A galactose moiety was introduced into the fiber surface of a vegetable sponge by the covalent binding of lactobionic acid. The galactosylated sponge was used as scaffold for the culture of rat hepatocytes in a packed-bed bioreactor. Hepatocytes could be dynamically seeded into and uniformly distributed throughout the scaffold, and the immobilized cells maintained high albumin and urea production rates during long-term perfusion culture. The hepatocytes showed an increasing albumin production rate from 49 to log mu g/10(6) cells/d over the 7-d culture.