Adult stem cells

Adult stem cells (also known as somatic stem cells or tissue stem cells) are rare populations of cells that are found in the body throughout the majority of postnatal life and give rise to a limited number of mature cell types that build the tissue in which they reside. Their progeny replaces cells that are lost owing to tissue turnover or injury, thus ensuring the maintenance of tissue homeostasis. Well-studied examples in mammals include blood, skin, intestine and muscle stem cells, but it is not clear whether all organs contain dedicated tissue-specific stem cells. This series looks at the progress that has been made in identifying stem cells in different tissues and in understanding their regulation during normal tissue turnover and following injury.



Intestinal epithelium showing different cell types, including crypt stem cells.