Accelerated stem cell labeling with ferucarbotran and protamine.
OBJECTIVE
To develop and characterize a clinically applicable, fast and efficient method for stem cell labeling with ferucarbotran and protamine for depiction with clinical MRI.


METHODS
The hydrodynamic diameter, zeta potential and relaxivities of ferucarbotran and varying concentrations of protamine were measured. Once the optimized ratio was found, human mesenchymal stem cells (MSCs) were labeled at varying incubation times (1-24 h). Viability was assessed via Trypan blue exclusion testing. 150,000 labeled cells in Ficoll solution were imaged with T1-, T2- and T2*-weighted sequences at 3 T, and relaxation rates were calculated.


RESULTS
Varying the concentrations of protamine allows for easy modification of the physicochemical properties. Simple incubation with ferucarbotran alone resulted in efficient labeling after 24 h of incubation while assisted labeling with protamine resulted in similar results after only 1 h. Cell viability remained unaffected. R2 and R2* relaxation rates were drastically increased. Electron microscopy confirmed intracellular iron oxide uptake in lysosomes. Relaxation times correlated with results from ICP-AES.


CONCLUSIONS
Our results show internalization of ferucarbotran can be accelerated in MSCs with protamine, an approved heparin antagonist and potentially clinically applicable uptake-enhancing agent.
Golovko
Daniel M
DM
Department of Radiology & Biomedical Imaging, University of California San Francisco, San Francisco, CA, USA.
Henning
Tobias
T
Bauer
Jan S
JS
Settles
Marcus
M
Frenzel
Thomas
T
Mayerhofer
Artur
A
Rummeny
Ernst J
EJ
Daldrup-Link
Heike E
HE
D003287:Contrast Media; D003911:Dextrans; D052203:Ferrosoferric Oxide; D006801:Humans; D058185:Magnetite Nanoparticles; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D011479:Protamines; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods; D055815:Young Adult
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D011479:Protamines; C065507:ferumoxides; D052203:Ferrosoferric Oxide