Fig. 3

Short-term fate of mMSCs imaged in vivo and post mortem. a BLI, MRI (in vivo, post mortem) and fluorescence microscopy images of the kidneys immediately (on day 0, within 5 h) or on day 1 or day 2 after IC administration of SPION-labelled mMSCs. Fluorescence images were obtained from tissue sections where green fluorescence corresponds to ZsGreen expression and blue fluorescence to DAPI staining. Arrowheads indicate individual glomeruli. Scale bar corresponds to 100 μm. T₂^* relaxation time of the b kidney cortices or c liver before (baseline) and up to 2 days after cell administration. The T₂^* relaxation time in the cortex of the kidney was significantly lower on the day of cell administration (day 0, mean = 7.98 ms ± SE = 0.29) than at baseline (14.56 ± 0.32 ms; one-way ANOVA, p < 0.001). The T₂^* relaxation time then increased towards baseline levels at day 1 (12.57 ± 0.50 ms) and day 2 (13.19 ± 0.23 ms), and by day 2, the difference compared with baseline levels was no longer statistically significant. In the livers, T₂* relaxation time revealed a subtle but significant decrease in relaxation time from baseline to day 2 (baseline, 7.19 ± 0.29 ms; day 0, 5.48 ± 0.38 ms; day 1, 5.10 ± 0.16 ms; day 2, 5.02 ± 0.94 ms; one-way ANOVA, p = 0.006). Time points that do not share the same letters are significantly different from one another, p < 0.05 (Tukey’s post hoc test)