Immunogenicity of induced pluripotent stem cells

Rejection of iPS cells Induced pluripotent stem (iPS) cells, which are produced by reprogramming fully differentiated adult cells back to an embryonic-like state by expression of specific genes, have important therapeutic potential. As iPS cells are derived entirely from the patient, one hoped-for advantage of using them in therapy is that there should be no immune rejection. Now it seems this might not be the case. In experiments in which iPS cells were reprogrammed using a retroviral or non-integrative episomal approach and then transplanted into mice, teratoma cells derived from the iPS cells were rejected by the immune system, even in syngeneic recipients. This finding suggests that altered gene expression in some cells differentiated from iPS cells can induce T-cell-dependent immune responses. The authors suggest that the immunogenicity of therapeutically valuable cells derived from patient-specific iPS cells should be evaluated before they are used in any clinical applications.