and, when grown in culture, are difficult to maintain in the undifferentiated state. It is because of those limitations that even stem cells from bone marrow, the type most studied, are not available in sufficient numbers to support many potential applications of regenerative medicine. Finding ways to culture adult stems cells outside the body is a high priority of stem cell research.
Additional terms used throughout this report are defined in the Glossary. Although stem cells from all sources are important, the focus of this report is on the characteristics and therapeutic potential of ESCs and adult stem cells that have been at the center of scientific debate.