Transfer of the human glucocerebrosidase gene into hematopoietic stem cells of nonablated recipients: successful engraftment and long-term expression of the transgene.

In trying to develop methods of gene therapy for Gaucher disease that will avoid the morbidity and mortality associated with bone marrow (BM) ablation, we transplanted BM stem cells transduced with a retroviral vector containing the human glucocerebrosidase cDNA into normal, nonablated, syngeneic mice. Donor BM from untreated male mice or treated with 5-fluorouracil (5-FU) was transduced ex vivo using a standard 4-day transduction protocol. Recipient female mice were injected one time only or once daily for 5 consecutive days or once a week for 5 consecutive weeks using 2 x 10(7) (untreated BM) or 2 x 10(6) (5-FU-treated BM) cells per injection. Initial transduction efficiency into colony-forming unit-spleen (CFU-S) was 80% to 100%. Recipient analysis was performed at least 6 months after the last transplantation. The best engraftment of donor stem cells, up to 5% by secondary CFU-S analysis, was obtained with multiple injections of transduced BM not previously treated with 5-FU. Polymerase chain reaction (PCR) amplification for both the transgene and the Y chromosome identified the progeny of transduced stem cells in various hematopoietic and non-hematopoietic organs. The copy number of the transgene in stem cells was 0.13 to 2.8. Transgene expression was shown by reverse transcriptase-PCR, in situ hybridization, and immunohistochemistry. No serious side effects of the procedure were noted. We conclude that multiple transplants of retrovirally transduced BM cells into nonablated recipients may be a safe and effective therapeutic modality for a number of genetic hematopoietic disorders.