Abstract: Objective To observe the immunoregulatory effects of Sca-1+ bone marrow mesenchymal stem cells (BM-MSCs) on the delayed type hypersensitivity (DTH) mouse. Methods Balb/c mice were randomly divided into two groups, control group and MSCs infusion group. MSCs infusion group mice were intraperitoneally injected with Sca-1+ BM-MSCs from Balb/c mice on 0, 2 and 6 d, while control group mice were injected with normal saline. All the recipient mice were then injected with C57BL/6 splenocytes into the dorsal flank on 7 and 14 d into the hind footpad. After 24 h, footpad thickness, cytokines levels in the peripheral blood and the proportion of regulatory immune cells in spleen were measured by Micrometer, ELISA and FACS, respectively. Results Footpad thickness of MSCs infusion group mice (0.368 ? 0.126 mm) was significantly lower than the control group (0.731 ? 0.111 mm, p < 0.01). In the peripheral blood of MSCs infusion group mice, levels of IL-10 and TGF-β were higher than that of control group mice; while levels of IL-12 and TNF-α were lower than that of control group (p < 0.05). The proportion of regulatory T cells and dendritic cells in the MSCs infusion group mice exceeded that of control group mice (p < 0.05). Conclusion Transplantation of BM-MSCs alleviated DTH in vivo via up-regulating the levels of anti-inflammatory cytokines and regulatory immunocytes.

Key words: mesenchymal stem cells, delayed type hypersensitivity, immune response