The stiffness of three-dimensional biomimetic matrices regulates insulin secretion via the Piezo1 mechanosensitive ion channel.

INTRODUCTION: The extracellular matrix (ECM) within the pancreatic microenvironment plays an integral role in the pathogenesis of diabetes. However, how matrix stiffness regulates islet β-cell function through mechanosensitive ion channels remains poorly understood.

METHODS: A three-dimensional biomimetic islet culture system with graded matrix stiffness was established using hyaluronic acid methacrylate (HAMA) hydrogels with different crosslinking times. MIN6 insulin-secreting cells were encapsulated in soft and stiff HAMA matrices, and cell viability, Piezo1 expression, intracellular Ca2+ levels, β-cell function-related gene expression, and glucose-stimulated insulin secretion (GSIS) were evaluated. Pharmacological modulation of mechanosensitive ion channels and Piezo1 knockdown were used to investigate the potential role of Piezo1 in stiffness-dependent β-cell responses. RNA sequencing and pathway enrichment analyses were performed to identify signaling pathways associated with matrix stiffness. In addition, stiff or soft matrix-encapsulated MIN6 cells were transplanted into diabetic mice to evaluate in vivo glucose regulation and biocompatibility.

RESULTS: Stiffer HAMA hydrogels significantly increased Piezo1 expression in MIN6 cells and were associated with elevated intracellular Ca2+ levels. Compared with the soft matrix, the stiff matrix significantly increased the expression of β-cell function-related genes, including Insulin, Pdx1, Mafa, and Nkx6-1, and enhanced insulin secretion under both basal and glucose-stimulated conditions. Pharmacological activation of Piezo1 in the soft matrix partially mimicked the effects of the stiff matrix, whereas inhibition of mechanosensitive ion channels reduced insulin-associated signals and β-cell function-related gene expression. RNA-seq and pathway enrichment analyses identified HIF-related signaling and metabolic pathways as potential molecular responses to matrix stiffness. However, the present data did not establish a direct mechanistic relationship between HIF signaling and Piezo1. In diabetic mice, transplantation of stiff matrix-encapsulated MIN6 cells was associated with improved blood glucose control during the observation period and showed good in vivo biocompatibility.

DISCUSSION: These findings indicate that matrix stiffness can modulate β-cell function and glucose-responsive insulin secretion within a three-dimensional microenvironment. Overall, this study provides evidence that biomechanical properties of the three-dimensional ECM may influence β-cell function and highlights matrix mechanics as a potential regulatory component of the islet microenvironment.