Identification of specific markers for human pluripotent stem cell‐derived small extracellular vesicles

Abstract Pluripotent stem cell‐derived small extracellular vesicles (PSC‐sEVs) have demonstrated great clinical translational potential in multiple aging‐related degenerative diseases. Characterizing the PSC‐sEVs is crucial for their clinical applications. However, the specific marker pattern of PSC‐sEVs remains unknown. Here, the sEVs derived from two typical types of PSCs including induced pluripotent stem cells (iPSC‐sEVs) and embryonic stem cells (ESC‐sEVs) were analysed using proteomic analysis by liquid chromatography with tandem mass spectrometry (LC‐MS/MS), and surface marker phenotyping analysis by nanoparticle flow cytometry (NanoFCM). A group of pluripotency‐related proteins were found to be enriched in PSC‐sEVs by LC‐MS/MS and then validated by Western Blot analysis. To investigate whether these proteins were specifically expressed in PSC‐sEVs, sEVs derived from seven types of non‐PSCs (non‐PSC‐sEVs) were adopted for analysis. The results showed that PODXL, OCT4, Dnmt3a, and LIN28A were specifically enriched in PSC‐sEVs but not in non‐PSC‐sEVs. Then, commonly used surface antigens for PSC identification (SSEA4, Tra‐1‐60 and Tra‐1‐81) and PODXL were gauged at single‐particle resolution by NanoFCM for surface marker identification. The results showed that the positive rates of PODXL (>50%) and SSEA4 (>70%) in PSC‐sEVs were much higher than those in non‐PSC‐sEVs (