The Neurobiology of Schwann Cells

Abstract

This selective review of Schwann cell biology focuses on questions relating to the origins, development and differentiation of Schwann cells and the signals that control these processes. The importance of neuregulins and their receptors in controlling Schwann cell precursor survival and generation of Schwann cells, and the role of these molecules in Schwann cell biology is addressed. The reciprocal signalling between peripheral glial cells and neurons in development and adult life revealed in recent years is highlighted, and the profound change in survival regulation from neuron‐dependent Schwann cell precursors to adult Schwann cells that depend on autocrine survival signals is discussed. Besides providing neuronal and autocrine signals, Schwann cells signal to mesenchymal cells and influence the development of the connective tissue sheaths of peripheral nerves. The importance of Desert Hedgehog in this process is described. The control of gene expression during Schwann cell development and differentiation by transcription factors is reviewed. Knockout of Oct‐6 and Krox‐20 leads to delay or absence of myelination, and these results are related to morphological or physiological observations on knockout or mutation of myelin‐related genes. Finally, the relationship between selected extracellular matrix components, integrins and the cytoskeleton is explored and related to disease.

The effect of the alignment of electrospun fibrous scaffolds on Schwann cell maturation

“…Following nerve injury, denervated Schwann cells express higher levels of neurotrophic factors such as NGF, IL-6, LIF, BDNF, PTN and NT4/5 [41] due to the need to establish a more conducive microenvironment for the regeneration, maintenance and regulation of neuronal function [42,43]. The fact that the gene expression of neurotrophic factors is generally downregulated on electrospun fibers in this study suggests that the seeded hSCs have adopted a more mature phenotype.…”

“…Since P0 and MBP are later gene products of myelin-differentiation [41] and PMP22 is associated with myelin formation, the general lack of differences in gene expression between the two-dimensional film and electrospun fibers is not unexpected. The more significant up-regulation of P0 in hSCs cultured on aligned fibers, however, seems to suggest that the alignment and elongation of hSCs on aligned fibers could promote the maturation of hSCs more than the randomly oriented fibers.…”

“…As MAG is an important promyelinogenic marker in Schwann cells [47] and an early marker for myelin-differentiation [41], the significant up-regulation of MAG expression in hSCs cultured on electrospun fibers indicates the efficacy of these fibers in driving hSCs towards the pro-myelinating state. Since P0 and MBP are later gene products of myelin-differentiation [41] and PMP22 is associated with myelin formation, the general lack of differences in gene expression between the two-dimensional film and electrospun fibers is not unexpected.…”

Expression of CD1d Molecules by Human Schwann Cells and Potential Interactions with Immunoregulatory Invariant NK T Cells

“…These considerations led us to study the expression of CD1d molecules on Schwann cells, the myelin forming glial cells of the peripheral nervous system. Schwann cells not only form the myelin sheath that insulates the enclosed nerve axons, but also provide trophic and survival factors for neurons and facilitate regeneration following nerve injury (7). The degeneration of Schwann cells is involved in pathogenesis of peripheral neuropathies observed in autoimmune, inflammatory, and infectious diseases (8 -11).…”

Schwann Cell-Derived Factors Modulate Synaptic Activities at Developing Neuromuscular Synapses

“…Schwann cells release a variety of molecules, including neurotrophins and growth factors (Scherer and Salzer, 1996;Mirsky and Jessen, 1999). To investigate the identity of active factors in SC-CM that increased the SSC frequency, we first determined the range of the molecular weights of active factors in SC-CM using several molecular weight cutoff centrifugal filters.…”