Non-Myelinating Schwann Cells in Health and Disease

Non-myelinating Schwann cells (NMSCs) are one of the two major phenotypes of Schwann cells. NMSCs are of different types and have various locations. In the peripheral nervous system, NMSC, named Remak Schwann cells (RSC), accommodate multiple small-caliber axons, forming Remak bundles. NMSC, named perisynaptic/terminal Schwann cells, are found at the distal end of motor nerve terminals at the neuromuscular junction (NMJ). Thus, NMSCs proved to serve different functions according to their distribution such as maintenance of the axon and NMJ, peripheral nerve regeneration, or remodeling of the NMJ. Schwann cells (SCs) retain their proliferation capacity in the case of nerve injury or demyelination and provide support for the neuronal cells through paracrine signaling. Here we present an overview of their phenotypes and tissue distribution focusing on their emerging involvement in various peripheral nerve diseases.