Abstract: 【Abstract】 Objective To investigate the effect of ultrasound combined with 4-hydroxyphenyl-retinamide （4-HPR） lipid microbubbles on type Ⅰ collagen α1 chain （COL1A1） protein expression in keloid-derived fibroblasts. Methods In vitro cultured keloid-derived fibroblasts were divided into 3 groups: control group receiving conventional culture with incomplete Dulbecco′s modified Eagle′s medium （DMEM）, 4-HPR lipid microbubble group cultured with incomplete DMEM containing 15 mg/L 4-HPR lipid microbubbles, and ultrasound + 4-HPR lipid microbubble group cultured with incomplete DMEM containing 15 mg/L 4-HPR lipid microbubbles under ultrasound treatment. After 24-hour treatment, reverse transcription （RT）-PCR and Western blot analysis were performed to determine the mRNA and protein expression of COL1A1 in keloid-derived fibroblasts in each group. Intergroup comparison was carried out by using t test. Results The mRNA relative expression level of COL1A1 was 1.00 ± 0.18, 0.69 ± 0.15 and 0.35 ± 0.18 in the control group, 4-HPR lipid microbubble group and ultrasound + 4-HPR lipid microbubble group respectively, and the protein relative expression level of COL1A1 was 0.93 ± 0.03, 0.74 ± 0.07 and 0.44 ± 0.06 in the above 3 groups respectively. Moreover, the mRNA and protein expression of COL1A1 was significantly lower in the 4-HPR lipid microbubble group and ultrasound + 4-HPR lipid microbubble group than in the control group （P < 0.05 or 0.001）, and lower in the ultrasound + 4-HPR lipid microbubble group than in the 4-HPR lipid microbubble group （P < 0.05）. Conclusion Ultrasound combined with 4-HPR lipid microbubbles could markedly inhibit the mRNA and protein expression of COL1A1 in keloid-derived fibroblasts.

Key words: Keloid, Collagen type I, Tretinoin, Sonication, 4-Hydroxyphenyl-retinamide, COL1A1, Microbubble