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. Author manuscript; available in PMC: 2013 Jun 14.
Published in final edited form as: Methods Mol Biol. 2012;906:239–252. doi: 10.1007/978-1-61779-953-2_18

Fig. 2.

Fig. 2

Importance of facilitator agents for labeling cells with SPIONs. Representative images showing that cationic compounds, such as protamine, are necessary for the efficient uptake of SPIONs. Detection of SPIONs is with anti-dextran antibody. (a) Mesenchymal stem cells incubated only with protamine without ferumoxides. (b) Cells incubated with ferumoxides in the absence of facilitating agent. (c) Cells exposed to FeProt complexes using low protamine concentration (1 μg/mL), which is five times less than the recommended concentration (5 μg/mL). (d ) Mesenchymal cells incubated with FeProt complexes with 5 μg/mL protamine. The arrows are showing some of the ferumoxide-labeled cells. Cell nuclei are labeled blue with DAPI; no cells with SPIONs are detected in (a ), approximately 7 % cells contain SPIONs in (b ), and 95 % in (d). We did not quantify the percentage of labeled cells in group (c). Scale bar = 50 μm.