http://creativecommons.org/licenses/by/4.0/legalcode Spanish Society for Extracellular Vesicles, GEIVEX info:eu-repo/semantics/conferenceProceedings Functionalized-gold nanoparticles (fGNPs) gained a lot of interest as perspective theranostics agents due to their stability, high loading capacity, oxidation resistance, surface plasmon resonance in NIR-spectra and scaled-up production. However, their pathology-targeting remain challenging, leading to off-target accumulation, lower therapeutic efficacy and potential systemic toxicity. The use of extracellular vesicles (EVs) could overcome these limitations by sequesteration of fGNPs from undesired interactions and improving targeting capabilities. The aim of this study is to characterize EVs from human mesenchymal stem/stromal cells (MSCs) loaded with neutravidin-coated GNPs, as a first step in the development of a novel theranostics system. MSCs were treated with fGNPs for 24h before rinsing and cultivation in EVs-free medium for 24h. Interleukin (IL)-6 and IL-8 levels were measured in media by ELISA before EVs separation by differential centrifugation. EVs count and size were determined by NTA. EVs markers were assessed by Western blot. Identification of EVs loaded with fGNPs was assessed by transmission electron microscopy (TEM). MSCs internalized fGNPs and the secretion of IL-6 and IL-8 was altered compared to the untreated MSCs. The concentrations of EVs from control and fGNPs-treated MSCs had average concentration of 7.5x1010 ± 2.1x109 p/mL and 5.5x1010 ± 5.9x109 p/mL and the average sizes were 163.4±1.4 nm and 166.1±06 nm, respectively. Both preparations were positive for CD63 and CD81 markers, with similar Western blot bands. TEM analysis suggested that MSCs are indeed able to release fGNPs within EVs, but also free fGNPs and the ratio between fGNPs-loaded EVs and unloaded-EVs was relatively low. In conclusion, MSCs are potential producers of fGNPs-loaded EVs. Therefore, in the next step, loading of EVs with GNPs will be further optimized and their functional properties will be assessed to fully exploit a combination of beneficial properties of specific therapeutics, GNPs and MSC EVs for designing novel theranostics tools. https://phaidrabg.bg.ac.rs/o:36275 eng 2023 application/pdf 2633168 bytes Characterisation of extracellular vesicles from mesenchymal stem/stromal cells as newdelivery system for functionalized gold nanoparticles Characterisation of extracellular vesicles from mesenchymal stem/stromal cells as newdelivery system for functionalized gold nanoparticles Kosanović, Maja Bekić, Marina Glamočlija, Sofija Tomić, Sergej