Transplantation of granulocytic myeloid-derived suppressor cells (G-MDSCs) could reduce colitis in experimental murine models

Objective Myeloid-derived suppressor cells (MDSCs) are a group of myeloid cells expressing CD11b and Gr-1 marker in mice and comprise at least two subsets: granulocytic MDSCs (G-MDSCs) and monocytic MDSCs (M-MDSCs). This study aimed to evaluate the therapeutic efficacy of transplantation of G-MDSC subsets from normal mice to colitis mice. Methods Murine colitis model was induced by the intrarectal administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS). The mice were divided into four groups: control group, TNBS-induced colitis, TNBS-induced colitis plus normal saline injection and TNBS-induced colitis plus bone marrow-derived G-MDSCs injection (transplantation group). G-MDSCs were sorted and enriched via magnetic-activated cell sorting (MACS) program, the purity of the sorted cells was then identified using flow cytometry analysis. Sex cross-transplantation of dominant G-MDSCs was applied from normal mice to colitis models using i.v. injection. Changes of body weight, survival rate, myeloperoxidase (MPO) activity were monitored and macroscopic and microscopic injury scores are calculated. Donor cell Y chromosomes were assessed by in situ hybridization to assess reconstitutions. Results After the transplantation of bone marrow-derived G-MDSCs from normal mice to colitis models, recipient mice showed increased survival rate, decreased macroscopic and microscopic injury scores and MPO activity, as well as lowered concentration of serum interleukin-6. Y chromosomes staining displayed colonization of donor cells of liver, spleen and colon tissues. Conclusion Bone marrow-derived G-MDSCs are effective in the improvement of murine colitis, but its effect in human needs further investigation.