Tem cells in radiation exposed mice Sicheng Wena, Mark Doonerb, Laura Goldbergc, Elaine Papac, Michael Del Tattoc, Mandy Pereirac, Yang Chenc, Theodor Borgovand and Peter QuesenberrybaBrown University/Rhode Island Hospital, Providence, RI, USA; bBrown University Division of Hematology Oncology; Rhode Island Hospital, Providence, RI, USA; cRhode Island Hospital, Providence, RI, USA; dRhode Island Hospital/ Brown University, Providence, RI, USAIntroduction: We have shown that pretreated irradiated murine bone marrow stem cells (BMSCs) with mesenchymal stem cells-extracellular vesicles (MSCEVs) in vitro, could significantly boost the engraftment capacity of radiation damaged BMSCs having a predominant reversal effect in later periods of posttransplant from 12 weeks as much as 36 weeks. This indicates a long-term effect of MSC-EVs on reversal of radiation harm of BMSCs. Solutions: In this study, we investigated the long-term effect of MSC-EVs around the restoration of engraftment of BMSCs in radiation-exposed mice in vivo up to 53 weeks. Furthermore, the security and toxicity of MSCEVs remedy had been also evaluated. Outcomes: 500cGy radiated mice were injected with human MSC-EVs by tail vein injection at 24, 48 and 72h post-radiation. We followed the peripheral blood cell counts up to 53 weeks post-EV injection. There was a considerable RBC, HGB and platelet restoration in EV treated radiated mice when compared with untreated mice in the early period (just before day 35). For the evaluation of reversal effect on BMSCs, bone marrow, harvested at six, 12, 26 and 53 weeks. post-EV injection, were Gastrin Proteins Biological Activity transplanted into 950 cGy exposed B6.SJL mice. The engraftment was evaluated at 4 and 12 weeks posttransplantation. In these transplanted mice at 6 weeks post-EV injection, there was a slight boost in the restoration of engraftment price in EV treated mice (17.58 two.32) compared to untreated mice (13.80 1.41) immediately after 1 month post-transplantation. Having said that, for those mice transplanted at 12, 26, and 53 weeks post-EV injection, there have been significantly greater restorations of engraftment in EV treated mice (40.48 six.03 , 33.93 three.76 , and 56.62 three.63) compared to untreated mice (12.39 1.30 , 15.14 two.21 ,36.21 3.63) immediately after 4 weeks transplantation, respectively. The equivalent restorations of engraftment have been also seen in 12 weeks post-transplantation. These data suggested that EVs have early and late mitigating effects on peripheral blood cytopenias and BMSCs. No toxic Siglec-5/CD170 Proteins Storage & Stability impact was observed in bone marrow, kidney, liver, spleen, lung and heart as much as 53 weeks post-EV injection. Summary/Conclusion: Our information recommend that there’s a long-term effect of MSC-EVs on the restoration of engraftment of BMSCs in radiation-exposed mice, and MSC-EV therapy is a secure therapeutic technique. Funding: NIH grants 5UH2TR000880 and 5T32HL116249.OF17.Connexin43-positive exosomes released by osteoarthritic chondrocytes favours osteoarthritis progression by spreading senescence and inflammatory mediators to nearby tissues Marta Varela-Eir a, Mar D. May possibly Santosb, Adri Varela-V queza, Amanda Guiti -Caama a, Susana B. Bravo-L ezc, Carlos Pa od, Raquel Largoe, Eduardo Fonsecaa, Mustapha Kandouzf, Trond Aaseng, Arantxa Taberneroh, Alfonso Blancoi, JosR. Caeiroj and Mar D. May well aaCellCOM analysis group. Instituto de Investigaci Biom ica de A Coru (INIBIC), Servizo Galego de Sa e (SERGAS), A Coru , Spain; b Translational Analysis in Cell Communication and Signalling (CellCOM), Instituto de Investigaci Biom ica de A C.