Table 1.

Historical key developments in studies of the EVs after 1980s

Year	Milestone discovery	References
1981	EVs were reported	[17]
1985	EVs were detected by electron microscopy	[18]
1996	EVs presenting immune antigen were discovered	[15]
1998	RNAi was discovered	[3]
2007	Valadi et al. first reported that EVs contain mRNA and miRNA	[10]
2010	Three groups confirmed that miRNAs in EVs functionally transfer between cells	[20–22]
2011	Delivery of siRNA by EVs in vivo was demonstrated	[29]