Far-Infrared Therapy Promotes Nerve Repair following End-to-End Neurorrhaphy in Rat Models of Sciatic Nerve Injury

Advancements in stimulation therapies for peripheral nerve regeneration

Soft-tissue injuries affecting muscles, nerves, vasculature, tendons, and ligaments often diminish the quality of life due to pain, loss of function, and financial burdens. Both natural healing and surgical interventions can result in scarring, which potentially may impede functional recovery and lead to persistent pain. Scar tissue, characterized by a highly disorganized fibrotic extracellular matrix, may serve as a physical barrier to regeneration and drug delivery. While approaches such as drugs, biomaterials, cells, external stimulation, and other physical forces show promise in mitigating scarring and promoting regenerative healing, their implementation remains limited and challenging. Ultrasound, laser, electrical, and magnetic forms of external stimulation have been utilized to promote soft tissue as well as neural tissue regeneration. After stimulation, neural tissues experience increased proliferation of Schwann cells, secretion of neurotropic factors, production of myelin, and growth of vasculature, all aimed at supporting axon regeneration and innervation. Yet, the outcomes of healing vary depending on the pathophysiology of the damaged nerve, the timing of stimulation following injury, and the specific parameters of stimulation employed. Increased treatment intensity and duration have been noted to hinder the healing process by inducing tissue damage. These stimulation modalities, either alone or in combination with nerve guidance conduits and scaffolds, have been demonstrated to promote healing. However, the literature currently lacks a detailed understanding of the stimulation parameters used for nerve healing applications. In this article, we aim to address this gap by summarizing existing reports and providing an overview of stimulation parameters alongside their associated healing outcomes.

Outcomes of Sciatic Nerve Injury Repairs: A Systematic Review

Background

The objective of this study was to investigate the surgical repair techniques and the outcomes of sciatic nerve injuries in traumatic wounds.

Methods

A literature search was conducted using the following keywords:sciatic, nerve, repair, technique, conduit, graft, reconstruction, outcome, rehabilitation, recovery, function, surgery, and NOT anesthesia.

Results

In total, 715 studies were retrieved. After abstract review, 13 articles fit the criteria. A total of 2627 repairs were carried out, including nerve grafts (n = 953), suture (n = 482), and neurolysis (n = 1192). Six studies reported good motor outcome, and good sensory outcome was reported across 2 studies. The thigh region accounted for 81.5% of lesions. Sciatic, peroneal, and tibial nerves were all equally affected. Gunshot wounds were the most common mechanism of injury (22.6%).

Conclusions

The cumulative evidence demonstrates sciatic nerve injury repair has poor motor and sensory outcomes. This study shows there is a lack of standardized outcome measures, making comparisons very difficult. Graft lengths of <4 cm within the intermediate region yielded more successful outcomes. Further higher quality studies of nerve transfers in the lower limbs are needed to determine the optimal repair to restore sciatic nerve function.

THz-PCR Based on Resonant Coupling between Middle Infrared and DNA Carbonyl Vibrations

The carbonyl groups of deoxyribonucleotide can resonantly couple with 53 THz middle infrared, which can highly transmit water without ionization-based damage to DNA molecules. Herein, we predict that vibrational coupling with THz irradiation could lower down the hybridization landscape of nucleic acids and thus affect DNA replication. Using polymerase chain reaction (PCR) as a measure, we found that THz shining can reduce the denature temperature of DNA duplexes by about 3 °C, which allows one to conduct PCR at lower temperature, facilitating long-time amplification reaction without losing enzymatic fidelity, i.e., normal PCR should be carried out at denaturing temperature ∼4 °C higher than the melting temperature (T_m), but THz-PCR only requires temperature ∼1 °C higher than T_m due to the nonthermal effect of THz shining. Moreover, the melting time can also be shortened to 1/5 due to the enhanced vibration coupling with 53 THz irradiation. We proposed THz-PCR as an innovated DNA amplification technique with ultrahigh specificity and sensitivity and also successfully demonstrated its advantages in forensic detections.

Far-Infrared Therapy Decreases Orthotopic Allograft Transplantation Vasculopathy

Orthotopic allograft transplantation (OAT) is a major strategy for solid heart and kidney failure. However, the recipient’s immunity-induced chronic rejection induces OAT vasculopathy that results in donor organ failure. With the exception of immunosuppressive agents, there are currently no specific means to inhibit the occurrence of OAT vasculopathy. On the other hand, far-infrared (FIR) therapy uses low-power electromagnetic waves given by FIR, with a wavelength of 3–25 μm, to improve human physiological functions. Previous studies have shown that FIR therapy can effectively inhibit inflammation. It has also been widely used in adjuvant therapy for various clinical diseases, especially cardiovascular diseases, in recent years. Thus, we used this study to explore the feasibility of FIR in preventing OAT vasculopathy. In this study, the model of transplantation of an aorta graft from PVG/Seac rat to ACI/NKyo rat, and in vitro model of human endothelial progenitor cells (EPCs) was used. In this report, we presented that FIR therapy decreased the serious of vasculopathy in OAT-recipient ACI/NKyo rats via inhibiting proliferation of smooth muscle cells, accumulation of collagen, and infiltration of fibroblast in the vessel wall; humoral and cell-mediated immune responses were decreased in the spleen. The production of inflammatory proteins/cytokines also decreased in the plasma. Additionally, FIR therapy presented higher mobilization and circulating EPC levels associated with vessel repair in OAT-recipient ACI/NKyo rats. In vitro studies demonstrated that the underlying mechanisms of FIR therapy inhibiting OAT vasculopathy may be associated with the inhibition of the Smad2-Slug axis endothelial mesenchymal transition (EndoMT). Thus, FIR therapy may be the strategy to prevent chronic rejection-induced vasculopathy.

Is Decorin a Promising New Agent for Facial Nerve Regeneration? An Experimental Study

OBJECTIVE

The aim of this study was to investigate the effects of systemic administration of decorin (DC) on facial nerve (FN) regeneration.

METHODS

A total of 32 female albino Wistar rats were divided into 4 groups: control (C) group: no bilateral FN neurorrhaphy (B-FNN), no DC application, sham-operated group: B-FNN without DC application, DC group: DC application without B-FNN, and B-FNN + DC group: B-FNN and DC application. Nerve conduction studies were performed before and after skin incisions at 1st, 3rd, 5th, and 7th weeks in all groups. The amplitude and latency of compound muscle action potentials were recorded. FN samples were obtained and were investigated under light microscopy and immunohistochemical staining. The nerve and axon diameter, number of axons, H score, Schwann cell proliferation, and myelin and axonal degeneration were recorded quantitatively.

RESULTS

In the sham group, the 3rd and 5th postoperative week, amplitude values were significantly lower than those of the B-FNN + DC group (p < 0.05). Nerve diameters were found to be significantly larger in the sham, DC, and B-FNN + DC groups than in the C group (p < 0.05). The number of axons, the axon diameter, and the H scores were found to be significantly higher in the B-FNN + DC group than in the sham group (p < 0.05). The Schwann cell proliferation, myelin degeneration, and axonal degeneration scores were significantly lower in the B-FNN + DC group than in the sham group (p < 0.05).

CONCLUSION

Electrophysiological and histopathological evaluation revealed the potential benefits provided by DC. This agent may increase FN regeneration.

Platelet-rich plasma can release nutrient factors to promote facial nerve crush injury recovery in rats

To evaluate the effects of platelet-rich plasma (PRP) on promoting neural repair after facial nerve compression in rats and the mechanism by which this occurs.  Methods: Adult Wistar rats (n=100) were divided into 3 groups: healthy controls, surgery-only, and surgery+PRP groups. The rats underwent nerve crush injury to establish a facial palsy model. The blood from the rats was used to prepare the PRP for application to the injury site. The evaluation methods included vibrissae movement, eyelid closure, and electrophysiology. Electron microscopy, immunohistochemistry, and real-time polymerase chain reaction (PCR) were used to detect nutrient factor expression in the brain and nerve sections. This study was conducted in Shandong Provincial ENT Hospital Affiliated to Shandong University,  Shandong, China between January and November 2018.  Results: Platelet-rich plasma promotes the recovery of vibrissae movement, eyelid closure, and electrophysiological function in a rat model of nerve crush injury. Hematoxylin and eosin staining, toluidine blue staining, and electron microscopy showed significant recovery of Schwann cells and axons in the PRP group. Polymerase chain reaction results showed that PRP releases growth factors, which include nerve growth factor and brain-derived neurotrophic factor. Immunohistochemistry also demonstrated higher levels of S-100 protein expression in the PRP group compared to the other groups.  Conclusions: Platelet-rich plasma releases nutrient factors in the brainstem, and the use of PRP can promote injury recovery.

Effect of intensive inpatient physical therapy on whole-body indefinite symptoms in patients with whiplash-associated disorders

BACKGROUND

A considerable number of patients with whiplash-associated disorders (WAD) report variable and indefinite symptoms involving the whole body, despite there being no evidence of direct injuries to organs other than the neck. However, little is known about their management or underlying mechanism. This study examined the effect of intensive physical therapy at the cervical muscles in patients with WAD reporting whole-body indefinite symptoms.

METHODS

A total of 194 hospitalized patients with WAD who were resistant to outpatient care by reporting whole-body indefinite symptoms between May 2006 and May 2017 were enrolled in this observational study. All patients underwent daily physical therapies by low-frequency electric stimulation therapy and far-infrared irradiation to the cervical muscles during hospitalization. Self-rated records in the medical interview sheets on 22 representative whole-body symptoms at admission and discharge were compared.

RESULTS

The number of symptoms was markedly decreased by the physical therapies during hospitalization. Almost all symptoms showed recovery rates of more than 80% at discharge as compared to those at admission. Although the percentage of patients reporting at least four of the 22 representative indefinite symptoms was 99.0% at admission, it decreased to 7.7% at discharge. Sixteen percent of patients recovered completely without any residual symptoms. The mean number of symptoms significantly decreased from 13.1 at admission to 2.0 at discharge. Notably, symptoms other than those in the neck or shoulder recovered to a greater extent than those in the neck or shoulder.

CONCLUSIONS

This study, for the first time, examined the management of whole-body indefinite symptoms in patients with WAD. The intensive physical therapy markedly improved the symptoms, suggesting the involvement of cervical muscles in the pathogenesis.

TRIAL REGISTRATION

UMIN000035435 (Retrospectively registered on Jan 3, 2019).

Dihydrotestosterone Treatment Accelerates Autograft Reversal Sciatic Nerve Regeneration in Rats

Neuroactive steroids such as progesterone, testosterone, and their derivatives have been widely studied for their neuroprotective roles in the nervous system. Autologous nerve transplantation is considered as the gold standard repair technique when primary suture is impossible; nevertheless, this method is far from ideal. In this study, we aimed to explore the impact of dihydrotestosterone (DHT), a 5α-reduced derivative of testosterone, on the recovery of peripheral nerve injury treated with autologous nerve transplantation. Sprague-Dawley rats were subjected to a 10-mm right side sciatic nerve reversed autologous nerve transplantation and randomly divided into groups that received DHT or DHT + flutamide (an androgen receptor blocker) daily for 8 weeks after operation. Our results demonstrated that DHT could speed up the rate of axonal regeneration and increase the expression of myelin protein zero (P0) in autograft reversal sciatic nerves. Thus, our study provided new insights into improving the prognosis of patients with long gap peripheral nerve defects.

Effect of electrical stimulation on motor nerve regeneration in sciatic nerve ligated-mice

The purpose of this study was to investigate the effect of electrical stimulation on sciatic nerve regeneration and functional recovery of target muscles. Mice were randomly divided into 3 groups: ligated without electrical stimulation, ligated with electrical stimulation and control (non-ligated). The unilateral peripheral mononeuropathy was produced on the right hind limb. Sciatic nerve was then electrically stimulated daily for a period of 2 weeks (duration: 0.2 msec, frequency: 100Hz, amplitude: 15mA). Evoked surface EMG was recorded from biceps femoris (BF) and gluteus maximus (GM) muscles on the 3rd, 7th, 10th and 14th day after sciatic nerve ligation. Muscle force and sensitivity was determined by processing of the recorded EMG signals in time and frequency domains respectively. The results showed electrical stimulation (ES) produced a significant increase in the EMG response of BF, and muscle force significantly increased on the 14th day (p<0.001), however no significant difference was found in GM muscle force between experimental groups. This may be due to possible innervation by inferior gluteal nerve. Frequency analysis of BF signals indicates that hyperalgesia remained after 14 days in both ligated groups. On the 14th day no difference in GM muscle sensitivity was found between groups. In conclusion, the results of this study have shown that the electrical stimulation of sciatic nerve accelerates nerve repair and indirectly improves BF muscle force to a comparable level with control without effect on muscle sensitivity. However, ES had no effect on GM muscle force and sensitivity.

Far-infrared radiation protects viability in a cell model of Spinocerebellar Ataxia by preventing polyQ protein accumulation and improving mitochondrial function

Far infrared radiation (FIR) is currently investigated as a potential therapeutic strategy in various diseases though the mechanism is unknown. Presently, we tested if FIR mediates beneficial effects in a cell model of the neurodegenerative disease spinocerebellar ataxia type 3 (SCA3). SCA3 is caused by a mutation leading to an abnormal polyglutamine expansion (PolyQ) in ataxin-3 protein. The consequent aggregation of mutant ataxin-3 results in disruption of vital cell functions. In this study, neuroblastoma cells (SK-N-SH) was transduced to express either non-pathogenic ataxin-3-26Q or pathogenic ataxin-3-78Q proteins. The cells expressing ataxin-3-78Q demonstrated decreased viability, and increased sensitivity to metabolic stress in the presence rotenone, an inhibitor of mitochondrial respiration. FIR exposure was found to protect against these effects. Moreover, FIR improved mitochondrial respiratory function, which was significantly compromised in ataxin-3-78Q and ataxin-3-26Q expressing cells. This was accompanied by decreased levels of mitochondrial fragmentation in FIR treated cells, as observed by fluorescence microscopy and protein expression analysis. Finally, the expression profile LC3-II, Beclin-1 and p62 suggested that FIR prevent the autophagy inhibiting effects observed in ataxin-3-78Q expressing cells. In summary, our results suggest that FIR have rescuing effects in cells expressing mutated pathogenic ataxin-3, through recovery of mitochondrial function and autophagy.