Abstract

Expansion of intestinal progenitors and putative stem cells (pISC) occurs early and transiently following ileo-cecal resection (ICR). The mechanism controlling this process is not defined. We hypothesized that glucagon-like peptide-2 (GLP-2) would augment jejunal pISC expansion only when administered to mice immediately after ICR. Since recent reports demonstrated increases in intestinal insulin-like growth factor (IGF)-I following GLP-2 administration, we further hypothesized that increased intestinal IGF-I expression would correlate with pISC expansion following ICR. To assess this, GLP-2 or vehicle was administered to mice either immediately after resection (early) or before tissue harvest 6 wk following ICR (late). Histological analysis quantified proliferation and intestinal morphometrics. Serum levels of GLP-2 were measured by ELISA and jejunal IGF-I mRNA by qRT-PCR. Expansion of jejunal pISC was assessed by fluorescent-activated cell sorting of side population cells, immunohistochemistry for phosphorylated beta-catenin at serine 552 (a pISC marker), percent of crypt fission, and total numbers of crypts per jejunal circumference. We found that early but not late GLP-2 treatment after ICR significantly augmented pISC expansion. Increases in jejunal IGF-I mRNA correlated temporally with early pISC expansion and effects of GLP-2. Early GLP-2 increased crypt fission and accelerated adaptive increases in crypt number and intestinal caliber. GLP-2 increased proliferation and intestinal morphometrics in all groups. This study shows that, in mice, GLP-2 promotes jejunal pISC expansion only in the period immediately following ICR. This is associated with increased IGF-I and accelerated adaptive increases in mucosal mass. These data provide clinical rationale relevant to the optimal timing of GLP-2 in patients with intestinal failure.