Latest progress in low-intensity pulsed ultrasound for studying exosomes derived from stem/progenitor cells.

Stem cells have self-renewal, replication, and multidirectional differentiation potential, while progenitor cells are undifferentiated, pluripotent or specialized stem cells. Stem/progenitor cells secrete various factors, such as cytokines, exosomes, non-coding RNAs, and proteins, and have a wide range of applications in regenerative medicine. However, therapies based on stem cells and their secreted exosomes present limitations, such as insufficient source materials, mature differentiation, and low transplantation success rates, and methods addressing these problems are urgently required. Ultrasound is gaining increasing attention as an emerging technology. Low-intensity pulsed ultrasound (LIPUS) has mechanical, thermal, and cavitation effects and produces vibrational stimuli that can lead to a series of biochemical changes in organs, tissues, and cells, such as the release of extracellular bodies, cytokines, and other signals. These changes can alter the cellular microenvironment and affect biological behaviors, such as cell differentiation and proliferation. Here, we discuss the effects of LIPUS on the biological functions of stem/progenitor cells, exosomes, and non-coding RNAs, alterations involved in related pathways, various emerging applications, and future perspectives. We review the roles and mechanisms of LIPUS in stem/progenitor cells and exosomes with the aim of providing a deeper understanding of LIPUS and promoting research and development in this field.

[Expression and significance of Nrf2/ARE pathway ralated factors in the HepG2 cell model of steatosis].

OBJECTIVE: To explore a new method of establishing HepG2 cell model of steatosis and observe the expression and significance of nuclear factor erythroid-2p45-related factor 2(Nrf2)/antioxidative response element (ARE) pathway related factors in HepG2 cells of steatosis. METHODS: HepG2 cells were induced with DMEM containing 25% fetal bovine serum, 0.1% MCT/LCT Fat Emulsion and 0.1 mmol/L free fatty acid (FFA) at different stages and the control group cells were cultured with normal DMEM medium. After the cell models were successfully established, lipid droplets in cytoplasm were observed with Oil Red 0 staining, and the triglyceride (TG) accumulation in HepG2 cells were tested by biochemical assay. Intracellular reactive oxygen species (ROS) concentration were detected by flow cytometry. Nitric oxide (NO), superoxide dismutase(SOD), malonyldialdehyde(MDA) and glutathione peroxidase(GSH-Px) were tested by biological reagent kit, while the protein expression of nuclear factor erythroid-2p45-related factor 2(Nrf2), heme oxygenase-1 (HO-1) and NAD(P)H: quinone oxidoreductase-1(NQO1) were analyzed by Western blot. RESULTS: Compared with that in the control group, red cytoplasmic lipid droplets were visible in model group; TG,ROS, NO, MDA concentration (P < 0.05, P < 0.01) and the protein expression of Nrf2, HO-1 and NQO1 (P < 0.05, P < 0.01)were significantly higher in model group, while SOD, GSH-Px concentration reduced significantly (P < 0.01). CONCLUSION: The in vitro cell model of steatosis and oxidative stress was successfully established. The activation of Nrf2/ARE pathway related factors maybe relevant to the overreaction of oxidative stress in HepG2 cells of steatosis.