Current Perspectives on In Vivo Noninvasive Tracking of Extracellular Vesicles with Molecular Imaging

Table 1

Strategies of in vivo tracking of extracellular vesicles.

Imaging; modality	Labeling; strategy	Types of cells	Isolation method	Labeling method	Injection Site	Subject	Duration of tracking	Purpose	Clinical translation	Reference
BLI	Indirect	HEK 293T cells	UC	Gluc	IV	Mice	30 to 360; minutes	Biodistribution/Tumor Targeting	x	[22]
		Melanoma cell line	UC	Gluc	IV	Mice	10 to 240 minutes	Biodistribution	x	[23]
		Melanoma cell line	UC	Gluc	IV	Mice	10 to 240 minutes	Biodistribution	x	[38]
FLI	Direct	MSC	UC	DiD	IV	Mice	10 minutes to 24 hours	Targeting to injured kidney	x	[12]
		Mouse B16-F10 (CRL 6475) melanoma cells	UC	DiR	Intradermal	Mice	48 hours	Nodal trafficking	x	[39]
		HEK293	UC	DiR	IV	Mice	24 hours	Biodistribution/Tumor Targeting	x	[40]
		4T1, MCF-7, and; PC3 cells	Sucrose density cushion/UC	DiR	IV and IT	Mice	30 minutes to 7 hours	Biodistribution/Tumor Targeting	x	[20]
NI	Direct	4T1, MCF-7, and; PC3 cells	Sucrose density cushion/UC	^111In-oxine	IV and IT	Mice	30 min to 7 hours	Biodistribution/Tumor Targeting	o	[20]
		Raw 264.7, HB1.F3	Nanovesicles (sequential filtration); iodixanol gradient/UC	-HMPAO	IV	Mice	30 minutes to 5 hours	Biodistribution	o	[23]
		Erythrocyte	UC	-tricarbonyl	IV	Mice	1 hour	Biodistribution	o	[41]
		B16BL6 murine melanoma cell line	UC	^125I-biotin derivatives	IV	Mice	1 minute to 4 hours	Biodistribution	x	[42]
MRI	Direct	Mouse B16-F10 (CRL 6475) melanoma cells	UC	USPIO	Intradermal	Mice	1 hour, 48 hours	Nodal trafficking	o	[43]
		Murine adipose stem cell (C57BL/6)	PureExo® Exosome Isolation Kit	USPIO	IM	Mice	1 hour	Retention at injection site	o	[19]

BLI, bioluminescence imaging; FLI, fluorescence Imaging; NI, nuclear imaging; MRI, magnetic resonance imaging; UC, ultracentrifuge; MSC, mesenchymal stem cell; USPIO, ultrasmall super paramagnetic iron oxide; IV, intravenous; IT, intratumor; I.M, intramuscular; DiD and DiR, near-infrared dyes; Gluc, Gaussia luciferase.