Analysis of gene transfer efficiency of retrovirus producer cell transplantation for in situ gene transfer to hematopoietic cells

Objective. The aim of this study was to assess the gene transfer efficiency of an in situ administration protocol for hematopoietic stem/progenitor ce lls in the rhesus macaque (Macaca mulatta) animal model, Materials and Methods. Moloney murine leukemia virus amphotropic vector pro ducer cells (1-2 x 10(8) cells/animal) were transplanted into the femoral b one marrow cavities of six macaques, To determine if the levels of gene tra nsfer could be increased, a second injection at the same dose of producer c ells was performed into the iliac crest in three of the six macaques, Results. We demonstrated that 0.02-0.1% of peripheral blood mononuclear cel ls contained the vector transgene for up to 12 months following the initial administration of producer cells. Hematopoietic progenitor cell assays ind icated that the neomycin phosphotransferase gene was detected in 10-30% of progenitor cell colonies, A humoral immune response directed toward viral p articles was demonstrated in all animals. Additionally, we demonstrated tha t an increase in the levels of transduced cells, up to 1% of circulating pe ripheral blood mononuclear cells and granulocytes, contain the transgene fo llowing producer cell readministration, Conclusions. These data demonstrate the successful in situ gene transfer to hematopoietic stem/progenitor cells and circulating peripheral blood monon uclear cells that persists as long as 12 months postinjection, in the absen ce of any preconditioning, (C) 2001 International Society for Experimental Hematology. Published by Elsevier Science Inc.