Hypothermic Storage and Cryopreservation of Hepatocytes: The Protective Effect of Alginate Gel against Cell Damages

Abstract

Hepatocyte-based therapy has been proposed as an alternative to organ transplantation in the treatment of liver disorders. In the clinical context, a major issue is the constant supply of quality assurance-controlled hepatocytes, thereby requiring their cold storage in good conditions. We have analyzed the protective effects of alginate entrapment of rat hepatocytes after either 24 or 48 h of hypothermic storage or cryopreservation on the cell viability, cell yield, both mitochondrial and other cytoplasmic functional activities, and apoptosis. Decrease in viability, as evaluated by the MTT inclusion test, was 4% and 13% (24 h at 4°C), 15% and 33% (48 h at 4°C), and 9% and 19% (liquid nitrogen) for entrapped and free suspended hepatocytes, respectively. Viable cell yields were 86 ± 8% and 51 ± 6% for cryopreserved entrapped and free suspended hepatocytes, respectively. The mitochondrial (MTS assay), 7-ethoxyresorufin O-deethylase (EROD), and glutathione-S-transferase (GST) activities were better preserved in entrapped than in free suspended hepatocytes. Both hypothermic storage and cryopreservation were found to induce early caspase-3-like activities, being always much lower in entrapped hepatocytes, particularly after cryopreservation (98.4 ± 42.4 vs. 6.4 ± 4.0 fluorescence arbitrary units/hours/μg protein). Thus, cold-induced apoptosis in hepatocytes can be significantly reduced following their entrapment within alginate gel beads and this is associated with an improvement of both their viability and function.