Bone Mesenchymal Stem Cells Origin Exosomes are Effective Against Sepsis-Induced Acute Kidney Injury in Rat Model.

Introduction: The incidence and mortality rates of sepsis-induced acute kidney injury (SAKI) remain high, posing a substantial healthcare burden. Studies have implicated a connection between the development of SAKI and inflammation response, apoptosis, and autophagy. Moreover, evidence suggests that manipulating autophagy could potentially influence the prognosis of this condition. Notably, exosomes derived from bone mesenchymal stem cells (BMSCs-Exo) have exhibited promise in mitigating cellular damage by modulating pathways associated with inflammation, apoptosis, and autophagy. Thus, this study aims to investigate the influence of BMSCs-Exo on SAKI and the potential mechanisms that drive this impact.

Methods: The SAKI model was induced in HK-2 cells using lipopolysaccharide (LPS), while rats underwent cecal ligation and puncture (CLP) to simulate the condition. Cell viability was assessed using the CCK-8 kit, and kidney damage was evaluated through HE staining, blood urea nitrogen (BUN), and serum creatinine (SCr) measurements. Inflammatory-related RNAs and proteins were quantified via qPCR and ELISA, respectively. Apoptosis was determined through apoptosis-related protein levels, flow cytometry, and TUNEL staining. Western blot analysis was utilized to measure associated protein expressions.

Results: In vivo, BMSCs-Exo ameliorated kidney injury in CLP-induced SAKI rats, reducing inflammatory cytokine production and apoptosis levels. Fluorescence microscope observed the absorption of BMSCs-Exo by renal cells following injection via tail vein. In the SAKI rat kidney tissue, there was an upregulation of LC3-II/LC3-I, p62, and phosphorylated AMP-activated protein kinase (p-AMPK) expressions, indicating blocked autophagic flux, while phosphorylated mammalian target of rapamycin (p-mTOR) expression was downregulated. However, BMSCs-Exo enhanced LC3-II/LC3-I and p-AMPK expression, concurrently reducing p62 and p-mTOR levels. In vitro, BMSCs-Exo enhanced cell viability in LPS-treated HK-2 cells, and exerted anti-inflammation and anti-apoptosis effects which were consistent with the results in vivo. Similarly, rapamycin (Rapa) exhibited a protective effect comparable to BMSCs-Exo, albeit partially abrogated by 3-methyladenine (3-MA).

Conclusion: BMSCs-Exo mitigate inflammation and apoptosis through autophagy in SAKI, offering a promising avenue for SAKI treatment.