OBJECTIVEThis study investigated the hypothesis that 5-aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) might alleviate acute graft-versus-host disease (GVHD) following allogenic bone marrow transplantation (allo-BMT) in mice.

METHODSAcute GVHD model following allo-BMT was established in 40 recipient BALB/C mice. Fifty C57BL/6J mice were used as donors and another 10 BALB/C mice as blank control without any intervention. Recipients received a lethal dose of 8.5 Gy (60)Co radiation for 10 minutes before transplantation and then were randomly divided into four groups of 10 mice (A-D). Group A was injected with normal saline injection and served as controls. Group B received pure donor bone marrow and spleen cell infusion. Group C received donor bone marrow and mixed donor-recipient spleen cell infusion. Group D was administered with an infusion of donor bone marrow cells and mixed donor-recipient spleen cells treated with ALA-PDT. The 28th day survival rate, incidence of acute GVHD and hematological and pathological changes after transplantation were examined.

RESULTSAll the mice from the Blank control group survived. The survival rates for Groups A-D on the 28th day were 0, 0, 10% and 60% respectively. Group D showed a significantly higher survival rate than the other three groups (P < 0.01). Most of the mice in Groups B and C developed GVHD but only two developed in Group D. Moreover Group D had less severe hematological and pathological changes when compared with Groups B and C.

CONCLUSIONSALA-PDT significantly alleviated GVHD and increased the 28th day survival rate for allo-BMT mice. ALA-PDT may be a promising therapy for GVHD following allo-BMT. Future studies should focus on the underlying mechanism of its therapeutic effect.