FETAL-RAT HEPATOCYTES - ISOLATION, CHARACTERIZATION, AND TRANSPLANTATION IN THE NAGASE ANALBUMINEMIC RATS

Background. In contrast to adult hepatocytes, fetal hepatocytes (FH) a re thought to be highly proliferative, less immunogenic, and resistant to cryopreservation and ischemic injury. These qualities could enhanc e FH engraftment, proliferation, and gene transfer requiring active DN A synthesis, Methods. Rat FH were obtained using the nonperfusion coll agenase/DNase digestion method, Free and cultured cells were studied u sing electron microscopy, fluorescence-activated cell sorting, and Nor thern analysis using alpha-fetoprotein and albumin as markers of hepat ocyte lineage, DNA synthetic activity was measured in quiescent and mi togen-stimulated fetal and adult hepatocytes by [H-3]thymidine incorpo ration, Susceptibility of cultured FH to retrovirally mediated gene tr ansfer was studied using an amphotropic retroviral vector carrying the Escherichia coli lac-Z gene, Nagase analbuminemic rats were used as r ecipients to study the effects of intraportal FH transplantation, Anal ysis of serum albumin was carried out by enzyme-linked immunosorbent a ssay. Results, In fetal liver, 87+/-2%? of the cells showed morphologi cal and molecular features of hepatocytes. DNA synthetic activity in n onstimulated cultured FH was 10 times greater than the maximal hepatoc yte growth factor-driven response in adult rat hepatocytes., A total o f 5-15% FH stained positive for X-gal; results of transduction in adul t hepatocyte cultures were negative. In Nagase analbuminemic rat recip ients, FH produced significant amounts of albumin only when a hepatic regenerative stimulus was applied. Immunohistochemistry confirmed pres ence of albumin-positive hepatocytes, Conclusions, Fetal rat liver fro m the late gestation period is highly enriched with hepatocyte progeni tors, They are highly proliferative and susceptible to retroviral tran sduction and can engraft and function in the adult rat liver if transp lanted under a hepatic regenerative stimulus.