Circadian Rhythm Influences the Promoting Role of Pulsed Electromagnetic Fields on Sciatic Nerve Regeneration in Rats

Melatonin signalling in Schwann cells during neuroregeneration

It has widely been thought that in the process of nerve regeneration Schwann cells populate the injury site with myelinating, non–myelinating, phagocytic, repair, and mesenchyme–like phenotypes. It is now clear that the Schwann cells modify their shape and basal lamina as to accommodate re–growing axons, at the same time clear myelin debris generated upon injury, and regulate expression of extracellular matrix proteins at and around the lesion site. Such a remarkable plasticity may follow an intrinsic functional rhythm or a systemic circadian clock matching the demands of accurate timing and precision of signalling cascades in the regenerating nervous system. Schwann cells react to changes in the external circadian clock clues and to the Zeitgeber hormone melatonin by altering their plasticity. This raises the question of whether melatonin regulates Schwann cell activity during neurorepair and if circadian control and rhythmicity of Schwann cell functions are vital aspects of neuroregeneration. Here, we have focused on different schools of thought and emerging concepts of melatonin–mediated signalling in Schwann cells underlying peripheral nerve regeneration and discuss circadian rhythmicity as a possible component of neurorepair.

Pulsed Electromagnetic Field Alleviates Intervertebral Disc Degeneration by Activating Sirt1-Autophagy Signaling Network

Intervertebral disc (IVD) degeneration is regarded as a major contributor to low back pain (LBP), causing serious economic burden on individuals and society. Unfortunately, there are limited effective treatment for IVD degeneration. Pulsed electromagnetic field (PEMF) is an economical and effective physical therapy method, with reduced side-effects. It offers certain protection to a number of degenerative diseases. Therefore, understanding the underlying mechanism of PEMF on IVD is important for improving the PEMF therapeutic efficiency. In this study, PEMF up-regulated extracellular matrix (ECM) related genes in degenerated nucleus pulposus (NP) cells. It also increased SIRT1 expression and promoted autophagy in degenerated NP cells. In contrast, the autophagy suppressor 3-methyladenine (3-MA) reversed the beneficial effect of PEMF on ECM production. Similarly, the SIRT1 enzyme activity suppressor EX 527 also inhibited the effect of PEMF on autophagy and ECM production in NP cells, thereby suggesting that PEMF regulated ECM related genes expression through SIRT1-autophagy signaling pathway. Lastly, PEMF significantly reduced IVD degeneration in a rat model of IVD degeneration in vivo. In summary, our study uncovers a critical role of SIRT1-dependent autophagy signaling pathway in ECM protection and thus in the establishment of therapeutic effect of PEMF on IVD degeneration.

Promising application of Pulsed Electromagnetic Fields (PEMFs) in musculoskeletal disorders

Increasing evidence suggests that an exogenous electromagnetic field might be involved in many biologic processes which are of great importance for therapeutic interventions. Pulsed electromagnetic fields (PEMFs) are known to be a noninvasive, safe and effective therapy agent without apparent side effects. Numerous studies have shown that PEMFs possess the potential to become a stand-alone or adjunctive treatment modality for treating musculoskeletal disorders. However, several issues remain unresolved. Prior to their widely clinical application, further researches from well-designed, high-quality studies are still required to standardize the treatment parameters and derive the optimal protocol for health-care decision making. In this review, we aim to provide current evidence on the mechanism of action, clinical applications, and controversies of PEMFs in musculoskeletal disorders.