Effect of 670 nm laser photobiomodulation on vascular density and fibroplasia in late stages of tissue repair.

This study aimed to investigate the effects of gallium-aluminum-arsenium (GaAlAs) (670 nm) laser therapy on neoangiogenesis and fibroplasia during tissue remodelling. Forty male Wistar rats underwent cutaneous surgery and were divided into 2 experimental groups: the Control and Laser group (9 mW, 670 nm, 0.031 W/cm2 , 4 J/cm2 ). After 14, 21, 28, and 35 days, the animals were euthanised. Descriptive and quantitative analyses were performed in sections stained with haematoxylin-eosin and Sirius Red, respectively. The amounts of VEGF+ and CD31+ cells were evaluated by immunohistochemistry and histomorphometric analysis, respectively. Statistical analysis was performed using the Mann-Whitney, Friedman, and Spearman correlation test, P < 0.05. The collagen expression was significantly higher in the laser group compared with the control group on days 14 and 21 after the creation of the skin wound (P = 0.008; P = 0.016) and in the control group between 14 and 28 and 14 and 35 days (P = 0.001; P = 0.007). There were more blood vessels in three periods of the study only in the (Laser) treated group, with statistical significance at day 14 (P = 0.016). There was no statistically significant difference in VEGF+ cell count in the different experimental groups throughout the study, although a positive correlation was shown with the area of collagen on days 14 and 28 (P = 0.037). Laser treatment had a positive effect in the late course of healing, particularly with regards to collagen expression and the number of newly formed vessels. VEGF+ cells were present in both experimental groups, and VEGF appeared to influence fibroplasia in the treated group.

Influence of laser (λ670 nm) and dexamethasone on the chronology of cutaneous repair.

OBJECTIVE: This study aimed to assess the effect of LLLT associated with and without dexamethasone on inflammation and wound healing in cutaneous surgical wounds. BACKGROUND: Limited studies are directed at the possible interference of laser photobiomodulation on the formation of myofibroblasts, associated with an antiinflammatory drug. METHODS AND MATERIALS: Standard skin wounds were performed on 80 Wistar rats, distributed into four groups: no treatment (sham group), laser only (λ670 nm, 9 mW, 0.031 W/cm(2), 4 J/cm(2), single dose after surgery), dexamethasone only (2 mg/kg 1 h before surgery), and laser with dexamethasone. Tissue was examined histologically to evaluate edema, presence of polymorphonuclear, mononuclear cells, and collagen. The analysis of myofibroblasts was assessed by immunohistochemistry and transmission electron microscopy. The intensity was rated semiquantitatively. RESULTS: The results showed that laser and dexamethasone acted in a similar pattern to reduce acute inflammation. Collagen synthesis and myofibroblasts were more intense in the laser group (p = 0.048), whereas animals treated with dexamethasone showed lower results for these variables. In a combination of therapies, the synthesis of collagen and actin and desmin-positive cells was less than laser group. CONCLUSIONS: Laser was effective in reducing swelling and polymorphonuclear cells and accelerated tissue repair, even in the presence of dexamethasone.

Effect of 670-nm laser therapy and dexamethasone on tissue repair: a histological and ultrastructural study.

OBJECTIVE: In this study we investigated the role of extracellular matrix elements and cells during the wound healing phases following the use of low-level laser therapy (LLLT) and anti-inflammatory drugs. BACKGROUND DATA: There are few scientific studies that characterize the possible interactions of LLLT and anti-inflammatory medications. MATERIALS AND METHODS: Thirty-two rats submitted to a wound inflicted with a 6-mm-diameter punch. The animals were divided into four groups: sham treated, those treated with the GaAlAs laser (4 J/cm(2), 9 mW, lambda = 670 nm, spot size 28.27 x 10(2) cm(2)), those treated with dexamethasone (2 mg/kg), and those treated with both LLLT and dexamethasone. After 3 and 5 d, the cutaneous wounds were assessed by histopathology using polarized light and ultrastructural assessment using transmission electron microscopy. Changes seen in polymorphonuclear inflammatory cells, edema, mononuclear cells, and collagen fiber deposition were semi-quantitatively evaluated. RESULTS: The laser-treated group demonstrated increased collagen content and better arrangement of the extracellular matrix (p < 0.05). Fibroblasts in these tissues were increased in number and were more synthetically active. In the dexamethasone group, the collagen was shown to be non-homogenous and disorganized, with a scarcity of fibroblasts. In the group treated with both types of therapy, fibroblasts were more common and they exhibited vigorous rough endoplasmic reticulum, but they had less collagen production compared to those seen in the laser group. CONCLUSION: LLLT alone accelerates post-surgical tissue repair and reduces edema and the polymorphonuclear infiltrate even in the presence of dexamethasone.

Action of low-level laser therapy on living fatty tissue of rats.

Little is known about the action of laser rays on normal adipose cells. The present study attempts to observe the behavior of fatty cells submitted to laser therapy. Dorsal fat pads of normal adult rats were submitted to low-level laser irradiation applied locally through intact skin, with four different dose schedules (4, 8, 12, and 16 J/cm(2)), with a further group being sham-irradiated. Histology, morphometry, immunofluorescence, and electron microscopy were all used to analyze irradiated tissues. Changes were restricted to the brown fatty tissue, in which a tendency was shown for multivacuolar cells to be transformed into the unilocular type. The number of cells which exhibited enlargement and fusion of small vacuoles was greater in the 4- and 16-J/cm(2) groups (p<0.05). Increased vascular proliferation and congestion was another more evident finding in laser-treated animals compared to nontreated animals. Low-level laser rays cause brown adipose fat droplets to coalesce and fuse. Additionally, they stimulated proliferation and congestion of capillaries in the extracellular matrix.