Objective To explore the effects and mechanisms of human umbilical cord mesenchymal stem cell (HUC-MSC)-derived exosomes (Exo) pretreated with Huangkui capsules on renal ischemia-reperfusion injury (IRI).

Methods HUC-MSCs were cultured in media containing different concentrations of Huangkui capsules for 24 hours to determine cell viability and select an appropriate concentration for subsequent experiments. HUC-MSCs were pretreated with 50 μg/mL Huangkui capsules for 24 hours, and Exo were extracted using an exosome extraction kit. The morphology was observed under a transmission electron microscope, particle size was measured by nanoparticle tracking analysis, and the expression of exosomal membrane surface marker proteins was detected by Western blot. Human renal tubular epithelial cells (HK-2 cells) were randomly divided into hypoxia/reoxygenation group (M group), hypoxia/reoxygenation + Exo group (E group), and hypoxia/reoxygenation + Huangkui capsules pretreated Exo group (H group). Western blotting was used to measure the expression of endoplasmic reticulum stress (ERS)-related proteins, and real-time fluorescent quantitative reverse transcription polymerase chain reaction was used to measure the expression of ERS-related gene messenger RNA (mRNA). Mice were randomly divided into sham operation group (Sham group), ischemia-reperfusion group (I/R group), ischemia-reperfusion + Exo group (E group), and ischemia-reperfusion + Huangkui capsules pretreated Exo group (H group). Renal histological assessment, serum creatinine (Scr), blood urea nitrogen (BUN) measurement and inflammatory factor detection were performed 24 hours later.

Results Both Exo and Huangkui capsules prereated Exo had a bilayer membrane structure and a cup-shaped morphology; their average particle sizes were 116.8 nm and 81.3 nm, respectively. Both expressed CD9, CD63, TSG101. Compared with the M group, the E group had decreased relative expression of transcription factor 6 (ATF6) and protein kinase R-like endoplasmic reticulum kinase (PERK) proteins, increased mRNA relative expression, increased relative expression of C/EBP homologous protein (CHOP) protein, and decreased mRNA relative expression. Compared with the E group, the H group had decreased relative expression of ATF6, PERK, CHOP proteins, and decreased mRNA relative expression of ATF6 and PERK (all P<0.05). Animal experimental results showed that compared with the Sham group, the I/R group had increased renal tubular injury scores, Scr, BUN, interleukin (IL)-1β, IL-10, IL-18, tumor necrosis factor (TNF)-α levels. Compared with the I/R group, the E and H groups had decreased renal tubular injury scores, Scr, BUN, IL-1β, IL-10, IL-18, TNF-α levels. Compared with the E group, the H group had decreased renal tubular injury scores, Scr, BUN, IL-1β, IL-10, IL-18, TNF-α levels (all P<0.05).

Conclusions Huangkui capsules pretreatment HUC-MSC-derived Exo may alleviate renal IRI by inhibiting ERS.