(1355-D) Patch clamp and HD-MEA profiling the functional properties of human iPSC-derived nociceptors

Abstract: Human iPSC-derived nociceptors are becoming an increasingly important model system to perform drug discovery assays in pain. However, despite their importance as an in vitro model, it is important to characterize the cell properties to understand and qualify iPSCs as a 'fit-for-purpose' model.
We recorded from over 100 Anatomic RealDRG™ hiPSC-derived nociceptors from 1-8 weeks in vitro.
Human nociceptors plated at low density on rat astrocytes appeared healthier and were easier to patch compared to neurons plated without
astrocytes. Nociceptors grew larger with time in culture as evidenced by an increase in Cm, with decreased Rm. The RMP became more
hyperpolarized after three weeks and remained stable thereafter.
We observed little spontaneous activity in cells at every developmental timepoint, as would be expected from sensory neurons. The nociceptors were excitable, however, as action potentials were elicited with depolarizing current injections. Further, the amount of current injection required to elicit the first action potential (rheobase) increased over developmental time, as expected from neurons with lower Rm.
Additionally, nociceptors at all developmental timepoints exhibited sodium currents. The voltage-dependent sodium current amplitudes increased with time in culture, while the peak sodium current density (pA/pF) remained stable. We also evaluated the presence of TTX-R sodium currents at 5-8 weeks in vitro and detected their presence at all evaluated time points. The proportion of TTX-R among nociceptors varied.
We also observed an increased spontaneous neuronal activity in sensory neurons with longer time in vitro, using HD-MEA.
Overall, we determined that Anatomic RealDRGs® develop a mature neuronal phenotype by three weeks in culture, with hyperpolarized
resting membrane potential, the ability to evoke spike trains, and exhibit TTX-sensitive and resistant Na currents, suggesting they may be suitable for further assay development.