Superparamagnetic Iron Oxide Labeling And MR Trace Of Labeled RSCs Translated Into The Eye Of Mice

Objects: To evaluate the effect of Superparamagnetic iron oxide (SPIO) labeling on retinal stem cells(RSCs)'ability to survive in vitro to provide a possible way of Magnetic resonance imaging (MRI) to trace the implanted labeled cells in retina. Methods: RSCs were prepared from the retina of embryonic day 19 SD rats and labeled with different concentration of SPIO (Fe3+ 5.6μg/ml,11.2μg/ml,16.8μg/ml,22.4μg/ml). Prussian blue staining, electronmicroscope were used to evaluate the labeling efficiency of SPIO labeled RSCs. Cell proliferation and apoptosis were quantified by FACS, MTT and Turnel. Results: Above 90% of the cells was positively labeled and iron particles were found in their endochylema by the TEM when SPIO was at the concentration of 11.2-16.8μg/ml in the medium. Labeling rate was below 60% when SPIO was under 5.6μg/ml. Dead cells increased when SPIO was 16.8μg/ml or 22.4μg/ml in the medium. MRI showed remarkable low-signal intensity changes in part of the rat retina transplanted with labeled RSCs by sub-retina injection. Conclusion: The efficiency of labeling was high and SPIO labeling did not affect the ability of RSCs to survive in vitro when SPIO was in concentration of 11.2-16.8μg/ml in medium. SPIO can be used to label RSCs in vitro and MRI plays a role in tracking of SPIO-labeled RSCs after transplantation by sub retina injection. Objects: To investigate the MR tracing of retinal transplantation. Method: 14 BN mice whose retina are hurt by laser are separated into SPIO and no SPIO groups. Retinal stem cells labeled with SPIO and without SPIO were injected into the subretinal space of the mice separately. Then, track the trail of the cells with MR in the following days( 1st , 2nd , 3rd, 5th days and 1st ,2nd, 3rd week). After tracing, kill the animals and make paraffin sections of their eyes. Prussian blue staining were used to check the authenticity and accuracy of MR. Results: After transplantation, MR of the SPIO group showed there are well-defined hyperintensity in retina, which became fuzzy with time process and finally disappeared in 3 weeks. In the corresponding parts, positive cells were found by Prussian blue staining. Conclusion: Retinal stem cells labeled with SPIO can proliferate and move after they are transplanted into the subretinal space of retina-hurt mice. Under the help of MR, their path can be followed clearly in a living animal instead of a dead one.