Human hepatocytes (10(6) cells) isolated from unused donor livers were incubated at 37°C for 30 minutes with ICG (0-2mg/mL) in both cell suspension and on collagen-coated culture plates. 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. 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). HepG2 cells were also used.