Abstract： Objective:To label mesenchymal stem cells (MSCs) with 89Zr-oxine complex, and assess its characteristics of PET imaging in systemic lupus erythematosus (SLE) model (MRL/lpr mice). Methods:SLE mice were screened by 18F-FDG PET imaging. 89Zr-oxine was prepared and used for labeling MSCs (10 6 MSCs and 1 MBq 89Zr-oxine). 89Zr-oxine-labeled MSCs (0.2 MBq) were injected into MRL/lpr mice and BALB/c mice (each n=5) via tail vein at a dose of 1.2×10 6 cells per mouse, and followed with microPET imaging in vivo at 2 h, 6 h, 1 d, 3 d, 7 d, 10 d and 14 d after injection. The percentage activity of injection dose per gram of tissue (%ID/g) was calculated. Independent-sample t test was used to analyze the data. Results:MSCs was successfully labeled with 89Zr-oxine, with the labeling efficiency of 20% and cell viability >90%. MicroPET imaging showed that MSCs were mainly distributed in lungs and the liver sites at 2 h after injection. The number of MSCs homing to kidneys of MRL/lpr mice ( n=5) increased significantly 24 h after the injection, and the renal uptake of MSCs in MRL/lpr mice was much higher than that in BALB/c mice ((8.28±1.27) vs (4.33±0.94) %ID/g; t=3.54, P=0.024). The renal uptake increased firstly and then decreased and then leveled off, indicating MSCs homing to kidneys. Conclusions:A method for 89Zr-oxine labeling of MSCs is successfully established. 89Zr-labeled MSCs can home to kidneys of SLE mice. PET imaging of 89Zr-labeled MSCs can be effectively used to explore the in vivo distribution and migration behavior of transplanted MSCs during the treatment of diseases such as SLE.