Combination of low level light therapy and nitrosyl-cobinamide accelerates wound healing

From functional neuroimaging to neurostimulation: fNIRS devices as cognitive enhancers

Functional near-infrared spectroscopy (fNIRS) relies on near-infrared (NIR) light for changes in tissue oxygenation. For decades, this technique has been used in neuroscience to measure cortical activity. However, recent research suggests that NIR light directed to neural populations can modulate their activity through "photobiomodulation" (PBM). Yet, fNIRS is being used exclusively as a measurement tool. By adopting cognitive tests sensitive to prefrontal functioning, we show that a 'classical' fNIRS device, placed in correspondence of the prefrontal cortices of healthy participants, induces faster RTs and better accuracy in some of the indexes considered. A well-matched control group, wearing the same but inactive device, did not show any improvement. Hence, our findings indicate that the 'standard' use of fNIRS devices generates PBM impacting cognition. The neuromodulatory power intrinsic in that technique has been so far completely overlooked, and future studies will need to take this into account.

Synergistic effect of photobiomodulation and phthalocyanine photosensitizer on fibroblast signaling responses in an in vitro three-dimensional microenvironment

Photobiomodulation (PBM) is a promising medical treatment modality in the area of photodynamic therapy (PDT). In this study, we investigated the effect of combined therapy in a 3D microenvironment using aluminum chloride phthalocyanines (AlClPc) as the photosensitizing agent. Normal human fibroblast-containing collagen biomatrix was prepared and treated with an oil-in-water (o/a) AlClPc-loaded nanoemulsion (from 0.5 to 3.0 μM) and irradiated at a range of fluences (from 0.1 to 3.0 J/cm²) using a continuous-wave light-emitting diode (LED) irradiation system (660 nm). PBM at 1.2 J/cm² and AlClPc/NE at 0.5 μM modified the fibroblast signaling response under 3D conditions, promoting collagen synthesis, ROS production, MMP-9 secretion, proliferation of the actin network, and facile myofibroblastic differentiation. PBM alone (at 1.2 J/cm² and 0.3 J/cm²) had no significant effect on any of these parameters. The combined therapy affected myofibroblastic differentiation, inflammatory response, and extracellular matrix pliability, and should thus be examined further in subsequent studies considering that no side effects of PBM have been reported. Even though significant progress has been made in the field of phototherapy in recent years, it is necessary to further elucidate the detailed mechanisms underlying its effects already shown in 2D conditions to increase the acceptance of this beneficial and non-invasive therapeutic approach.

The biological processes during wound healing

Numerous individuals suffer from impaired wound healing, such as chronic ulcers, severe burns and immune disorders, resulting in both public health and economic burdens. Skin is the first line of defense and the largest organ of the human body, however, an incomplete understanding of underlying cellular and molecular mechanisms of dermal repair leads to a lack of effective therapy for healing impaired wounds. There are strong clinical and social needs for improved therapeutic approaches to enhance endogenous tissue repair and regenerative capacity. The purpose of this review is to illuminate the cellular and molecular aspects of the healing process and highlight potential therapeutic strategies to accelerate translational research and the development of clinical therapies in dermal wounds.

Photobiomodulation (low-level light therapy) and dry eye disease

Dry eye disease is one of the most common, chief-complaints presenting in clinical practice, with a prevalence of up to 50%. Evaporative dry eye, as a result of meibomian gland dysfunction, is thought to be the biggest component factor. Treatments for meibomian gland dysfunction aim to restore tear film homoeostasis and include warm compress therapy, eyelid hygiene, in-office meibomian gland expression and lipid-containing, artificial tears. A recent introduction to the in-office treatments available for meibomian gland dysfunction has been low-level light therapy, also known as photobiomodulation. The technique involves applying red, or near infra-red, radiation using low-power light sources and is suggested to promote tissue repair, decrease inflammation, and relieve pain. This work aims to review the available literature on the efficacy and safety of photobiomodulation in meibomian gland dysfunction and dry eye disease, as well as what is currently known about its mechanism of action.

In Vitro Wound Healing Potential of Photobiomodulation Is Possibly Mediated by Its Stimulatory Effect on AKT Expression in Adipose-Derived Stem Cells

Increasing evidence suggests that adipose-derived stem cells (ADSCs) serve as a therapeutic approach for wound healing. The aim of this study was to determine the effect of photobiomodulation (PBM) on antioxidant enzymes in ADSCs. Four ADSC cell models, namely, normal, wounded, diabetic, and diabetic wounded, were irradiated with 660 nm (fluence of 5 J/cm² and power density of 11.2 mW/cm²) or 830 nm (fluence of 5 J/cm² and power density of 10.3 mW/cm²). Nonirradiated cells served as controls. Cell morphology and wound migration were determined using light microscopy. Cell viability was determined by the trypan blue exclusion assay. The enzyme-linked immunosorbent assay (ELISA) was used to measure the levels of antioxidants (superoxide dismutase (SOD), catalase (CAT), and heme oxygenase (HMOX1)). AKT activation and FOXO1 levels were determined by immunofluorescence and western blotting. The gaps (wound) in PBM-treated wounded and diabetic wounded cell models closed faster than the controls. PBM treatment significantly increased antioxidant levels in all cell models. This reflects that oxidative stress is reduced on the counterpart of increased antioxidant levels. This might be due to the activation of the AKT signaling pathway as evidenced by the increased AKT signals via western blotting and immunofluorescence. This data suggests that PBM promotes wound healing by increasing antioxidant levels by activating AKT signaling.

Photobiomodulation for Alzheimer's Disease: Has the Light Dawned?

Next to cancer, Alzheimer's disease (AD) and dementia is probably the most worrying health problem facing the Western world today. A large number of clinical trials have failed to show any benefit of the tested drugs in stabilizing or reversing the steady decline in cognitive function that is suffered by dementia patients. Although the pathological features of AD consisting of beta-amyloid plaques and tau tangles are well established, considerable debate exists concerning the genetic or lifestyle factors that predispose individuals to developing dementia. Photobiomodulation (PBM) describes the therapeutic use of red or near-infrared light to stimulate healing, relieve pain and inflammation, and prevent tissue from dying. In recent years PBM has been applied for a diverse range of brain disorders, frequently applied in a non-invasive manner by shining light on the head (transcranial PBM). The present review discusses the mechanisms of action of tPBM in the brain, and summarizes studies that have used tPBM to treat animal models of AD. The results of a limited number of clinical trials that have used tPBM to treat patients with AD and dementia are discussed.

Photobiomodulation (660 nm) therapy reduces oxidative stress and induces BDNF expression in the hippocampus

Photobiomodulation therapy (PBMT) effects an important role in neural regeneration and function enhancement, such as expression of nerve growth factor and nerve regeneration, in neuronal tissues, and inhibition of cell death by amyloid beta in neurons is inhibited by PBMT. However, there no studies evaluated the effects of PBMT on oxidative stress in the hippocampus. The aim of this study is to evaluate the effects of PBMT on oxidative stress in the hippocampus. This study assessed the anti-oxidative effect, the expression of BDNF and antioxidant enzymes, as well as the activation of cAMP response element binding (CREB) and extracellular signal-regulated kinase (ERK) signal transduction pathways assess using a hippocampal cell line (HT-22) and mouse organotypic hippocampal tissues by PBMT (LED, 660 nm, 20 mW/cm²). PBMT inhibited HT-22 cell death by oxidative stress and increased BDNF expression via ERK and CREB signaling pathway activation. In addition, PBMT increased BDNF expression in hippocampal organotypic slices and the levels of phosphorylated ERK and CREB, which were reduced by oxidative stress, as well as the expression of the antioxidant enzyme superoxide dismutase. These data demonstrate that PBMT inhibits hippocampal damage induced by oxidative stress and increases the expression of BDNF, which can be used as an alternative to treat a variety of related disorders that lead to nerve damage. Activation and redox homeostasis in neuronal cells may be a notable mechanism of the 660-nm PBMT-mediated photobioreactivity.

Low-level light emitting diode therapy promotes long-term functional recovery after experimental stroke in mice

We aimed to investigate the effects of low-level light emitting diode therapy (LED-T) on the long-term functional outcomes after cerebral ischemia, and the optimal timing of LED-T initiation for achieving suitable functional recovery. Focal cerebral ischemia was induced in mice via photothrombosis. These mice were assigned to a sham-operated (control), ischemic (vehicle), or LED-T group [initiation immediately (acute), 4 days (subacute) or 10 days (delayed) after ischemia, followed by once-daily treatment for 7 days]. Behavioral outcomes were assessed 21 and 28 days post-ischemia, and histopathological analysis was performed 28 days post-ischemia. The acute and subacute LED-T groups showed a significant improvement in motor function up to 28 days post-ischemia, although no brain atrophy recovery was noted. We observed proliferating cells (BrdU⁺ ) in the ischemic brain, and significant increases in BrdU⁺ /GFAP⁺ , BrdU⁺ /DCX⁺ , BrdU⁺ /NeuN⁺ , and CD31⁺ cells in the subacute LED-T group. However, the BrdU⁺ /Iba-1⁺ cell count was reduced in the subacute LED-T group. Furthermore, the brain-derived neurotrophic factor (BDNF) was significantly upregulated in the subacute LED-T group. We concluded that LED-T administered during the subacute stage had a positive impact on the long-term functional outcome, probably via neuron and astrocyte proliferation, blood vessel reconstruction, and increased BDNF expression. Picture: The rotarod test for motor coordination showed that acute and subacute LED-T improves long-term functional recovery after cerebral ischemia.

Effect of low-level light therapy on diabetic foot ulcers: a near-infrared spectroscopy study

Diabetic foot ulcer (DFU) is a diabetic complication due to peripheral vasculopathy and neuropathy. A promising technology for wound healing in DFU is low-level light therapy (LLLT). Despite several studies showing positive effects of LLLT on DFU, LLLT’s physiological effects have not yet been studied. The objective of this study was to investigate vascular and nervous systems modification in DFU after LLLT. Two samples of 45 DFU patients and 11 healthy controls (HCs) were recruited. The total hemoglobin (totHb) concentration change was monitored before and after LLLT by near-infrared spectroscopy and analyzed in time and frequency domains. The spectral power of the totHb changes in the very-low frequency (VLF, 20 to 60 mHz) and low frequency (LF, 60 to 140 mHz) bandwidths was calculated. Data analysis revealed a mean increase of totHb concentration after LLLT in DFU patients, but not in HC. VLF/LF ratio decreased significantly after the LLLT period in DFU patients (indicating an increased activity of the autonomic nervous system), but not in HC. Eventually, different treatment intensities in LLLT therapy showed a different response in DFU. Overall, our results demonstrate that LLLT improves blood flow and autonomic nervous system regulation in DFU and the importance of light intensity in therapeutic protocols.