Abstract:Objective　To collect extracellular vesicles（ EVs） secreted by adipose mesenchymal stem cells（ ADSCs） after ultrasound stimulation， compare with EVs secreted by normal ADSCs， and to explore the effects of EVs secreted after ultrasound stimulation on the biological characteristics of ADSCs， including cell proliferation， migration， and adipogenic differentiation abilities. Methods　Firstly， some ADSCs were treated with low-intensity ultrasound， cell culture supernatant was collected and extracellular vesicles （U-EVs） were extracted by ultrafiltration method. Some ADSCs were cultured normally and their extracellular vesicles（ N-EVs） were also collected. The experiments were performed in the following three groups： PBS （blank control group）， EVs secreted by untreated cells （N-EVs group）， and EVs secreted by ultrasoundtreated cells （U-EVs group）. The CCK-8 assay was used to assess the viability of ADSCs under treatment with EVs at different concentrations. The concentration that most strongly enhanced cell viability was selected. At this concentration， cell migration was detected by scratch test， cell proliferation was detected by EdU method， and adipogenic induction medium was used to induce and compare adipogenic differentiation ability of ADSCs. Results　EVs secreted after ultrasound stimulation met the identification standards， and the optimal concentration for affecting ADSCs was about 150 µg/mL. At this concentration， the cell proliferation rate of the U-EVs group（ 19.2%±1.8%） was significantly higher than that of the N-EVs group（ 11.9%±3.4%）， and the Oil Red O staining area of the U-EVs group was（ 2.78±0.23） times that of the control group， significantly higher than （2.11±0.18） times of the N-EVs group. However， there was no significant difference in cell migration rates between the N-EVs （16.3%±2.0%） and U-EVs （21.5%±2.3%） groups. Conclusion　 EVs secreted by ultrasound-stimulated ADSCs significantly enhance the vitality of ADSCs and improve their abilities in cell proliferation， migration， and adipogenic differentiation.

Key words:Extracellular vesicles,　Adipose-derived mesenchymal stem cell,　Ultrasound