This week Nature published the surprising results of a study that suggests reprogrammed stem cells might be rejected by a recipient, even when the cells had originated with that individual. Paul Fairchild, Director of the Oxford Stem Cell Institute, discussed the unexpected findings in the media.
A team led by Yang Xu at the University of California, San Diego, found that induced pluripotent (iPS) mouse stem cells triggered immune reactions when they were implanted back into mice with the same genetic makeup. In some cases, the cells were completely destroyed by the animals’ immune systems. The findings raise doubts about the future use of iPS cells in human trials.
Speaking to the Guardian and to Nature News, Dr Fairchild said, “It does beg an important question as to whether the same would happen in humans, but ... we have no idea if human cells would respond in the same way.” Dr Fairchild points out that the iPS cells in Xu’s study were derived from embryonic skin cells, rather than from adult skin cells, as would be the case for human patients. “If they had started with adult cells, they may not have seen an immune response, but we simply don’t know.” He adds that the study “doesn't really mirror the clinical situation at all.”
It is too soon to know what these results mean for the future of iPS research, but it seems clear that further investigation is needed into what triggered the mice’s immune response. Until then, Dr Fairchild cautions, the study “might cast a cloud over the whole field of regenerative medicine unnecessarily.”