Immune Editing: Overcoming Immune Barriers in Stem Cell Transplantation

PURPOSE OF REVIEW: Human pluripotent stem cells have the potential to revolutionize the treatment of inborn and degenerative diseases, including aging and autoimmunity. A major barrier to their wider adoption in cell therapies is immune rejection. Genome editing allows for tinkering of the human genome in stem and progenitor cells and raises the prospect for overcoming the immune barriers to transplantation. RECENT FINDINGS: Initial attempts have focused primarily on the major histocompatibility barrier that is formed by the human leukocyte antigens (HLA). More recently, immune checkpoint inhibitors, such as PD-L1, CD47, or HLA-G, are being explored both, in the presence or absence of HLA, to mitigate immune rejection by the various cellular components of the immune system. SUMMARY: In this review, we discuss progress in surmounting immune barriers to cell transplantation, with a particular focus on genetic engineering of human pluripotent stem and progenitor cells and the therapeutic cell types derived from them.