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11/11Gut homeostasis is not passive crowd control. It’s an active, force-regulated process. Cells constantly test each other’s strength; those that fail the tug-of-war extrude.A collaboration between the @hubrechtinstitute.bsky.social , @amolf-nl.bsky.social & @IHB lead by @danielkrueger.bsky.social

10/11 Disease link: In EpCAM loss (tufting enteropathy), hyperactive myosin caused excessive extrusion, growth defects, and tissue disruption. Too much force destabilizes the barrier. Mixing mutant & WT cells made healthy cells extrude. Myosin inhibition rescued this effect.

9/11 With point ablations at the base, we intentionally weakened individual cells. Within minutes, these cells extruded - loss of tension likely triggers extrusion.

8/11 Local optogenetic activation of cells on villus substrates, creating boundaries between highly- and less-contractile cells caused preferential extrusion on the weaker side. In mosaic organoids, less contractile cells were consistently eliminated.

7/11 Optogenetics let us induce contractility with blue light and spatial precision. Extrusion rates jumped up upon activation, showing that globally increased tension directly drives extrusion.

6/11 A basal actomyosin network drives epithelial tension. On hydrogel villus substrates (generated @ IHB, Basel), resembling the in vivo topology, we saw pulsatile contractions—one cell contracts, neighbors expand. A tissue-wide tug-of-war.

5/11 Using CRISPR-generated myosin reporters, we first observed myosin increasing in extruding cells, together with a synchronized response in their neighbors—explaining extrusion dynamics as a coordinated process.

4/11 Are villus tips—where extrusion peaks—compressed by crowding? At the Hubrecht, laser ablation revealed they are under tension, not compression. That tension sets the stage for extrusion.

3/11 Using long-term live imaging & tracking (with @amolf-nl.bsky.social), we followed hundreds of extrusion events. Most villus cells extruded alive, not apoptotic. Extrusion did not correlate with density.

2/11 The intestinal lining renews every few days. Old cells are shed by extrusion—a process essential for barrier integrity and linked to diseases like IBD. But what actually triggers extrusion in mammals was unclear.

3D Reconstruction of human fetal pancreatic organoid with an endogenous (knock-in) reporter for the endocrine cell marker Chromogranin-A (green), while stained for the acinar cell marker CarboxyPeptidase A1/2 (magenta) and nuclei, DAPI (blue)

Clonal organoids grown from a single LGR5+ cell recapitulate this tri-potency in vitro. Our study describes a human fetal tri-potent stem cell, capable of long-term expansion in vitro and of generating all three pancreatic cell lineages 5/

The four lines expand exponentially for >2 years under optimized culture conditions. Single cell RNA seq identifies rare LGR5+ cells in fetal pancreas and in hfPOs as the root of the developmental hierarchy. These LGR5+ cells share multiple markers with adult gut stem cells 4/

Mouse studies indicate that these three compartments derive from a transient, common pancreatic progenitor. Amanda et al derive 18 human fetal pancreas organoid (hfPO) lines from gestational week 8-17 samples. Four lines generate acinar-, ductal- and endocrine lineage cells 3/