Rapid Lentiviral Transduction Preserves the Engraftment Potential of Fanca^-/- Hematopoietic Stem Cells

Fanconi anemia (FA) is a rare recessive syndrome, characterized by congenital anomalies, bone marrow failure, and predisposition to cancer. Two earlier clinical trials utilizing γ-retroviral vectors for the transduction of autologous FA hematopoietic stem cells (HSCs) required extensive in vitro manipulation and failed to achieve detectable long-term engraftment of transduced HSCs. As a strategy for minimizing ex vivo manipulation, we investigated the use of a "rapid" lentiviral transduction protocol in a murine Fanca^-/- model. Importantly, while this and most murine models of FA fail to completely mimic the human hematopoietic phenotype, we observed a high incidence of HSC transplant engraftment failure and low donor chimerism after conventional transduction (CT) of Fanca^-/- donor cells. In contrast, rapid transduction (RT) of Fanca^-/- HSCs preserved engraftment to the level achieved in wild-type cells, resulting in long-term multilineage engraftment of gene-modified cells. We also demonstrate the correction of the characteristic hypersensitivity of FA cells against the cross-linking agent mitomycin C (MMC), and provide evidence for the advantage of using pharmacoselection as a means of further increasing gene-modified cells after RT. Collectively, these data support the use of rapid lentiviral transduction for gene therapy in FA.