Tracking of transplanted human umbilical cord-derived mesenchymal stem cells labeled with fluorescent probe in a mouse model of acute lung injury

The aim of the present study was topreliminarily visualize the distribution of humanumbilical cord-derived-mesenchymal stem cells (hUC-MSCs) in treating acute lung injury (ALI) using a targeted fluorescent technique. Anovel fluorescent molecule probe was first synthesized via the specific binding of antigen and antibody in vitro to label the hUC-MSCs. Two groups of mice, comprising a normal saline (NS)+MSC group and lipopolysaccharide (LPS)+MSC group, were subjected to optical imaging. At 4 h following ALI mouse model construction, the labeled hUC-MSCs were transplanted into the mice in the NS+MSC group and LPS+MSC group by tail vein injection. The mice were sacrificed 30 min, 1 day, 3 days and 7 days following injection of the labeled hUC-MSCs, and the lungs, heart, spleen, kidneys and liver were removed. The excised lungs, heart, spleen, kidneys and liver were then detected on asmall animal fluorescent imager. The fluorescent results showed that the signal intensity in the lungs of the LPS+MSC group was significantly higher, compared with that of the NS+MSC group at 30 min (3.53 +/- 0.06x10(-4), vs. 1.95 +/- 0.05x10(-4) scaled counts/sec), 1 day (36.20 +/- 0.77x10(-4), vs. 23.45 +/- 0.43x10(-4) scaled counts/sec), 3 days (11.83 +/- 0.26x10(-4), vs. 5.39 +/- 0.10x10(-4) scaled counts/sec), and 7 days (3.14 +/- 0.04x10(-4), vs. 0.00 +/- 0.00x10(-4) scaled counts/sec; all P<0.05). The fluorescence intensity in the liver of the LPS+MSC group, vs. NS+MSC group was measured at 30 min (0.00 +/- 0.00x10(-4), vs. 0.00 +/- 0.00x10(-4) scaled counts/sec); 1 day (5.53 +/- 0.08x10(-4), vs. 5.44 +/- 0.16x10(-4) scaled counts/sec); 3 days (0.00 +/- 0.00x10(-4), vs. 8.67 +/- 0.05x10(-4) scaled counts/sec); 7 days (0.00 +/- 0.00x10(-4), vs. 0.00 +/- 0.00x10(-4) scaled counts/sec). The signal intensity of the heart, spleen and kidneys was minimal. In conclusion, the novel targeted fluorescence molecular probe was suitable for tracking the distribution processes of hUC-MSCs in treating ALI.