Cultivation of immortalized human hepatocytes HepZ on macroporous CultiSpher G microcarriers

Cultivation of the new immortalized hepatocyte cell line HepZ was performed with a 1:1 mixture of DMEM and Ham's F12 media containing 5% FCS. The cell s were grown in their 40th passage in 100 mL and 1 L volumes in spinner fla sks and in a bioreactor, respectively. For the production of adherently gro wing HepZ cells macroporous CultiSpher G gelatin microcarriers were used in various concentrations from 1 to 3 g/L. The cells were seeded in a density of 2 x 10(5) cells/mL when using a microcarrier concentration of 1 g/L and 5 x 10(5) cells/mL at a microcarrier concentration of 3 g/L. After 7 days of cultivation a maximum cell concentration of 4.5 x 10(6) cells/mL was obt ained in the spinner culture using a microcarrier concentration of 1 g/L. W ith bubble-free aeration and daily medium exchange from day 7, 7.1 x 10(6) cells/mL were achieved in the bioreactor using a microcarrier concentration of 3 g/L. The cells exhibited a maximum specific growth rate of 0.84 per d ay in the spinner system and 1.0 per day in the bioreactor, respectively. D uring the growth phase the lactate dehydrogenase (LDH) activity rose slight ly up to values of 200 U/L. At the end of cultivation the macroporous carri ers were completely filled with cells exhibiting a spherical morphology whe reas the hepatocytes on the outer surface were flat-shaped. Concerning thei r metabolic activity the cells predominantly consumed glutamine and glucose . During the growth phase lactate was produced up to 19.3 mM in the spinner culture and up to 9.1 mM in the bioreactor. Maximal oxygen consumption was 1950 nmol/(10(6) cells day). HepZ cells resisted a 4-day long chilling per iod at 9.5 degrees C. The cytochrome P450 system was challenged with a puls e of 7 mu g/mL lidocaine at a cell density of 4.5 x 10(6) cells/mL. Five ng /mL monoethylglycinexylidide (MEGX) was generated within 1 day without phen obarbital induction compared to 26 ng/mL after a preceded three day inducti on period with 50 mu g/mL of phenobarbital indicating hepatic potency. Thus , the new immortalized HepZ cell line, exhibiting primary meta-belie functi ons and appropriate for a mass cell cultivation, suggests its application f or a bioartificial liver support system. (C) 2000 John Wiley & Sons, Inc.