CONICET | Buscador de Institutos y Recursos Humanos

Exosomes are 40-100 nm nanovesicles released bymost of cells. Tumor cells derived exosomes (Tex), usedas a vaccine, elicit a specific cytotoxic response againsttumor cells, with a greater immunogenicity than lysatedtumoral cells. The utilization of exosomes as an easilyobtainable and stable defined source of antigens is anovel technique for treating cancer. However, the amountof exosomes purified from culture cells is limited. 􀀫n recentstudies it was observed that cells respond to differentstressors stimuli (hypoxia, acidosis, radiation, cytotoxicdrugs, oxidative stress and heat shock) by releasingmicrovesicles. The purpose of this work was to use differentstressors to enhance the exosome production, tobe used as acellular immunogens for the developmentof an antitumor vaccine. Tex released from tumor cellsin a culture of the murine T-cell lymphoma, either growingin normal or stressed conditions, 􀁙ere purified bydifferential centrifugation and ultracentrifugation. Theirconcentration was measured by Bradford; the purity andalso the expression of exosomes protein markers, suchas Hsp?s, Alix and TSG-101 and tumor antigens weredetermined by flo􀁙 cytometry and 􀀦ot 􀀤lot. 􀀫t 􀁙as foundthat cyclophosphamide cellular stress enhances the exosomeproduction (61 ± 16) % and that these exosomesexpress more Hsp90 in their membrane compared withexosomes of the same cells growing without stressors.Likewise, the immune response generated by the inoculationof exosomes in normal mice was study, evaluatingthe humoral response by Dot Blot, as well as the survivalpost-challenge with tumor cells. Tex isolated from tumorcells grown with 3mM cyclophosphamide or without stressinduced an immune response with a high and similar titerof antibodies in serum, previous to the inoculation withthe tumor cells and this induction 􀁙as reflected in thepercentage of the tumor rejection in mice, without differenceswithin the groups.