Extracellular vesicles derived from induced pluripotent stem cells mediate anti- inflammatory effects in primary human macrophages

Extracellular vesicles derived from induced pluripotent stem cells (iPSC EVs) have immunoregulatory potential with the ability to alter the macrophage phenotype. Modulating the macrophage phenotype towards an anti-inflammatory, pro-resolving state may be beneficial in the treatment of chronic inflammatory diseases. The contents of iPSC EVs and their effects on macrophages are poorly understood. Here iPSC EVs were characterized and analysed by mass-spectrometry based proteomics and a targeted microRNA (miR) panel and their immunomodulatory effects on primary human macrophages were assessed. Podocalyxin-like protein 1 (PODXL1) and Insulin (INS) were the most abundant proteins unique to the iPSC EVs while miR-302d-3p was the most abundant miR. Notably, thioredoxin- and peroxiredoxin-related proteins were detected. iPSC EVs increased the anti-inflammatory associated Mannose Receptor C-Type 1 ( MRC1 ) and miR-21, while monocyte chemoattractant protein 1 (MCP-1) and IL-8 were decreased. Proteomics revealed that treated macrophages had decreased levels of chemoattractant proteins, Azurocidin 1 (AZU1), Growth Differentiation Factor 15 (GDF15), and Ribosomal Protein S19 (RPS19). Conditioned media from macrophages treated with iPSC EVs inhibited monocyte transmigration, a key component in the propagation of inflammation. This study provides insights into the protein and miR cargo of iPSC EVs and highlights their capacity to inhibit chemotactic proteins in macrophages.