Modulation of soft tissue inflammation in cases of soft tissue defects using photobiomodulation therapy
Abstract
Objective. To assess the potential of photobiomodulation therapy for modulating soft tissue inflammation in cases of soft tissue defects by analysing its effect on the levels of interleukin-8, platelet-derived growth factor and the amino-terminal propeptide of type III procollagen, including their correlation with histological findings.Materials and methods. An experimental study was conducted on 24 rats, which were randomly divided into four groups: a group of intact animals, a control group, and the first and second experimental groups. Soft tissue defects were simulated in the rats of the control group and both experimental groups. Animals in the control group underwent simulated wound irradiation, whilst those in the experimental groups received photobiomodulation therapy at a wavelength of 660 nm, a power of 10 mW, an energy density of 1 J/cm² (first experimental group) or 2 J/cm² (second experimental group); the spot area was 3.14 cm²; the duration of a single session was 314 or 628 s; and the power density was 3.18 mW/cm². Three days later, levels of interleukin-8, platelet-derived growth factor and the N-terminal propeptide of type III procollagen in blood serum were assessed using an enzyme-linked immunosorbent assay (ELISA), and wound healing parameters were evaluated histologically.Results. After 3 days, thanks to photobiomodulation therapy, interleukin-8 levels increased 2.08-fold in the first experimental group and 2.5-fold (p < 0.05) in the second experimental group. The level of platelet-derived growth factor increased by a factor of 1.71 (p < 0.05) in the second experimental group. Levels of the amino-terminal propeptide of type III procollagen were elevated in both the control group and the second experimental group compared with intact animals. Histologically, in wounds treated with photobiomodulation, there was enhanced granulation tissue formation, as evidenced by an increase in the number of fibroblasts, neovascularisation and collagen deposition. Semi-quantitative analysis revealed a lower number of polymorphonuclear leukocytes in the first experimental group and an increase in the number of fibroblasts in both experimental groups compared with the control group (p < 0.05).Conclusions. Photobiomodulation therapy exerts a parameter-dependent and non-linear effect on inflammatory and early reparative processes in soft tissues. The data obtained support the need to standardise the parameters of laser treatment for chronic wounds in order to improve the effectiveness of their treatment.