The one hundred or so genes on Chromosome 6 that make up the Major Histocompatibility Complex govern the cell surface molecules called human leukocyte antigens and are important in a person’s immune response to transplanted tissue-whether in the form of blood transfusion, whole organs, or stem cells. Japanese researchers have determined that, just as there are universal blood donors, a universal stem cell donor (even for induced pluripotent stem cells) exists.  They believe that as few as fifty different HLA types, in iPS cells, could serve over ninety percent of all Japanese people for regenerative applications. This is a rationale for creating banks of stem cells.                  MORE