Related Experiment Video
Updated: Jul 1, 2026
Experimental Melanoma Immunotherapy Model Using Tumor Vaccination with a Hematopoietic Cytokine
Published on: February 24, 2023
Eliminating PD-L1 on Dendritic Cell Extracellular Vesicles for Immunotherapy Potentiates Immune-Mediated Tumour
Loes Teeuwen1,2,3, Loïc Steiner1,2,3, Chantal Reinhardt1,2,3
1Division of Immunology and Respiratory Medicine, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
Abstract:
Extracellular vesicles (EVs) are emerging as promising vehicles for cancer immunotherapy, yet the molecular determinants of their immunogenicity remain poorly defined. While PD-L1 expression on cancer-derived EVs has been shown to suppress immune responses, its role on immunotherapeutic EVs remains unexplored. In this study, we investigated how eliminating PD-L1 from antigen-loaded bone marrow-derived dendritic cell (BMDC) EVs affects the efficacy of EV-based cancer vaccines. We generated and characterized ovalbumin (OVA)-loaded BMDC EVs from wild-type (WT) and PD-L1-/- C57BL/6 mice. EVs were administered intravenously into WT mice in immunization experiments and in therapeutic and prophylactic B16 OVA-secreting melanoma models. Immune responses were assessed by flow cytometry, ELISpot, and ELISA, and tumour growth was monitored. Proteomic analysis confirmed high EV purity and similar protein profiles between WT and PD-L1-/- EVs, with PD-L1 being the major difference. Functionally, PD-L1-/- EVs induced significantly stronger anti-tumour responses in vivo, particularly in the prophylactic setting. Mice treated with PD-L1-/- EVs showed increased CD8+ T cell tumour infiltration, enhanced IFNγ secretion, and higher tumour rejection rates compared to WT EVs (72.7% vs. 37.5%). Additionally, the frequency of tumour-infiltrating, antigen-specific CD8+ T cells was significantly higher in PD-L1-/- EV-treated mice. In summary, BMDC-derived EVs loaded with antigen are potent immune stimulators, and removal of immune checkpoint molecules such as PD-L1 further enhances their immunogenicity. These findings support the development of engineered EVs as improved platforms for cancer immunotherapy.
Insights
Removing PD-L1 from antigen-loaded dendritic cell extracellular vesicles (EVs) significantly boosts anti-tumor immune responses. This engineered EV cancer immunotherapy shows enhanced efficacy and tumor rejection rates.
Area of Science:
- Immunology
- Biotechnology
- Oncology
Background:
- Extracellular vesicles (EVs) are promising for cancer immunotherapy, but their immunogenicity determinants are unclear.
- PD-L1 on cancer EVs suppresses immunity; its role on therapeutic EVs is unexplored.
Purpose of the Study:
- Investigate the impact of PD-L1 elimination on antigen-loaded bone marrow-derived dendritic cell (BMDC) EV efficacy for cancer vaccines.
- Assess if PD-L1 knockout enhances the anti-tumor immune response of BMDC-derived EVs.
Main Methods:
- Generated ovalbumin (OVA)-loaded BMDC EVs from wild-type and PD-L1 knockout mice.
- Administered EVs intravenously in prophylactic and therapeutic melanoma models in mice.
- Assessed immune responses via flow cytometry, ELISpot, ELISA, and monitored tumor growth.
Main Results:
- PD-L1 knockout EVs showed significantly stronger anti-tumor responses, especially in prophylaxis.
- PD-L1 knockout EVs increased CD8+ T cell infiltration, IFNγ secretion, and tumor rejection rates (72.7% vs. 37.5%).
- Higher frequencies of tumor-infiltrating antigen-specific CD8+ T cells were observed with PD-L1 knockout EVs.
Conclusions:
- Antigen-loaded BMDC EVs are potent immune stimulators.
- Eliminating immune checkpoint PD-L1 enhances EV immunogenicity and anti-tumor efficacy.
- Engineered EVs represent an improved platform for developing advanced cancer immunotherapies.
