Light promotes regeneration and functional recovery and alters the immune response after spinal cord injury

Photobiomodulation After Neurotization (Oberlin Procedure) in Brachial Plexus Injury: A Randomized Control Trial

Objective: To investigate effect of photobiomodulation (PBM) on nerve regeneration after neurotization with the Oberlin Procedure (ulnar fascicle to motor branch to biceps) to restore elbow flexion in patients with brachial plexus injury. Materials and methods: This prospective randomized controlled trial was conducted with 14 patients with high brachial plexus injury who underwent neurotization with the Oberlin Procedure to restore elbow flexion. The patients were randomly allocated to two groups of equal numbers: control group and PBM group. In this study, the PBM used has a wavelength of 808 nm, 50 mW power, continuous mode emission, 4 J/cm² dosimetry, administered daily for 10 consecutive days, with an interval of 2 days (weekends). The outcome of surgery was assessed after 1, 2, 3, and 6 months. The nonparametric Mann-Whitney U-test and chi-square test were utilized to compare the results between both groups. Results: After 3 months postoperatively, more patients in the PBM group had demonstrated signs of reinnervation and the mean muscle power was significantly higher in the PBM group. No adverse effects resulted from the administration of PBM. Conclusions: PBM is a treatment modality that can improve nerve regeneration after neurotization with the Oberlin Procedure.

Clinical Efficacy of Photobiomodulation on Dental Implant Osseointegration: A Systematic Review

Background:

Photobiomodulation (PBM) has been shown to have a positive effect on dental implant osseointegration and stability in in vitro and animal studies; however, its usefulness in dental implant clinical practice is yet unclear.

Objective:

The objective was to assess the clinical effectiveness of PBM on dental implants’ osseointegration.

Methods:

Two reviewers independently conducted a comprehensive electronic search of articles published from inception up to January 10, 2020, in PubMed, Cochrane Library and Embase databases following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Randomized clinical trials (RCTs) and nonrandomized clinical studies that compared the effect of PBM on dental implant stability with control groups were included. Animals and in vitro studies studies as well as studies with confounders such as application of orthodontic were excluded. Risk of bias (using Cochrane Risk of Bias tool for RCTs and Risk of Bias in Non-Randomized Studies of Interventions tool for nonrandomized studies) was assessed by both authors. Owing to substantial heterogeneity, only a narrative synthesis of the included studies is presented.

Results:

Seven relevant clinical studies were included, and they used a variety of PBM parameters and devices. The posterior region of the jaw was found to be more frequently evaluated. For assessing the effect of PBM on implant stability, five studies used resonance frequency analysis and two used periotest; three studies additionally used biomarkers for assessment. Four studies found that PBM has a potential positive effect on the outcome of dental implant stability, whereas three studies reported that PBM has no effect on implant stability.

Conclusion:

The findings of this systematic review suggest that postoperative application of PBM may potentially have some positive effect on dental implant’s osseointegration and stability. However, additional studies are required with uniformity in methods to provide a more robust assessment of this effect.

Mitochondrial Dysfunction and Parkinson's Disease-Near-Infrared Photobiomodulation as a Potential Therapeutic Strategy

As the main driver of energy production in eukaryotes, mitochondria are invariably implicated in disorders of cellular bioenergetics. Given that dopaminergic neurons affected in Parkinson's disease (PD) are particularly susceptible to energy fluctuations by their high basal energy demand, it is not surprising to note that mitochondrial dysfunction has emerged as a compelling candidate underlying PD. A recent approach towards forestalling dopaminergic neurodegeneration in PD involves near-infrared (NIR) photobiomodulation (PBM), which is thought to enhance mitochondrial function of stimulated cells through augmenting the activity of cytochrome C oxidase. Notwithstanding this, our understanding of the neuroprotective mechanism of PBM remains far from complete. For example, studies focusing on the effects of PBM on gene transcription are limited, and the mechanism through which PBM exerts its effects on distant sites (i.e., its "abscopal effect") remains unclear. Also, the clinical application of NIR in PD proves to be challenging. Efficacious delivery of NIR light to the substantia nigra pars compacta (SNpc), the primary site of disease pathology in PD, is fraught with technical challenges. Concerted efforts focused on understanding the biological effects of PBM and improving the efficiency of intracranial NIR delivery are therefore essential for its successful clinical translation. Nonetheless, PBM represents a potential novel therapy for PD. In this review, we provide an update on the role of mitochondrial dysfunction in PD and how PBM may help mitigate the neurodegenerative process. We also discussed clinical translation aspects of this treatment modality using intracranially implanted NIR delivery devices.

Photobiomodulation by diffusing optical fiber on spinal cord: A feasibility study in piglet model

Previous studies on spinal cord injury (SCI) have confirmed that percutaneous photobiomodulation (PBM) therapy can ameliorate immunoinflammatory responses at sites of injury, accelerate nerve regeneration, suppress glial scar formation and promote the subsequent recovery of locomotor function. The current study was performed to evaluate a large-animal model employing implanted optical fibers to accurately irradiate targeted spinal segments. The method's feasibility and irradiation parameters that do not cause phototoxic reaction were determined, and the methodology of irradiating the spinal cord with near-infrared light was investigated in detail. A diffusing optical fiber was implanted above the T9 spinal cord of Bama miniature pigs and used to transfer near-infrared light (810 nm) onto the spinal cord surface. After daily irradiation with 200, 300, 500 or 1000 mW for 14 days, both sides of the irradiated area of the spinal cord were assessed for temperature changes. The condition of the spinal cord and the position of optical fiber were investigated by magnetic resonance imaging (MRI), and different parameters indicating temperature increases or phototoxicity were measured on the normal spinal cord surface due to light irradiation (ie, heat shock responses, inflammatory reactions and neuronal apoptosis), and the animals' lower-limb neurological function and gait were assessed during the irradiation process. The implanted device was stable inside the freely moving animals, and light energy could be directly projected onto the spinal cord surface. The screening of different irradiation parameters preliminary showed that direct irradiation onto the spinal cord surface at 200 and 300 mW did not significantly increase the temperature, stress responses, inflammatory reactions and neural apoptosis, whereas irradiation at 500 mW slightly increased these parameters, and irradiation at 1000 mW induced a significant temperature increase, heat shock, inflammation and apoptosis responses. HE staining of spinal cord tissue sections did not reveal any significant structural changes of the tissues compared to the control group, and the neurological function and gait of all irradiated animals were normal. In this study, we established an in-vivo optical fiber implantation method, which might be safe and stable and could be used to directly project light energy onto the spinal cord surface. This study might provide a new perspective for clinical applications of PBM in acute SCI.

Photobiomodulation Mediates Neuroprotection against Blue Light Induced Retinal Photoreceptor Degeneration

Potent neuroprotective effects of photobiomodulation with 670 nm red light (RL) have been demonstrated in several models of retinal disease. RL improves mitochondrial metabolism, reduces retinal inflammation and oxidative cell stress, showing its ability to enhance visual function. However, the current knowledge is limited to the main hypothesis that the respiratory chain complex IV, cytochrome c oxidase, serves as the primary target of RL. Here, we demonstrate a comprehensive cellular, molecular, and functional characterization of neuroprotective effects of 670 nm RL and 810 nm near-infrared light (NIRL) on blue light damaged murine primary photoreceptors. We show that respiratory chain complexes I and II are additional PBM targets, besides complex IV, leading to enhanced mitochondrial energy metabolism. Accordingly, our study identified mitochondria related RL- and NIRL-triggered defense mechanisms promoting photoreceptor neuroprotection. The observed improvement of mitochondrial and extramitochondrial respiration in both inner and outer segments is linked with reduced oxidative stress including its cellular consequences and reduced mitochondria-induced apoptosis. Analysis of regulatory mechanisms using gene expression analysis identified upregulation α-crystallins that indicate enhanced production of proteins with protective functions that point to the rescued mitochondrial function. The results support the hypothesis that energy metabolism is a major target for retinal light therapy.

The influence of educational measures and low-level laser phototherapy on temporomandibular disorders: Study protocol clinical trial (SPIRIT Compliant)

Photobiomodulation therapy (PBMT) with low-power laser is used for pain relief in several clinical conditions, including temporomandibular disorders (TMD). As musculoskeletal pain often produces changes in motor behavior, it is common for patients with TMD to present limited mandibular movements. To the date, there is no consensus about the optimal dosimetric parameters of PMBT for TMD. This randomized, controlled, double-blind clinical trial aims to evaluate pain relief and mandibular mobility in patients with TMD following treatments with 2 laser wavelengths, red (660 nm) and infrared (808 nm) individually and in combination as compared to a placebo treatment. One-hundred participants presenting myalgia and arthralgia, with disk displacement or not, will be selected based on the Research Diagnostic Criteria for Temporomandibular Disorders. All participants will be instructed about the etiology, prognosis, and self-care techniques for pain control on TMD, and followed up for 2 weeks. After this period, those who still present pain score over 4 in a visual analog scale (VAS) will be included in the study. Participants will be randomly assigned to 4 treatment groups: G1 = placebo (SHAM); G2 = PBMT with red laser (660 nm, 0.034 cm, 88 J/cm, 100 mW, 3 J/point); G3 = PBMT with infrared laser (808 nm, 0.034 cm, 88 J/cm, 100 mW, 3 J/point); and G4 = PBMT with red and infrared laser alternated between sessions. The treatment consists of 8 sessions, 2 times a week. The effect of the proposed therapies will be measured by: pain reduction in VAS; pressure pain threshold on TMJ, masseter and temporal muscles; and the amplitude of mandibular movements (opening, protrusion, and right and left lateral movements). The data will be collected at the following times: initial (T1), after the 1st treatment session (T2), at the end of treatment (T3), and 30 days after the last PBMT session (T4). For statistical analysis will be used 2-way repeated measures analysis of variance test, complemented by a post hoc Tukey test (P < .05).

Attenuation of the inflammatory response and polarization of macrophages by photobiomodulation

In spinal cord injury (SCI), inflammation is a major mediator of damage and loss of function and is regulated primarily by the bone marrow-derived macrophages (BMDMs). Photobiomodulation (PBM) or low-level light stimulation is known to have anti-inflammatory effects and has previously been used in the treatment of SCI, although its precise cellular mechanisms remain unclear. In the present study, the effect of PBM at 810 nm on classically activated BMDMs was evaluated to investigate the mechanisms underlying its anti-inflammatory effects. BMDMs were cultured and irradiated (810 nm, 2 mW/cm²) following stimulation with lipopolysaccharide and interferon-γ. CCK-8 assay, 2',7'-dichlorofluorescein diacetate assay, and ELISA and western blot analysis were performed to measure cell viability, reactive oxygen species production, and inflammatory marker production, respectively. PBM irradiation of classically activated macrophages significantly increased the cell viability and inhibited reactive oxygen species generation. PBM suppressed the expression of a marker of classically activated macrophages, inducible nitric oxide synthase; decreased the mRNA expression and secretion of pro-inflammatory cytokines, tumor necrosis factor alpha, and interleukin-1 beta; and increased the secretion of monocyte chemotactic protein 1. Exposure to PBM likewise significantly reduced the expression and phosphorylation of NF-κB p65 in classically activated BMDMs. Taken together, these results suggest that PBM can successfully modulate inflammation and polarization in classically activated BMDMs. The present study provides a theoretical basis to support wider clinical application of PBM in the treatment of SCI.

Lanthanide nanoparticles with efficient near-infrared-II emission for biological applications

We discuss designing efficient NIR-II-emitting lanthanide NPs and summarize their recent progress in bioimaging, therapy, and biosensing, as well as their limitations and future opportunities.

Raman spectroscopy of dorsal root ganglia from streptozotocin-induced diabetic neuropathic rats submitted to photobiomodulation therapy

In this study, we used Raman spectroscopy as a new tool to investigate pathological conditions at the level of chemical bond alterations in biological tissues. Currently, there have been no reports on the spectroscopic alterations caused by diabetic neuropathy in the dorsal root ganglia (DRG). DRG are a target for the treatment of neuropathic pain, and the need for more effective therapies is increasing. Photobiomodulation therapy (PBMT) through infrared low-level laser irradiation (904 nm) has shown analgesic effects on the treatment of neuropathy. Thus, the aim of this study was to use Raman spectroscopy to characterize the spectral DRG identities of streptozotocin (STZ)-induced diabetic neuropathic (hyperalgesic) rats and to study the influence of PBMT over such spectra. Characteristic DRG peaks were identified at 2704, 2850, 2885, 2940, 3061 and 3160 cm^-1 , whose assignments are CH₂ /CH₃ symmetric/asymmetric stretches, and C─H vibrations of lipids and proteins. DRG from hyperalgesic rats showed an increased normalized intensity of 2704, 2850, 2885 and 3160 cm^-1 . These same peaks had their normalized intensity reduced after PBMT treatment, accompanied by an anti-hyperalgesic effect. Raman spectroscopy was able to diagnose spectral alterations in DRG of hyperalgesic rats and the PBMT reduced the intensity of hyperalgesia and the altered Raman spectra.

Functionalized theranostic nanocarriers with bio-inspired polydopamine for tumor imaging and chemo-photothermal therapy

Nanocarriers sensitive to near infrared light (NIR) are useful templates for chemo-photothermal therapy (PTT) and imaging of tumors due to the ability to change the absorbed NIR energy to heat. The conventional photo-absorbing reagents lack the efficient loading and release of drug before reaching the target site leading to insufficient therapeutic outcomes. To overcome these limitations, the surface of nanocarriers can be modified with different polymers with wide functionalities to provide systems with diagnostic, therapeutic, and theranostic capabilities. Among various polymers, polydopamine (PDA) has been more interested due to complex structure with various chemical moieties, and the capacity to be used through different coating mechanism. In this review, we describe the complex structure, chemical properties, and coating mechanisms of PDA. Moreover, the advantage and surface modification of some relevant nanosystems based on carbon materials, gold, iron oxide, manganese, and upconverting nanomaterials by using PDA will be discussed, in detail.

Sex, but not skin tone affects penetration of red-light (660 nm) through sites susceptible to sports injury in lean live and cadaveric tissues

Red-light treatment is emerging as a novel therapy for promoting tissue recovery but data on red-light penetration through human tissues are lacking. We aimed to: (1) determine the effect of light irradiance, tissue thickness, skin tone, sex and bone/muscle content on 660 nm light penetration through common sites of sports injuries, and (2) establish if cadaver tissues serve as a useful model for predicting red-light penetration in live tissues. Live and cadaver human tissues were exposed to 660 nm light at locations across the skull, spinal cord and upper and lower limbs. Red-light was produced by a light emitting diode array of various irradiances (15-500 mW/cm² ) and measured by a light-probe positioned on the tissue surface opposite to the light emitting diodes. 100 mW/cm² successfully penetrated tissue <50 mm thick; a disproportionate irradiance increase was required to achieve deeper penetration. Penetration was unaffected by skin tone, increased with irradiance and relative bone/muscle composition, and decreased with greater tissue thickness and in males. Live and cadaveric tissue penetration did not differ statistically for tissues <50 mm but cadavers required more red-light to penetrate >50 mm. These results assist clinicians and researchers in determining red-light treatment intensities for penetrating human tissues.

Evaluation of the Effects of Low-Level Laser Therapy on Diabetic Bone Healing

The aim of the present study was to evaluate the effects of low-level laser therapy (LLLT) and biphasic alloplastic bone graft material on diabetic bone healing. Induction of diabetes was performed in 14 male Sprague-Dawley rats by intraperitoneal injection of a 50 mg/kg dose of streptozotocin. Two bilaterally symmetrical non-critical-sized bone defects were created in the parietal bones in each rat. Right defects were filled with biphasic alloplastic bone graft. Rats were randomly divided into 2 groups, with 1 group receiving 10 sessions of LLLT (GaAlAs, 78.5 J/cm, 100mW, 0.028 cm beam). The LLLT was started immediately after surgery and once every 3 days during postoperative period. At the end of treatment period, new bone formation and osteoblast density were determined using histomorphometry. Empty (control), graft-filled, LLLT-treated and both graft-filled and LLLT-treated bone defects were compared. New bone formation was higher in the graft treatment samples compared with the control (P = 0.009) and laser samples (P = 0.029). In addition, graft-laser combination treatment samples revealed higher bone formation than control (P = 0.008) and laser (P = 0.026) samples. Osteoblast density was significantly higher in the laser treatment (P <0.001), graft treatment (P = 0.001) and graft-laser combination treatment (P <0.001) samples than control samples. In addition, significantly higher osteoblast density was observed in the graft-laser combination treatment samples compared to the graft treatment samples (P = 0.005). The LLLT was effective to stimulate osteoblastogenesis but failed to increase bone formation. Graft augmentation for treatment of bone defects seems essential for proper bone healing in diabetes, regeneration may be supported by the LLLT to enhance osteoblastogenesis.

Applications of photobiomodulation in hearing research: from bench to clinic

Hearing loss is very common and economically burdensome. No accepted therapeutic modality for sensorineural hearing loss is yet available; most clinicians emphasize rehabilitation, placing hearing aids and cochlear implants. Photobiomodulation (PBM) employs light energy to enhance or modulate the activities of specific organs, and is a popular non-invasive therapy used to treat skin lesions and neurodegenerative disorders. Efforts to use PBM to improve hearing have been ongoing for several decades. Initial in vitro studies using cell lines and ex vivo culture techniques have now been supplanted by in vivo studies in animals; PBM protects the sensory epithelium and triggers neural regeneration. Many reports have used PBM to treat tinnitus. In this brief review, we introduce PBM applications in hearing research, helpful protocols, and relevant background literature.

The effect of 808 nm and 905 nm wavelength light on recovery after spinal cord injury

We investigated the effect of a Multiwave Locked System laser (with a simultaneous 808 nm continuous emission and 905 nm pulse emission) on the spinal cord after spinal cord injury (SCI) in rats. The functional recovery was measured by locomotor tests (BBB, Beam walking, MotoRater) and a sensitivity test (Plantar test). The locomotor tests showed a significant improvement of the locomotor functions of the rats after laser treatment from the first week following lesioning, compared to the controls. The laser treatment significantly diminished thermal hyperalgesia after SCI as measured by the Plantar test. The atrophy of the soleus muscle was reduced in the laser treated rats. The histopathological investigation showed a positive effect of the laser therapy on white and gray matter sparing. Our data suggests an upregulation of M2 macrophages in laser treated animals by the increasing number of double labeled CD68+/CD206+ cells in the cranial and central parts of the lesion, compared to the control animals. A shift in microglial/macrophage polarization was confirmed by gene expression analysis by significant mRNA downregulation of Cd86 (marker of inflammatory M1), and non-significant upregulation of Arg1 (marker of M2). These results demonstrated that the combination of 808 nm and 905 nm wavelength light is a promising non-invasive therapy for improving functional recovery and tissue sparing after SCI.

Efficacy of low-level laser therapy in pain management after root canal treatment or retreatment: a systematic review

The aim of this study was to assess the effectiveness of low-level laser therapy (LLLT) for pain management after root canal treatment or retreatment. An electronic search for randomized controlled trials was conducted prior to November 2018, through PubMed, EMBASE, the Cochrane library (CENTRAL), and Web of Science. After filtering, seven articles were included, five related to root canal therapy (RCT) and two related to root canal retreatment (RCR). Six of the included studies presented a moderate risk of bias and a one low risk of bias, based on the Cochrane tool of risk of bias evaluation. The laser treatment included diode laser and indium-gallium-aluminum laser. LLLT was compared with placebo, blank, and ibuprofen treatment. Clinical outcome variables included the prevalence of pain, pain intensity, and need for analgesics after treatment. Three studies showed LLLT could reduce the prevalence of pain significantly after RCT or RCR. Although the effect of LLLT on pain intensity varied at different observation time points and among different studies, most of them found patients had lower pain intensity in the LLLT group. Of the three studies that assessed the need for analgesics after treatment, two studies showed significant benefits. Based on the current evidence, the use of LLLT for pain control in postendodontic therapy may be promising. However, solid conclusions should not be drawn definitely, given that more high-quality randomized controlled trials are required to further evaluate the efficacy of LLLT for pain management after RCT and RCR.

Transcutaneous transmission of photobiomodulation light to the spinal canal of dog as measured from cadaver dogs using a multi-channel intra-spinal probe

The target level photobiomodulation (PBM) irradiances along the thoracic to lumbar segment of the interior spinal canal in six cadaver dogs resulting from surface illumination at 980 nm were measured. Following a lateral hemi-laminectomy, a flexible probe fabricated on a plastic tubular substrate of 6.325 mm diameter incorporating nine miniature photodetectors was embedded in the thoracic to lumbar segment of the spinal canal. Intra-spinal irradiances at the nine photodetector sites, spanning an approximate 8 cm length caudal to T13, were measured for various applied powers of continuous wave (CW) surface illumination at 980 nm with a maximal power of 10 W corresponding to a surface irradiance of 3.14 W/cm². The surface illumination conditions differed in skin transmission when the probe was off-contact with tissue and probe-skin contact when the skin was in place. For each condition of surface illumination, the beam was directed to respectively T13 (surface site 1), a spinal column site 4 cm caudal to T13 (surface site 5), and a spinal column site 8 cm caudal to T13 (surface site 9). Off-contact surface irradiation of 3.14 W/cm² at surface sites 1, 5, and 9 transmitted respectively 234.0 ± 120.7 μW/cm², 230.7 ± 178.3 μW/cm², and 130.2 ± 169.6 μW/cm² to the spinal canal without the skin, and respectively 35.7 ± 33.2 μW/cm², 50.9 ± 75.3 μW/cm², and 15.7 ± 16.3 μW/cm² with the skin. Transmission with skin was as low as 12% of the transmission without the skin. On-contact surface irradiation of 3.14 W/cm² at surface sites 1, 5, and 9 transmitted respectively 44.6 ± 43.1 μW/cm², 85.4 ± 139.1 μW/cm², and 22.0 ± 23.6 μW/cm² to the spinal canal. On-contact application increased transmission by a maximum of 67% comparing to off-contact application. The information gathered highlights the need to clinically consider the impact of skin transmission and on-contact application technique when attempting to treat spinal cord disease with PBM.

Evaluation of low-level diode laser irradiation and various irrigant solutions on the biological response of stem cells from exfoliated deciduous teeth

This study aimed to evaluate cytotoxic effects and the apoptosis of Gallium-Aluminum-Arsenide (GaAlAs) diode laser irradiation, sodium hypochlorite (NaOCl), ozonated water and ethylene diamine tetraacetic acid (EDTA) on stem cells from human exfoliated deciduous teeth (SHEDs). Cells were exposed to EDTA (5%, 8.5%, 17%), NaOCl (1%, 2.5%, 5%) ozonated water (5, 10, 20 μg/ml) and GaAlAs diode laser irradiation (energy densities of 0.5, 1, 1.5 j/cm²). Culture medium included D-MEM, supplemented with 15% foetal bovine serum, 1% l-glutamine, 1% penicillin-streptomycin, 1% gentamycin, amphotericin-B and served as control group. The prepared irrigants were added to the relevant wells and incubated with the cells at 37 °C for 5, 10 and 15 min. The cells in the laser group were also incubated at 37 °C for 5, 10 and 15 min after the laser application. Cell viability and proliferation were analysed with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. The percentage of cell viability showed a significant reduction in all concentrations of the EDTA and NaOCl groups when compared to the control group, diode laser irradiation and ozonated water groups at 5th, 10th and 15th minutes respectively but high cytotoxic effects of all EDTA and NaOCl groups with decreased over 50% of cell viability were observed at the 15th minute. Also EDTA group with 17% concentration (17%E) presented the lowest survival rate on SHEDs with mean of 21.67% ± 6.101 at this time interval. The lowest toxic effects were observed at the 5th minutes compared to other time periods at experimental groups. For detection of apoptotic cells, the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labelling (TUNEL) method was performed. According to the MTT results, doses showed the highest toxicity (cell survival decreased over 50%) in each group were selected for TUNEL assay (17% EDTA; 1% NaOCl; 10 μg/ml Ozonated water; 1.5 j/cm² diode laser irradiation). The significantly lowest percentages of TUNEL-positive cells were detected in ozonated water (10.67% ± 2.93) and diode laser irradiation (13.24% ± 7.61) compared to EDTA (39.89% ± 11.54) and NaOCl (31.15% ± 10.64) respectively. Also the difference between percentage of TUNEL-positive cells in EDTA and NaOCl groups was not significant. Synergistic combination of ozonated water and diode laser irradiation may be used in the disinfection step of necrotic root canals.

Pre-conditioning with Remote Photobiomodulation Modulates the Brain Transcriptome and Protects Against MPTP Insult in Mice

Transcranial photobiomodulation (PBM), which involves the application of low-intensity red to near-infrared light (600-1100 nm) to the head, provides neuroprotection in animal models of various neurodegenerative diseases. However, the absorption of light energy by the human scalp and skull may limit the utility of transcranial PBM in clinical contexts. We have previously shown that targeting light at peripheral tissues (i.e. "remote PBM") also provides protection of the brain in an MPTP mouse model of Parkinson's disease, suggesting remote PBM might be a viable alternative strategy for overcoming penetration issues associated with transcranial PBM. This present study aimed to determine an effective pre-conditioning regimen of remote PBM for inducing neuroprotection and elucidate the molecular mechanisms by which remote PBM enhances the resilience of brain tissue. Balb/c mice were irradiated with 670-nm light (4 J/cm² per day) targeting dorsum and hindlimbs for 2, 5 or 10 days, followed by injection of the parkinsonian neurotoxin MPTP (50 mg/kg) over two consecutive days. Despite no direct irradiation of the head, 10 days of pre-conditioning with remote PBM significantly attenuated MPTP-induced loss of midbrain tyrosine hydroxylase-positive dopaminergic cells and mitigated the increase in FOS-positive neurons in the caudate-putamen complex. Interrogation of the midbrain transcriptome by RNA microarray and pathway enrichment analysis suggested upregulation of cell signaling and migration (including CXCR4⁺ stem cell and adipocytokine signaling), oxidative stress response pathways and modulation of the blood-brain barrier following remote PBM. These findings establish remote PBM preconditioning as a viable neuroprotective intervention and provide insights into the mechanisms underlying this phenomenon.

The Mechanistic Basis for Photobiomodulation Therapy of Neuropathic Pain by Near Infrared Laser Light

Background and Objective Various irradiances have been reported to be beneficial for the treatment of neuropathic pain with near infrared light. However, the mechanistic basis for the beneficial outcomes may vary based on the level of irradiance or fluence rate used. Using in vivo and in vitro experimental models, this study determined the mechanistic basis of photobiomodulation therapy (PBMT) for the treatment of neuropathic pain using a high irradiance.

Study Design/Materials and Methods ln vitro experiments: Cultured, rat DRG were randomly assigned to control or laser treatment (L T) groups with different irradiation times (2, 5, 30, 60 or 120s). The laser parameters were: output power = 960 mW, irradiance = 300mW/cm2, 808 nm wavelength and spot size = 3cm diameter/ area = 7.07cm2, with different fluences according to irradiation times. Mitochondrial metabolic activity was measured with the MTS assay. The DRG neurons were immunostained using a primary antibody to β-Tubulin III. ln vivo experiments: spared nerve injury surgery (SNI), an animal model of persistent peripheral neuropathic pain, was used. The injured rats were randomly divided into three groups (n = 5). 1) Control: SNI without LT, 2) Short term: SNI with LT on day 7 and euthanized on day 7, 3) Long term: SNI with LT on day 7 and euthanized on day 22. An 808 nm wavelength laser was used for all treatment groups. Treatment was performed once on Day 7 post-surgery. The transcutaneous treatment parameters were: output power: 10 W, fluence rate: 270 mW/cm2, treatment time: 120s. The laser probe was moved along the course of the sciatic/sural nerve during the treatment. Within 1 hour of irradiation, behavior tests were performed to assess its immediate effect on sensory allodynia and hyperalgesia caused by SNI.

Results ln vitro experiments: Mitochondrial metabolism was significantly lower compared with controls for all LT groups. Varicosities and undulations formed in neurites of DRG neurons with a cell body diameter 30µm or less. ln neurites of DRG neurons with a cell body diameter of greater than 30µm, varicosities formed only in the 120s group. ln vivo experiments: For heat hyperalgesia, there was a statistically significant reduction in sensitivity to the heat stimulus compared with the measurements done on day 7 prior to LT. A decrease in the sensitivity to the heat stimulus was found in the LT groups compared with the control group on day 15 and 21. For cold allodynia and mechanical hyperalgesia, a significant decrease in sensitivity to cold and pin prick was found within 1 hour after L T. Sensitivity to these stimuli returned to the control levels after 5 days post-L T. No significant difference was found in mechanical allodynia between control and L T groups for all time points examined.

Conclusion These in vitro and in vivo studies indicate that treatment with an irradiance/fluence rate at 270 m W/cm2 or higher at the level of the nerve can rapidly block pain transmission. A combination therapy is proposed to treat neuropathic pain with initial high irradiance/fluence rates for fast pain relief, followed by low irradiance/fluence rates for prolonged pain relief by altering chronic inflammation.

Near-infrared laser photons induce glutamate release from cerebrocortical nerve terminals

Although photons have been repeatedly shown to affect the functioning of the nervous system, their effects on neurotransmitter release have never been investigated. We exploited in vitro models that allow effects involving neuron-astrocyte network functioning to be detected (mouse cerebrocortical slices) and dissected these effects at cerebrocortical nerve endings and astrocyte processes. Infrared light proved able to induce glutamate release by stimulating glutamatergic nerve endings.

Low-level laser therapy modulates demyelination in mice

There are no effective therapies for remyelination. Low-level laser therapy (LLLT) has been found advantageous in neurogenesis promotion, cell death prevention, and modulation of inflammation in central and peripheral nervous system models. The purpose of this study was to analyse LLLT effects on cuprizone-induced demyelination. Mice were randomly distributed into three groups: Control Laser (CTL), Cuprizone (CPZ), and Cuprizone Laser (CPZL). Mice from CPZ and CPZL groups were exposed to a 0.2% cuprizone oral diet for four complete weeks. Six sessions of transcranial laser irradiation were applied on three consecutive days, during the third and fourth weeks, with parameters of 36 J/cm², 50 mW, 0.028 cm² spot area, continuous wave, 1 J, 20 s, 1.78 W/cm² in a single point equidistant between the eyes and ears of CTL and CPZL mice. Motor coordination was assessed by the rotarod test. Twenty-four hours after the last laser session, all animals were euthanized, and brains were extracted. Serum was obtained for lactate dehydrogenase toxicity testing. Histomorphological analyses consisted of Luxol Fast Blue staining and immunohistochemistry. The results showed that laser-treated animals presented motor performance improvement, attenuation of demyelination, increased number of oligodendrocyte precursor cells, modulated microglial and astrocytes activation, and a milder toxicity by cuprizone. Although further studies are required, it is suggested that LLLT represents a feasible therapy for demyelinating diseases.

Therapeutic effects of simultaneous Photobiomodulation therapy (PBMT) and Meloxicam administration on experimental acute spinal cord injury: Rat animal model

STUDY DESIGN

Application of Photobiomodulation therapy (PBMT) and meloxicam in acute spinal cord injury, functional recovery and histological evaluation.

OBJECTIVE

Evaluation of the effect of simultaneous PBMT and meloxicam on treatment of acute experimental spinal cord injury and comparing it with the effect of application of each of them separately.

SETTING

The study was conducted at the Department of Surgery & Radiology, Faculty of Veterinary Medicine and Institute of Biomedical Research, University of Tehran, Tehran, Iran.

METHODS

Twenty four rats were used in this study. A compression injury was induced to the T8-T9 segment of the spinal cord of rats using a Fogarty embolectomy catheter. Rats were randomly divided into 4 groups including: Control group, PBMT (810 nm-200 mw-8 s-2 weeks) group, Meloxicam (1 mg/kg) group, and PBMT and Meloxicam (mixed) group. After inducing injury, hind limb performance of the rats was evaluated, using BBB test and then treatment intervention was performed and continued for 2 weeks.

RESULTS

Four  weeks after injury induction, BBB test results were significantly higher in all treatment groups in comparison to control group, however, there were no significant differences among the treatment groups. In addition, histological findings revealed no significant difference between all 4 study groups.

CONCLUSION

According to the results of this study we can conclude that simultaneous and separate application of PBMT and Meloxicam play an effective role in treatment of acute spinal cord injuries.

Optogenetic surface stimulation of the rat cervical spinal cord

Electrical intraspinal microstimulation (ISMS) at various sites along the cervical spinal cord permits forelimb muscle activation, elicits complex limb movements and may enhance functional recovery after spinal cord injury. Here, we explore optogenetic spinal stimulation (OSS) as a less invasive and cell type-specific alternative to ISMS. To map forelimb muscle activation by OSS in rats, adeno-associated viruses (AAV) carrying the blue-light sensitive ion channels channelrhodopsin-2 (ChR2) and Chronos were injected into the cervical spinal cord at different depths and volumes. Following an AAV incubation period of several weeks, OSS-induced forelimb muscle activation and movements were assessed at 16 sites along the dorsal surface of the cervical spinal cord. Three distinct movement types were observed. We find that AAV injection volume and depth can be titrated to achieve OSS-based activation of several movements. Optical stimulation of the spinal cord is thus a promising method for dissecting the function of spinal circuitry and targeting therapies following injury.

NEW & NOTEWORTHY Optogenetics in the spinal cord can be used both for therapeutic treatments and to uncover basic mechanisms of spinal cord physiology. For the first time, we describe the methodology and outcomes of optogenetic surface stimulation of the rat spinal cord. Specifically, we describe the evoked responses of forelimbs and address the effects of different adeno-associated virus injection paradigms. Additionally, we are the first to report on the limitations of light penetration through the rat spinal cord.

Photobiomodulation prevents DNA fragmentation of alveolar epithelial cells and alters the mRNA levels of caspase 3 and Bcl-2 genes in acute lung injury

Acute respiratory distress syndrome (ARDS) and acute lung injury (ALI) are defined as pulmonary inflammation that could occur from sepsis and lead to pulmonary permeability and alveolar edema making them life-threatening diseases. Photobiomodulation (PBM) properties have been widely described in the literature in several inflammatory diseases; although the mechanisms of action are not always clear, this could be a possible treatment for ARDS/ALI. Thus, the aim of this study was to evaluate the mRNA levels from caspase-3 and BCL-2 genes and DNA fragmentation in lung tissue from Wistar rats affected by ALI and subjected to photobiomodulation by exposure to a low power infrared laser (808 nm; 100 mW; 3.571 W cm-2; four points per lung). Adult male Wistar rats were randomized into 6 groups (n = 5, for each group): control, PBM10 (10 J cm-2, 2 J and 2 seconds), PBM20 (20 J cm-2, 5 J and 5 seconds), ALI, ALI + PBM10 and ALI + PBM20. ALI was induced by intraperitoneal Escherichia coli lipopolysaccharide injection. Lung samples were collected and divided for mRNA expression of caspase-3 and Bcl-2 and DNA fragmentation quantifications. Data show that caspase-3 mRNA levels are reduced and Bcl-2 mRNA levels increased in ALI after low power infrared laser exposure when compared to the non-exposed ALI group. DNA fragmentation increased in inflammatory infiltrate cells and reduced in alveolar cells. Our research shows that photobiomodulation can alter relative mRNA levels in genes involved in the apoptotic process and DNA fragmentation in inflammatory and alveolar cells after lipopolysaccharide-induced acute lung injury. Also, inflammatory cell apoptosis is part of the photobiomodulation effects induced by exposure to a low power infrared laser.

Photobiomodulation Therapy in Veterinary Medicine: A Review

Laser therapy, or photobiomodulation, has rapidly grown in popularity in human and veterinary medicine. With a number of proposed indications and broad, sometimes anecdotal, use in practice, research interest has expanded aimed at providing scientific support. Recent studies have shown that laser therapy alters the inflammatory and immune response as well as promotes healing for a variety of tissue types. This review will cover the history of the modality, basic principles, proposed mechanisms of action, evidence-based clinical indications, and will guide the practitioner through its application in practice.

Photobiomodulation Optimization for Spinal Cord Injury Rat Phantom Model

Spinal Cord Injury (SCI) causes interruption along the severed axonal tract(s) resulting in complete or partial loss of sensation and motor function. SCI can cause tetraplegia or paraplegia. Both these conditions can have lifelong excessive medical costs, as well as can reduce life expectancy. Preclinical research showed that Photobiomodulation therapy (PBMT), also known as Low-level laser (light) therapy (LLLT), possesses reparative and regenerative capabilities that have the potential to be used as a complimentary or supplementary SCI therapy. Despite the promising effects of PBMT, there are still no standardized irradiation parameters (i.e. different wavelengths, power, fluence, irradiance, beam type, beam diameters, and irradiation time) and there is also a lack of standardized experimental protocol(s), which makes it difficult to compare different studies. It is, nonetheless, essential to standardize such irradiation parameters in order to provide better PBMTs. The aim of this study, therefore, is to evaluate the delivery of light in a 3D voxelated SCI rat model for PBMT using different irradiation parameters (wavelengths: 660, 810, and 980 nm; beam types: Gaussian and Flat beam; and beam diameters: 0.04-1.2 cm) using Monte Carlo simulation. This study also aids in providing standardization for preclinical research for PBMT, which will eventually translate into clinical standardization upon clinical research studies and results.

Advancing porphyrin's biomedical utility via supramolecular chemistry

Porphyrins are organic heterocyclic macrocycles with photophysical properties well-suited for clinical phototherapy and cancer imaging. However, their wider application in the clinical management of disease is barred by poor aqueous solubility, bioavailability, tumour accumulation and skin phototoxicity. These limitations instigated the development of supramolecular platforms that improved porphyrin pharmacokinetics and tumour-homing. The supramolecular formulation of porphyrins also facilitates single agent-mediated deeper tissue photoactivation, extended imaging and theranostic multimodality, and synergistic application of multiple therapies. Supramolecular porphyrin structures can overcome additional limitations of porphyrin-mediated photodynamic therapy (PDT), including low depths of tissue penetration that restrict PDT to superficial lesions, inability to treat hypoxic tumours, and incomplete tumour damage. In this review, we discuss the photophysical properties of porphyrins, and overview the clinically-relevant advantages and challenges arising from their incorporation within supramolecular platforms. Specifically, fundamentals underlying the ability of these platforms to ameliorate passive and active porphyrin delivery to tumours, achieve deeper tissue PDT via red-shifted porphyrin Q-bands, energy transfer and sonodynamic effects, and enable new porphyrin-mediated theranostics and synergistic therapeutic capabilities will be explained and exemplified with seminal and cutting-edge in vivo studies.

Characterization of Macrophage/Microglial Activation and Effect of Photobiomodulation in the Spared Nerve Injury Model of Neuropathic Pain

Objective

Neuropathic pain is common and debilitating with limited effective treatments. Macrophage/microglial activation along ascending somatosensory pathways following peripheral nerve injury facilitates neuropathic pain. However, polarization of macrophages/microglia in neuropathic pain is not well understood. Photobiomodulation treatment has been used to decrease neuropathic pain, has anti-inflammatory effects in spinal injury and wound healing models, and modulates microglial polarization in vitro. Our aim was to characterize macrophage/microglia response after peripheral nerve injury and modulate the response with photobiomodulation.

Methods

Adult male Sprague-Dawley rats were randomly assigned to sham (N = 13), spared nerve injury (N = 13), or injury + photobiomodulation treatment groups (N = 7). Mechanical hypersensitivity was assessed with electronic von Frey. Photobiomodulation (980 nm) was applied to affected hind paw (output power 1 W, 20 s, 41cm above skin, power density 43.25 mW/cm 2 , dose 20 J), dorsal root ganglia (output power 4.5W, 19s, in skin contact, power density 43.25 mW/cm 2 , dose 85.5 J), and spinal cord regions (output power 1.5 W, 19s, in skin contact, power density 43.25 mW/cm 2 , dose 28.5 J) every other day from day 7-30 post-operatively. Immunohistochemistry characterized macrophage/microglial activation.

Results

Injured groups demonstrated mechanical hypersensitivity 1-30 days post-operatively. Photobiomodulation-treated animals began to recover after two treatments; at day 26, mechanical sensitivity reached baseline. Peripheral nerve injury caused region-specific macrophages/microglia activation along spinothalamic and dorsal-column medial lemniscus pathways. A pro-inflammatory microglial marker was expressed in the spinal cord of injured rats compared to photobiomodulation-treated and sham group. Photobiomodulation-treated dorsal root ganglion macrophages expressed anti-inflammatory markers.

Conclusion

Photobiomodulation effectively reduced mechanical hypersensitivity, potentially through modulating macrophage/microglial activation to an anti-inflammatory phenotype.

The influence of low level laser irradiation on vascular reactivity

PURPOSE

The mechanism of action of low level laser irradiation on tissues is unclear. Authors of publications present the positive clinical impact of low and medium power laser irradiation on vascular reactivity. The purpose of this study was to analyze the role of vascular endothelium in laser-induced constricted by endothelin-1 and phenylephrine.

MATERIALS AND METHODS

Experiments were performed on isolated and perfused rat tail arteries of weighing 250-350g male Wistar rats. Contractility of arteries as a response to endothelin-1 and phenylephrine was measured after exposure to laser stimulation (10, 30 and 110mW).

RESULTS

Laser irradiation inhibits vascular smooth muscle contraction induced by endothelin-1 and an alpha-adrenergic receptor agonist, phenylephrine proportionally to the laser power. Concentration-response curves were shifted to the right with significant reduction in maximal response. Laser irradiation at the power of 10mW, 30mW, and 110mW reduced the maximum response of arteries stimulated with phenylephrine sequentially to 88%, 72%, and 52%. Similar findings were observed during stimulation of endothelin-1. Laser irradiation at the power of 10mW, 30mW and 110mW resulted in maximal response respectively reduced to 94%, 62% and 38%.

CONCLUSION

Our results strongly suggest that during low level laser irradiation vascular smooth muscle cells reactivity is reduced, this effect is present in arteries with normal endothelium. The mechanism of action of laser biosimulation on tissues is unclear. Authors of publications present the positive clinical impact of low level laser irradiation on vascular reactivity.

Photobiomodulation improves motor response in patients with spinal cord injury submitted to electromyographic evaluation: randomized clinical trial

Photobiomodulation is a treatment that has been widely used in neurotrauma and neurodegenerative diseases. In the present study, low-level laser therapy was administered to patients with spinal cord injury. Twenty-five individuals were divided into two groups: placebo photobiomodulation plus physiotherapy and active photobiomodulation plus physiotherapy. Electromyographic evaluations were performed before and after 12 sessions of phototherapy as well as 30 days after the end of treatment. In the active phototherapy group, median frequency values of the brachial biceps and femoral quadriceps muscles were higher at rest and during isotonic contraction 30 days after photobiomodulation (p = 0.0258). No significant results were found regarding the rest and isotonic conditions in the pre-photobiomodulation period (p = 0.950) or immediately following photobiomodulation (p = 0.262). The data provide evidence that phototherapy improves motor responses in individuals with spinal cord injury, as demonstrated by differences in the EMG signal before and after treatment.

TRIAL REGISTRATION

NCT 03031223.

Improved urethral fluorescence during low rectal surgery: a new dye and a new method

BACKGROUND

The aim of this study was to demonstrate highlighting of the urethra during surgery through the use of two different methods: a new near-infrared fluorophore IRDye800BK, and indocyanine green (ICG) mixed with silicone.

METHODS

Male cadavers from the department of anatomy at the University of Oxford were used to visualise the urethra during near-infrared fluorescence excitation. To assess IRDye800BK, a perineal incision was utilised after infiltrating the urethra directly with an IRDye800BK solution mixed with Instillagel. ICG-silicone was assessed when the urethra was purposely exposed as part of a simulated transanal total mesorectal dissection. ICG was previously mixed with ethanol and silicone and left to set in a Foley catheter. Fluorescence was visualised using an in-house manufactured fluorescence-enabled laparoscopic system.

RESULTS

IRDye800BK demonstrated excellent penetration and visualisation of the urethra under fluorescence at an estimated tissue depth of 2 cm. An ICG-silicone catheter demonstrated excellent fluorescence without leaving any residual solution behind in the urethra after its removal.

CONCLUSIONS

The newly described ICG-silicone method opens up the possibility of new technologies in this area of fluorescence guided surgery. IRDye800BK is a promising alternative to ICG in visualising the urethra using fluorescence imaging. Its greater depth of penetration may allow earlier detection of the urethra during surgery and prevent wrong plane surgery sooner.

Brain Photobiomodulation Therapy: a Narrative Review

Brain photobiomodulation (PBM) therapy using red to near-infrared (NIR) light is an innovative treatment for a wide range of neurological and psychological conditions. Red/NIR light is able to stimulate complex IV of the mitochondrial respiratory chain (cytochrome c oxidase) and increase ATP synthesis. Moreover, light absorption by ion channels results in release of Ca²⁺ and leads to activation of transcription factors and gene expression. Brain PBM therapy enhances the metabolic capacity of neurons and stimulates anti-inflammatory, anti-apoptotic, and antioxidant responses, as well as neurogenesis and synaptogenesis. Its therapeutic role in disorders such as dementia and Parkinson's disease, as well as to treat stroke, brain trauma, and depression has gained increasing interest. In the transcranial PBM approach, delivering a sufficient dose to achieve optimal stimulation is challenging due to exponential attenuation of light penetration in tissue. Alternative approaches such as intracranial and intranasal light delivery methods have been suggested to overcome this limitation. This article reviews the state-of-the-art preclinical and clinical evidence regarding the efficacy of brain PBM therapy.

Photobiomodulation using low-level laser therapy (LLLT) for patients with chronic traumatic brain injury: a randomized controlled trial study protocol

BACKGROUND

Photobiomodulation using low-level laser therapy (LLLT) has been tested as a new technique to optimize recovery of patients with traumatic brain injury (TBI). The aim of this study is to evaluate inhibitory attentional control after 18 sessions of active LLLT and compare with the placebo group (sham LLLT). Our exploratory analysis will evaluate the efficacy of the active LLLT on verbal and visuospatial episodic memory, executive functions (working memory, verbal and visuospatial fluency, attentional processes), and anxiety and depressive symptoms compared to the sham group.

METHODS/DESIGN

A randomized double-blinded trial will be made in 36 patients with moderate and severe TBI. The active LLLT will use an optical device composed of LEDs emitting 632 nm of radiation at the site with full potency of 830 mW. The cranial region with an area of 400 cm² will be irradiated for 30 min, giving a total dose per session of 3.74 J/cm². The sham LLLT group contains only an LED device with power < 1 mW, only serving to simulate the irradiation. Each patient will be irradiated three times per week for six weeks, totaling 18 sessions. Neuropsychological assessments will be held one week before the beginning of the sessions, after one week, and three months after the end of LLLT sessions. Memory domain, attention, executive functioning, and visual construction will be evaluated, in addition to symptoms of depression, anxiety, and social demographics.

DISCUSSION

LLLT has been demonstrated as a safe and effective technique in significantly improving the memory, attention, and mood performance in healthy and neurologic patients. We expect that our trial can complement previous finds, as an effective low-cost therapy to improve cognitive sequel after TBI.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02393079 . Registered on 20 February 2015.

Combine effect of Chondroitinase ABC and low level laser (660nm) on spinal cord injury model in adult male rats

After spinal cord injury (SCI) there are many recoveries inhibiting factors such as chondroitin sulfate proteoglycan (CSPG) and inflammation. The present study investigated the combinational effect of low level laser therapy (LLLT) as anti-inflammatory agent and Chondroitinase ABC (ChABC) enzyme as CSPG digesting factor on spinal cord after injury. This study performed on 44 male Wistar rats, spinal cord injury induced by a clip compression injury. Animals received two-weeks treatment of 660nm low level laser (LLL) and intraspinal injection of 1μg ChABC. Functional recovery, cavity size, myelination, axonal projections around the cavity, fibroblast invasion and expression of glycogen synthase kinase-3β (GSk 3β), CSPG and aquaporin 4 (AQP4) expression were evaluated. In statistical evaluation p<0.05 considered significant. Result showed the combination of LLLT and ChABC have more effect on reduction of cavity size, improvement of myelination and number of axons around the cavity and decreasing the expression of GSK3β, CSPG and AQP4 expression compared to LLLT and ChABC alone. In the laser and laser+enzyme groups AQP4 expression decreased significantly after SCI. Functional recovery, improved in LLLT and ChABC treated animals, but higher recovery belonged to the combination therapy group. The current study showed combination therapy by LLLT and ChABC is more efficient than a single therapy with each of them.

Non-invasive diagnosis and treatment strategies for traumatic brain injury: an update

PURPOSE OF REVIEW

Traumatic Brain Injury (TBI) remains the leading cause of morbidity and mortality in U.S. Since the last decade, there have been several advances in the understanding and management of TBI that have shown the potential to improve outcomes. The aim of this review is to provide a useful overview of these potential diagnostic and treatment strategies that have yet to be proven, along with an assessment of their impact on outcomes after a TBI.

RECENT FINDINGS

Recent technical advances in the management of a TBI are grounded in a better understanding of the pathophysiology of primary and secondary insult to the brain after a TBI. Hence, clinical trials on humans should proceed in order to evaluate their efficacy and safety.

SUMMARY

Mortality associated with TBI remains high. Nonetheless, new diagnostic and therapeutic techniques have the potential to enhance early detection and prevention of secondary brain insult.

Clinical Effects of Laser Acupuncture plus Chinese Cupping on the Pain and Plasma Cortisol Levels in Patients with Chronic Nonspecific Lower Back Pain: A Randomized Controlled Trial

Objectives

Chronic nonspecific lower back pain (LBP) is a common disease. Insufficient data is currently available to conclusively confirm the analgesic effects of laser acupuncture on LBP. This study evaluated the effectiveness of laser acupuncture plus Chinese cupping in LBP treatment.

Methods

Patients with chronic nonspecific LBP were enrolled for a randomized controlled trial and assigned to the laser acupuncture group (laser acupuncture plus Chinese cupping) and control group (sham laser plus Chinese cupping). Laser acupuncture (808 nm; 40 mW; 20 Hz; 15 J/cm²) and Chinese cupping were applied on the Weizhong (BL40) and Ashi acupoints for 5 consecutive days. Plasma cortisol levels were assessed before and after the 5-day treatment session. The visual analog scale (VAS) scores were recorded at baseline and throughout the 5-day treatment session.

Results

After the treatment session, the plasma cortisol levels and VAS scores decreased significantly in both groups. In the laser acupuncture group, the VAS scores decreased significantly on days 4 and 5, and an enhanced reduction in VAS scores was observed.

Conclusion

Laser acupuncture plus Chinese cupping at the Weizhong (BL40) and Ashi acupoints effectively reduced pain and inflammation in chronic nonspecific LBP. This therapy could be a suitable option for LBP treatment in clinical settings.

Remote tissue conditioning - An emerging approach for inducing body-wide protection against diseases of ageing

We have long accepted that exercise is 'good for us'; that - put more rigorously - moderate exercise is associated with not just aerobic fitness but also reduced morbidity and reduced mortality from cardiovascular disease and even malignancies. Caloric restriction (moderate hunger) and our exposure to dietary phytochemicals are also emerging as stresses which are 'good for us' in the same sense. This review focuses on an important extension of this concept: that stress localized within the body (e.g. in a limb) can induce resilience in tissues throughout the body. We describe evidence for the efficacy of two 'remote' protective interventions - remote ischemic conditioning and remote photobiomodulation - and discuss the mechanisms underlying their protective actions. While the biological phenomenon of remote tissue conditioning is only partially understood, it holds promise for protecting critical-to-life tissues while mitigating risks and practical barriers to direct conditioning of these tissues.

The potential of transcranial photobiomodulation therapy for treatment of major depressive disorder

Major depressive disorder is a common debilitating mood disorder that affects quality of life. Prefrontal cortex abnormalities, an imbalance in neurotransmitters, neuroinflammation, and mitochondrial dysfunction are the major factors in the etiology of major depressive disorder. Despite the efficacy of pharmacotherapy in the treatment of major depressive disorder, 30%–40% of patients do not respond to antidepressants. Given this, exploring the alternative therapies for treatment or prevention of major depressive disorder has aroused interest among scientists. Transcranial photobiomodulation therapy is the use of low-power lasers and light-emitting diodes in the far-red to near-infrared optical region for stimulation of neuronal activities. This non-invasive modality improves the metabolic capacity of neurons due to more oxygen consumption and ATP production. Beneficial effects of transcranial photobiomodulation therapy in the wide range of neurological and psychological disorders have been already shown. In this review, we focus on some issue relating to the application of photobiomodulation therapy for major depressive disorder. There is some evidence that transcranial photobiomodulation therapy using near-infrared light on 10-Hz pulsed mode appears to be a hopeful technique for treatment of major depressive disorder. However, further studies are necessary to find the safety of this method and to determine its effective treatment protocol.

Photostimulation of mitochondria as a treatment for retinal neurodegeneration

Absorption of photon energy by neuronal mitochondria leads to numerous downstream neuroprotective effects. Red and near infrared (NIR) light are associated with significantly less safety concerns than light of shorter wavelengths and they are therefore, the optimal choice for irradiating the retina. Potent neuroprotective effects have been demonstrated in various models of retinal damage, by red/NIR light, with limited data from human studies showing its ability to improve visual function. Improved neuronal mitochondrial function, increased blood flow to neural tissue, upregulation of cell survival mediators and restoration of normal microglial function have all been proposed as potential underlying mechanisms of red/NIR light.

Self-assembled photoadditives in polyester films allow stop and go chemical release

Near-infrared (NIR) triggered chemical delivery allows on-demand release with the advantage of external tissue stimulation. Bioresorbable polyester poly-l-lactic acid (PLLA) was compounded with photoadditives of neat zinc oxide (ZnO) nanoparticles and 980→365nm LiYF₄:Tm³⁺, Yb³⁺ upconverting nanoparticles (UCNP). Subsequently, neat ZnO and UCNP blended PLLA films of sub-50μm thickness were knife casted with a hydrophobic small molecule drug mimic, fluorescein diacetate. The PLLA films displayed a 500 times increase in fluorescein diacetate release from the 50mW NIR irradiated PLLA/photoadditive film compared to non-irradiated PLLA control films. Larger ratios of UCNP/neat ZnO increased photocatalysis efficiency at low NIR duty cycles. The synergistic increase results from the self-assembled photoadditives of neat zinc oxide and upconverting nanoparticles (UCNPs), as seen in transmission electron microscopy. Colloidal ZnO, which does not self-assemble with UCNPs, had less than half the release kinetics of the self-assembled PLLA films under similar conditions, advocating Förster resonance energy transfer as the mechanism responsible for the synergistic increase. Alternative to intensity modulation, pulse width modulation (duty cycles from 0.1 to 1) of the low intensity 50mW NIR laser diode allowed tailorable release rates from 0.01 to 1.4% per day. With the low intensity NIR activation, tailorable release rates, and favorable biocompatibility of the constituents, implanted PLLA photoadditive thin films could allow feedback mediated chemical delivery.

STATEMENT OF SIGNIFICANCE

Upconverting nanoparticles and zinc oxide nanorods were found to spontaneously self-assemble into submicron particles in organic solvents. Exposure of the submicron particles to near-infrared light allows stop and go chemical release from biocompatible polymers. Sample preparation of thin films is done with ease through physical mixing of the photoadditives followed by air-dried knife casting. A colloidal ZnO variant that does not self-assemble with upconverting nanoparticles had slower chemical release, suggesting that synergistic chemical release is brought upon by highly efficient energy transfer mechanisms when the nanoparticles are less than 10nm apart. Never before seen composite particles of UCNP/ZnO are displayed, which shows the close interaction of the photoadditives within the polymer matrix.

Low-level laser facilitates alternatively activated macrophage/microglia polarization and promotes functional recovery after crush spinal cord injury in rats

Macrophages and resident microglia play an import role in the secondary neuroinflammation response following spinal cord injury. Reprogramming of macrophage/microglia polarization is an import strategy for spinal cord injury restoration. Low-level laser therapy (LLLT) is a noninvasive treatment that has been widely used in neurotrauma and neurodegenerative diseases. However, the influence of low-level laser on polarization of macrophage/microglia following spinal cord injury remains unknown. The present study applied low-level laser therapy on a crush spinal cord injury rat model. Using immunofluorescence, flow cytometry, RT-qPCR, and western blot assays, we found that low-level laser therapy altered the polarization state to a M2 tendency. A greater number of neurons survived in the pare injury site, which was accompanied by higher BBB scores in the LLLT group. Furthermore, low-level laser therapy elevated expression of interleukin 4 (IL-4) and interleukin 13 (IL-13). Results from this study show that low-level laser therapy has the potential for reducing inflammation, regulating macrophage/microglia polarization, and promoting neuronal survival. These beneficial effects demonstrate that low-level laser therapy may be an effective candidate for clinical treatment of spinal cord injury.