In the normal peripheral nervous system, Schwann cells (SCs) are present in two different states of differentiation: myelinating SCs that surround large-caliber axons, forming myelin sheath, and non-myelinating SCs that surround more small-caliber axons forming Remak bundles. Under pathological conditions (injury or inflammation), SCs, with a remarkable plasticity, undergo phenotypic transformations, downregulating the production of myelin proteins mRNAs, upregulating neurotrophic factors and cytokines, thus promoting the axonal regeneration. Dedifferentiated SCs activate the protein degradation, participating in the demyelination process and clearance of myelin debris; attract macrophages helping wound healing; proliferate to replace lost cells; guide axonal growth; and protect against secondary axonal damage. Thus, SC functions have a critical contribution to regeneration processes that occur in peripheral nerve after injury.
Part of the book: Demyelination Disorders