Functional characterization of human iPSC-derived sensory neuron processes in microfluidic cultures

Rodent cell culture models have long underpinned research into nociceptive signaling; however, their limited recapitulation of human nociceptor biology has created a translational gap in analgesic development. While primary human sensory neurons are relevant, their use is hampered by scarcity, ethical constraints, donor variability, and difficulties in long-term culture. Furthermore, conventional cultures lack the compartmentalization needed to study sensory neuron processes and fail to recapitulate the synaptic connectivity between sensory and spinal cord neurons, limiting their translational relevance. To address these limitations, we utilized a microfluidic platform enabling compartmentalized culture of human induced pluripotent stem cell (hiPSC) derived sensory neurons (hiPSC-SNs) to study the function of their processes. We also demonstrate the feasibility of microfluidic co-cultures of hiPSC-SN with human iPSC-derived cortical excitatory neurons (hiPSC-CNs) as a basis for future development of models for sensory-to-CNs communication circuit. Using optimized protocols, we maintained stable microfluidic cultures and confirmed expression of pain-relevant sodium channels (Nav1.7, Nav1.8) in hiPSC-SN in both mono- and co-culture configurations. Leveraging this compartmentalized platform, we demonstrate that pharmacological blockade of Nav1.7 and Nav1.8 inhibits signal propagation along sensory neuron processes. We also demonstrate that growth factors modulate excitability of these processes. This functional validation underscores the platform's capability to investigate signal transmission along human sensory processes and demonstrates its potential for modelling more complex cellular interactions. Thus, we present a human iPSC-based microfluidic culture model that enables detailed study of sensory neuron processes and assessment of analgesics targeting nociceptive transmission, offering a significant advance toward analgesic drug discovery.