Human Spinal Organoid-on-a-Chip to Model Nociceptive Circuitry for Pain Therapeutics Discovery.

The discovery of new pain therapeutics targeting human nociceptive circuitry is an emerging, exciting, and rewarding field. However, current models for evaluating prospective new therapeutics [e.g., animals and two-dimensional (2D) in vitro cultures] fail to fully recapitulate the complexity of human nociceptive neuron and dorsal horn neuron biology, significantly limiting the development of novel pain therapeutics. Here, we report human spinal organoid-on-a-chip devices for modeling the biology and electrophysiology of human nociceptive neurons and dorsal horn interneurons in nociceptive circuitry. Our device can be simply made through the integration of a membrane with a three-dimensional (3D)-printed organoid holder. By combining air-liquid interface culture and spinal organoid protocols, our devices can differentiate human stem cells into human sensori-spinal-cord organoids with dorsal spinal cord interneurons and sensory neurons. By easily transferring from culture well plates to the multiple-electrode array (MEA) system, our device also allows the plug-and-play measurement of organoid activity for testing nociceptive modulators (e.g., mustard oil, capsaicin, velvet ant venom, etc.). Our organoid-on-a-chip devices are cost-efficient, scalable, easy to use, and compatible with conventional well plates, allowing the plug-and-play measurement of spinal organoid electrophysiology. By the integration of human sensory-spinal-cord organoids with our organoid-on-a-chip devices, our method may hold the promising potential to screen and validate novel therapeutics for human pain medicine discovery.