Umbilical cord blood stem cell and its immunoregulatory properties initiative towards clinical application

he lack of maternal rejection of the allogenic fetus, suggests that adaptation of the immune system occurs during normal pregnancy. Umbilical cord blood (UCB) cells have unique properties to overcome the maternal rejection of allogenic fetus. Human umbilical cord blood cells (UCBC) has been shown to be an effective source in allogenic stem cell transplantation, however there is concern due for graft-versus host disease. Non-classical human leukocyte antigens HLA E, HLA-F and HLA-G are strongly positive in umbilical cord blood cells. These molecules help in the immunosuppressive action via non-classical major histocompatibility complex (MHC) and natural killer (NK) mediated response. HLA-G expressed by target tissue engages inhibitory receptors on effectors cells thereby acts as a shield against immune aggregation. The relevance of HLA-G and HLA-E has been seen in several pathological conditions such as graft transplantation, autoimmune disorders and malignancies. There is clear need to explore non classical MHC molecules for the preclinical and clinical trial after umbilical cord blood stem cell transplantation. This review highlights the immunosuppressive and immunomodulatory properties of UCB cells for further intensive research to explore its beneficial effects. We highlight how the properties of non-classical MHC-1 molecules can be used as therapeutic agent for future clinical trial.