Fig. 4.

MPIO tracking of DAPCs in the rat brain. a Yellow fluorescence of unlabelled and MPIO-labelled DAPCs. b Forward vs. side scatter plot of unlabelled and MPIO-labelled DAPCs. c Schematic of injection and experimental timeline of DAPC administration and magnetic resonance imaging. d Representative RARE MRI scans of a rat that received MPIO-labelled DAPC (left hemisphere: unlabelled, right hemisphere: labelled) as imaged on day 1, 14, 28, 42, 70 and 126 post administration. Hypointense contrast, indicative of a reduction in relaxation time as caused by MPIO labelling, is seen in the right hemisphere throughout the experimental period (indicated with an arrowhead in the first image). No abnormal growth is observed in either of the hemispheres. e Immunofluorescence microscopy of the injection sites. Cells express human NCAM, showing that MPIO-labelled DAPCs survived in the rats’ brains and TH, suggesting that DAPCs matured into DAs. MPIO-specific fluorescence is only seen in the right hemisphere and tends to be localised near to the cell nuclei. Note that the MPIO fluorophore, Suncoast Yellow, is also excited at 405 nm and bleeds into the DAPI channel. Scale bar = 50 μm.