Department of Rehabilitation Science, Kobe University Graduate School of Health Sciences, 10-2 Tomogaoka 7-chome, Suma-ku, Kobe, Hyogo, 654-0142, Japan.
Shanghai Yangzhi Rehabilitation Hospital (Shanghai Sunshine Rehabilitation Center), Tongji University School of Medicine, 2209 Guangxing Rd., Songjiang District, Shanghai, 201619, China.
J Med Ultrason (2001). 2024 Jul;51(3):397-405. doi: 10.1007/s10396-024-01429-9. Epub 2024 Apr 4.
Extracellular vesicles (EVs) serve as carriers of intracellular factors with therapeutic effects, including tissue regeneration and attenuation of inflammatory responses. The majority of EVs in vivo are derived from skeletal muscle, which is reported to have anti-inflammatory effects. While high-intensity pulsed ultrasound (US) irradiation has been shown to promote EV secretion from myotubes, the impact of pulse repetition frequency, a US parameter affecting pulse length, on EV release remains unclear. This study aimed to investigate the impact of pulse repetition frequency of US on the release of EVs from myotubes.
C2C12 myoblasts were used in this study. After differentiation into C2C12 myotubes, US was performed for 5 min at an intensity of 3.0 W/cm, duty cycle of 20%, acoustic frequency of 1 MHz, and different pulse repetition frequencies (100 Hz, 10 Hz, or 1 Hz). After 12 h, EVs and cells were collected for subsequent analyses.
US did not cause a reduction in cell viability across all US groups compared to the control. The concentration of EVs was significantly higher in all US groups compared to the control group. In particular, the highest increase was observed in the 1-Hz group on EV concentration as well as intracellular Ca level.
This study investigated the effect of three different pulse repetition frequencies of US on the release of EVs from cultured myotubes. It is concluded that a low-pulse repetition frequency of 1 Hz is the most effective for enhancing EV release from cultured myotubes with pulsed ultrasound.
细胞外囊泡（EVs）作为具有治疗作用的细胞内因子的载体，包括组织再生和减轻炎症反应。体内大多数 EVs 来源于骨骼肌，据报道其具有抗炎作用。虽然高强度脉冲超声（US）照射已被证明可促进肌管中 EV 的分泌，但影响脉冲长度的 US 参数——脉冲重复频率对 EV 释放的影响尚不清楚。本研究旨在探讨 US 的脉冲重复频率对肌管中 EV 释放的影响。
本研究使用 C2C12 成肌细胞。分化为 C2C12 肌管后，以 3.0 W/cm2 的强度、20%的占空比、1 MHz 的声频和不同的脉冲重复频率（100 Hz、10 Hz 或 1 Hz）进行 5 分钟的 US。12 小时后，收集 EV 和细胞进行后续分析。
与对照组相比，所有 US 组的细胞活力均未降低。与对照组相比，所有 US 组的 EV 浓度均显著升高。特别是，在 EV 浓度和细胞内 Ca 水平方面，1 Hz 组的增加最高。
本研究调查了三种不同的 US 脉冲重复频率对培养的肌管中 EV 释放的影响。研究结论为，低脉冲重复频率 1 Hz 是最有效的增强脉冲超声培养的肌管中 EV 释放的方法。
