OBJECTIVETo observe the in vivo migration of human umbilical cord mesenchymal stem cells (hUCMSCs) labeled with the PKH26 red fluorescent dye after transplantation into rats with liver cirrhosis.

METHODSFrozen hUCMSCs were resuscitated and labeled with PKH26. Labeling efficiency and fluorescent maintenance time of the PKH26-1abeled cells were measured. Morphology of the labeled and unlabeled (control) cells was observed by microscopy. The cell growth curve was determined using the MTT method. The PKH26-1abeled hUCMSCs were transplanted via tail vein injection into healthy (control) rats and rats with liver cirrhosis. Migration of the PKH26-1abeled hUCMSCs observed 48 h later in frozen liver sections under a fluorescence microscope.

RESULTSThe labeling ratio of PKH26 to hUCMSCs was 100%. Growth of the labeled cells was good. The cell morphology was not significantly different between the labeled and unlabeled cells; all cells were long and spindle-like. Cell proliferation was not impacted significantly by labeling.Fluorescence was maintained for at least 20 days, as detected by in vitro analysis. After transplantation into the rats, the PKH26-1abeled hUCMSCs were mainly distributed in the area surrounding the portal vein, the blood vessels, and the false lobule of the cirrhotic liver; a small amount ofhUCMSCs were present in the spleen and lung.

CONCLUSIONPKH26 is an ideal fluorescent dye to label hUCMSCs. The PKH26 labeling technique can be used to study the migration of hUCMSCs in cirrhotic liver.