The potential of regenerative medicine based on the use of stem cells to promote endogenous regenerative processes or replace damaged tissues after cellular transplantation has attracted considerable interest. Since the discovery of human ESCs in 1998150 and of human iPSCs in 20072,3, the stem cell research community has continued to identify more suitable sources for exploring cell therapy and endogenous repair in humans. A general approach to develop iPSC-based cell therapy products is summarized in Fig. 2. Of the 13 clinical trials with stem cell therapy products being conducted currently, 8 are for ESC- and 1 for iPSC-derived retinal pigment epithelial (RPE) cells to treat macular degeneration, which causes the progressive deterioration of light-sensing photoreceptors in the eye (https://clinicaltrials.gov)151. In 2014, the first clinical study using human iPSC products was initiated by transplanting RPE sheets derived from the patient’s own iPSCs. The therapy has resulted in positive results, stopping macular degeneration and improving the vision of the patient. Although the trial was subsequently put on hold due to mutations observed in a second patient’s iPSCs4, it is expected to resume6.
