This link will take you to a series of articles on stem cell biology and medicine that was collected and presented by three of BioMed Central's flagship journals, BMC Biology, BMC Medicine and Genome Medicine. The series highlights some of the most important and topical issues - including recent advances, controversies and challenges in stem cell research, and of course their clinical implications. To supplement the comment and review, relevant original research articles will be added to the series as they are published.