Anniversary reflections: ISSCR presidents on 20 years of progress

This year, Cell Stem Cell and the International Society for Stem Cell Research (ISSCR) are celebrating their 15^th and 20^th anniversaries, respectively. We took the opportunity to ask the current and four former ISSCR presidents to reflect on major stem cell advances during this time, the evolution of policy, clinical translation and ethical aspects, and future challenges for the field.