The aim of this study was to investigate whether the uptake and release of indocyanine green (ICG) by hepatocytes could be used. Currently, it is difficult to assess rapidly hepatocyte function before transplantation. Hepatocyte transplantation is a promising alternative to liver transplantation in children with liver metabolic disorders and acute liver failure. With further refinement, ICG could be used to develop a rapid assay for assessment of the function of isolated human hepatocytes. Addition of taurine (20 mM) to plated hepatocytes gave greater release of ICG and hepatocyte attachment compared to controls, at all ICG concentrations (SRB 1.360 ± 0.083 optical density units vs. Incubation of HepG2 cells with ICG reduced albumin production (98.9 ± 0.02 ng/mL, 66.6 ± 0.05 ng/mL and 39.1 ± 0.4 ng/mL for control cells, and 0.5 mg/mL and 1.0 mg/mL ICG, respectively), and decreased -thymidine incorporation in a dose-dependent manner. Hepatocytes incubated with 1.0 mg/mL ICG had higher mitochondrial dehydrogenase activity compared to 0.5 mg/mL ICG or control cells (0.025 ± 0.0004 OD unit vs. Concentrations of ICG > 1.0 mg/mL had toxic effects on hepatocytes. ICG was taken up and secreted by hepatocytes with the release reaching a plateau level soon after 1 hour. Cell viability was determined by trypan blue exclusion, (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay (mitochondrial dehydrogenase activity) and sulforhodamine B (SRB) assay (cell attachment). Cells were then incubated in medium without ICG for 3 hours with supernatants collected at 1, 2 and 3 hours for measurement of ICG release. Human hepatocytes (106 cells) isolated from unused donor livers were incubated at 37☌ for 30 minutes with ICG (0–2 mg/mL) in both cell suspension and on collagen-coated culture plates.

Assessment of human hepatocytes for transplantation

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