Investigation of effects of ultrasound on dermal wound healing in diabetic mice

Chronic wounds, including diabetic, leg, and pressure ulcers, impose a significant health care burden worldwide. Currently, chronic wound therapy is primarily supportive. Ultrasound therapy is used clinically to promote bone healing and some evidence indicates that ultrasound can enhance soft tissue repair. Here, we investigated effects of ultrasound on dermal wound healing in a murine model of chronic wounds. An ultrasound exposure system and protocol were developed to provide daily ultrasound exposures to full-thickness, excisional wounds in genetically diabetic mice. Punch biopsy wounds were made on the dorsal skin and covered with acoustically transparent dressing. Mice were exposed to 1-MHz pulsed ultrasound (2 ms pulse, 100 Hz PRF, 0–0.4 MPa) for a duration of 8 min per day. Mice were exposed on 10 days over a 2-week period. No significant differences in the rate of re-epithelialization were observed in response to ultrasound exposure compared to sham-exposed controls. However, two weeks after injury, a statistically significant increase in granulation tissue thickness at the wound center was observed in mice exposed to 0.4 MPa (389 + /  85 μm) compared to sham exposures (105 + /Ő 50 μm). Additionally, histological sections showed increased collagen deposition in wounds exposed to 0.4 MPa compared to shams.