EFFICIENT TRANSFER OF GENES INTO MURINE CARDIAC GRAFTS BY STARBURST POLYAMIDOAMINE DENDRIMERS

Starburst dendrimer, a structurally defined, spherical macromolecule c omposed of repeating polyamidoamino subunits, was investigated to augm ent plasmid-mediated gene transfer efficiency in a murine cardiac tran splantation model, The grafts were directly injected with naked pCH110 , a plasmid encoding beta-galactosidase (beta-Gal), or pCH110-dendrime r complex, and reporter gene expression determined by X-Gal staining, The grafts injected with pCH110-dendrimer demonstrated widespread and extended beta-Gal expression in both myocytes and the graft infiltrati ng cells from 7 to 28 days, compared to the grafts injected with naked pCH110 that expressed beta-Gal only in myocytes for less than 14 days . p alpha MHC-vIL-10, as plasmid encoding viral interleukin-10 (vIL-10 ) under the control of alpha-myosin heavy chain promoter, was able to prolong allograft survival from 13.9 +/- 0.9 days to 21.4 +/- 2.3 days (p < 0.005). When dendrimer G5EDA was used with p alpha MHC-vIL-10, 6 0-fold less DNA resulted in significant prolongation of graft survival to 38.6 +/- 4.7 days (p < 0.0005). The dose of DNA, the charge ratio of DNA to dendrimer, and the size generation of the dendrimers were al l determined to be critical variables for prolongation of allograft su rvival in this model system, Thus, the use of the Starburst dendrimer dramatically increased the efficiency of plasmid-mediated gene transfe r and expression, Production of immunosuppressive cytokines at higher amounts for longer periods of time in a greater expanse of tissue enha nced the immunosuppressive effect and prolonged graft survival further .