Differential Effects of Confinement on the Dynamics of Normal and Tumor-Derived Pancreatic Ductal Organoids

Pancreatic ductal adenocarcinoma (PDAC) is a cancer of the epithelia
comprising the ductal network of the pancreas. During disease progression,
PDAC tumors recruit fibroblasts that promote fibrosis, increasing local
tissue stiffness and subjecting epithelial cells to increased compressive
forces. Previous in vitro studies have documented cytoskeletal and nuclear
adaptation following compressive stresses in 2D and 3D. However,
comparison of the responses of normal and tumor-derived ductal epithelia
to physiologically relevant confinement remains underexplored, especially
in 3D organoids. Here we control confinement with an engineered 3D
microenvironment composed of Matrigel® mixed with a low yield stress
granular microgel. Normal and tumor-derived murine pancreas organoids
(normal and tumor) were cultured for 48 h within this composite 3D
environment or in pure Matrigel® to investigate the effects of confinement
on lumen morphogenesis. In confinement, tumor organoids (mT) formed lumen
that expanded rapidly, whereas normal organoids (mN) expanded more slowly.
Moreover, normal organoids in more confined conditions exhibited inverted
apicobasal polarity compared to those in less confined conditions. Tumor
organoids exhibited a collective “pulsing” behavior that increased in
confinement. These pulses generated forces sufficient to locally overcome
the yield stress of microgels in the direction of organoid expansion.
Normal organoids more commonly exhibited unidirectional rotation. Our in
vitro microgel confinement platform enabled the discovery of two distinct
modes of collective force generation in organoids that may shed light on
the mutual interactions between tumors and the microenvironment. These
insights into in vitro dynamics may deepen our understanding of how
confinement of healthy cells within a fibrotic tumor niche disrupts tissue
organization and function in vivo.