Effect of ultrasound irradiation on α-SMA and TGF-β1 expression in human dermal fibroblasts.

Ultrasound therapy is used to promote pressure ulcer healing as an adjunctive therapy. However, the efficacy and the scientific basis of this treatment are unclear. We investigated the effect of ultrasound irradiation on alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta1 (TGF-β1) expression in human dermal fibroblasts. These are important factors for acceleration of wound closure. We used pulsed ultrasound of 0, 0.1, 0.5, and 1.0 W/cm2. TGF-β1 and α-SMA mRNA was measured by quantitative real-time polymerase chain reaction, α-SMA protein was examined by western blot, and localization of α-SMA was evaluated by immunofluorescence staining. Expression of α-SMA and TGF-β1 mRNA was increased at 24 h but not at 48 h after ultrasound irradiation. There were significant differences between controls of 0 W/cm² and 0.1 W/cm² with a 1.34 ± 0.26 fold increase in α-SMA (P < 0.05) and a 1.78 ± 0.57 fold increase in TGF-β1 (P < 0.05). Protein levels of α-SMA were also increased and detected in ultrasound irradiated fibroblasts at 24 h. Ultrasound irradiation promotes α-SMA expression in human dermal fibroblasts and this suggests the biological mechanism of ultrasound efficacy on chronic wound treatment.