Pulsed LLLT improves tendon healing in rats: a biochemical, organizational, and functional evaluation

Abstract

In the last decades, the tendon injuries have increased substantially. Previous results suggested that low-level laser treatment (LLLT) promotes synthesis of extracellular matrix and improves the functional properties of the tendon. The aim of this study was to evaluate the effects of different protocols of LLLT on partially tenotomized tendons. Adult male rats were divided into the following: G1-intact, G2-injured, G3-injured + LLLT (4 J/cm(2) continuous), G4-injured + LLLT (4 J/cm(2) at 20 Hz). G2, G3, and G4 were euthanized 8 days after injury. G5-injured, G6-injured + LLLT (4 J/cm(2) continuous), and G7-injured + LLL (4 J/cm(2) at 20 Hz until the seventh day and 2 kHz from 8 to 14 days). G5, G6, and G7 were euthanized on the 15th day. Glycosaminoglycan (GAG) level was quantified by dimethylmethylene blue method and analyzed on agarose gel. Toluidine blue (TB) stain was used to observe metachromasy. CatWalk system was used to evaluate gait recovery. Collagen organization was analyzed by polarization microscopy. The GAG level increased in all transected groups, except G5. In G6 and G7, there was a significant increase in GAG in relation to G5. In G3 and G4, the presence of dermatan sulfate band was more prominent than G2. TB stains showed intense metachromasy in the treated groups. Birefringence analysis showed improvement in collagen organization in G7. The gait was significantly improved in G7. In conclusion, pulsed LLLT leads to increased organization of collagen bundles and improved gait recovery.

Green tea and glycine aid in the recovery of tendinitis of the Achilles tendon of rats

“…Regarding MMP-9, the absence of significant differences between the groups after 7 and 21 days was most likely due to high enzyme activity at the beginning of acute or chronic inflammations (37,47,50,51). Only a low level of activity was observed at seven days, and an even lower level was found after 21 days.…”

“…Under injury, collagen fibers lose their organization and appear darker when viewed under a polarizing microscope (51). High birefringence values were found in group G2 and G3, indicating a better organization of collagen bundles at seven days after treatment.…”

“…However, in this study, positive changes were observed when GT was administered together with a glycine diet. Our group has searched for different therapies, such as the use of a low level laser (8,51), electroacupuncture (45) and plant extracts (46,57), to improve the structure of the Achilles tendon, considering biochemical and structural elements after partial rupture. These alternatives mainly aim to accelerate tissue healing because the tendon shows low vascularity and cellularity, which directly influences the tissue remodeling and recovery time.…”

Low‐level laser and adipose‐derived stem cells altered remodelling genes expression and improved collagen reorganization during tendon repair

“…No differences were observed in the expression of Tgfb1 among groups, but the higher concentration of IL-10 in the SC group corroborates the Our results do not demonstrate differences in the amount of TNF-α in the different groups, although the literature describes the anti-inflammatory role of LLL 38 and ASCs. 7,30,44 Low-level laser-treated group presented a larger organization of the fibres, followed by the SCL, SC and T groups. Significant differences between groups marked with the same letter (P < 0.05).…”

“…5 There is a growing search for methodologies that aim to stimulate the proliferation and differentiation of native tendon MSCs during the repair process. 7 Low-level laser therapy promotes tissue repair mainly due to its anti-inflammatory effect, but also has a mitogenic potential. 6 The photobiostimulation promoted by the low-level laser (LLL) has attracted the attention of researchers in recent years, already being used in clinical practice for the treatment of tendinous and post-operative injuries, accelerating the repair process, with the improvement of the tissue reorganization.…”