Estudo comparativo dos efeitos do laser de baixa intensidade e do ultrassom terapêutico no reparo tecidual de feridas cirúrgicas cutâneas em ratos Wistar: avaliação histomorfométrica e imunoistoquímica

Abstract

Low level laser therapy (LLLT) and therapeutic ultrasound have been demonstrated to be options for healing modulation, but the mechanisms of action involved in these processes are not clear. The effects of laser therapy and therapeutic ultrasound on surgical skin wounds in Wistar rats (n=24) were evaluated using four groups: I (control), II (LLLT), III (ultrasound) and IV (laser therapy and ultrasound). On the tenth day, the wounds were photographed and measured, and after excision at the moment of euthanasia, they were processed for histopathological evaluation to assess the density and organization of collagen fibers. In addition, histomorphometric evaluations were conducted to quantify angiogenesis and inflammatory infiltrates, and immunohistochemistry was performed to assess TGF1 expression. The samples from the treated group had a more mature macroscopic appearance compared to the untreated group, with no significant difference in wound closure. Microscopically, the results suggested that the laser therapy had a better immunomodulatory effect when used alone and that the therapeutic ultrasound showed a higher angiogenic potential. The immunohistochemical evaluation revealed that most of the inflammatory cells in the scar area did not express TGF1. Still, although the application of laser therapy and ultrasound act directly in the reduction of infiltration, the concomitant therapies do not potentiate the effect observed when applied in isolation, despite the time of wound closure was not influenced by therapy alone or associated, all treatments favored collagenous extracellular matrix organization. The LLLT alone and the combination of both techniques allowed the re-epithelialization of wounds under these treatment modalities. The majority of cells that migrated in the proliferation or entered in the cicatricial area is not expressed TGFβ1, suggesting that the control exercised by the inflammatory infiltrate and the LLLT UST is not modulated by this cytokine.