Continuous therapeutic ultrasound in the healing process in rat skin

Effect of Therapeutic Ultrasound on the Mechanical and Biological Properties of Fibroblasts

Purpose

This paper explores the effect of therapeutic ultrasound on the mechanical and biological properties of ligament fibroblasts.

Methods and Results

We assessed pulsed ultrasound doses of 1.0 and 2.0 W/cm2 at 1 MHz frequency for five days on ligament fibroblasts using a multidisciplinary approach. Atomic force microscopy showed a decrease in cell elastic modulus for both doses, but the treated cells were still viable based on flow cytometry. Finite element method analysis exhibited visible cytoskeleton displacements and decreased harmonics in treated cells. Colorimetric assay revealed increased cell proliferation, while scratch assay showed increased migration at a low dose. Enzyme-linked immunoassay detected increased collagen and fibronectin at a high dose, and immunofluorescence imaging technique visualized β-actin expression for both treatments.

Conclusion

Both doses of ultrasound altered the fibroblast mechanical properties due to cytoskeletal reorganization and enhanced the regenerative and remodeling stages of cell repair.

Lay Summary

Knee ligament injuries are a lesion of the musculoskeletal system frequently diagnosed in active and sedentary lifestyles in young and older populations. Therapeutic ultrasound is a rehabilitation strategy that may lead to the regenerative and remodeling of ligament wound healing. This research demonstrated that pulsed therapeutic ultrasound applied for 5 days reorganized the ligament fibroblasts structure to increase the cell proliferation and migration at a low dose and to increase the releasing proteins that give the stiffness of the healed ligament at a high dose.

Future Works

Future research should further develop and confirm that therapeutic ultrasound may improve the regenerative and remodeling stages of the ligament healing process applied in clinical trials in active and sedentary lifestyles in young and older populations.

Graphical abstract

Comparative Study Between Low Level Laser and Therapeutic Ultrasound in Second Intention Ulcers Repair in Mice

Introduction: An ulcer is an injury that affects the skin and has many causes. Healing is a way of protecting the body against any infectious agent that tries to infect you through the wound. Low level laser (LLL) in the treatment of ulcers, aims at maintaining the stability of the physiological process of tissue repair and ultrasound (US) acts by increasing the elasticity of tissue and scarring. The aim of this study was to analyze the effects of LLL and US in wound healing of ulcers induced in mice. Methods: In this experimental study, a sample of 36 guinea pigs was divided into 6 groups of 6 mice, 2 groups as control (C7) and (C14), 2 treated with laser (GL7) and (GL14) and the others 2 treated with ultrasound (GU7) and (GU14). The ulcer was induced and after 7 days, 6 mice from each group were sacrificed to obtain the histological sections for analysis, and the remaining 6 mice from each group continued under treatment and in day 14, they were sacrificed to obtain histologic specimens while macroscopic image was also carried out. Results: Three aspects were analyzed, the percentage of wound regression where it was observed that there was a significant difference in the first 7 days. Regarding the inflammatory process, it was observed that in the first 7 days GL7 and GU7 improved significantly and within 14 days of the experimental period GU14 showed a significant difference when compared to C14. The number of fibroblasts present in the GL at 7 days showed a significant difference compared to the others, and at 14 days, the US group had a significant difference compared to the other groups. Conclusion: Thus, it was evident that the US had more effective results with anti-inflammatory action, better organization and increased deposition of collagen and fibroblasts. Therefore, it can be concluded that other studies are consistent with this taking into account the laser must be used during the early days of the initial healing process and the US during the end of this process.