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posted on 2025-11-26, 12:46 authored by Rosanne E. Veerman, Gözde Güclüler Akpinar, Annemarijn Offens, Loïc Steiner, Pia Larssen, Andreas Lundqvist, Mikael C.I. Karlsson, Susanne Gabrielsson <p>Characterization of BMDC-derived EVs. BMDC-derived EVs were characterized using multiple methods. <b>A,</b> Morphologic analysis of EVs was performed by TEM. Two different magnifications are shown. <b>B,</b> Five EV batches, shown individually, were subjected to NTA analysis to determine EV size (nm), and a mean and mode size 184 and 157 nm, respectively was measured. <b>C,</b> EVs were bound to anti-CD9–coated magnetic beads, stained for surface markers as indicated, and detected by flow cytometry. The data are shown as the mean fluorescence intensity ratio between the specific antibody and its corresponding isotype control. A signal above 1 (dotted line) was considered positive. Data are presented as mean ± SD, <i>n</i> = 6. <b>D,</b> Western blot analysis was performed on proteins extracted from the five EV batches for the presence of MHC class II and OVA. <b>E,</b> The presence of OVA on the surface of EVs was determined by ELISA. Data are shown as the mean ± SEM, <i>n</i> = 8.</p>
Funding
Vetenskapsrådet (VR)
Cancerfonden (Swedish Cancer Society)
Radiumhemmets Forskningsfonder (Cancer Research Foundations of Radiumhemmet)
Stockholm läns landsting (Stockholm County Council)
Hjärt-Lungfonden (Swedish Heart-Lung Foundation)
Karolinska Institutet (KI)
History
ARTICLE ABSTRACT
Extracellular vesicles (EV) are important mediators of intercellular communication and are potential candidates for cancer immunotherapy. Immune checkpoint blockade, specifically targeting the programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) axis, mitigates T-cell exhaustion, but is only effective in a subset of patients with cancer. Reasons for therapy resistance include low primary T-cell activation to cancer antigens, poor antigen presentation, and reduced T-cell infiltration into the tumor. Therefore, combination strategies have been extensively explored. Here, we investigated whether EV therapy could induce susceptibility to anti–PD-1 or anti–PD-L1 therapy in a checkpoint-refractory B16 melanoma model. Injection of dendritic cell–derived EVs, but not checkpoint blockade, induced a potent antigen-specific T-cell response and reduced tumor growth in tumor-bearing mice. Combination therapy of EVs and anti–PD-1 or anti–PD-L1 potentiated immune responses to ovalbumin- and α-galactosylceramide–loaded EVs in the therapeutic model. Moreover, combination therapy resulted in increased survival in a prophylactic tumor model. This demonstrates that EVs can induce potent antitumor immune responses in checkpoint refractory cancer and induce anti–PD-1 or anti–PD-L1 responses in a previously nonresponsive tumor model.
