Pyroptosis-preconditioned mesenchymal stromal cell-derived extracellular vesicles as advanced nanomedicines for treating inflammatory diseases.

Uncontrolled inflammation is one of the major causes of various forms of tissue injury, and nanomedicines with immunoregulatory effects are needed. Mesenchymal stromal cell-derived extracellular vesicles (e.g., MSC-EVs) have been proposed as promising therapies, but the highly efficient generation of EVs with desirable properties is still a considerable challenge in this field. Here, we report that preconditioning MSCs with a critical immune process (pyroptosis) is a robust method for improving both the yield and anti-inflammatory potency of MSC-EVs. In brief, pyroptosis-preconditioned MSCs using a combined lipopolysaccharide (LPS) and adenosine triphosphate (ATP) stimulation showed elevated EV yields compared with those of MSCs cultured under normal conditions. Pyroptosis preconditioning upregulated multiple pathways (e.g., cell proliferation, DNA repair, and the immune response) in MSCs, leading to the enrichment of immunoregulatory cargos (e.g., PD-L2 and STC2) in MSC-EVs. In vitro, pyroptosis-preconditioned MSC-EVs (P-EVs) treatment has greater potential to suppress cytokine expression and cell death in pyroptotic macrophages than treatment with normal MSC-EVs (N-EVs). Compared with N-EV treatment, P-EV treatment showed superior potency in attenuating proinflammatory cell infiltration, cytokine/chemokine expression, resident tissue cell death, and the severity of pathological injury in different models of inflammatory diseases (acute lung or kidney injury), and these effects are likely the joint result of diverse functional cargos delivered by such EVs. This study highlights that pyroptosis preconditioning is a promising strategy for the highly efficient production of MSC-EVs with advanced therapeutic potential for treating diverse inflammatory diseases.