Author(s): Chuah MK, Van Damme A, Zwinnen H, Goovaerts I, Vanslembrouck V,
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Abstract The potential of using bone marrow (BM)-derived human stromal cells for ex vivo gene therapy of hemophilia A was evaluated. BM stromal cells were transduced with an intron-based Moloney murine leukemia virus (Mo-MuLV) retroviral vector that contained the B domain-deleted human factor VIII (FVIIIdeltaB) cDNA. This FVIII-retroviral vector was pseudotyped with the gibbon ape leukemia virus envelope (GALV-env) to attain higher transduction efficiencies. Using optimized transduction methods, high in vitro FVIII expression levels of 700 to 2500 mU of FVIII/10(6) cells per 24 hr were achieved without selective enrichment of the transduced BM stromal cells. After xenografting of 1.5-3 x 106 engineered BM stromal cells into the spleen of nonobese diabetic severe combined immunodeficient (NOD-SCID) mice, human plasma FVIII levels rose to 13 +/- 4 ng/ml but declined to basal levels by 3 weeks postinjection because of promoter inactivation. About 10\% of these stromal cells engrafted in the spleen and persisted for at least 4 months after transplantation in the absence of myeloablative conditioning. No human BM stromal cells could be detected in other organs. These findings indicate that retroviral vector-mediated gene therapy using engineered BM stromal cells may lead to therapeutic levels of FVIII in vivo and that long-term engraftment of human BM stromal cells was achieved in the absence of myeloablative conditioning and without neo-organs. Hence, BM stromal cells may be useful for gene therapy of hemophilia A, provided prolonged expression can be achieved by using alternative promoters.
This article was published in Hum Gene Ther
and referenced in Journal of Genetic Syndromes & Gene Therapy