Microscale stiffness mapping of the human foetal pancreas defines hydrogels that promote the differentiation of pancreatic organoids

Mechanical cues influence organ development, but the mechanical properties of human foetal organs remain poorly defined. Here we used atomic force microscopy (AFM) to map microscale stiffness in human foetal pancreatic tissue from 8 to 21 post-conception weeks, and to relate these mechanical properties to the differentiation of pancreatic progenitor organoids. AFM indentation of unfixed cryosections revealed reproducible apparent Young's modulus distributions that increased with gestational age and showed pronounced spatial heterogeneity. Early in development, insulin-positive regions were modestly softer than adjacent tissue, suggesting transient niche-specific mechanics during endocrine emergence. Measurements on fresh and cryosectioned tissues yielded comparable stiffness values, validating cryosectioned material for quantitative mapping of scarce human specimens. Guided by these data, we created hyaluronic acid hydrogels spanning the physiological stiffness range of the foetal pancreas and used them to culture human induced pluripotent stem cell-derived pancreatic progenitor organoids. Organoid growth and endocrine differentiation, defined by increased insulin and somatostatin expression and formation of compact islet-like aggregates, were most efficient in hydrogels matching foetal stiffness, whereas matrices that were either softer or stiffer impaired both processes. Together, these results define the mechanical maturation of the human foetal pancreas and demonstrate that recapitulating developmental stiffness in vitro enhances pancreatic organoid growth and endocrine specification. STATEMENT OF SIGNIFICANCE: Understanding the mechanical environment of developing human tissues remains a major gap in biomaterials and developmental biology. This study provides the first systematic characterisation of microscale stiffness in the human foetal pancreas across key stages of gestation, revealing dynamic, spatially heterogeneous mechanical niches associated with endocrine emergence. By translating these human developmental measurements into tunable hyaluronic acid hydrogels, this work demonstrates that matching matrix stiffness to physiological values markedly enhances the growth and endocrine differentiation of human induced pluripotent stem cell-derived pancreatic organoids, while non-physiological mechanics are detrimental. These findings establish tissue mechanics as a critical, previously underappreciated regulator of human pancreatic development in vitro. More broadly, the study offers a rational framework for integrating human developmental biomechanics into biomaterial design, with direct implications for improving organoid fidelity, disease modelling, and regenerative strategies targeting the pancreas and other organs.