title: Deciphering the 'black box' of the intestinal stem cell niche: taking direction from other systems.
abstract: OBJECTIVE
  Study of developmental signaling pathways suggests that the intestinal stem cell niche regulates the activity of the crypt-based epithelial progenitors during homeostasis and injury states. The cellular origin of these signals, however, remains poorly defined. Here, we examine the current state of knowledge regarding intestinal epithelial progenitor niches and highlight applicable lessons learned from other systems.
  
  
  RESULTS
  Cell-cell contact, regulatory factor delivery, stem cell polarity, and mesenchymal stem cells are considered.
  
  
  CONCLUSIONS
  Based on the findings in other niche systems as well as the overall complexity and unique organization of the intestinal progenitor niche, future studies will focus on defining peri-cryptal architecture, cellular sources of regulatory factors, and the dynamic nature of the niche during homeostasis and injury repair. These insights may lead to novel cell-based therapies for a variety of conditions that damage the mucosal lining of the gut.
authors.affiliation: Department of Pathology and Immunology, Washington University School of Medicine, St Louis, Missouri, USA.
authors.forename: Monica R
authors.initials: MR
authors.lastname: Walker
authors.forename: Thaddeus S
authors.initials: TS
authors.lastname: Stappenbeck
mesh_terms: D006801:Humans; D007413:Intestinal Mucosa / Q000502:physiology; D007422:Intestines / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*