Rejuvenation of photoaged aged mouse skin using high-intensity focused ultrasound

Abstract

High-intensity focused ultrasound (HIFU) therapy has emerged as an option for skin rejuvenation. However, the application against photo-damaged skin remains obscure. This study evaluates the effect of HIFU against photoaged skin using a mouse model. A total of 60 mice were used and divided into 3 groups; group 1: natural aging control group (n=20), group 2: UVB irradiation group (n=20), and group 3: UVB irradiation followed by HIFU treatment (n=20). The evaluation was made grossly by analyzing wrinkles and histologically by performing H&E, Toluidine Blue, Masson's Trichrome, and immunohistochemistry for TGF-β and MMP3. Imaging software was used to quantify the findings. Gross findings showed HIFU treated group 3 with similar findings with the control group supporting the rejuvenation effect for photo-aged skin. Histology findings with H&E show a significant reduction in skin thickness after HIFU treatment (60.115 units (group 2) vs. 40.853 units (group 3), p<0.05). Toluidine Blue and Masson's Trichrome showed improved collagen array and significantly increased distribution for group 3 over group 2 (272,879.88 units (group 2) vs. 533,805.78 units (group 3), p<0.05). Immunohistochemistry for TGF-β showed a significantly higher value for group 3 (2.45450 units) over group 2 (0.58880 units) and MMP3 with a significantly lower value for group 3 (99,180 units) over group 2 (559,830 units) (p<0.05). The treatment of HIFU supports the rejuvenation effect for photoaged skin. Findings show that HIFU provides benefits of collagen formation and rearrangement by enhancing TGF-β and inhibiting MMP3 activity. This study is the first animal study to show the direct effect of HIFU on photo-aged skin further supporting the use of HIFU in aging skin aiming to reverse the morphological effects of aging.