Retrograde movements determine effective stem cell numbers in the intestine

Abstract

Morphology and functionality of the epithelial lining differ along the intestinal tract, yet tissue renewal at all sites is driven by stem cells at the base of crypts 1-3 . Whether stem cell numbers and behaviour vary at different sites is unknown. Here, we show by intravital microscopy that despite similarities in the number and distribution of proliferative cells with an Lgr5 signature, small intestinal (SI) crypts contain twice as many effective stem cells as large intestinal (LI) crypts. We find that, although passively displaced by a conveyor belt-like upward movement, SI cells positioned away from the crypt base can function as long-term effective stem cells due to Wntdependent retrograde cellular movement. By contrast, the near absence of retrograde movement in the LI restricts cell repositioning, leading to a reduced effective stem cell number. Moreover, upon suppression of the retrograde movement in the SI, the number of effective stem cells is reduced, and the rate of monoclonal conversion of crypts is accelerated. Together, these results show that effective stem cell number is determined by active retrograde movement, revealing a new channel of stem cell regulation that can be experimentally and pharmacologically manipulated.

Autophagic state prospectively identifies facultative stem cells in the intestinal epithelium

“…We evaluated autophagic state as a predictor of f‐ISC potential and found that cells with high autophagic vesicle content exhibit plasticity in vitro , are protected from injury in vivo , and are biased toward noncycling secretory lineages and against cycling stem and absorptive progenitor cells. A recent study demonstrated that organoid‐formation efficiency is inversely correlated with Lgr5‐GFP expression in the small intestine, lending support to our findings that cellular plasticity in vitro is enhanced within differentiated secretory cells compared with CBCs and Lgr5‐expressing progenitors (Azkanaz et al , 2022). The requirement for autophagy in intestinal regeneration has been demonstrated previously using pan‐epithelial genetic ablation (Asano et al , 2017; Trentesaux et al , 2020), although these studies did not dissect the contribution of autophagy prior to injury versus a requirement for injury‐induced autophagy.…”

Stem cell retrograde: A new reason why colorectal cancer is more common than small intestinal cancer?

“…These LGR5+ cells in the center of the crypt can initiate the differentiation process under the suitable conditions. 2 These results indicate that structural characteristics of all crypts in the whole intestines are consistent with functional roles of LGR5+ cells, implying a stable dynamic repair mechanism in healthy intestines. 2 This is essential for maintenance of the intestinal environment and epithelial functions.…”

“…They found that in large intestine (LI) crypts, marginal Lgr5 -positive (LGR5+) cells lack retrograde movement and are unable to effectively function for long periods of time. 2 These results suggest that LGR5+ cells can effectively self-renew and further differentiate in the intestines only in a specific environment containing niche cells.…”

“…found that in addition to the normally differentiated upward migration movement, stem cells in the crypt of the SI are actively driven by Wnt signaling for retrograde movement toward the crypt center. 2 This phenomenon determines that stem cells in the crypt can maintain long-term proliferation. They found that in large intestine (LI) crypts, marginal Lgr5 -positive (LGR5+) cells lack retrograde movement and are unable to effectively function for long periods of time.…”

Homeostasis, injury and recovery dynamics at multiple scales in a self-organizing intestinal crypt

“…Specifically, from all dedifferentiated cells, about 60% were Paneth cells, 30% absorptive progenitors and 10% secretory progenitors, which could be considered quiescent +4 stem cells as previously suggested (53). Furthermore, we used our model to explore the retrograde motion, reported using intravital microscopy (54), of cells returning to the niche to de-differentiate into stem cells. For cells outside the niche, movement is retrograde when its velocity is negative in the z direction.…”