Cellular magnetic resonance with iron oxide nanoparticles: long-term persistence of SPIO signal in the CNS after transplanted cell death.
OBJECTIVE
To study the specificity of cellular MRI based on superparamagnetic iron oxide particles (SPIOs), especially within the CNS.


METHODS
A microglial cell line was engineered for the expression of a suicide gene, the receptor of diphtheria toxin (DT), and two reporter genes, green fluorescent protein and luciferase, in order to induce, in a controlled manner, cell death and test it through bioluminescence. SPIO-labeled DT-sensitive and control DT-insensitive cells were transplanted into the brains of mice, which underwent serial MRI and bioluminescence studies before and up to 90 days after DT-induced cell death.


RESULTS
No variations in SPIO signal voids were detected along longitudinal monitoring in brain hemispheres transplanted with DT-sensitive cells. Ex vivo analyses showed persistence of iron nanoparticle deposits at transplantation sites.


CONCLUSIONS
Due to the long-term persistence of signal after transplanted cell death, caution is advised when SPIOs are employed for cell tracking.
Neuroradiology Department & Neuroradiology Research Group, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy.
Chiara
C
Cianciaruso
Antonella
A
Pagani
Cristina
C
Martelli
Marco
M
Bacigaluppi
Mario Leonardo
ML
Squadrito
Alessia
A
Lo Dico
Michele
M
De Palma
Roberto
R
Furlan
Giovanni
G
Lucignani
Andrea
A
Falini
Alessandra
A
Biffi
Luisa
L
Ottobrini
Letterio Salvatore
LS
Politi
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D001921:Brain / Q000166:cytology* / Q000601:surgery; D002460:Cell Line; D058948:Cell Tracking / Q000379:methods*; D003911:Dextrans; D005260:Female; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D051379:Mice; D008819:Mice, Nude; D017628:Microglia / Q000166:cytology* / Q000637:transplantation*
D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10
cell death; cellular MRI; diphtheria toxin; microglial cell; specificity; superparamagnetic iron oxide