Addressing myelination disorders: Novel strategies using human 3D peripheral nerve model

Peripheral myelination disorders encompass a variety of disorders that affect myelin sheaths in the peripheral nervous system. The Charcot-Marie-Tooth disease (CMT), the most common inherited peripheral neuropathy, is one of the most prevalent among them. CMT stems from a wide range of genetic causes that disrupt the nerve conduction, leading to progressive muscle weakness and atrophy, sensory loss, and motor function impairment. Historically, the study of these disorders has relied heavily on animal studies, owing to the challenges in accessing human cells. However, the advent of human induced pluripotent stem cell (hiPSC)-derived neuronal cells has addressed these limitations in the realm of peripheral myelination disorders. Despite this, obtaining myelin in these models remains an expensive, time-consuming, and material-intensive process. This study presents a novel, cost-effective method utilizing hiPSC-derived Schwann cells and motor neurons in a three-dimensional culture system. Our method successfully enabled the acquisition of myelin in a control clone within just four weeks, as confirmed by electron microscopy. Furthermore, the utility of these approaches was validated by studying CMT4C, also named AR-CMTde-SH3TC2, the most common recessive demyelinating form of CMT. This revealed defects in Schwann cell support to motor neuron neurite outgrowth and impaired myelination in disease-specific hiPSC-derived lines. This approach offers valuable insights into the pathogenesis of peripheral myelination disorders and provides a platform for testing potential therapeutic strategies.