OBJECTIVETo trace magnetically labeled MSCs transplanted into the rat livers by magnetic resonance imaging (MRI).

METHODSFeridex and DAPI labeled rat mesenchymal stem cells (MSCs) were injected via portal veins into carbon tetrachloride treated rats. MRI was performed with a clinical 1.5 T MRI machine immediately before the MSCs injection and at h 1, d 3, d 7, and d 14 after the injection, and then the signal-to-noise ratio (SNR) was measured. MRI findings were compared with the liver histopathologies after the slides were stained with fluorescence dye and Prussian blue.

RESULTSThe SNR for liver was 1.10+/-0.26 at hour 1, 8.18+/-1.55 at day 3, 11.08+/-1.30 at day 7, and 14.15+/-1.02 at day 14 respectively. Within 7 days after the MSCs transplantation, the SNRs of the livers were significantly lower than those before the transplantation (P less than 0.05). Histologically, the blue fluorescent particles under the fluorescence microscopy matched in distribution with the iron particles on the Prussian blue stained slides.

CONCLUSIONThe magnetically labeled MSCs transplanted into livers give rise to an obvious signal decrease, and can be tracked with a 1.5 T clinical MRI machine for up to 7 days after MSCs transplantation.