Sílvia Regina de Almeida Reis

Influence of 670 nm low-level laser therapy on mast cells and vascular response of cutaneous injuries

Laser biomodulation has been getting considerable attention when it comes to its effects on the inflammatory process. Its action upon mast cells have been already studied, but none of the previous papers related the resulting effect to the inflammatory and vascular status of the wounds. Therefore, the acute inflammatory process as well as the mast cells behavior and the vascular response were analyzed under the influence of laser treatment on cutaneous wounds. Surgical procedures were performed on 60 rats divided into sham and laser groups. Low-level laser therapy was performed following surgical procedures (670 nm, 9 mW, 4 J/cm(2), 124 s). Histological specimens were analyzed for cell morphology and immunohistochemistry using anti-von Willebrand Factor and anti-Vascular Endothelial Growth Factor antibody. Laser treatment resulted in an increased acute inflammatory response in irradiated tissues; surgical wounds treated with laser therapy had increased polymorphonuclear cells, mast cells and vasodilation and lower numbers of vessels than those in control rats. Laser treatment resulted in higher expression of VEGF in irradiated tissues 6-24h post-treatment (p=0.002). It is possible to observe an amplification of acute inflammatory process during the first hours after surgical procedure in rats submitted to laser therapy.

Influence of the HPA axis on the inflammatory response in cutaneous wounds with the use of 670-nm laser photobiomodulation.

This study evaluated the influence of hypothalamic-pituitary-adrenal (HPA) axis in cutaneous wounds subjected to laser biomodulation. A total of 48 rats were divided into two groups: Group I (GI) with 24 adrenalectomized animals and Group II (GII) with 24 non-adrenalectomized animals. Each group was divided into two subgroups: the irradiated subgroup which laser was applied to four points at the edges of the wound (670 nm laser, 9 mW) and control subgroup. Rats in each subgroup were sacrificed at 24 or 72 h. Adrenal glands were only removed from GI rats. Three days after adrenalectomy, a cutaneous wound was made. An immunohistochemical analysis was performed using anti-CD45 and anti-CD8 antibodies. Flow cytometry was used to count T lymphocytes and their subpopulations in blood. Decreases in the number of CD45-positive inflammatory cells and in the total numbers of CD8- and CD45-positive cells were observed in histological sections of adrenalectomized animals subjected to laser biomodulation at 24h. Similar results were observed for distribution of total lymphocytes in blood (p<0.05). The action of 670 nm laser does not depend exclusively on HPA axis. It is believed that corticosteroid-promoting enzymes liberated in non-adrenal tissues may influence immune response under the influence of this type of phototherapy.

BIOMODULATORY POTENTIAL OF LOW-LEVEL LASER ON NEOANGIOGENESIS AND REMODELING TISSUE. A LITERATURE REVIEW

| Introduction: In recent years, cellular biostimulation induced by low-level laser therapy has been widely studied. Among some of the processes stimulated by low-level laser are cell cycle, phenotypic modulation as well as vascular changes, such as vasodilation and neoangiogenesis. The increased number of new blood vessels accelerates inflammation, and also increases wound healing. Neoangiogenesis is still an important process of tissue repair, since it always precedes collagen synthesis and matrix extracellular remodeling. Increasing scientific evidence has shown that photobiomodulation stimulates neoangiogenesis, fibroblast proliferation and collagen biosynthesis. Objective: Review the literature about the effects of low level laser therapy on neoangiogenesis and fibroplasia and describe how these processes occur in the tissue subjected to an injury. Methods and Matereials: The search tool used was the Medline / Pubmed and the following keywords were used: remodeling, wound healing, neoangiogenesis, fibroplasia, laser therapy, low-level laser. Manuscripts published from 1990 to 2017 were selected. Results: Increasing scientific evidence has shown that photobiomodulation stimulates neoangiogenesis, fibroblast proliferation and collagen biosynthesis. Conclusion: Neoangiogenesis always precedes collagen synthesis and matrix extracellular remodeling. However, little is known of the action of laser therapy in the late stages of tissue repair.