[Comparison of Acute Graft-Versus-Host Disease Mouse Models Established by TBI and BU/CY Conditioning Regimens]

To investigate the effect of acute graft-versus-host disease (aGVHD) mouse models established respectively by total body irradiation (TBI) and busulfan combined with cyclophosphamide (BU/CY) conditioning regimens after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Bone marrow cells and splenic mononuclear cells were isolated respectively from femur, tibia, and spleen of C57BL/6 male mice (H-2Kb) which were selected as donors. After TBI pretreatment, BALB/c female mice (H-2Kd) were injected with donor bone marrow cells 1×10⁷/50 μl and splenic mononuclear cells 2×10⁷/100 μl through caudal vein, while CB6F1 female mice (H-2Kd/b) with donor bone marrow cells 2×10⁷/100 μl and splenic mononuclear cells 1×10⁸/500 μl after BU/CY pretreatment. The successful establishment of the aGVHD models were determined by post-transplant manifestations, rate of chimerism, target organ damage, etc. Results: After transplantation, mice of both groups showed listlessness, low activity, continued weight loss, and typical manifestations of aGVHD such as alopecia, hunched posture, diarrhea, and anal swelling. and died within 4 weeks. Flow cytometry detection showed complete chimerism in all the mice. Pathological examination of skin, intestines, liver, lung, and spleen tissues showed obvious aGVHD pathological changes. However, the weight loss, ruffled fur, and alopecia combined with severe scurf on those hair-free areas were significantly apparent in TBI group than BU/CY group, as well as higher aGVHD score, and the differences were statistically significant (P<0.05).

Both TBI and BU/CY as conditioning regimens can successfully establish stable mouse models of aGVHD after fully allo-HSCT and haploidentical HSCT for further research about mechanism of aGVHD. BU/CY conditioning regimen can more truly simulate physiological status in vivo of patients with chemotherapy based conditioning regimen, while TBI conditioning regimen shows significantly more typical aGVHD symptoms and easier to operate.