Engraftment of NOD/SCID mice with human CD34(+) cells transduced by concentrated oncoretroviral vector particles pseudotyped with the feline endogenous retrovirus (RD 114) envelope protein

Oncoretrovirus vectors pseudotyped with the feline endogenous retrovirus (R D114) envelope protein produced by the FLYRD18 packaging cell line have pre viously been shown to transduce human hematopoietic progenitor cells with a greater efficiency than similar amphotropic envelope-pseudotyped vectors. In this report, we describe the production and efficient concentration of R D114-pseudotyped murine leukemia virus (MLV)-based vectors. Following a sin gle round of centrifugation, vector supernatants were concentrated approxim ately 200-fold with a 50 to 70% yield. Concentrated vector stocks transduce d prestimulated human CD34(+) (hCD34(+)) cells with approximately 69% effic iency (n = 7, standard deviation = 4.4%) using a single addition of vector at a low multiplicity of infection (MOI = 5). Introduction of transduced hC D34(+) cells into irradiated NOD/SCID recipients resulted in multilineage e ngraftment with long-term transgene expression. These data demonstrate that RD114-pseudotyped MLV-based vectors can be efficiently concentrated to hig h titers and that hCD34(+) cells transduced with concentrated vector stocks retain in vivo repopulating potential. These results highlight the potenti al of RD114-pseudotyped oncoretrovirus vectors for future clinical implemen tation in hematopoietic stem cell gene transfer.