Comparison of Photobiomodulation and Anti-Inflammatory Drugs on Tissue Repair on Collagenase-Induced Achilles Tendon Inflammation in Rats.

BACKGROUND: Tendinopathy is characterized by pain, edema, and structural changes in tendon tissue. OBJECTIVE: In this animal study we decided to compare the short- and medium-term effects of low-level laser therapy (LLLT), dexamethasone, and diclofenac on inflammation and tendon tissue repair in collagenase-induced tendinitis. MATERIALS AND METHODS: Two hundred five female Wistar rats were randomly divided into five groups. Animals in the control group were given a saline injection and the experimental groups received a collagenase injection (100 µg/tendon) in the peritendinous Achilles and received no treatment, LLLT (3 J, 810 nm, 100 mW), diclofenac (1.1 mg/kg), or dexamethasone (0.02 mg/kg). Histological analyses were performed at 10 time points up to 60 days (n = 5/group each time point), and included an assessment of the severity of inflammation, collagen fiber content, and organization. RESULTS: Collagenase injection induced a severe inflammatory reaction with significant reduction in collagen content for 48 h, and disorientation of collagen fibers lasting between 14 and 21 days. Diclofenac and dexamethasone reduced inflammatory signs during the first 2 days, although there was prolongation of the inflammatory phase and slower normalization of tendon quality, particularly in the dexamethasone group. LLLT prevented hemorrhage, reduced inflammation severity, and preserved tendon morphology compared with the other groups. CONCLUSIONS: LLLT showed a significant superiority over commonly used anti-inflammatory pharmaceutical agents in acute collagenase-induced tendinitis.

Low-level laser irradiation (InGaAlP-660 nm) increases fibroblast cell proliferation and reduces cell death in a dose-dependent manner.

BACKGROUND AND OBJECTIVE: Impaired cell metabolism and increased cell death in fibroblast cells are physiological features of chronic tendinopathy. Although several studies have shown that low-level laser therapy (LLLT) at certain parameters has a biostimulatory effect on fibroblast cells, it remains uncertain if LLLT effects depend on the physiological state. STUDY DESIGN/MATERIAL AND METHODS: High-metabolic immortal cell culture and primary human keloid fibroblast cell culture were used in this study. Trypan blue exclusion and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test were used to determine cell viability and proliferation. Propidium iodide stain was used for cell-cycle analysis by flow cytometry. Laser irradiation was performed daily on three consecutive days with a GaAlAs 660-nm laser (mean output: 50 mW, spot size 2 mm(2), power density =2.5 W/cm(2)) and a typical LLLT dose and a high LLLT dose (irradiation times: 60 or 420 s; fluences:150 or 1050 J/cm(2); energy delivered: 3 or 21 J). RESULTS: Primary fibroblast cell culture from human keloids irradiated with 3 J showed significant proliferation by the trypan blue exclusion test (p < 0.05), whereas the 3T3 cell culture showed no difference using this method. Propidium iodide staining flow cytometry data showed a significant decrease in the percentage of cells being in proliferative phases of the cell cycle (S/g(2)/M) when irradiated with 21 J in both cell types (hypodiploid cells increased). CONCLUSIONS: Our data support the hypothesis that the physiological state of the cells affects the LLLT results, and that high-metabolic rate and short- cell-cycle 3T3 cells are not responsive to LLLT. In conclusion, LLLT with a dose of 3 J reduced cell death significantly, but did not stimulate cell cycle. A LLLT dose of 21 J had negative effects on the cells, as it increased cell death and inhibited cell proliferation.

Low-Level Laser Irradiation (InGaAlP-660 nm) Increases Fibroblast Cell Proliferation and Reduces Cell Death in a Dose-Dependent Manner

Background and Objective: Impaired cell metabolism and increased cell death in fibroblast cells are physiologicalfeatures of chronic tendinopathy. Although several studies have shown that low-level laser therapy (LLLT) atcertain parameters has a biostimulatory effect on fibroblast cells, it remains uncertain if LLLT effects depend on thephysiological state. Study Design/Material and Methods: High-metabolic immortal cell culture and primaryhuman keloid fibroblast cell culture were used in this study. Trypan blue exclusion and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test were used to determine cell viability and proliferation. Propidiumiodide stain was used for cell-cycle analysis by flow cytometry. Laser irradiation was performed daily onthree consecutive days with a GaAlAs 660-nm laser (mean output: 50mW, spot size 2mm2, power density»2.5W=cm2) and a typical LLLT dose and a high LLLT dose (irradiation times: 60 or 420 s; fluences:150 or1050 J=cm2; energy delivered: 3 or 21 J). Results: Primary fibroblast cell culture from human keloids irradiated with3 J showed significant proliferation by the trypan blue exclusion test ( p<0.05), whereas the 3T3 cell cultureshowed no difference using this method. Propidium iodide staining flow cytometry data showed a significantdecrease in the percentage of cells being in proliferative phases of the cell cycle (S=g2=M) when irradiated with 21 Jin both cell types (hypodiploid cells increased). Conclusions: Our data support the hypothesis that the physiologicalstate of the cells affects the LLLT results, and that high-metabolic rate and short- cell-cycle 3T3 cells are notresponsive to LLLT. In conclusion, LLLT with a dose of 3 J reduced cell death significantly, but did not stimulatecell cycle. A LLLT dose of 21 J had negative effects on the cells, as it increased cell death and inhibited cellproliferation.