The intestinal epithelial stem cell

Abstract

This article considers the role of the adult epithelial stem cell, with particular reference to the intestinal epithelial stem cell. Although the potential of adult stem cells has been revealed in a number of recent publications, the organization and control of the stem cell hierarchy in epithelial tissues is still not fully understood. The intestinal epithelium is an excellent model in which to study such hierarchies, having a distinctive polarity and high rate of cell proliferation and migration. Studies on the small intestinal crypt provide insight into the characteristics of the stem cells in normal and regenerating circumstances and demonstrate why a thorough understanding of these cells is an essential pre-requisite for stem cell based therapeutic approaches.

Attributes of adult stem cells

“…Stem cells are a small percentage of the total cellularity. In the small intestine there are perhaps up to 10 stem cells near the bottom of the crypt out of a total crypt population of <300 cells [3]. In skeletal muscle, satellite (stem) cells comprise about 5% of all nuclei, but in the bone marrow the multipotential haematopoietic stem cell is much rarer, with a frequency of perhaps 1 in 10 000 or more amongst all bone marrow cells.…”

“…Thus, in many tissues we see that stem cells divide less frequently than transit-amplifying cells (TACs). In the mouse small intestine, the stem cells located four or five cell positions up from the crypt base cycle less often than the more luminally located TACs [3]; on the other hand, another population of stem cells has been identified, located at the crypt base (so-called 'crypt base columnar cells'), that are invariably (??) in the cell cycle [4].…”

Epigenetics and the plasticity of differentiation in normal and cancer stem cells

“…Epigenetic control of differentiation and transcription accessibility for genes of different tissues in normal adult stem cells Normal adult tissues contain stem cells that are responsible for regenerating these tissues (Spangrude et al, 1991;Nagano et al, 1998;Gage, 2000;Temple, 2001;Marshman et al, 2002;Alonso and Fuchs, 2003;Kubota et al, 2004;Collins et al, 2005;Shackelton et al, 2006). Adult stem cells reside in specific niches within different issues (Fuchs and Segre, 2000;Calvi et al, 2003;Zhang et al, 2003;Li and Xie, 2005).…”

Biomechanical Modelling of Colorectal Crypt Budding and Fission

“…At the bottom of each crypt lie stem cells which produce semi-differentiated transit cells that proliferate and move up the crypt. As these transit cells progress along the crypt they differentiate, stop dividing and are eventually shed into the lumen of the colon; the turnover of cells in the crypt is rapid, of the order of days (Marshman et al, 2002).…”