Influência de dois regimes de entrega do laser em baixa intensidade no reparo cutâneo de ratos diabéticos - avaliação do infiltrado inflamatório

Abstract

The tissue repair of diabetics is changed and often inefficient, leading to the post surgical complications, dehiscence and infection. Lasertherapy is a promising tool to assist the closure of these wounds, but the lack of standardization of dosimetry, energy delivery systems and lack of understanding of the cellular and molecular mechanisms of action limited the spread of its use. Thus, the objective of this work is to evaluate the tissue repair of cutaneous lesions of diabetic animals subjected to two schemes of laser light delivery, namely: single dose and dose fractionation. 54 Wistar rats were used (Rattus novergicus albinus) with diabetes induced by intraperitoneal injection of Streptozotocina (50 mg/kg). The ulcer was held with punch of 8 mm on the back of the animal after shaving. Experimental groups: (1) control group (GC)-dorsal ulcer is not treatment; (2) single dose (GU)-dorsal ulcer received laser therapy two hours after the completion of the wound; (3) fractionated dose (GF)-dorsal ulcer received lllt in days 1, 3, 8 and 10. The parameters of the laser application on GU group were: λ = (660 ± 2) nm, P= 30mW, D = 4 J/cm2, spot area of 0,785 cm2, t = 104 s; and the Group GF were four applications of λ = (660 ± 2) nm, P=30 mW, D = 1 J/cm2, spot area of 0,785 cm2, t = 26 s totaling 4 J/cm2. The ulcers were photographed and three animals in each group were submitted to euthanasia, the ulcers were removed, processed routinely for hematoxylin and eosin staining and immunohistochemistry for the detection of neutrophils, lymphocytes, macrophages and activated T cells of the angiogenic lineage. When compared to the control group, the two forms of energy delivery proved effective in the treatment of cutaneous lesions in experimental models used. The single-dose group showed the highest acceleration in immune system activation and faster wound healing, but with greater intensity of collagen deposition causing fibrosis. The fractional dose group showed from the start trend of modulated inflammatory response, without peaks and the healing occurred more slowly, however collagen deposition was lower providing a scar with higher quality.