AAT-MSC-EVs: Novel implications for suppressing ferroptosis, fibrosis and pain associated with chronic pancreatitis.

Chronic pancreatitis (CP) is characterized by inflammation, acinar cell death, fibrosis, and persistent pain. We investigated mesenchymal stem/stromal cell (MSC)-derived extracellular vesicles (EVs) for CP treatment. CP was modeled in male mice using bile duct TNBS infusion, and pancreatic tissues from CP patients were also analyzed. EVs from immortalized human MSCs overexpressing alpha-1 antitrypsin (iAAT-MSCs) were tested for their effects on ferroptosis, fibrosis, and pain. CP tissues showed reduced glutathione peroxidase 4 (GPx4) activity (p < 0.05) and iron accumulation, indicating ferroptosis. iMSC and iAAT-MSC-EVs alleviated CP symptoms by suppressing ferroptosis, restoring GPx4 activity, reducing MDA levels, and mitigating fibrosis markers (α-smooth muscle actin, transforming growth factor-β1, matrix metalloproteinase 2). EV treatment also alleviated pain by decreasing macrophage and mast cell infiltration into the pancreas and dorsal root ganglia while reducing pain-related gene expression (TRVP1, TacR1, Necab3). Additionally, iAAT-MSC-EVs were distinct in cytokine signaling, PI3K-Akt pathway activation, and upregulation of miRNAs like miR-9, miR-10a-5p, miR-92a, miR-200, miR-370, and miR-146a. These results suggest ferroptosis as a key mechanism in CP and highlight the therapeutic potential of iAAT-MSC-EVs in addressing ferroptosis, fibrosis, and pain, presenting a promising, cell-free therapeutic strategy for CP.