In situ gene transfer into rat auxiliary liver transplant

Abstract

Background. A replication-defective retrovirus BAG vector was tested for in situ delivery of the β-galactosidase gene to auxiliary liver transplant in a rat model. Methods. The BAG vector, which was shown to be effective in genetic transduction of cultured NIH/3T3 cells, was produced in a ψ2 packaging cell and later amplified in a selected PA317 clone. Hepatocyte replication was induced by one-third hepatectomy of the donor liver, and the procedure was followed by auxiliary partial liver transplantation. Twenty- four hours after hepatic induction or transplantation, vital supernatant at 37°C was perfused into the liver graft via the portal vein during a temporary occlusion of the graft portal vein. Results. All animals survived the transplantation procedures and were killed at specified time intervals. Histochemical staining of the liver graft specimens indicated the expression of β-galactosidase in the gene transferred group but not in the control animals. As demonstrated by polymerase chain reaction assay, the proviral β- galactosidase sequence was present in the graft specimens, but absent from all other tissues tested. Conclusions. In short, the retrovirus BAG vector can be useful for in situ delivery of foreign genes to liver graft in transplantation and other clinical settings, providing a simple, consistent, and reliable alternative in hepatic gene therapy experiments.