Stem Cell Plasticity
Stem cell plasticity refers to the ability of some stem cells to give rise to cell types, formerly considered outside their normal repertoire of differentiation for the location where they are found. Included under this umbrella title is often the process of “transdifferentiation,” the conversion of one differentiated cell type into another, and metaplasia, the conversion of one tissue type into another. From the point of view of this essay, some metaplasias have a clinical significance because they predispose individuals to the development of cancer. Circulating bone marrow-derived cells (BMDCs) that usually generate all blood cell lineages can switch cell lineage commitment and contribute to the regeneration of several damaged non-hematopoietic tissues, and some carcinomas may even have their origins in BMDCs. The bone marrow origin of some tumor stromal cells and vasculature is now widely acknowledged, but since this pathway was...