Intestinal stem cells rely on signals from underlying tissue for expansion following cytotoxic damage (899.1)

Abstract

Objective: Characterize signals required for epithelial regeneration after damage from Doxorubicin (Doxo). We hypothesize these signals arise from underlying tissue. Methods: Jejuni from Doxo‐treated mice were harvested for histology, assessment of ISC proliferation by flow cytometry, crypt culture, and microarray. Results: Crypt depth increases 4 days after Doxo; flow data confirm increased ISC proliferation at this time: 14±5 % of CD24lo cells are EdU+ in controls vs. 37±4%, 4d after Doxo (p=0.02). Interestingly, Lgr5‐EGFPhi cells are 7‐fold decreased at this time. In culture, crypts harvested from Doxo‐treated mice are equally proliferative as those of control mice. Addition of de‐epithelialized intestinal tissue (DEIT) from mice 4d after Doxo yields an increased average bud number per enteroid [1.45±0.31 buds vs. 5.10±0.96 buds (p <0.05)]; it also induces proliferation of crypts from treated animals [1.16±0.30 buds vs. 4.83±0.29 buds (p<0.0001)]. Microarray analysis of DEIT shows differentially expressed genes and pathways, potentially driving this observed effect. Conclusions: These data suggest a critical role of underlying tissue in regulating ISC behavior after damage, and warrant further investigation of mechanisms.