Comparison of miRNA Cargo within Wharton's Jelly mesenchymal stem cell-derived exosomes manufactured in FBS and hPLT expansion media

Background & Aim Wharton's Jelly Mesenchymal Stem Cell (WJMSCs)-derived exosomes have been studied extensively in animal models of degenerative and chronic diseases. Thus, the development of a large-scale manufacturing procedure to harvest clinical-grade exosomes is required for the translation of exosome to the clinic. We have developed an exosome production technique to manufacture large quantities of exosomes using the quantum bioreactor (Terumo BCT) with both fetal bovine serum (FBS) and human platelet lysate (hPLT) supplemented expansion media. AWe aimed to compare the miRNA cargo of exosomes isolated from FBS-expanded and PLT-expanded WJMSC to determine if growth media is a significant contributor to exosome product preparation. Methods, Results & Conclusion WJMSCs were isolated from Wharton's Jelly and expanded to passage 1. After harvest, 30 × 106 cells were loaded into the quantum bioreactor and expanded for 1 week to achieve maximum confluence. Expansion media was washed and replaced with serum-free aMEM media. Conditioned media was collected every 24 hours for 120 hours and exosomes were precipitated by sequential centrifugation and ultracentrifugation. NanoSight analysis of the final products revealed a production of 15.0 × 1012± 0.32 × 1012 total particles with an average mode size of 111±4.78 nm. Surface protein analysis revealed positive expression of exosome markers CD9, CD63, and CD81. Exosome products were subjected to miRNA isolation, sequencing, and miRNA identification for bioinformatics analysis with the Qiagen IPA software. miRNA analysis was completed using 3 WJMSC donors grown in 20% FBS or 5%PLT supplemented media. Sequencing results identified 157 miRNAs in the PLT group and 154 miRNAs in the FBS group (with a 100-copy minimum expression cut off). FBS and PLT comparison revealed 142 common miRNAs with 15 unique to PLT and 12 unique to FBS. Further RNA target analysis revealed 68 miRNAs that target 1024 mRNA in the PLT group and 64 miRNA that target 1048 mRNA in the FBS group. The two groups share 998 common mRNA targets with 27 unique to PLT and 51 unique to FBS. Canonical pathway analysis of the unique targets reveals the top pathway hits, serotonin receptor and JAK/Stat signaling for PLT and IL-7 and RANK signaling for FBS. We found both expansion medias to be effective for large scale expansion and downstream exosome production. miRNA sequencing revealed small variations in the total number of predicted mRNA targets, suggesting a conserved therapeutic effect between the two groups.