Comparative effects of two different doses of low‐level laser therapy on wound healing third‐degree burns in rats

Abstract

Burns are injuries caused by direct or indirect contact to chemical, physical, or biological agents. Low-level laser therapy (LLLT) is a promising treatment since it is low-cost, non-invasive, and induces cell proliferation. This study aimed to investigate the effects of LLLT (660 nm) at two different fluences (12.5 J/cm(2) and 25 J/cm(2) ) per point of application on third-degree burns in rats. Thirty rats (Wistar) divided into GC, GL12.5, and GL25 were used in the study, and submitted to burn injury through a soldering iron at 150°C, pressed on their back for 10 s. LLLT was applied immediately, and 2, 4, 6, and 8 days after wound induction. Histological analysis revealed a decreased inflammatory infiltrate in the group treated with 25 J/cm(2) , and intense inflammatory infiltrate in the control group and in the group treated with 12.5 J/cm(2) . The immunostaining of COX-2 was more intense in the control groups and in the group treated with 12.5 J/cm(2) than in the group treated with 25 J/cm(2) . Conversely, VEGF immunomarking was more expressive in the group treated with 25 J/cm(2) than it was in the other two groups. Therefore, our findings suggest that the use of 25 J/cm(2) and 1 J of energy was more effective in stimulating the cellular processes involved in tissue repair on third-degree burns in rats by reducing the inflammatory phase, and stimulating angiogenesis, thus restoring the local microcirculation which is essential for cell migration.

Effect of photobiomodulation associated with cell therapy in the process of cutaneous regeneration in third degree burns in rats

“…Due to the complexity involved in the healing process of total thickness burns, the most commonly used treatment is graft surgery, however, by observing unsatisfactory esthetic and functional results due to rejection and/or tissue contraction, as well as the reduction of local vascularization. Thus, the literature has been seeking alternative ways to treat this type of injury, highlighting that the combination of resources may benefit the conventional treatments already used, such as graft surgery for large burns (Rasulov et al, 2005), as well as providing effective treatments for these lesions to a lesser extent to ensure tissue reconstruction that resembles the characteristics of healthy tissue (Brassolatti et al, 2016; Caliari‐Oliveira et al, 2016; Trajano et al, 2015; Zhang et al, 2007).…”

The photobiomodulation (658, 830 and 904nm) on wound healing in histomorphometric analysis

“…In fact, -2021876821 in vitro research shows a greater proliferation of cells with laser in the red spectrum, visible, with radiation of 1 to 3 J/cm 2 , while the laser in the infrared spectrum showed no positive or potential negative effect on proliferation cell [35]. Moreover, according to Brassolatti et al [36], the 660 nm laser is able to stimulate the cellular production of areas with third degree burn injuries, contributing to the tissue regeneration process.…”

Alternative animal model for studies of total skin thickness burns

“…Among the various experimental burn models currently found in the literature are: the hot water model 13,14 , a model using electricity 15 and the experimental model with incandescent instruments [16][17][18] . However, the first two models cited are not considered adequate procedures to produce burns, as they limit the control of the area to be burned, impairing both treatment and evaluations 15 .…”

“…Several works using aluminum coupled to the soldering iron have been presented as an effective method for the reproduction of the experimental model of third degree burns 8,9,[16][17][18][19] , but there is a great discrepancy in the temperature used, which may vary from 100ºC to 200ºC, in addition to the time of application that varies between 5 to 30 seconds. Caliari-Oliveira et al…”

“…Brassolatti et al 18 presented a study in which the experimental model of third degree burn was carried out through an aluminum plate coupled to a soldering iron, but the temperature used was significantly lower, being 150ºC with application on the back of the animal for 10 seconds, demonstrating that it is not necessary to use very high temperatures to perform this type of injury. The literature also shows lower temperatures, 100°C 16,19 and 130°C, using the model with soldering iron for the reproduction of third degree burns, but several other studies have used these temperatures with different exposure times, in order to perform 20,21 , thus generating disagreement regarding the morphological results that characterize the involvement of the tissue thickness.…”