Mouse Label-Retaining Cells Are Molecularly and Functionally Distinct From Reserve Intestinal Stem Cells

Area of Science:

• Gastroenterology
• Stem Cell Biology
• Regenerative Medicine

Background:

• Intestinal homeostasis and regeneration involve reserve intestinal stem cells (ISCs) and actively proliferative ISCs.
• Label-retaining cells (LRCs) are dormant stem cells found in various tissues, including the intestine, and share properties with reserve ISCs.
• Previous studies identified putative reserve ISCs using methods like CreER insertions and DNA label retention.

Purpose of the Study:

• To investigate the relationship between label-retaining cells (LRCs) and reserve intestinal stem cells (ISCs) in the mouse intestine.
• To compare the molecular and functional characteristics of LRCs and reporter allele-marked reserve ISCs.

Main Methods:

• Utilized mouse models including Lgr5-EGFP-IRESCreERT2, Bmi1-CreERT2, Hopx-CreERT2, and TRE-H2BGFP::Hopx-CreERT2::lox-stop-lox-tdTomato.
• Purified intestinal epithelial cell populations for comparative analysis.
• Employed histologic flow cytometry, functional assays, and single-cell gene expression analysis to characterize cell populations.

Main Results:

• Label-retaining cells (LRCs) exhibited dynamic cellular composition over time.
• Short-term LRCs showed progenitor cell properties, differentiating into Paneth or enteroendocrine lineages while retaining stem cell activity.
• Long-term LRCs lost stem cell activity and comprised terminally differentiated Paneth cells; reserve ISCs marked by HopxCreER were quiescent with active stem cell function.

Conclusions:

• Label-retaining cells (LRCs) are molecularly and functionally distinct from reporter-marked reserve intestinal stem cells (ISCs).
• This distinction provides a foundation for future research into the complex relationships among different intestinal stem cell populations.