Abstract: AIM: To investing ate a new superparamagnetic iron oxide(SPIO) which could label stem cell seff ciently and be traced in vivo by magnetic resonance with out poly-L-ly sine or othertrans fection agent. METHODS: SPIO nano particles was prepared with Fe2O3 coated by athin layer of 3-amino pro py ltriethoxy silane, and then the compound (SPIO) was used to labeled Marrow Mesenchymal Stem Cells (MSCs).The labeled MSCs were identif icated by prussian blue stain and counted by MTT. Atlast, labeled MSCs was transplanted into rat brain and scanned by MRI. RESULTS: Prussian blue stain indicated that MSCs could be high efficiently labeled by SPIO, and there was no significant effect on the proliferation and viability of labeled MSCs by MTT. Hypo-intense changes of MRI T2 examination could be o bserved in the transplanted area of MSCs labeled by SPIO after t ransplantation in rats brain. CONCLUSION: The new SPIO(Fe2O3 coated by a thin layer of 3-aminopropy ltrie thoxy silane) had no significant toxicity on cells. MSCs still could be label led with the new SPIO directly and high efficiently without the use of poly-L-lysine or other additional transfecting agents. The transplanted cells could be well imaged and traced in vivo.ysine or other additional t ransfecting agents. The transplanted cells could be well imaged and t raced in vivo.

Key words: Superparamagneticiron oxide, Stem cell, Mag netic resonance imaging