Figure 1. In vitro labeling with ferumoxytol does not affect biological properties of swine MSCs.

(a,b) The ferumoxytol uptake, as assessed by colorimetric ferrozine assay, was proportional to the iron concentration in the culture medium (a) and inversely correlated to subculturing passages of MSCs (b). (c,d) Representative light microscopy images of unstained (c) and Prussian-blue-stained (d) MSCs. (e) Transmission electron microscopy image of iron-labeled MSCs showing iron complex was encapsulated in the endosomes. (f) Cell viability of MSCs were tested by 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium assay with doses of ferumoxytol up to 100 μg/ml and incubation time up to 72 hours. Error bars from three independent experiments were not shown for better visual effect. (g–i) Proliferation of MSCs not labeled or labeled with ferumoxytol was evaluated with 5-ethynyl-2´-deoxyuridine assay. (j–l) In vitro migration of MSCs not labeled or labeled with ferumoxytol was determined by transwell migration assay. (m–o) Cell cycle analysis was performed using propidium iodide staining followed by flow cytometric analysis. Data are mean ± SD. **P < 0.01 between comparisons indicated by bracket; ns = not significant. Scale bar in e, 1.0 μm. Scale bars in others, 10 μm.