TABLE 4.

The role of neural cell-derived exosomes in PD pathology.

	Function	Exosome-producing cells	Stimulation	Cargo	Mechanism	References
Neuron	Propagation of toxic proteins	Differentiated SH-SY5Y cell line	Over-expression of wild-type α-syn	α-syn	Propagation of α-syn and triggering neuronal apoptosis.	Emmanouilidou et al., 2010; Alvarez-Erviti et al., 2011
	Protein aggregation and inflammation	MN9D cell model	Environmental neurotoxicant manganese	miR-210-5p, miR128-1-5, miR-325-5p, miR-16-5p. etc.	Carrying miRNA involving in protein aggregation, autophagy, inflammation, and hypoxia and aggravating the degeneration of PD.	Harischandra et al., 2018
Microglia	Propagation of toxic proteins	BV-2 microglial cell line	Plasma exosomes from PD patients/human α-synuclein preformed fibrils	α-syn	α-syn propagation and the aggregation of α-syn in recipient neurons.	Xia et al., 2019; Guo et al., 2020
	Transmission of neuroinflammation	BV-2 microglial cell line	α-syn	MHC II, TNF-α	Inducing neuroinflammatory response and neuronal apoptosis.	Chang et al., 2013
Astrocyte	Neuronal protection	Primary mouse astrocyte	–	miR-200A-3p	Inhibiting apoptotic signaling pathway and reducing MPP+-induced apoptosis of hippocampal neurons.	Shakespear et al., 2020