Analysis of the effect of phototherapy in model with traumatic Achilles tendon injury in rats

Abstract

The aim of this study was to investigate the effect of low-intensity laser (LILT) infrared (830 nm) therapy in tendon inflammation, tendinitis induced by mechanical trauma in rat Achilles tendon. For this, we used 65 young male Wistar rats, weighing ± 300 g divided into different groups: C = control (n = 5) and experimental (n = 10/group), with two different times of sacrifice such as treated with L = laser, D = treated with diclofenac, and T = untreated injured. The tendon inflammation was induced by controlled contusion in the medial region of the Achilles tendon of the animals. The treated groups received some kind of intervention every 24 h, all groups were sacrificed on the 7th or 14th day after the trauma. The tendons were dissected, extracted, and sent for analysis. Histological analysis of the L group showed a decrease in the number of inflammatory cells in relation to other groups in both periods studied. The comparative results between the number of inflammatory cells in the control and treated groups at 7 and 14 days showed statistically significant differences. Qualitative analysis findings obtained by the picrosirius red technique under polarized light showed that in 7 days, the T group presented collagen types I and III in the same proportion; group D presented a predominance of type III fibers, while in group L, type I collagen predominated. The 14-day group D showed collagen types I and III in the same proportion, while in group L, there was a predominance of type I fibers. Biomechanical analysis showed that 7-day groups L and C showed similar stiffness and increased breaking strength. The 14-day groups L and C showed greater rupturing strength as well as increased stiffness angle. Group D showed a decrease of maximum traction strength and degree of rigidity. It was concluded that treatment with LIL in the parameters used and the times studied reduces migration of inflammatory cells and improves the quality of repair while reducing the functional limitations.

Effect of low‐level laser therapy on chemoradiotherapy‐induced oral mucositis and salivary inflammatory mediators in head and neck cancer patients

“…Experimental studies have shown that, in both in vitro and in vivo conditions, LLLT can modulate the responses of tissue repair , as well as the levels of pro‐inflammatory and anti‐inflammatory cytokines . To date, no clinical trials have investigated the biologic modulation of inflammatory mediators by LLLT in the prevention or treatment of chemoradiotherapy‐induced OM.…”

Phototherapy With LED Light Modulates Healing Processes in an In Vitro Scratch-Wound Model Using 3 Different Cell Types

“…Photostimulation with laser light enhanced neovascularization in damaged Achilles tendons and stimulated the growth of the trabecular area in a rat model. 8,9 The majority of these studies, however, were performed with lasers in the red or near-infrared spectrum. Laser devices may cause significant patient discomfort, continue to be expensive, can produce heat, and apply light only on a narrow spot.…”

Second messengers mediating the proliferation and collagen synthesis of tenocytes induced by low-level laser irradiation

“…For instance, Guerra et al found increased type III collagen production in rat Achilles tendons 8 days after stimulation with pulsed low-level laser [6]. However, on the contrary, Casalechi et al reported type I collagen predominated over type III collagen in rat Achilles tendon 7 and 14 days after low-intensity laser treatment [3]. Wood et al also found that ultrasound, LLLT, and the combined use of LLLT and ultrasound resulted in greater synthesis of type I collagen (but not type III collagen) [25].…”

“…Some controlled clinical studies were performed using different laser types and dosages to delineate the role of laser phototherapy in the management of tendon injuries, such as lateral elbow and Achilles tendinopathy [2]. Several studies using animal models showed that LLLT could improve healing of tendons by improving organization or synthesis of collagen, increasing matrix metalloproteinase (MMP) activity, and preventing oxidative stress [3][4][5][6]. Although those studies have demonstrated the potential of LLLT in the facilitation of the tendon healing process, the understandings of the underlying molecular and biochemical mechanisms remain to be limited.…”