he application of LED in the medical field (Bum and Plastic Surgery, Xi'an Railway Central Hospital, Xi'an, Shaanxi 710054) [Abstract] This article reviews the research and application of light-emitting diodes (LED) in animal models and clinical medicine in recent years, including LED applications in animal cells And the research of human tissue cells, the research of LED application in animal models, and the experimental research of LED in clinical treatment. Looking forward to the prospects of LED applications in clinical treatment. [Keywords] LED phototherapy cell animal clinical light-emitting diode (1ight  emitting  diode, LED) drive circuit is easy to control, long service life, low price. With the continuous development of semiconductor technology, LEDs have greatly improved the performance of parameters such as luminous intensity, peak wavelength, and half-wave bandwidth. At this stage, the light effect of a single LED has exceeded 1001mW; the peak wavelength is more and more stable, the half-wave bandwidth is narrower, and the monochromatic performance is good; the directivity is good; covering wavelengths from ultraviolet to infrared, monochromatic LEDs of almost any wavelength can be found. These characteristics provide a technical basis for LED applications in the medical field. This article summarizes the work that LED has done in the medical field, and looks forward to the application prospects of LED in the biomedical field.

1    Research on the effect of LED on animal tissue cells. Whelan et al. irradiated cells cultured in vitro with LEDs of different wavelengths and irradiation doses. For example, 688nm LEDs were used for human normal epithelial cells, and they were measured after being irradiated with a dose of 4J/cm2. Cell reproduction increased by 55% to 71% compared to the control group. Whelan extracted fibroblasts from Sprague Dawley mouse skin and irradiated them with 670nm  LEDs at a dose of 4J/cm2. Osteoblasts (MC3T3-E1) were extracted from mouse bones, using 670nm, 728nm and 880nm LEDs, respectively. With 4J/cm2 agent

The percentage increase of DNA synthesis in fibroblasts and osteoblasts compared with the control group was measured on the second day after irradiation. It was found that the percentage of increase in DNA synthesis in cells after LED irradiation was significantly increased, and the percentage of The percentage of days is increasing.  

  Liu Jiang et al. cultured mouse skeletal muscle C2C12 cells with different concentrations of simvastatin, and then irradiated them with red LEDs of varying intensity [wavelength (640±15)nm] for 2d, 15 min/d. Cell proliferation was evaluated by methylthiazolyltetrazole colorimetry. The results showed that the proliferation of C2C12 cells in the experimental group with a simvastatin concentration of 2.0×10-5mol/L was inhibited, and this inhibition could be antagonized by the photobiological regulation of red LEDs [1]. It was further confirmed that the photobiomodulation effect only regulates abnormally functioning cells or tissues, and has no effect on normal functioning tissues or cells.         

   For canine neuroma cells (2A9) and human glioblastoma cells (U373) cultured in vitro, Lutetium Texaphyrin  (Lutex, absorption peak 740nm ) and Benzoporphyrin Derivative (BPD, absorption peak 690nm ) are used as photosensitizers, and PDT method is used In the experiment of killing tumor cells, when LEDs with emission peaks at 728nm and 680nm  were used as light sources, 50% to 86% of cancer cells in the two cell lines were killed.          

2    LED in the treatment of animal body research           Whelan conducted LED rehabilitation phototherapy on traumatized hyperglycemic rats, and conducted research on the changes in gene expression. The drug was implanted under the skin of the mouse's back, and LED light therapy was performed every day. Finally, the skin was cut to remove the drug sponge to extract RNA, and then the eDNA array was used for analysis. The results show that: relative to samples without phototherapy, gene regeneration is obvious in the sample tissues after phototherapy. LED light therapy can accelerate the healing process of natural wounds, so that patients can quickly return to the level of activity before the disease.       Li Fengmin and others used blue-violet light with a wavelength of 380-460nm, a peak of 410 nm, and an output power of 40 mW to irradiate burn and trauma rat models with an irradiation distance of 8 cm and a spot diameter of 65 mm.

 3 The irradiation dose per time is 0.72 J/cm2, 10 min, and the irradiation starts on the first day after surgery, once a day, for 12 d. Experiments show that blue-violet light in this wavelength range can significantly increase the hydroxyproline content in the skin tissue of burn wounds in rats, thereby promoting the growth of granulation tissue and wound healing, and improving the tensile strength of healed wounds. Blue-violet light irradiation can increase the phagocytic rate and phagocytic index of peritoneal phagocytic cells in burn rats, that is, increase the phagocytic ability of rat peritoneal phagocytic cells to improve the body's immunity and promote wound healing [2].

 3  LED's research in clinical medical experiments      

    3.1 Acne treatment Acne is a common sebaceous gland disease, with an incidence rate of up to 80% in adolescents. Excessive sebum secretion and proliferation of Propionibacterium acnes are the main causes of the disease. At present, local and systemic treatments are mainly based on antibiotics and isotretinoin drugs. However, the use of antibiotics can cause P. acnes resistance, and isotretinoin drugs can have obvious side effects, which limits clinical application. LED blue light with a wavelength of about 415 nm can cause the endogenous porphyrins (mainly protoporphyrin IV and coproporphyrin III) of anaerobic P. acnes to undergo photochemical reactions to produce singlet oxygen. Thereby killing bacteria and achieving the effect of curing acne. LED blue light therapy is safe and effective without the drug resistance and side effects of traditional treatments.          

   3.2  Treatment of neonatal jaundice        

 The typical application of LED blue light therapy is the treatment of neonatal jaundice. The light that bilirubin can absorb is best with a wavelength of 450-460nm, and the main peak of the blue light wavelength of LED is between 425-475nm , and it is still the best light source for phototherapy. Zhao Xinchun and others randomly divided 120 neonates clinically diagnosed with hyperbilirubinemia into

In the LED phototherapy group and the luminal group, experimental observation results: the clinical effective rate of the LED blue light therapy group was 83.3%, and the clinical effective rate of the luminal group was 33.3%. Obviously, LED blue light irradiation is safer and more effective for neonatal jaundice.          

3.3   Wound healing treatment  According to the research results of low-energy laser on wound healing, many companies have launched products that use LEDs to promote wound healing and tissue healing, and have done a lot of clinical research, and have obtained satisfactory results. Whelan et al. in animal body research and cell research believed that LED irradiation can make human muscle and skin cells grow at a five times normal speed. The research was conducted by the Wisconsin-Madison School of Medicine Midwest Athletes Against Childhood Cancer (MACC) Foundation Research Center. The FDA has approved the team led by WHELAN to conduct clinical trials on the experimental treatment of LED, and the results of the wound recovery are satisfactory. At the same time, Whelan's research is also used in tissue healing in a gravity-free environment, applying this technology to long-distance and long-term space travel to treat astronauts injured. In addition, this technology was also used in an American submarine equipped with a set of LED arrays to treat potential training injuries. 3.4 Increase the body's endurance and anti-fatigue ability Jia Danbing et al. After irradiating with red light with a wavelength of 600nm-1200nm from LEDs, they detected the content of myocardial enzyme spectra, blood coagulation series and blood routine related molecules, and studied the effects of red light on the human body's anti-fatigue ability and The impact of endurance. Results Compared with the control group, the contents of HB, IBC and Ca  in the experimental group were significantly increased after red light irradiation, and other indicators were not significantly changed. HB and Rt3C played an important role in tissue oxygen supply. In the process of body exercise, by improving the tissue's hypoxia tolerance, reducing tissue anaerobic metabolism and reducing the production of lactic acid during exercise, the body's soreness and fatigue under the same intensity of exercise can be significantly reduced, and the body's endurance and resistance Fatigue ability. The experiment showed through self-control and inter-group control studies: the content of HB and  5  was significantly increased after red light irradiation compared with before irradiation. Although this experiment did not find significant changes in platelets, the changes in HB and RBC content further confirmed the red light. After light irradiation, the blood's oxygen-carrying capacity is obviously increased, and the body's endurance and anti-fatigue ability are increased.          

3.5  Oral ulcer inflammation treatment       

For some pediatric patients with leukemia, before implanting the bone marrow that matches their cell antigens, they must receive the maximum dose of radiochemical therapy to kill the neoplastic bone marrow in their body. Chemotherapy drugs and radiotherapy will not be added. Differentiately kill fast dividing cells, such as oral mucosal cells and gastrointestinal cell lines. These chemotherapy patients often cause acute oral ulcers, leading to dysphagia and severe gastrointestinal reactions. Using LEDs with a wavelength of 688nm , after the last chemotherapy, they received 4J/cm2 of LED radiation dose. Among the 30 patients treated with LEDs, 47%  had alleviated oral pain, and their oral ulcers were cured more than expected Better.         

 3.6   Treatment of seasonal depression        

 One of the best ways to overcome seasonal depression is to use light. Light can stimulate the retina, and the retina transmits this stimulus information to the nervous system, and then to the light-sensitive melatonin in the brain. Melatonin plays an extremely important role in adjusting the body's circadian rhythm. In patients with seasonal depression, the secretion of melatonin will increase. Since full-spectrum light can reduce the secretion of melatonin, it is very effective to treat SAD patients with light. Green light (wavelength 540nm) is the most obvious spectrum for inhibiting melatonin secretion. In 1991, IBERMAN mentioned that LEWY believed that irradiating white light with an intensity of 10mW for 30 minutes after getting up every day can inhibit the secretion of melatonin and relieve seasonal depression. This observation is not only very important for understanding the physiological results of melatonin, but also helps to regulate the secretion rhythm.

 6 SAD and other health problems. At present, related patents for the application of LEDs have been applied, and the content is for light therapy for various physiological and mental disorders, such as light therapy for SAD.

[References] Photobiological regulation of C2C12 cell proliferation by red light-emitting diode irradiation [J]. Chinese Clinical Rehabilitation, 2006, l0(13): 107-109

The effect of blue-violet light on the healing of rat skin wounds and burns. Chinese Journal of Physiotherapy[J].2001,24(5):294-295.

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Source: Queendom Technology Co., Ltd. Author: JACKY Date: 22 May 2020     http://www.china66.net