title: Hematopoietic potential of neural stem cells: plasticity versus heterogeneity.
abstract: Organ-specific stem cells have been identified in a variety of mammalian tissues. These cells hold great promise for cellular therapy if they can reliably produce functional progeny of specific lineages. A central dogma in development has been that organ-specific stem cells are restricted to making the differentiated cell types of the tissue from which they are isolated. However, a substantial body of evidence exists that stem-cell populations from neural and hematopoietic tissues can generate the other cell types, suggesting that adult organ-specific stem cells may have a broader differentiation potential than originally thought. It remains unclear whether this apparent stem cell plasticity is attributable to transdifferentiation of tissue specific stem cells, the co-existence of multiple stem cells with different potentials, or resident totipotent stem cells in these tissues. Recent evidence, in fact, indicates that there may be a fourth explanation for the "apparent" plasticity of stem cells: cell fusion. Here, the authors critically examine the existing data to assess the extent of phenotypic conversion of bone marrow-to-brain and brain-to-blood and discuss some of the contentious issues surrounding these studies. We conclude that there is strong evidence for a multipotent neurohematopoietic stem-cell population in human and mouse brain, although further characterization of these cells will be required if the goal of engineering tissues for therapeutic applications is to be realized.
authors.affiliation: Division of Hematology/Bone Marrow Transplantation, City of Hope National Medical Center, Beckman Research Institute at City of Hope, Duarte, CA 91010, USA. cshih@coh.org
authors.forename: Chu-chih
authors.initials: CC
authors.lastname: Shih
authors.forename: David
authors.initials: D
authors.lastname: DiGiusto
authors.forename: Adam
authors.initials: A
authors.lastname: Mamelak
authors.forename: Thomas
authors.initials: T
authors.lastname: Lebon
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Forman
mesh_terms: D000818:Animals; D001773:Blood Cells / Q000166:cytology*; D002454:Cell Differentiation; D002465:Cell Movement / Q000502:physiology; D006801:Humans; D039902:Multipotent Stem Cells / Q000166:cytology; D009474:Neurons / Q000166:cytology*; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology*