MULTIPLE VECTORS EFFECTIVELY ACHIEVE GENE-TRANSFER IN A MURINE CARDIAC TRANSPLANTATION MODEL - IMMUNOSUPPRESSION WITH TGF-BETA-1 OR VIL-10

The application of gene transfer techniques to organ transplantation o ffers the potential for modulation of immunity directly within an allo graft without systemic side effects. Expression vectors and promoter e lements are important determinants of gene transfer and expression. In this study, various vectors (naked plasmid DNA, retroviral vector, he rpes simplex viral vector, and adenoviral vector) with various promote rs (RSV-LTR, SV40, MuLV-LTR, HCMVie1) were directly compared to demons trate the successful gene transfer and expression of beta-galactosidas e in murine myoblasts in vitro and within murine heterotopic, nonvascu larized cardiac isografts or allografts in vivo. Expression of transfe rred genes was not toxic to cells and strength of expression varied ac cording to the type of vector. Plasmid DNA was expressed in myocytes, retroviral vector was expressed in the graft infiltrating cells, and h erpes simplex and adenoviral vectors were expressed in both myocytes a nd graft-infiltrating cells. Preliminary studies evaluated the ability of these vectors to deliver immunologically important signals. Allogr afts injected with pSVTGF-beta 1, a plasmid-encoding transforming grow th factor beta 1 (TGF-beta 1) under the control of the SV40 promoter, showed significant prolongation of graft survival of 26.3+/-2.5 days c ompared with 12.6+/-1.1 days for untreated allografts, and 12.5+/-1.5 days for the allografts injected with control plasmid (P<0.05). Allogr afts injected with MFG-vIL-10, a retroviral vector encoding viral inte rleukin-10 under the control of the MuLV-LTR, showed prolongation of g raft survival of 36.7+/-1.3 days versus 12.6+/-1.1 days for the untrea ted allograft, and 13.5+/-2.0 days for the allografts injected with co ntrol retroviral vector (P<0.001). Both vectors were transcriptionally active in vivo and did not appear to have toxic effects. Gene therapy for transplantation can induce transient expression of immunologicall y relevant molecules within allografts that impede immune activation w hile avoiding the systemic toxicity of conventional immunosuppression.