What is a stem cell?

• Published in: Wiley interdisciplinary reviews. Developmental biology 2018-09, Vol.7 (5), p.e323-n/a
• Main Author: Slack, Jonathan M. W.
• Format: Article
• Language: English
• Subjects: Cell culture; Cell division; cell lineage labeling; Cell surface; Embryology; hematopoiesis; Pluripotency; stem cell; stem cell markers; Stem cells; Surface markers; Telomerase; Tissue culture
• ISSN: 1759-7684; 1759-7692
• DOI: 10.1002/wdev.323

The historical roots of the stem cell concept are traced with respect to its usage in embryology and in hematology. The modern consensus definition of stem cells, comprising both pluripotent stem cells in culture and tissue‐specific stem cells in vivo, is explained and explored. Methods for identifying stem cells are discussed with respect to cell surface markers, telomerase, label retention and transplantability, and properties of the stem cell niche are explored. The CreER method for identifying stem cells in vivo is explained, as is evidence in favor of a stochastic rather than an obligate asymmetric form of cell division. In conclusion, it is found that stem cells do not possess any unique and specific molecular markers; and stem cell behavior depends on the environment of the cell as well as the stem cell's intrinsic qualities. Furthermore, the stochastic mode of division implies that stem cell behavior is a property of a cell population not of an individual cell. In this sense, stem cells do not exist in isolation but only as a part of multicellular system. This article is categorized under: Adult Stem Cells, Tissue Renewal, and Regeneration > Tissue Stem Cells and Niches Adult Stem Cells, Tissue Renewal, and Regeneration > Methods and Principles Adult Stem Cells, Tissue Renewal, and Regeneration > Environmental Control of Stem Cells A consensus diagram showing stem cell behavior. The stem cell exists in a specific niche which enables it to undergo self‐renewing divisions. It also generates differentiated cells via a population of committed but still dividing transit‐amplifying cells. Not all stem cell types generate multiple types of differentiated cell.