Xiao-Yang Xu

Low-intensity laser irradiation improves the mitochondrial dysfunction of C2C12 induced by electrical stimulation.

OBJECTIVE We investigated the effects of electrical stimulation and low-intensity laser (LIL) energy on the mitochondrial function of cultured C2C12 myotubes in order to find a dosage that could be used to improve the function of mitochondria, and then rehabilitate exercise-induced damage and fatigue. BACKGROUND DATA Many other studies in the past demonstrated that LIL had a cytoprotective effect, and a recent study also found that LIL could reduce muscular fatigue during tetanic contractions in rats. METHODS Cultured C2C12 myotubes were subjected to electrical stimulation or/and LIL irradiation at various intensities. Reactive oxygen species (ROS) were detected with a fluorescent probe (DCFH-DA) and mitochondrial function was assessed with an MTT assay. RESULTS The results showed that electrical stimulation at 20 ms, 5 Hz, and 45 V for 75 min can induce mitochondrial dysfunction in cultured C2C12 myotubes. Electrical stimulation-induced mitochondrial dysfunction was improved, but degeneration occurred with LIL at doses of 0.33-8.22 and 11.22-14.16 J/cm2, respectively, and these changes were markedly increased with LIL at 0.33 and 1.34 J/cm2, respectively. CONCLUSIONS We conclude that treatment of myotubes with the proper dosage of LIL irradiation significantly diminished production of ROS and restored mitochondrial function, and this may provide a foundation for the use of photobiomodulation to treat exercise-induced mitochondrial dysfunction or skeletal muscular fatigue.

Photobiomodulation: phenomenology and its mechanism

There are two kinds of pathways mediating cellular photobiomodulation, the specific one is mediated by the resonant interaction of light with molecules such as cytochrome nitrosyl complexes of mitochondrial electron transfer chain, singlet oxygen, hemoglobin or photosensentor such as endogenous porphyrines, the non-specific one is mediated by the non-resonant interaction of light with membrane proteins. Some of specific pathways mediating photobiomodulation can damage membrane or cell compartments such as mitochondria, lysosomes, endoplasmic reticulum by photodynamic damage if the light intensity is very high so that photodynamic damage will limit the maximum intensity of the light of photobiomodulation although the non-specific pathways mediating photobiomodulation might not damage cells. As the reciprocity law, the rule of Bunsen and Roscoe, was not obeyed for almost all the studied photobiomodulation, and the light energy reaps the greatest benefit where it is most needed, photobiomodulation was thought to be dominantly mediated by the non-specific pathways although the specific pathways can act as a role, which is supported by the dose relationship research in which the photobiomodulation effects were found to be the SIN function of radiation time in many works on the dose relationship when the intensity is kept constant. The non-specific pathways were mainly mediated by membrane receptors and the ultraweak non-resonant interaction of light with membrane receptors can be physically amplified by the coherent state of membrane receptors and then chemically exemplified by signal transduction according to our biological information model of photobiomodulation supported by its successful cellular, animal and clinic applications.

Changes of Myogenic Reactive Oxygen Species and Interleukin-6 in Contracting Skeletal Muscle Cells

The aim of this study was to measure changes in myotube reactive oxygen species (ROS) and the production of interleukin (IL)-6 in electrically stimulated mouse C2C12 skeletal muscle cells. After five days of differentiation, myotubes were stimulated using an electrical stimulator set at 45 V at a frequency of 5 Hz, with a pulse width of 20 ms. Acute stimulations were performed for 45, 60, 75, 90, or 120 min in each dish. ROSs were detected in the extracted cells directly using a fluorescent probe. IL-6 mRNA expression in C2C12 myotubes and IL-6 concentration in C2C12 myotube supernatants were determined using real-time PCR and ELISA, respectively. Compared with control cells, ROS generation was significantly increased at 45 min after the onset of stimulation (P < 0.01) and continued to increase, reaching a maximum at 120 min. IL-6 mRNA expression and IL-6 concentration in C2C12 cells were significantly increased after 75 min (P < 0.01) and 120 min (P < 0.05) of electrical stimulation (ES) compared with the control cells. Our data show that a specific ES intensity may modulate ROS accumulation and affect IL-6 gene expression in contracting skeletal muscle cells.

Reactive Oxygen Species Mediated Generalized Photobiomodulation

Photobiomodulation (PBM) is a modulation of monochromatic light or laser irradiation (LI) on biosystems, which stimulates or inhibits biological functions but does not result in irreducible damage. The PBM of low intensity LI (LIL), ~10 mW/cm2, moderate intensity LI (MIL), 102-3 mW/cm2, high intensity LI (HIL), ~10 W/cm2, and photodynamic effect (PDE) are called LPBM, MPBM, HPBM and PPBM, respectively. All of them are called generalized PBM (GPBM). Intravascular low energy laser therapy is just an intravascular MPBM. MPBM, HPBM and PPBM are mediated by reactive oxygen species (ROS). Their mitogen-activated protein kinase (MAPK) signaling pathways and homeostatic regulation are decided by intracellular ROS level so that they can be used in clinic applications such as microbial killing and cancer therapy.

PHOTOBIOMODULATION ON SPORTS INJURIES

Sports injuries healing has long been an important field in sports medicine. The stimulatory effects of Low intensity laser (LIL) irradiation have been investigated in several medical fields, such as cultured cell response, wound healing, hormonal or neural stimulation, pain relief and others. The aim of this study was to evaluate whether LIL irradiation can accelerate sports injuries healing. Some experimental and clinical studies have shown the laser stimulation effects on soft tissues and cartilage, however, controversy still exists regarding the role of LIL when used as a therapeutic device. Summarizing the data of cell studies and animal experiments and clinic trials by using the biological information model of photobiomodulation, we conclude that LIL irradiation is a valuable treatment for superficial and localized sports injuries and that the injuries healing effects of the therapy depend on the dosage of LIL irradiation.

Health-promoting low level laser therapy

Homeostasis is a classical concept of physiology, and will be developed into function-specific homeostasis (FSH) in this paper. FSH is a negative-feedback response of a biosystem to maintain the function-specific conditions inside the biosystem. Let Q be the quality of a FSH. A person might simultaneously have many kinds of FSH, {FSHi, i = 1, 2,... n}, and then has {Qi, i = 1, 2,...,n}. Let Qmax=max{Qi, i = 1, 2,...n}. Qmax represents the health level, and might be enhanced by training. An individual system might be classified as FSH-essential subsystems (FESs) and FSH-non-essential subsystems (FNSs) which homeostasis can be written as FESHs and FNSHs for short, respectively. The training to establish a new FSH can also be classified as extraordinary training (ET) and ordinary training (OT). ET disrupts the present FSH and establishes FESHs. OT maintains FESHs and establishes FNSHs and then a new FSH, and then maintains the new FSH. The cellular rehabilitation of low level laser irradiation or monochromatic light might promote the establishment of FESHs, FNSHs and then FSH, shorten ET or OT period and then promote health.

Photobiomodulation on Muscle Regeneration

Photobiomodulation (PBM) is a modulation of monochromatic light or laser irradiation (LI) on biosystems, which stimulates or inhibits biological functions but does not result in irreducible damage. As photonic approaches suggested to enhance muscle restoration, the PBM of low intensity LI (LIL), ~10 mW/cm2, moderate intensity LI (MIL), 102~3 mW/cm2, and photodynamic effect (PDE) on muscle regeneration have been reviewed in vitro and in vivo from the viewpoints of homeostatic regulation, respectively.

Cellular rehabilitation of photobiomodulation

Homeostasis is a term that refers to constancy in a system. A cell in homeostasis normally functions. There are two kinds of processes in the internal environment and external environment of a cell, the pathogenic processes (PP) which disrupts the old homeostasis (OH), and the sanogenetic processes (SP) which restores OH or establishes a new homeostasis (NH). Photobiomodualtion (PBM), the cell-specific effects of low intensity monochromatic light or low intensity laser irradiation (LIL) on biological systems, is a kind of modulation on PP or SP so that there is no PBM on a cell in homeostasis. There are two kinds of pathways mediating PBM, the membrane endogenetic chromophores mediating pathways which often act through reactive oxygen species, and membrane proteins mediating pathways which often enhance cellular SP so that it might be called cellular rehabilitation. The cellular rehabilitation of PBM will be discussed in this paper. It is concluded that PBM might modulate the disruption of cellular homeostasis induced by pathogenic factors such as toxin until OH has been restored or NH has been established, but can not change homeostatic processes from one to another one.

Photobiomodulation on senescence

Photobiomodulation (PBM) is an effect oflow intensity monochromatic light or laser irradiation (LIL) on biological systems. which stimulates or inhibits biological functions but does not result in irreducible damage. It has been observed that PBM can suppress cellular senescence, reverse skin photoageing and improve fibromyalgia. In this paper, the biological information model of photobiomodulation (BIMP) is used to discuss its mechanism. Cellular senescence can result from short, dysfunctional telomeres, oxidative stress, or oncogene expression, and may contribute to aging so that it can be seen as a decline of cellular function in which cAMP plays an important role, which provide a foundation for PBM on senescence since cellular senescence is a reasonable model of senescence and PBM is a cellular rehabilitation in which cAMP also plays an important role according to BIMP. The PBM in reversing skin photoageing and improving fibromyalgia are then discussed in detail.

Photobiomodulation in athletic training

Photobiomodulation (PBM) has been mainly used in athlete trauma care. In this paper, the possible applications of PBM in athlete medical care to maintain pro-oxidant-antioxidant homeostasis and in athlete trauma care to treat osteoarthritis and delayed onset of muscular soreness (DOMS) have been discussed. In order to maintain pro-oxidant-antioxidant homeostasis, PBM might be used in an intravascular way, in an endonasal way or in a directly irradiated way. DOMS was supposed to have three phases, z-line disruption, proteolysis of damaged proteins and protein synthesis for myofibril remodeling, each of which might have its own optimum dose of PBM.