Generation of human pineal gland organoids with melatonin production for disease modeling.

The pineal gland regulates circadian rhythms through melatonin production, yet human studies are limited by poor tissue access. To overcome this, we developed human pineal gland organoids (hPGOs) from pluripotent stem cells, modeling pineal development and function. Single-cell RNA sequencing revealed distinct mature and developing pinealocyte populations with transcriptomic profiles closely resembling the in vivo pineal gland. hPGOs produce melatonin, express adrenergic receptors, and respond to noradrenaline, mimicking physiological regulation. To model disease-related impairments, we generated hPGOs from Angelman syndrome (AS) patient-derived iPSCs, which exhibit disrupted pinealocyte differentiation and markedly reduced melatonin synthesis, reflecting AS-related developmental pathology. Additionally, transplanted hPGOs restored circulating melatonin in pinealectomized mice, demonstrating their potential for cell-therapy approaches. These findings establish hPGOs as a robust platform for probing pineal development, circadian regulation, and their disruption in neurodevelopmental and sleep-related disorders.