Cord blood multipotent stromal cells exploit a unique immune suppressive mechanism

Expression patterns of Dendritic cells co cultured with cord blood MSC were compared with cord blood MSC (USSC). Putative immune suppressive candidates were tested to explain this inhibition. We find that cord blood MSC themselves are hardly immunogenic as tested with allogeneic T-cells. Dendritic cells cocultured with second party T-cells evoked abundant proliferation that was inhibited by third party cord blood USSC. Optimal inhibition was seen with one cord blood USSC for every dendritic cell. Blocking HLA-G only saw partial recovery of proliferation. Several cytokines, prostaglandins, gangliosides, enzymes like arginase, NO synthase and indole amine 2,3-dioxygenase as well as the induction of Treg were not involved in the inhibition based on the microarrays and functional tests. Although the mechanism by which it does so remains partially undefined and subject to further study, cord blood multipotent stromal cells are strong inhibitors of the immune response and therefore allow their use in tissue regeneration settings in an allogeneic setting. Keywords: Adult stem cells, developmental biology, gene expression, genomics, human cord blood, mesenchymal stem cells, cel type comparison Dendritic cells co cultured with cord blood MSC compared with cord blood MSC (USSC).