Porcine endogenous retroviruses: no infection in patients treated with a bioreactor based on porcine liver cells

Abstract

Background: Acute liver failure (ALF) remains a disease with high mortality. Bioartificial liver support systems, which combine living cells of the liver in an extracorporeal circuit, have been successfully used in first clinical trials. The shortage of human organs to be used for bioreactors and the lack of safe and effective human liver cell lines have resulted in pigs becoming an important hepatic cell source. However, using these cells may be associated with the risk of transmission of porcine endogenous retroviruses (PERVs). PERVs are present in the genome of all pigs and are able to infect human cells in vitro. However, it remains unclear whether PERVs infect transplant recipients in vivo and, if so, whether they are pathogenic.

Objectives: To detect antibodies directed against specific epitopes from PERVs in seven individuals who were treated with porcine liver cell bioreactor therapy prior to liver transplantation.

Methods: Sera from seven patients treated with a hybrid liver support system based on porcine liver cells for ALF who survived the treatment and were discharged from hospital were investigated for antibodies against PERV. For this in addition to methods already reported (Xenotransplantation (2001) 125), new immunological detection methods were developed.

Results: PERV-specific antibodies were found in none of the patients using Western blot assays based on purified virus or recombinant viral core and envelope proteins or ELISA based on synthetic diagnostic peptides.

Conclusion: The assays used are specific and sensitive, and correlated in their diagnostic value. The data indicate that no PERV infection had occurred in none of the patients treated with the CellModule bioreactor containing porcine cells.