Pulsed electromagnetic fields accelerate functional recovery of transected sciatic nerve bridged by chitosan conduit: An animal model study

Adjunctive Use of Bone Growth Stimulation Increases Cervical Spine Fusion Rates in Patients at Risk for Pseudarthrosis

STUDY DESIGN

A prospective multicenter clinical trial (NCT03177473) was conducted with a retrospective cohort used as a control arm.

OBJECTIVE

The purpose of this study was to evaluate cervical spine fusion rates in subjects with risk factors for pseudarthrosis who received pulsed electromagnetic field (PEMF) treatment.

SUMMARY OF BACKGROUND DATA

Certain risk factors predispose patients to pseudarthrosis, which is associated with prolonged pain, reduced function, and decreased quality of life.

METHODS

Subjects in the PEMF group were treated with PEMF for 6 months postoperatively. The primary outcome measure was fusion status at the 12-month follow-up period. Fusion status was determined using anterior/posterior, lateral, and flexion/extension radiographs and computed tomography (without contrast).

RESULTS

A total of 213 patients were evaluated (PEMF, n=160; Control, n=53). At baseline, the PEMF group had a higher percentage of subjects who used nicotine ( P =0.01), had osteoporosis ( P <0.05), multi-level disease ( P <0.0001), and were >65 years of age ( P =0.01). The PEMF group showed over two-fold higher percentage of subjects that had ≥3 risk factors (n=92/160, 57.5%) compared with the control group (n=14/53, 26.4%). At the 12-month follow-up, the PEMF group demonstrated significantly higher fusion rates compared with the control (90.0% vs. 60.4%, P <0.05). A statistically significant improvement in fusion rate was observed in PEMF subjects with multi-level surgery ( P <0.0001) and high BMI (>30 kg/m 2 ; P =0.0021) when compared with the control group. No significant safety concerns were observed.

CONCLUSIONS

Adjunctive use of PEMF stimulation provides significant improvements in cervical spine fusion rates in subjects having risk factors for pseudarthrosis. When compared with control subjects that did not use PEMF stimulation, treated subjects showed improved fusion outcomes despite being older, having more risk factors for pseudarthrosis, and undergoing more complex surgeries.

Pulsed Electromagnetic Fields Improved Peripheral Nerve Regeneration After Delayed Repair of One Month

The goal of this study was to determine if postoperative pulsed electromagnetic fields (PEMFs) could improve the neuromuscular rehabilitation after delayed repair of peripheral nerve injuries. Thirty-six Sprague-Dawley rats were randomly divided into sham group, control group, and PEMFs group. The sciatic nerves were transected except for the control group. One month later, the nerve ends of the former two groups were reconnected. PEMFs group of rats was subjected to PEMFs thereafter. Control group and sham group received no treatment. Four and 8 weeks later, morphological and functional changes were measured. Four and eight weeks postoperatively, compared to sham group, the sciatic functional indices (SFIs) of PEMFs group were higher. More axons regenerated distally in PEMFs group. The fiber diameters of PEMFs group were larger. However, the axon diameters and myelin thicknesses were not different between these two groups. The brain-derived neurotrophic factor and vascular endothelial growth factor expressions were higher in PEMFs group after 8 weeks. Semi-quantitative IOD analysis for the intensity of positive staining indicated that there were more BDNF, VEGF, and NF200 in PEMFs group. It's concluded that PEMFs have effect on the axonal regeneration after delayed nerve repair of one month. The upregulated expressions of BDNF and VEGF may play roles in this process. © 2023 Bioelectromagnetics Society.

Biomechanical microenvironmental stimulating effect of pulsed electromagnetic field on the regeneration of crush injured rat sciatic nerve

This study evaluated the biomechanical microenvironmental stimulating effect of pulsed electromagnetic field (PEMF) on the regeneration of crush-injured rat sciatic nerve, when combined with bone marrow mesenchymal stem cells (BMSCs) and recombinant human nerve growth factor (rhNGF-β), in the form of an adenoviral vector-mediated NGF. Sprague-Dawley rats were equally distributed into six groups; PBS, BMSC, NGF-Ad + BMSC, PEMF + PBS, PEMF + BMSC and PEMF + NGF-Ad + BMSC. The PBS group received PBS (volume: 10μL/rat), the BMSC group with BMSCs (1 × 106 cell/10 μL/rat) and NGF-Ad group with the rhNGF-β Ad infected BMSCs (1 × 106 cell/10 μL/rat) immediate after right sciatic nerve crush injury. The PEMF groups were exposed to PEMF of 1mT, 50 Hz, 1 h/day. The rats were observed for 3 weeks. PEMF alone did not showed the positive effect compared with negative control group. The groups transplanted with BMSCs showed higher axonal regeneration compared with the groups without transplantation of the cells whether BMSC was infected with NGF-Ad or not and whether the animals received PEMF. PEMF + NGF-Ad + BMSC group showed the significantly highest number of axons than the other groups. Functionally, all groups showed marked improvement at 3 weeks postoperatively although the difference was not statistically significant among the groups. PEMF showed the positive effect when combined with BMSC and NGF-ad in aspect of number of axons. Therefore, combining the microenvironment stimulation methods of PEMF and conventional methods such as transplantation of stem cells and growth factor could be considered for the regeneration methods in the nerve damage.

Time course of functional recovery after 1 cm sciatic nerve resection in rats with or without surgical intervention - measured by grip strength and locomotor activity

The rat sciatic nerve (SN) is the most frequently used model in experimental research on peripheral nerve injuries. Within the broad range of evaluation methods to determine the experimental outcome, recovery of behavior represents the major criterion to assess functional regeneration. The grasping test indicates when recovery begins and its improvement with time. However, lesions of the SN have yet remained unstudied with this method. Therefore, rats received a SN resection and were divided into experimental groups: 1) control with lesion only, 2) nerve bridge, and 3) autograft. During weekly sessions, the grasping test measured the grip strength, and the locomotor behavior was assessed in the open field. Finally, the nerves were prepared for electrophysiology and histomorphometry. Autograft recovered grasping after 7 weeks with the strongest improvement afterwards. Nerve tube allowed grasping by week 12. Control animals did not recover. In the open field, no differences were observed between the groups. Recordings were possible only in the autograft group, which could be explained by higher number of regenerated fibers. This study indicates that grasping data correspond with physiological and anatomical findings. We conclude that the grasping test is a valid method to evaluate functional recovery after SN resection in rats.

The effects of pulsed electromagnetic field on experimentally induced sciatic nerve injury in rats

Some experimental research indicates that low-frequency pulsed electromagnetic field (PEMF) stimulation may accelerate regeneration in sciatic nerve injury. However, little research has examined the electrophysiological and functional properties of regenerating peripheral nerves under PEMF. The main aim of the present study is to investigate the effects of PEMF on sciatic nerve regeneration in short- and long-term processes with electrophysiologically and functionally after crushing damage. Crush lesions were performed using jewelery forceps for 30 s. After crush injury of the sciatic nerves, 24 female Wistar-Albino rats were divided into 3 groups with 8 rats in each group: SH(Sham), SNI (Sciatic Nerve Injury), SNI+PEMF(Sciatic Nerve Injury+Pulsed Electromagnetic Field). SNI+PEMF group was exposed to PEMF (4 h/day, intensity; 0.3mT, low-frequency; 2 Hz) for 40-days. Electrophysiological records (at the beginning and 1st, 2nd, 4th and 6th weeks post-crush) and functional footprints (at 1st, 2nd, 3rd, 4th, 5th and 6th weeks post crush) were measured from all groups during the experiment. The results were compared to SNI and SNI+PEMF groups, it was found that amplitude and area parameters in the first-week were significantly higher and latency was lower in the SNI+PEMF group than in the SNI group (p < 0,05). However, the effect of PEMF was not significant in the 2nd, 4th, 6th weeks. In addition, in the 1st and 2nd weeks, the SSI parameters were significantly higher in SNI+PMF group than SNI group (p < .05). These results indicate that low-frequency PEMF is not effective for long-periods of application time while PEMF may be useful during the short-term recovery period.

Efficiency of pulsed electromagnetic fields on pain, disability, anxiety, depression, and quality of life in patients with cervical disc herniation: a randomized controlled study

Background/aim

In this study, it was aimed to investigate the effects ofpulsed electromagnetic field(PEMF) therapy on pain, disability, psychological state, and quality of life in cervical disc herniation.

Materials and methods

Patients were randomly divided into two groups, including Group 1, which received a therapy consisting of transcutaneous electrical nerve stimulation (TENS), hot pack (HP), and PEMF, and Group 2, which received a magnetic field (sham magnetic field) without current flow in addition to TENS and HP therapy. Pain was assessed by a visual analog scale (VAS, 0–10 cm). The other outcome measures were function (Neck Pain and Disability Scale), anxiety-depressive mood (Hospital Anxiety and Depression Scale), and quality of life (Nottingham Health Profile). All evaluations were performed at baseline, in the 3rd week, and in the 12th week after treatment.

Results

A significant improvement was found in the neck pain, disability, depression, anxiety, and quality of life scores of both groups after treatment when compared to those before treatment. However, in the comparison between changes within groups, significant improvements were determined only in the VAS and Nottingham Health Profile sleep subparameter in the 12th week after treatment compared to those before treatment.

Conclusion

PEMF therapy in cervical disc herniation can be used safely in routine treatment in addition to conventional physical therapy modalities.

A comprehensive overview on utilizing electromagnetic fields in bone regenerative medicine

Stem cells are one of the most important sources to develope  a new strategy for repairing bone lesions through tissue engineering. Osteogenic differentiation of stem cells can be affected by various factors such as biological, chemical, physiological, and physical ones. The application of ELF-EMFs has been the subject of many research in bone tissue engineering and evidence suggests that this exogenous physical stimulus can promote osteogenic differentiation in several types of  cells. The purpose of this paper is to review the current knowledge on the effects of EMFs on stem cells in bone tissue engineering studies. We recapitulated and analyzed 39 articles that were focused on the application of EMFs for bone tissue engineering purposes. We tabulated scattered information from these articles for easy use and tried to provide an overview of conducted research and identify the knowledge gaps in the field.

Tissue engineering for the repair of peripheral nerve injury

Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering. The three key points in establishing a tissue engineering material are the biological scaffold material, the seed cells and various growth factors. Understanding the type of nerve injury, the construction of scaffold and the process of repair are necessary to solve peripheral nerve injury and promote its regeneration. This review describes the categories of peripheral nerve injury, fundamental research of peripheral nervous tissue engineering and clinical research on peripheral nerve scaffold material, and paves a way for related research and the use of conduits in clinical practice.

Bridging larger gaps in peripheral nerves using neural prosthetics and physical therapeutic agents

Peripheral nerve injuries are relatively common and can be caused by a variety of traumatic events such as motor vehicle accidents. They can lead to long-term disability, pain, and financial burden, and contribute to poor quality of life. In this review, we systematically analyze the contemporary literature on peripheral nerve gap management using nerve prostheses in conjunction with physical therapeutic agents. The use of nerve prostheses to assist nerve regeneration across large gaps (> 30 mm) has revolutionized neural surgery. The materials used for nerve prostheses have been greatly refined, making them suitable for repairing large nerve gaps. However, research on peripheral nerve gap management using nerve prostheses reports inconsistent functional outcomes, especially when prostheses are integrated with physical therapeutic agents, and thus warrants careful investigation. This review explores the effectiveness of nerve prostheses for bridging large nerve gaps and then addresses their use in combination with physical therapeutic agents.

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

Circadian rhythm (CR) plays a critical role in the treatment of several diseases. However, the role of CR in the treatment of peripheral nerve defects has not been studied. It is also known that the pulsed electromagnetic fields (PEMF) can provide a beneficial microenvironment to quicken the process of nerve regeneration and to enhance the quality of reconstruction. In this study, we evaluate the impact of CR on the promoting effect of PEMF on peripheral nerve regeneration in rats. We used the self-made “collagen-chitosan” nerve conduits to bridge the 15-mm nerve gaps in Sprague-Dawley rats. Our results show that PEMF stimulation at daytime (DPEMF) has most effective outcome on nerve regeneration and rats with DPEMF treatment achieve quickly functional recovery after 12 weeks. These findings indicate that CR is an important factor that determines the promoting effect of PEMF on peripheral nerve regeneration. PEMF exposure in the daytime enhances the functional recovery of rats. Our study provides a helpful guideline for the effective use of PEMF mediations experimentally and clinically.

Low frequency pulsed electromagnetic field promotes C2C12 myoblasts proliferation via activation of MAPK/ERK pathway

Low frequency pulsed electromagnetic field (PEMF) has been shown to affect the activity of various cell types and promote them proliferation. However, its effect on skeletal muscle cells remains to be determined. In our study, we confirmed that PEMF (100 Hz, 1 mT) could promote C2C12 myoblasts proliferation by using Cell Counting Kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) assays, yet hardly any distinction was found in the rate of cell apoptosis between PEMF and control groups by flow cytometry (Annexin V-FITC/PI double staining method). To further study the mechanism of action of PEMF, Western blot was utilized to detect the mitogen-activated protein kinase (MAPK) signaling pathways. After exposing C2C12 myoblasts to PEMF, we found the phosphorylation level of extracellular signal-regulated kinase (ERK) was significantly increased, while p38 MAPK and c-Jun N-terminal kinase (JNK) pathways were not affected. Pretreating the cells with the ERK kinase1/2 (MEK1/2) inhibitor U0126 obviously inhibited the proliferation of C2C12 cells. Taken together, our research for the first time demonstrated that PEMF promoted C2C12 myoblasts proliferation via activating MAPK/ERK pathway.

Degradation characteristics, cell viability and host tissue responses of PDLLA-based scaffold with PRGD and β-TCP nanoparticles incorporation

This study is aimed to evaluate the degradation characteristics, cell viability and host tissue responses of PDLLA/PRGD/β-TCP (PRT) composite nerve scaffold, which was fabricated by poly(d, l-lactic acid) (PDLLA), RGD peptide(Gly-Arg-Gly-Asp-Tyr, GRGDY, abbreviated as RGD) modified poly-{(lactic acid)-co-[(glycolic acid)-alt-(l-lysine)]}(PRGD) and β-tricalcium phosphate (β-TCP). The scaffolds’ in vitro degradation behaviors were investigated in detail by analysing changes in weight loss, pH and morphology. Then, the 3-(4,5-dimethyl-2-thiazolyl) -2,5-diphenyl-2 -H-tetrazolium bromide (MTT) assay and cell live/dead assay were carried out to assess their cell viability. Moreover, in vivo degradation patterns and host inflammation responses were monitored by subcutaneous implantation of PRT scaffold in rats. Our data showed that, among the tested scaffolds, the PRT scaffold had the best buffering capacity (pH = 6.1–6.3) and fastest degradation rate (12.4%, 8 weeks) during in vitro study, which was contributed by the incorporation of β-TCP nanoparticles. After in vitro and in vivo degradation, the high porosity structure of PRT could be observed using scanning electron microscopy. Meanwhile, the PRT scaffold could significantly promote cell survival. In the PRT scaffold implantation region, less inflammatory cells (especially for neutrophil and lymphocyte) could be detected. These results indicated that the PRT composite scaffold had a good biodegradable property; it could improve cells survival and reduced the adverse host tissue inflammation responses.

Controversies related to electromagnetic field exposure on peripheral nerves

Electromagnetic field (EMF) is a pervasive environmental presence in modern society. In recent years, mobile phone usage has increased rapidly throughout the world. As mobile phones are generally held close to the head while talking, studies have mostly focused on the central and peripheral nervous system. There is a need for further research to ascertain the real effect of EMF exposure on the nervous system. Several studies have clearly demonstrated that EMF emitted by cell phones could affect the systems of the body as well as functions. However, the adverse effects of EMF emitted by mobile phones on the peripheral nerves are still controversial. Therefore, this review summarizes current knowledge on the possible positive or negative effects of electromagnetic field on peripheral nerves.