title: p21(waf1/cip1) deficiency does not perturb the intestinal crypt stem cell population after massive small bowel resection.
abstract: BACKGROUND
  After small bowel resection (SBR), adaptation is initiated in intestinal crypts where stem cells reside. Prior studies revealed SBR-induced enterocyte proliferation requires the expression of p21(waf1/cip1). As deficient expression of p21(waf1/cip1) has been shown to result in reduced numbers of hematopoietic stem cells. We sought to test the hypothesis that p21(waf1/cip1)deficiency similarly perturbs the intestinal stem cell population after SBR.
  
  
  METHODS
  Control (n = 21; C57Bl/6) and p21(waf1/cip1)-null mice (n = 30) underwent 50% proximal SBR or sham operation. After 3 days, the ileum was harvested and the crypt stem cell population evaluated by counting crypt base columnar cells on histologic sections, determining the expression of Musashi-1 and Lgr5, and profiling the transcriptional expression of 84 known stem cell genes.
  
  
  RESULTS
  There were no significant differences in crypt base columnar cells, expression of Musashi-1 or Lgr5, or in stem cell gene expression after SBR in control mice. Furthermore, there were no differences in these markers between controls and p21(waf1/cip1)-null mice.
  
  
  CONCLUSIONS
  In contrast with bone marrow stem cells, the stem cell population of the gut is unaffected by deficient expression of p21(waf1/cip1). Additional mechanisms for the role of p21(waf1/cip1) in small bowel proliferation and adaptation after massive SBR must be considered.
authors.affiliation: Division of Pediatric Surgery, St. Louis Children's Hospital, Washington University School of Medicine, St Louis, MO 63110, USA.
authors.forename: Shannon W
authors.initials: SW
authors.lastname: Longshore
authors.forename: Rajalakshmi
authors.initials: R
authors.lastname: Nair
authors.forename: Erin E
authors.initials: EE
authors.lastname: Perrone
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Erwin
authors.forename: Jun
authors.initials: J
authors.lastname: Guo
authors.forename: Brad W
authors.initials: BW
authors.lastname: Warner
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000172:deficiency*; D020895:Enterocytes / Q000502:physiology*; D007413:Intestinal Mucosa / Q000503:physiopathology*; D007421:Intestine, Small / Q000502:physiology / Q000601:surgery*; D008297:Male; D051379:Mice; D013234:Stem Cells / Q000502:physiology*
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21