1064 nm Nd:YAG laser light affects transmembrane mitochondria respiratory chain complexes

Photobiomodulation (PBM) is a non‐plant‐cell manipulation through a transfer of energy by means of light sources at the non‐ablative or thermal intensity. Authors showed that cytochrome‐c‐oxidase (complex IV) is the specific chromophore's target of PBM at the red (600‐700 nm) and NIR (760‐900 nm) wavelength regions. Recently, it was suggested that the infrared region of the spectrum could influence other chromospheres, despite the interaction by wavelengths higher than 900 nm with mitochondrial chromophores was not clearly demonstrated. We characterized the interaction between mitochondria respiratory chain, malate dehydrogenase, a key enzyme of Krebs cycle, and 3‐hydroxyacyl‐CoA dehydrogenase, an enzyme involved in the β‐oxidation (two mitochondrial matrix enzymes) with the 1064 nm Nd:YAG (100mps and 10 Hz frequency mode) irradiated at the average power density of 0.50, 0.75, 1.00, 1.25 and 1.50 W/cm² to generate the respective fluences of 30, 45, 60, 75 and 90 J/cm². Our results show the effect of laser light on the transmembrane mitochondrial complexes I, III, IV and V (adenosine triphosphate synthase) (window effects), but not on the extrinsic mitochondrial membrane complex II and mitochondria matrix enzymes. The effect is not due to macroscopical thermal change. An interaction of this wavelength with the Fe‐S proteins and Cu‐centers of respiratory complexes and with the water molecules could be supposed.      

Light‐emitting diode irradiation using 660 nm promotes human fibroblast HSP90 expression and changes cellular activity and morphology

We evaluated changes in cell viability and morphology in response to low‐level light irradiation and underlying variations in the levels of heat shock proteins (HSPs). Human fibroblasts were irradiated with a light‐emitting diode (LED) array at 660 nm (50 mW for 15, 30, and 60 minutes). Cell viability and morphological changes were evaluated via epifluorescence analysis; we also assessed cell viability and length changes. The expression levels of adenosine triphosphate (ATP) and various HSPs (HSP27, 60, 70, and 90) were analyzed by immunohistochemical staining, Western blotting and microarray analysis. After LED irradiation, cellular viability and morphology changed. Of the several HSPs analyzed, the HSP90 level increased significantly, suggesting that this protein played roles in the morphological and cellular changes. Thus, low‐level irradiation triggered cellular changes mediated by increased HSP90 expression; this may explain why skin irradiation enhances wound‐healing.     

Light‐emitting diode therapy in exercise‐trained mice increases muscle performance,cytochrome c oxidase activity,ATP and cell proliferation

Light‐emitting diode therapy (LEDT) applied over the leg, gluteus and lower‐back muscles of mice using a LED cluster (630 nm and 850 nm, 80 mW/cm², 7.2 J/cm²) increased muscle performance (repetitive climbing of a ladder carrying a water‐filled tube attached to the tail), ATP and mitochondrial metabolism; oxidative stress and proliferative myocyte markers in mice subjected to acute and progressive strength training. Six bi‐daily training sessions LEDT‐After and LEDT‐Before‐After regimens more than doubled muscle performance and increased ATP more than tenfold. The effectiveness of LEDT on improving muscle performance and recovery suggest applicability for high performance sports and in training programs.

Positioning of the mice and light‐emitting diode therapy (LEDT) applied on mouse legs, gluteus and lower‐back muscles without contact.     

Superpulsed (Ga‐As, 904 nm) low‐level laser therapy (LLLT) attenuates inflammatory response and enhances healing of burn wounds

Low‐level laser therapy (LLLT) using superpulsed near‐infrared light can penetrate deeper in the injured tissue and could allow non‐pharmacological treatment for chronic wound healing. This study investigated the effects of superpulsed laser (Ga‐As 904 nm, 200 ns pulse width; 100 Hz; 0.7 mW mean output power; 0.4 mW/cm² average irradiance; 0.2 J/cm² total fluence) on the healing of burn wounds in rats, and further explored the probable associated mechanisms of action. Irradiated group exhibited enhanced DNA, total protein, hydroxyproline and hexosamine contents compared to the control and silver sulfadiazine (reference care) treated groups. LLLT exhibited decreased TNF‐α level and NF‐kB, and up‐regulated protein levels of VEGF, FGFR‐1, HSP‐60, HSP‐90, HIF‐1α and matrix metalloproteinases‐2 and 9 compared to the controls. In conclusion, LLLT using superpulsed 904 nm laser reduced the inflammatory response and was able to enhance cellular proliferation, collagen deposition and wound contraction in the repair process of burn wounds.

Photomicrographs showing no, absence inflammation and faster wound contraction in LLLT superpulsed (904 nm) laser treated burn wounds as compared to the non‐irradiated control and silver sulfadiazine (SSD) ointment (reference care) treated wounds     

Light‐emitting diode therapy in exercise‐trained mice increases muscle performance,cytochrome c oxidase activity,ATP and cell proliferation [J. Biophotonics 8, No. 9, 740–754 (2015)]

In the article by C. Ferraresi et al. (DOI: http://dx.doi.org/10.1002/jbio.201400087 ), published in J. Biophotonics 8 , 740–754 (2015), a statement regarding the approval of some data the authors used is incorrect. This erratum is published to rectify this.     

Which wavelength is optimal for transcranial low‐level laser stimulation?

One of the challenges in transcranial low‐level laser therapy (LLLT) is to optimally choose illumination parameters, such as wavelength. However, there is sparse study on the wavelengths comparison especially on human transcranial LLLT. Here, we employed Monte Carlo modeling and visible human phantom to compute the penetrated photon fluence distribution within cerebral cortex. By comparing the fluence distribution, penetration depth and the intensity of laser‐tissue‐interaction within brain among all candidate wavelengths, we found that 660, 810 nm performed much better than 980, 1064 nm with much stronger, deeper and wider photon penetration into cerebral tissue; 660 nm was shown to be the best and slightly better than 810 nm. Our computational finding was in a surprising accordance with previous LLLT‐neurobehavioral studies on mice. This study not only offered quantitative comparison among wavelengths in the effect of LLLT light penetration effectiveness but also anticipated a delightful possibility of online, precise and visible optimization of LLLT illumination parameters.      

Bio-modulated mice epithelial endometrial organoids by low-level laser therapy serves as an invitro model for endometrial regeneration

Endometrial regeneration is a dynamic process that is not well understood. The destruction of the endometrium with the formation of intrauterine adhesions is known as Asherman’s syndrome. The lesions range from minor to severe adhesions and their impact on pregnancy is well documented. Operative hysteroscopy is the mainstay of diagnosis and treatment of intrauterine adhesions. Nevertheless, the recurrence rates remain high. It was recorded that low-level laser therapy in low doses has a stimulatory effect on different tissues while the high dose produces a suppressive effect. Organoid is a three-dimensional assembly that displays architectures and functionalities similar to in vivo organs that are being developed from human or animal stem cells or organ-specific progenitors through a self-organization process. Our prospective was to study the effect of Low-Level Laser Therapy (LLLT) on mouse epithelial endometrial organoids regarding cell proliferation and endometrial regeneration as a new modality of treatment. An in vitro clinical trial to generate mouse epithelial organoid model and testing LLLT using He:Ne 632.8 nm device on organoids proliferation, function, and their response to ovarian hormones was performed. Trying endometrial regeneration by culturing organoids with decellularized uterine matrix (DUM) and studying the LLLT effect on the regeneration process. LLLT produced a proliferative effect on the epithelial mouse organoids confirmed by Ki67 and PCNA IHC. The organoids could regenerate the epithelial layer of the endometrium in vitro on DUM and LLLT could help in this process. In conclusion, organoids whether control or bio-stimulated proved a new modality to regenerate the endometrium.     

Low-level laser therapy with 850 nm recovers salivary function via membrane redistribution of aquaporin 5 by reducing intracellular Ca2+ overload and ER stress during hyperglycemia

The overall goal is to study the effect of low-level laser therapy (LLLT) on membrane distribution of major water channel protein aquaporin 5 (AQP5) in salivary gland during hyperglycemia. Par C10 cells treated with high glucose (50?mM) showed a reduced membrane distribution of AQP5. The functional expression of AQP5 was downregulated due to intracellular Ca²⁺ overload and ER stress. This reduction in AQP5 expression impairs water permeability and therefore results in hypo-salivation. A reduced salivary flow was also observed in streptozotocin (STZ)-induced diabetic mice model and the expression of AQP5 and phospho-AQP5 was downregulated. Low-level laser treatment with 850?nm (30?mW, 10?min?=?18?J/cm²) reduced ER stress and recovered AQP5 membrane distribution via serine phosphorylation in the cells. In the STZ-induced diabetic mouse, LLLT with 850?nm (60?J/cm²) increased salivary flow and upregulated of AQP5 and p-AQP5. ER stress was also reduced via downregulation of caspase 12 and CHOP. In silico analysis confirmed that the serine 156 is one of the most favorable phosphorylation sites of AQP5 and may contribute to the stability of the protein. Therefore, this study suggests high glucose inhibits phosphorylation-dependent AQP5 membrane distribution. High glucose induces intracellular Ca²⁺ overload and ER stress that disrupt AQP5 functional expression. Low-level laser therapy with 850?nm improves salivary function by increasing AQP5 membrane distribution in hyperglycemia-induced hyposalivation.     

Effects of photobiomodulation on bone defects grafted with bone substitutes: A systematic review of in vivo animal studies

A present, photobiomodulation therapy (PBMT) effectiveness in enhancing bone regeneration in bone defects grafted with or without biomaterials is unclear. This systematic review (PROSPERO, ref. CRD 42019148959) aimed to critically appraise animal in vivo published data and present the efficacy of PBMT and its potential synergistic effects on grafted bone defects. MEDLINE, CCCT, Scopus, Science Direct, Google Scholar, EMBASE, EBSCO were searched, utilizing the following keywords: bone repair; low-level laser therapy; LLLT; light emitting diode; LEDs; photobiomodulation therapy; in vivo animal studies, bone substitutes, to identify studies between 1994 and 2019. After applying the eligibility criteria, 38 papers included where the results reported according to “PRISMA.” The results revealed insufficient and incomplete PBM parameters, however, the outcomes with or without biomaterials have positive effects on bone healing. In conclusion, in vivo animal studies with a standardized protocol to elucidate the effects of PBMT on biomaterials are required initially prior to clinical studies.