Characterization of immobilized hepatocytes as liver support

Hepatocytes isolated from rat liver were immobilized within Ca-alginate. Immobilized hepatocytes could remove ammonia and other toxic substances causing hepatic coma, such as indole, phenol, bilirubin, and short chain fatty acids. Although free hepatocytes lost those activities within 2 days, immobilized hepatocytes maintained those activities for more than 7 days. Immobilized hepatocytes induced tyrosine aminotransferase (TAT) in the presence of dexamethasone and dibutyryl-cAMP and retained the ability to induce TAT for more than 7 days. Biologically active form of coagulation factor II, prothrombin could be synthesized and secreted into medium by immobilized hepatocytes. Moreover, immobilized hepatocytes produced glucose from lactate, alanine, fructose, and galactose. Like adult rat liver, growth-related function and liver-specific function in immobilized hepatocytes were reciprocally controlled by cell density. There are both alpha-, and beta-adrenergic receptors in membrane of liver cells, and the adrenergic action of epinephrine is alpha-predominant in adult rat liver. Monolayer-cultured hepatocytes can not maintain alpha-adrenergic response. However, immobilized hepatocytes maintained alpha-adrenergic response as shown in vivo. Those characteristics of immobilized and three-dimensionally cultured hepatocytes are regarded almost the same as liver cells in vivo. Furthermore, therapeutic effect of immobilized hepatocytes on the hepatic failure were confirmed in the experiment using hepatocytes damaged with D-galactosamine. Therefore, it is suggested that immobilized hepatocytes could be applied to a hybrid artificial liver support.