In Vivo Retrovirus-Mediated Gene Transfer into Multiple Hematopoietic Lineages in Rabbits Without Preconditioning

Hematopoietic progenitor cells are attractive targets for gene therapy of inherited and acquired disorders. We have developed a novel procedure for mediating gene transfer into hematopoietic cells using an in vivo approach. The procedure involves injection of irradiated retroviral producer cells into the femoral bone marrow cavity in rabbits without preconditioning. The emergence of vector-marked cells in multiple peripheral blood hematopoietic lineages was detected 1 week post-injection and persisted until the animals were sacrificed up to 20 months later. Vector-marked cells were also detected in different hematopoietic tissues including bone marrow, spleen, thymus, and lymph node. Expression of retrovirus-specific messages by reverse transcription polymerase chain reaction was detected at multiple time points up to 20 months. Retrovirally encoded protein was detected by enzyme-linked immunosorbent assay in supernatant from cultures of granulocytes isolated 14 months after the procedure. This work demonstrates the feasibility of effecting gene transfer into hematopoietic progenitor cells in vivo.

Overview summary

Gene transfer into hematopoietic progenitor cells has previously been demonstrated using ex vivo strategies. This study introduces a novel in vivo approach to progenitor cell gene transfer involving direct injection of retroviral producer cells into the bone marrow cavity. This report demonstrates emergence and long-term persistence of gene-marked cells in multiple peripheral blood fractions following injection of the producer cells. Expression of vector genes is also demonstrated by reverse transcriptase polymerase chain reaction. The in vivo approach may offer some advantages over the ex vivo approach, including minimizing stem cell manipulation, eliminating the significant morbidity required to enable ex vivo-treated stem cells to engraft, and providing a single clinical reagent to be used in the treatment of multiple patients.