The percentages of GFP-LT12 cells in the bone marrow of the late-SPDT rats decreased from 61.6% to 56.5% on day 17. Likewise, there was a decrease in the serum expression levels of IL-1β, IL-10, TNF-α, and IFN-γ in the late-SPDT rats (p < 0.05). Our findings indicate that SPDT could be an effective method for the treatment of leukemia, and that antitumor immunity may play a key role in this process.