Isolated hepatocytes represent a relevant model of the liver and are highly required both for research and therapeutic applications. However, sources of primary liver cells from human beings and from some animal species are limited. Therefore, cryopreservation of hepatocytes could greatly facilitate advances in various research areas. The aim of this study was to evaluate whether cryopreserved primary woodchuck hepatocytes could be used for woodchuck hepatitis B virus (WHV) infection studies, and whether they could maintain their regenerative potential in vivo after thawing. Critical steps for good quality of cryopreserved hepatocytes included the use of University of Wisconsin (UW) solution as a main component of the freezing medium, stepwise reduction of dimethylsulfoxide (DMSO) to avoid osmotic shock, and maintenance of low concentrations of DMSO in the culture medium. After cryopreservation, cell viability was still high (70% to 80%), and 50% to Liver transplantation is a successful and well-established treatment for end-stage liver disease and liver failure. However, donor-organ scarcity is a fundamental limitation of this therapy. The availability of highly differentiated primary liver cells to be used for cell-based therapies, such as hepatocyte transplantation, tissue-engineered organs, or for extracorporeal liver support systems, represents an attractive alternative to whole-organ transplantation. 1,2 Freshly isolated normal adult hepatocytes are already widely used in various research areas of hepatology, pharmacology, and toxicology, and initial clinical trials have also shown their potential for therapeutic applications. 3 Essential prerequisites for therapeutic use of hepatocyte transplantation in humans is that primary liver cells must be promptly available, remain highly differentiated, and maintain their proliferative capabilities within the host liver, because only a limited number of cells can be infused into a patient. 4 In past years, numerous research laboratories established procedures for the isolation of primary hepatocytes from commonly used laboratory animals, rat hepatocytes being the most studied. However, only a few laboratories have the possibility to procure livers and perform the isolation of highly viable hepatocytes from humans and animal species that are scarcely available. Therefore, efficient cryopreservation and banking of hepatocytes would greatly expand and facilitate the use of primary liver cells both for research and therapeutic applications, while decreasing the need of freshly procured livers for the preparation of hepatocytes both from animal species and humans.Persistent infection with hepatitis B virus (HBV) is one of the major causes of liver disease in humans, being associated with various degrees of chronic hepatitis, cirrhosis, and the development of hepatocellular carcinoma. 5,6 Replication of HBV can be successfully achieved by transfecting hepatoma cell lines with cloned HBV-DNA genomes. These systems have significantly contributed to elucidating various asp...
