Background & Aims
Schwann cells are the primary glia within the peripheral nervous system where they associate with and myelinate sensory neurons. They can modulate pain by releasing various factors that can increase sensitivity, such as neurotrophic factors, or contribute to pain alleviation, thereby playing a crucial role in the development and persistence of neuropathic pain. The scarce availability of primary human Schwann cells limits the scalability of in vitro models for pain drug discovery and disease modeling. Human induced pluripotent stem cell (hiPSC) derived Schwann cells provide a near-limitless number of cells for these applications.
Methods
In this study, we demonstrate the rapid and efficient production of Schwann cell precursors (SCPs) from human induced pluripotent stem cells using directed differentiation under defined media conditions in only 9 days. Sensory neurons were generated from the same hiPSC line using a previously published 7 day directed differentiation protocol. The identity of both cell types were validated by immunocytochemistry, qPCR, and RNA sequencing. Syngeneic SCPs and sensory neurons were co-cultured and evaluated for alignment and myelination via immunocytochemistry and transmission electron microscopy. Sensory neurons alone and in co-culture were seeded onto multi-electrode array plates to observe the functional effect of the Schwann cell precursors on sensory neuron activity through four weeks.
Results
Schwann cell progenitors (SCPs) were found to express traditional Schwann cell lineage markers, including SOX10, S100b, and OCT6, as verified by qPCR and immunocytochemistry. Bulk RNA sequencing through maturation revealed a resemblance to primary human Schwann cells on a whole-transcriptome level. In co-cultures, SCPs aligned with axons rapidly within 48 hours, and myelination was detected through transmission electron microscopy, alongside the expression of myelin-associated proteins -myelin basic protein and myelin protein zero- as early as 5 weeks.
Conclusions
In summary, SCPs can be efficiently and rapidly generated from hiPSCs and cultured with sensory neurons to form myelinating models of the peripheral nervous system. These co-culture systems will lay the groundwork for future pain models as well as modeling neuropathology in a patient-specific manner.
References
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