Tumour‐derived exosomes as antigen delivery carriers in dendritic cell‐based immunotherapy for malignant mesothelioma

Abstract

BackgroundIn 2001, it was postulated that tumour-derived exosomes could be a potent source of tumour-associated antigens (TAA). Since then, much knowledge is gained on their role in tumorigenesis but only very recently tumour-derived exosomes were used in dendritic cell (DC)-based immunotherapy. For this, DCs were cultured ex-vivo and loaded with exosomes derived from immunogenic tumours such as melanoma or glioma and re-administrated to induce anti-tumour responses in primary and metastatic tumour mouse models. In contrast, malignant mesothelioma (MM) is a non-immunogenic tumour and because only a few mesothelioma-specific TAA are known to date, we investigated whether mesothelioma-derived exosomes could be used as antigen source in DC-based immunotherapy.MethodsMouse MM AB1 cells were used to generate tumour lysate and tumour-derived exosomes. Tumour lysate was generated by 5 cycles of freeze–thawing followed by sonication of AB1 cells. Tumour exosomes were collected from the AB1 cell culture supernatant and followed a stepwise ultracentrifugation. Protein quantification and electron microscopy were performed to determine the protein amount and to characterise their morphology. To test whether MM derived exosomes are immunogenic and able to stimulate an anti-tumoral response, BALB/c mice were injected with a lethal dose of AB1 tumour cells at day 0, followed by intraperitoneal injection of a single dose of DCs loaded with tumour exosomes, DCs loaded with tumour lysate, or phosphate buffered saline (PBS), at day 7.ResultsMice which received tumour exosome-loaded DC immunotherapy had an increased median and overall survival compared to mice which received tumour lysate-loaded DC or PBS.ConclusionIn this study, we showed that DC immunotherapy loaded with tumour exosomes derived from non-immunogenic tumours improved survival of tumour bearing mice.

Opposite Prognostic Significance of Cellular and Serum Circulating MicroRNA-150 in Patients with Chronic Lymphocytic Leukemia

“…To elucidate if circulating microRNA-150 was encapsulated in exosomes, in microvesicles or in protein/lipid complexes, 15 CLL serums were centrifuged at 20,000g (to pellet microvesicles) and subsequently at 150,000g (to pellet exosomes) for 1 h at 4°C as previously described (25,26). Uncentrifuged, microvesicle-depleted and exosome-depleted sera were processed as described above to detect microRNA levels.…”

Therapeutic biomaterials based on extracellular vesicles: classification of bio‐engineering and mimetic preparation routes

“…In another study, DC-derived exosomes modified to express FasL on the surface (ligand involved in apoptosis induction) were tested as inflammatory and autoimmune therapy [36]. Other recent works are related to the role of tumour-released exosomes to load antigens into DCs for the therapy of malignant mesothelioma [37]. …”

Therapeutic and diagnostic applications of extracellular vesicles

“…CEA, GP100, HER2, melan-A, PSMA) [32,195] and likely to date unknown tumor antigens. This is not only of interest from a diagnostic point of view but also makes tumor-derived EVs, which have shown to outperform free antigens [193,196] and whole tumor lysate [197,198], an attractive candidate to evaluate as a cell-free vaccine. Building on these promising observations, a clinical trial has been conducted using EVs isolated from ascites fluid.…”