IN-SITU GENE-TRANSFER INTO RAT AUXILIARY LIVER-TRANSPLANT

Background A replication-defective retrovirus BAG vector was tested fo r in situ delivery of the P-galactosidase gene to auxiliary liver tran splant in a rat model, Methods, The BAG vector, which was shown to be effective in genetic transduction of cultured NIH/3T3 cells, was produ ced in a psi 2 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 l iver transplantation. Twenty-four hours after hepatic induction or tra nsplantation, viral supernatant at 37 degrees C was perfused into the liver graft via the portal vein during a temporary occlusion of the gr aft portal vein. Results. All animals survived the transplantation pro cedures and were killed at specified time intervals. Histochemical sta ining of the liver graft specimens indicated the expression of P-galac tosidase in the gene transferred group but not in the control animals, As demonstrated by polymerase chain reaction assay, the proviral P-ga lactosidase sequence was present in the graft specimens, but absent fr om all other tissues tested, Conclusions. In short, the retrovirus BAG vector can be useful for in situ delivery of foreign genes to liver g raft in transplantation and other clinical settings, providing a simpl e, consistent, and reliable alternative in hepatic gene therapy experi ments.