Table 1. Summary of exosome isolation methods and results of studies into the potential roles and uses of exosomes in pancreatic cancer.

EXOSOME SOURCE	EXOSOME ISOLATION METHOD	RESULTS	REFERENCE
Primary cultures of murine pancreatic ductal adenocarcinomas (PKCY)	Ultracentrifugation	Enhanced TGF-beta signalling in Kupffer cells, correlated with poor patient outcomes. Accumulation of fibronectin leading to influx of bone marrow derived macrophages to the liver microenvironment. Upregulation of macrophage inhibitory factor.	[25]
Human pancreatic cancer cell line PANC-1 in culture	Ultracentrifugation	Exosomes taken up by dendritic cells. PC exosomes deliver miR-212-3p, leading to inhibition of RFXAP and MHC II expression and consequently contributing to immune tolerance. miR-212-3p may hence be crucial for PC progression.	[75]
Human pancreas cacrcinoma cell line Colo357	Successive centrifugation	Exosomes contain high levels of Hsp70/Bag-4; Hsp70 is involved in transmembrane protein transport, while Bag-4 binds to Hsp70 on its ATPase domain. Exosomes were enriched with Rab-4, indicating biogenesis and export via an intracellular route.	[76]
Human serum (PC, chronic pancreatitis, benign pancreatic tumour, non PC controls)	Sucrose-gradient centrifugation	PC exosomes were positive for PC initiating cell markers CD44v5, Tspan8, EpCAM, MET and CD104 This effect was not observed for non-malignant PC. miR-1246, miR-4644, miR-3976 and miR-4306 were expressed at higher concentrations in the majority of PC exosomes compared to controls.	[55]
Human serum (PC, benign pancreatic disease, and healthy donors) Human cell lines (e.g. HMLE, MIA Paca2, Panc-1)	Ultracentrifugation and ultrafiltration	Glypican-1 positive exosomes were better at identifying early pancreatic cancer compared to CA19-9 when distinct changes in pancreatic histology were absent.	[57]
Human serum (PC, healthy controls)	ExoChip (antigen based)	Significantly higher exosome capture in PC patients, compared to controls.	[73]
ASML (metastatic rat adenocarcinoma BSp73ASML) exosomes recovered in draining lymph nodes; cells cultured in serum-free medium	Centrifugation	ASML CD44vkd cells with poor metastatic potential were largely able to recover metastatic capacity when treated with ADMLwt or ASML-CD44vkd exosomes alongside ASMLwt conditioned medium. CD44v6 affects gene and miRNA transcription and content of exosomes. miR-494 and miR-542-3p were abundant in ASMLwt exosomes, which in turn increased matrix metalloprotease transcription..	[18]
Cell line supernatant (human pancreatic carcinoma or adenocarcinoma)	Ultracentrifugation and ultrafiltration	Exosomes decreased hairy and enhancer-of-split homolog-1 (Hes-1) expression, which is the target of Notch-1 signaling, and activated apoptosis. Exosomes inhibited cell proliferation by blocking key regulators of the Notch-1 pathway. Interactions occurred at lipid rafts.	[71]
PDAC cell lines	Ultracentrifugation and ExoQuick-TC purification	PDAC cells released exosmes in an integrin-b4 dependent manner. Integrin-b4 in exosomes, led to mislocalisation of plectin to the cell surface. Plectin was also found to enhance growth of the tumour in immunocompromised mice. Additionally, plectin was found to be key in the secretion of exosomes and contributed to the tumorigenic properties of exosomes.	[53]