Extracellular vesicles from regenerative human cardiac cells act as potent immune modulators by priming monocytes
Creators: name: Beez, Christien M.
name: Haag, Marion
name: Klein, Oliver
name: Linthout, Sophie Van
name: Sittinger, Michael
name: Seifert, Martina
Publisher: name: Charité - Universitätsmedizin Berlin
Year: 2019
Subjects: subject: Extracellular vesicles
subject: Exosomes
subject: Cardiac cells
subject: Immunomodulation
subject: CD14+ myeloid suppressive cells
subject: Monocytes
subject: 600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::610 Medizin und Gesundheit

description: Background: Nano-sized vesicles, so called extracellular vesicles (EVs), from regenerative cardiac cells represent a promising new therapeutic approach to treat cardiovascular diseases. However, it is not yet sufficiently understood how cardiac-derived EVs facilitate their protective effects. Therefore, we investigated the immune modulating capabilities of EVs from human cardiac-derived adherent proliferating (CardAP) cells, which are a unique cell type with proven cardioprotective features. Results: Differential centrifugation was used to isolate EVs from conditioned medium of unstimulated or cytokinestimulated (IFNγ, TNFα, IL-1β) CardAP cells. The derived EVs exhibited typical EV-enriched proteins, such as tetraspanins, and diameters mostly of exosomes (&lt; 100 nm). The cytokine stimulation caused CardAP cells to release smaller EVs with a lower integrin ß1 surface expression, while the concentration between both CardAP-EV variants was unaffected. An exposure of either CardAP-EV variant to unstimulated human peripheral blood mononuclear cells (PBMCs) did not induce any T cell proliferation, which indicates a general low immunogenicity. In order to evaluate immune modulating properties, PBMC cultures were stimulated with either Phytohemagglutin or anti-CD3. The treatment of those PBMC cultures with either CardAP-EV variant led to a significant reduction of T cell proliferation, pro-inflammatory cytokine release (IFNγ, TNFα) and increased levels of active TGFβ. Further investigations identified CD14+ cells as major recipient cell subset of CardAP–EVs. This interaction caused a significant lower surface expression of HLA-DR, CD86, and increased expression levels of CD206 and PD-L1. Additionally, EV-primed CD14+ cells released significantly more IL-1RA. Notably, CardAP-EVs failed to modulate anti-CD3 triggered T cell proliferation and pro-inflammatory cytokine release in monocultures of purified CD3+ T cells. Subsequently, the immunosuppressive feature of CardAPEVs was restored when anti-CD3 stimulated purified CD3+ T cells were co-cultured with EV-primed CD14+ cells. Beside attenuated T cell proliferation, those cultures also exhibited a significant increased proportion of regulatory T cells. Conclusions: CardAP-EVs have useful characteristics that could contribute to enhanced regeneration in damaged cardiac tissue by limiting unwanted inflammatory processes. It was shown that the priming of CD14+ immune cells by CardAP-EVs towards a regulatory type is an essential step to attenuate significantly T cell proliferation and proinflammatory cytokine release in vitro.