Extensional Flow Microfluidics Reveal Size-Dependent Core-Shell Mechanical Heterogeneity in Pancreatic Tumor Spheroids

Large PANC-1 pancreatic tumor spheroids (mostly 90 < D0 < 145 m) show stiff core–deformable shell mechanics under extensional flow, unlike smaller spheroids (mostly 40 < D0 < 75 m).

• Why it matters: Multicellular spheroid mechanics are linked to how aggregates deform to migrate through constrictions, yet core–shell heterogeneity across spheroid size remains poorly characterized.
• What they did: PANC-1 spheroids from two diameter ranges were stretched in a cross-slot microfluidic device using non-contact extensional flow, with intra-spheroid strain mapped by digital image correlation and compared to 2D contour-based metrics. Confocal imaging quantified nuclear morphology and stiffness-associated proteins, including vimentin and E-cadherin.
• The result: Larger spheroids exhibited heterogeneous deformation with a stiff central core and deformable outer shell, alongside lower nuclear sphericity and outer-shell–localized vimentin, suggesting size-dependent cytoskeletal organization.

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