Derived EVs when compared with normal hepatocyte-derived EV controls, which includes let-7 family members. Treatment of human HSCs with TGF-/LPS (20 ng/ ml) for 72 h induced a significant lower of let-7a and let-7b in both activated and control states. Transfection of let-7a and let-7b precursors in human HSCs markedly induced the expression of cellular senescence markers p16 and CCl2, and blunted the enhanced expression of -SMA, collagen a1, MMP-2 and MMP9 (important genes involved in the activation of HHSCs) by TGF-/LPS remedy. Remedy with MSC/LSC derived EVs (30 g/ml, 72 h) phenocopied the senescence/anti-fibrosis effects of let-7 overexpression in activated HHSCs by TGF-/LPS. A complementary mass spectrometry-based proteomics strategy with luciferase reporter assay identified TLR4, the essential LPS receptor, as putative let-7 cluster target. Additionally, the expressions of senescent hepatic stellate markersIntroduction: MSC-based cell therapy has received excellent interest within the previous years, particularly in regenerative medicine and CD147 Proteins custom synthesis tissue repair. The idea of priming consists in preconditioning the cells in the course of the culture phase (generally with cytokines or hypoxia) to enhance their effects. The literature shows that MSC EVs can recapitulate a substantial aspect with the advantageous effects on the cells they originate from, and that miRNAs are important players in EVs action. Therefore, inside the present operate, our aim was to figure out if IFN or hypoxia priming of MSC could modify their EVs miRNA content material. Solutions: Human bone marrow MSC from five healthy donors have been isolated and cultured at 20 of O2 in MEM-alpha/FBS medium till 600 confluence, then with (IFN) or without having (CONT) interferongamma (25ng/ml, 48 h) or in hypoxia (3 O2 all through the duration of the culture procedure). Then the cells have been rinced with PBS and placed in serum totally free MEM for 48 h. The conditioned media was collected and EV have been isolated by ultracentrifugation (100 000g for 1h10). Total RNA was isolated and reverse transcribed. Pools of CONT, IFN and HYP cDNA have been prepared, miRNA profiling was performed working with Exiqon miRnome PCR panel I and II. Then, chosen miRNAs have been measured on each sample. Benefits: A set of 89 miRNAs was detected (quantification cycle 35) in a minimum of among the pools of MSC EVs. They were measured on every individual sample. 41 miRNAs had been measured in all samples; benefits wereJOURNAL OF EXTRACELLULAR VESICLESnormalized with 5 endogenous miRNAs. Hypoxia induced no significant modification of EVs miRNA content. IFN priming induced a substantial raise in hsa-miR-106a-5p, 25-3p, 126-3p, 451a and 665. Their validated targets have been determined with miRTarBase and also the PD-L1 Proteins Formulation proteins had been analysed with Panther classification system. Among essentially the most cited pathways, we identified p53, inflammation, Wnt signalling, Apoptosis signalling and Angiogenesis.Summary/conclusion: MSC priming can modify the miRNA landscape of their EVs. IFN priming modifies MSCs EVs miRNA involved in biological pathways relevant to tissue repair. Functional analysis of these EVs with chosen miRNAs inhibition is necessary to evaluate the biological effects of such an strategy. Funding: This work has been funded by the french Path G ale de l’Armement, Biomedef PDH-1SMO-1ISEV2019 ABSTRACT BOOKIndustry Poster Session Thursday 25 April 2019 Place: Level 3, Hall AIP.01 IP.Standardizing F-NTA measurements: evaluation of four-wavelengths nanoparticle tracking analysis with cell-line derived EVs Clemens Helmbrechta and Pao.