To explore the effects of rapamycin (RAP) combined with cyclosporine A (CsA) on the hematopoietic function and the levels of bone marrow vascular endothelial growth factor (VEGF), thrombopoietin (TPO), and vascular cell adhesion molecule-1 (VCAM-1) in aplastic anemia mice by regulating the T-box transcription factor (T-bet)/interferon-gamma (IFN-γ) signaling pathway.

Female Kunming mice of pure line were randomly divided into control group (without any treatment), model group (subcutaneously injected with 50 mg·kg^-1 cyclophosphamide, once every other day for a total of 4 times; meanwhile, inhaling 30 mg·L^-1 toluene once a day for 8 consecutive days), CsA group (intraperitoneally injected with 5 mg·kg^-1 CsA on the basis of the model group), RAP-L combined with CsA group (intraperitoneally injected with 5 mg·kg^-1 CsA and 0.1 mg·kg^-1 RAP on the basis of the model group), RAP-M combined with CsA group (intraperitoneally injected with 5 mg·kg^-1 CsA and 0.5 mg·kg^-1 RAP on the basis of the model group), RAP-H combined with CsA group (intraperitoneally injected with 5 mg·kg^-1 CsA and 1 mg·kg^-1 RAP on the basis of the model group), and RAP-H group (intraperitoneally injected with 1 mg·kg^-1 RAP on the basis of the model group), with 10 mice in each group. Except for the control group, the aplastic anemia model was established in the other groups. A biochemical analyzer was used to detect the levels of peripheral blood red blood cells (RBC), white blood cells, hemoglobin and platelets. Hematoxylin-eosin staining was used to observe the bone marrow morphology and conduct pathological injury scoring. The enzyme-linked immunosorbent assay method was used to detect the levels of VEGF, VCAM-1, TPO, IFN-γ and tumor necrosis factor-α in the bone marrow supernatant. Immunohistochemistry was used to detect the expression of TPO. Real-time fluorescence quantitative polymerase chain reaction and Western blotting were used to detect the messenger ribonucleic acid (mRNA) and protein expressions of T-bet in bone marrow mononuclear cells.

The RBC levels of the control group, model group, CsA group, RAP-H combined with CsA group and RAP-H group were (8.48±0.89)×10¹², (2.14±0.25)×10¹², (3.54±0.54)×10¹², (6.12±0.74)×10¹² and (3.26±0.61) ×10¹²·L^-1, respectively; the pathological injury scores were (0.20±0.04), (2.50±0.25), (1.10±0.10), (1.00±0.11) and (1.20±0.16) points, respectively; the TPO levels were (195.48±28.15), (145.81±15.24), (169.76±20.26), (190.54±22.37) and (165.52±20.29) pg·mL^-1, respectively; the VCAM-1 levels were (213.46±32.33), (132.81±21.94), (185.49±19.65), (204.19±19.82) and (183.67±20.87) ng·mL^-1, respectively; the IFN-γ levels were (132.04±18.10), (232.46±25.29), (205.98±21.26), (183.67±20.20) and (209.05±19.82) pg·mL^-1, respectively; the relative expression levels of T-bet mRNA were 1.00±0.10, 3.98±0.69, 2.18±0.21, 1.95±0.20 and 2.24±0.23, respectively; the relative expression levels of T-bet protein were 1.00±0.10, 2.46±0.29, 1.98±0.21, 1.67±0.20 and 2.01±0.22, respectively. When the above-mentioned indicators of the model group were compared with those of the control group, the above-mentioned indicators of the CsA group, the RAP-H combined with CsA group, and the RAP-H group were compared with those of the model group, and the above-mentioned indicators of the RAP-H combined with CsA group were compared with those of the CsA group and the RAP-H group, all the differences were statistically significant (all P<0.05).

CsA combined with RAP can significantly improve the hematopoietic function and cellular immune function of aplastic anemia model mice, which may be related to increasing the levels of bone marrow TPO and VCAM-1 and regulating the T-bet/IFN-γ signaling pathway.