Bone Marrow-derived Mesenchymal Stem Cells Of Neonatal Mice Suppress Dendritic Cells Maturation And T Lymphocyte Proliferation

Objective Bone marrow-derived mesenchymal stem cells (MSCs) may modulatethe function of immune cells in mice model. However, the MSCs cannot be easily harvestedbecause of the low MSC frequency and the mouse age. This study was designed to establisha simple and easy method of culturing MSCs from neonatal mouse, and elucidate theirmorphological characteristics and immunological function.Methods Bone marrow (BM) cells were obtained from C57BL/6neonatalmouse. The filtered BM cells were cultured for24h for MSCs adherent tightly to plasticculture dishes. The MSCs were culture to passage9and the surface markers of the MSCswere examined by flow cytometry. The MSCs of passage4were used to assess themultilineage differentiation capacity of these cells, including adipogenic and osteogenicinductions. The same procedure was performed using the BM cells from matured mice. Thecells were cultured in the presence of rhGM-CSF(20ng/ml)and rhIL-4(10ng/ml)for8days.Dendritic cells (DCs) were obtained from BALB/c mouse and then cocultured withthe neonatal MSCs, following analysis of CD86and MHCⅡon DCs by flow cytometry,the cells were allocated to four groups. Another coculture system of C57BL/6T cells andthe neonatal MSCs at a1:1ratio were stimulated with DCs for4days, and the T cellproliferation was analyzed using CFSE assay by flow cytometry.Results Immumophenotypic analysis showed that the neonatal MSCs werepositive for CD29/CD105and negative for CD34/MHC-Ⅱ, and the MSCs exhibitedmultipotency through their ability to differentiate into adipocytes and osteocytes. Meanwhile, the MSCs from matured mice failed to proliferation for the further experiments.After coculture with the neonatal MSCs, CD86and MHC class Ⅱwere down-regulated andthis result was found to be statistically significant compared with no MSCintervention(p<0.05), MSCs blocked the development of DCs and this blocked functionwas not reversed by lipopolysaccharide(LPS). CFSE assay showed that the neonatal MSCsstrongly inhibited CD4and CD8lymphocyte proliferation, with a proliferation ratio of5.36%CD4+T cells and3.94%CD8+T cells, compared with30.8%CD4+T cells and33.4%CD8+T cells in the absence of the neonatal MSCs.Conclusions MSCs from neonatal mice presents superior multilineagedifferentiation capacity, while MSCs from matured mice fail to proliferation. NeonatalMSCs exhibit capacity to suppress DC maturation and T-cell proliferation, and provide apromising means to induce transplant immune tolerance.