Phenotypic correction of Fanconi anemia group C knockout mice

Fanconi anemia (FA) is a genetic disorder characterized by bone marrow fail ure, congenital anomalies, and a predisposition to malignancy. FA cells dem onstrate hypersensitivity to DNA cross-linking agents, such as mitomycin C (MMC), Mice with a targeted disruption of the FANCC gene (fancc -/- nullizy gous mice) exhibit many of the characteristic features of FA and provide a valuable tool for testing novel therapeutic strategies. We have exploited t he inherent hypersensitivity of fancc -/- hematopoietic cells to assay for phenotypic correction following transfer of the FANCC complementary DNA (cD NA) into bone marrow cells, Murine fancc -/- bone marrow cells were transdu ced with the use of retrovirus carrying the human fancc cDNA and injected i nto lethally irradiated recipients. Mitomycin C (MMC) dosing, known to indu ce pancytopenia, was used to challenge the transplanted animals. Phenotypic correction was determined by assessment of peripheral blood counts. Mice t hat received cells transduced with virus carrying the wild-type gene mainta ined normal blood counts following MMC administration. All nullizygous cont rol animals receiving MMC exhibited pancytopenia shortly before death. Clon ogenic assay and polymerase chain reaction analysis confirmed gene transfer of progenitor cells. These results indicate that selective pressure promot es in vivo enrichment of fancc-transduced hematopoietic stem/progenitor cel ls, In addition, MMC resistance coupled with detection of the transgene in secondary recipients suggests transduction and phenotypic correction of lon g-term repopulating stem cells.