Evaluation of different protocols for gene transfer into non-obese diabetes/severe combined immunodeficiency disease mouse repopulating cells

Purpose Although gene transfer with retroviral vectors has shown distinct clinical success in defined settings, efficient genetic manipulation of hematopoietic progenitor cells remains a challenge. To address this issue we have evaluated different transduction protocols and retroviral constructs in the non-obese diabetes (NOD)/severe combined immunodeficiency disease (SCID) xenograft model. Methods An extended transduction protocol requiring 144 h of in vitro manipulation was compared to a more conventional protocol requiring 96 h only. Result While pretransplantation analysis of cells transduced with a retroviral vector, expressing the enhanced green fluorescent protein (EGFP) marker gene, demonstrated significantly higher overall transduction rates for the extended protocol (33.6 ± 2.3 vs. 22.1 ± 3.8%), EGFP expression in CD34+ cells before transplantation (4.0 ± 0.9 vs. 11.6 ± 2.5%), engraftment of human cells in NOD/SCID bone marrow 4 weeks after transplantation (4.5 ± 1.7 vs. 36.5 ± 9.4%) and EGFP expression in these cells (0 ± 0 vs. 11.3 ± 2.8%) were significantly impaired. When the 96 h protocol was used in combination with the spleen focus forming virus (SFFV)/murine embryonic stem cell (MESV) hybrid vector SFβ11-EGFP, high transduction rates for CD45+ (41.0 ± 5.3%) and CD34+ (38.5 ± 3.7%) cells prior to transplantation, as well as efficient human cell engraftment in NOD/SCID mice 4 weeks after transplantation (32.4 ± 3.5%), was detected. Transgene expression was observed in B-lymphoid (15.9 ± 2.0%), myeloid (36.5 ± 3.5%) and CD34+ cells (10.1 ± 1.5%). Conclusion Our data show that CD34+ cells maintained in cytokines for multiple days may differentiate and loose their capacity to contribute to the haematological reconstitution of NOD/SCID mice. In addition, the SFFV/MESV hybrid vector SFβ11-EGFP allows efficient transduction of and gene expression in haematopoietic progenitor cells.