Review: Myelin clearance is critical for regeneration after peripheral nerve injury

Abstract

Traumatic peripheral nerve injury occurs frequently and is a major clinical and public health problem that can lead to functional impairment and permanent disability. Despite the availability of modern diagnostic procedures and advanced microsurgical techniques, active recovery after peripheral nerve repair is often unsatisfactory. Peripheral nerve regeneration involves several critical events, including the recreation of the microenvironment and remyelination. Results from previous studies suggest that the peripheral nervous system (PNS) has a greater capacity for repair than the central nervous system. Thus, it will be important to understand myelin and myelination specifically in the PNS. This review provides an update on myelin biology and myelination in the PNS and discusses the mechanisms that promote myelin clearance after injury. The roles of Schwann cells and macrophages are considered at length, together with the possibility of exogenous intervention.

Proteomic analysis of peripheral nerve myelin during murine aging

“…Myelin is degraded after a peripheral nerve injury mainly by Schwann cells and macrophages ( Rotshenker, 2011 ; Brosius Lutz and Barres, 2014 ; Gomez-Sanchez et al, 2015 ; Liu et al, 2019 ). As efficient myelin clearance is critical for nerve de- and subsequent nerve regeneration ( Painter et al, 2014 ; Brosius Lutz et al, 2017 ; Yuan et al, 2022 ), we reasoned that we could further assess the validity of our dataset by examining the regulation of myelin proteins after a sciatic nerve injury. To this end, we performed proteomics from whole nerves, both from crushed and contralateral intact nerves 7 days and 28 days post crush injury (dpc), for comparative analyses to the obtained myelin proteome dataset.…”

Sarm1 is not necessary for activation of neuron-intrinsic growth programs yet required for the Schwann cell repair response and peripheral nerve regeneration

“…Macrophage phagocytosis plays a vital role in myelin removal, especially during the later phase of myelin clearing. Because some myelin-associated proteins strongly inhibit axon outgrowth (McKerracher et al 1994; Schäfer et al 1996), slow myelin clearance likely contributes to delayed regeneration (Yuan et al 2022).…”

Design of Mixed Medicinal Plants, Rich in Polyphenols, Vitamins B, and Palmitoylethanolamide-Based Supplement to Help Reduce Nerve Pain: A Preclinical Study

“…Additionally, p75 expression measurement demonstrated the effectiveness of this treatment as axonal degeneration and dysfunction during injury and cellular stress are caused by certain signaling molecules, including p75, whose expression rises dramatically after injury [55]. Finally, further evidence of the effectiveness of the combination of Hop 30.5 mg/mL, Propolis 2.8 µg/mL, Ginkgo Biloba 100 µg/mL, Vitamin B 1 mg/mL, and PEA 3 ng/mL is provided by the analysis of MPZ, a component of the myelin that undergoes at upregulation at the start of the myelination process forming a membrane structure and whose expression is decreased after peripheral nerve injury [56].…”