Plasticity of marrow-derived stem cells.
Bone marrow (BM) contains hematopoietic stem cells (HSCs), which differentiate into every type of mature blood cell; endothelial cell progenitors; and marrow stromal cells, also called mesenchymal stem cells (MSCs), which can differentiate into mature cells of multiple mesenchymal tissues including fat, bone, and cartilage. Recent findings indicate that adult BM also contains cells that can differentiate into additional mature, nonhematopoietic cells of multiple tissues including epithelial cells of the liver, kidney, lung, skin, gastrointestinal (GI) tract, and myocytes of heart and skeletal muscle. Experimental results obtained in vitro and in vivo are the subject of this review. The emphasis is on how these experiments were performed and under what conditions differentiation from bone marrow to epithelial and neural cells occurs. Questions arise regarding whether tissue injury is necessary for this differentiation and the mechanisms by which it occurs. We also consider which bone marrow subpopulations are capable of this differentiation. Only after we have a better understanding of the mechanisms involved and of the cells required for this differentiation will we be able to fully harness adult stem cell plasticity for clinical purposes.
Herzog
Erica L
EL
Department of Medicine, Yale University School of Medicine, 333 Cedar St, New Haven, CT 06520, USA.
Chai
Li
L
Krause
Diane S
DS
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology*; D002454:Cell Differentiation; D002465:Cell Movement; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D006801:Humans; D039902:Multipotent Stem Cells; D009928:Organ Specificity; D033581:Stem Cell Transplantation; D013234:Stem Cells / Q000166:cytology*; D017154:Stromal Cells / Q000166:cytology