MONITORING ENGRAFTMENT OF TRANSPLANTED HEPATOCYTES IN RECIPIENT LIVERWITH 5-BROMO-2'-DEOXYURIDINE

For studies on the intrahepatic engraftment of transplanted hepatocyte s, labeling of donor cells is necessary, Current labeling techniques e nable only short-term monitoring of engraftment, In the present study, we describe the use of 5-bromo-2'-deoxyuridine (BrdU) for a more perm anent hepatocyte labeling, BrdU is stably incorporated into replicatin g DNA; consequently, BrdU labeling was performed in regenerating liver s, In 10 Lewis rats, a two-thirds partial hepatectomy was performed, f ollowed by continuous, low-dose BrdU administration, This approach pro vided a fraction of 89+/-1.5% BrdU-labeled donor hepatocytes, without influencing the efficacy of the ensuing isolation of donor hepatocytes . Subsequently, +/-1x10(7) isolated hepatocytes were transplanted eith er intraportally or intrasplenically into syngeneic recipients, and th e engraftment of transplanted cells was evaluated in liver lobes at su ccessive time intervals after transplantation. BrdU-positive hepatocyt es could be identified and quantitated in recipient livers up to 180 d ays after transplantation Repetitive quantitative assessments over tim e revealed an initial, drastic loss of transplanted cells (<24 hr), fo llowed by a stabilization at approximately 7% of the injected cells, H istological monitoring showed that during this period (<48 hr) the tra nsplanted cells migrate from the portal venules to the liver parenchym a, In recipient livers a homogeneous lobe distribution of hepatocyte e ngraftment was found 30 days after both intraportal and intrasplenic t ransplantation, Moreover, no significant difference between the intrah epatic liver cell engraftment of the two transplantation routes was de monstrated, In conclusion, the BrdU-labeling technique of donor hepato cytes enables long-term histological monitoring and quantitative evalu ation of the engraftment of transplanted liver cells in recipient live rs.