The therapeutic potential of stem cells from adults

Adult stem cells seem to have the capacity to “transdifferentiate” into cells of many different tissue types; now further work is needed to establish their role in treating degenerative diseases The discovery of adult tissue specific stem cells, such as haematopoietic stem cells, which have the ability to “transdifferentiate” into other tissues, has generated much excitement among cellbiologists and transplant clinicians. It opens new avenues for basic biological research by using stem cells from adults as an alternative to stem cells from embryos. It also carries important implications for the treatment of many liver, heart, and neurodegenerative diseases. Despite strong evidence that multipotent stem cells (stem cells with the potential to differentiate into several cell types) reside in many adult organs and can be manipulated in ways that may confer a therapeutic advantage, several questions remain to be addressed before the development of clinical applications. We review recent findings on the “plasticity” of adult stem cells to adopt a fate different from their originally intended one, and we discuss the potential clinical importance of this finding. We also point out some directions for research in the future. ### Summary points Pluripotent embryonic stem cells divide indefinitely and ostensibly generate all cell types Stem cells from adults regenerate their resident tissue but may have broader potential for differentiation (multipotential) Further work must establish the broad differentiation and functional potential of stem cells from adults Clinical utility of all stem cells awaits further validation and development We searched Medline with both general keywords such as “stem cells,” “stem cell plasticity,” “adult stem cells,” and “embryonal stem cells” and with more specific terms such as “haematopoietic,hepatic or muscle stem cells,” “Parkinson's disease,” and “osteogenesis imperfecta.” We also cite published and unpublished data generated in our laboratory. After development of the embryo most tissues are fully differentiated, …