Book excerpt: Adult or postnatal stem cells offer life-long cell replacement in tissues and organs, and are thus unavoidable targets of long-term and transient regenerative/epigenetic gene therapy for both inherited and acquired diseases; and effective anticancer therapy. In particular, autologous stem cells have been instrumental to the success of gene therapy, enabling breakthrough endonuclease-boosted gene targeting for gene correction (inherited diseases) or targeted integration of therapeutic transgenes (other disorders).This timely book highlights the pioneering translation of adult pluripotent stem cells as a substitute for tissue-specific stem cells, thereby pinpointing the invaluable potential for stem cell gene therapy applications of autologous cells to contribute to all three germ players. Pathologies are discussed in terms of stem cell repopulation dynamics, with appropriate niches (long-term engraftment) and tissues (cell turnover). Focus is also placed on the increasing number of identified tissue-specific cancer stem cells as the ultimate targets for recurrence-free cancer recovery, and on the development of armed stem cells as tumor-homing vectors for targeted anticancer stem cell gene therapy.