Introduction and Objective: Understanding how human islet α and β cell electrical activities become functionally mature is critical to build fully functional SC-islets (stem cell-derived islets) for research and regenerative medicine. Methods: We implanted tissue-like, stretchable mesh electronics during organogenesis of human pancreatic organoids, enabling months-long, single-cell-resolved electrophysiology. Resolving single-unit action potentials revealed stimulus-coupled extracellular spike bursts of α and β-like cells and their dynamics over months of functional maturation and under daily metabolic entrainment. Results: We identified two major SC-α/β cells electrical states, distinguished by the glucose threshold for action potential firing. Tracing the evolution of these states over months of extended culture indicated that an improved glucose responsiveness reflects increasing numbers of SC-α/β cells in low basal firing states, linked to induction of energy and hormone metabolism pathways. Further, daily feeding cycles, which entrain circadian insulin and glucagon secretion rhythms, reflect daily cycling of both SC-α/β firing rates and their cell-level spike waveforms, tied to induction of cell-cell communication and exocytic gene networks. Finally, electrical stimulation, via implanted actuators, selectively enhances SC-α and β cell glucose responsiveness. Conclusion: Our bioelectronic framework to trace and modulate organoid maturation revealed three novel findings: 1) Mature SC-α/β cells exist from the beginning of in vitro culture and grow in proportion over time. 2) A higher glucose threshold for hormone secretion in mature SC-α/β cells entails a higher threshold for action potential firing. 3) Daily feeding cycles entrain circadian rhythms of SC-α/β electrical characteristics, revealing circadian coordination of stimulus-coupled electrical responses. These findings reveal electrical maturation principles informing how to build fully mature SC-islets for research and therapeutics. Disclosure J. Alvarez: None. Funding NIH/NIDDK (DP1DK130673), Human Islet Research Network (U24DK104162)NIH/NIGMS (R35GM157320, Breakthrough T1D (INO-20 2025-1707-A-N), Diabetes Research Center at the University of Pennsylvania (P30DK19525)
JUAN ALVAREZ (Fri,) studied this question.