Sickle cell disease iPSC-derived sensory neurons exhibit increased excitability and sensitization to patient plasma

Abstract

Individuals living with sickle cell disease (SCD) experience severe recurrent acute and chronic pain. Challenges to gaining mechanistic insight into pathogenic SCD pain processes include differential gene expression and function of sensory neurons between humans and mice with SCD, and extremely limited availability of neuronal tissues from SCD patients. Here we used SCD patient-derived induced pluripotent stem cells (iPSCs) differentiated into sensory neurons (SCD iSNs) to begin to overcome these challenges. We characterize key gene expression and function of SCD iSNs to establish a model to investigate intrinsic and extrinsic factors that may contribute to SCD pain. Despite similarities in receptor gene expression, SCD iSNs show pronounced excitability using patch clamp electrophysiology. Further, we find that plasma taken from SCD patients during acute pain associated with a vaso-occlusive event increases the calcium responses in SCD iSNs to the nociceptive stimulus capsaicin compared to those treated with paired SCD patient plasma at steady state baseline or healthy control plasma samples. We identified high levels of the polyamine spermine in baseline and acute pain states of SCD patient plasma, which sensitizes SCD iSNs to sub-threshold concentrations of capsaicin. Together, these data identify potential intrinsic mechanisms within SCD iSNs that may extend beyond a blood-based pathology.