Lentiviral vectors can confer high levels of gene transfer and transgene expression in a variety of cell types. However, the biodistribution and toxicity after intravenous administration have not been reported. To address these issues of biodistribution and toxicity, an HIV-1 -based vector, HR'cmvGFP, was administered to normal BALB/c mice by tail-vein injection. Nine different organs and bone marrow were evaluated by real-time quantitative PCR (QPCR) assay capable of a broad range of quantitation (5-log fold) to detect as few as one copy of the green fluorescent protein gene (GFP) per 105 cells. Four days after vector administration, high levels of transgene and gene expression were observed in liver, spleen, and bone marrow in all animals. By 40 days after injection, GFP levels had decreased in liver and spleen, but bone marrow exhibited a consistently high,level of transgene. This finding was consistent with the increase in both GFP frequency and expression levels observed in peripheral blood by fluorescence-activated cell-sorting (FACS) analysis. Between 0 and 1% transgene was detected in all other organs. No significant pathologic lesions were found attributable to vector in any of the tissues examined. The observation of bone marrow transduction after intravenous vector administration suggests the possibility of an in vivo approach to stem cell gene therapy.
Bibliographical noteFunding Information:
We thank R. Scott McIvor (University of Minnesota) for cell line 32Dp210-LNChRGFP and invaluable discussion, and Joel L. Frandsen (University of Minnesota) for expert assistance on animal manipulation. This work was supported by the NIH Grant PO1-HD32652 and the Children’s Medical Research Foundation (Susan and Brad Wilson, Evanston, IL).
- Bone marrow transduction
- Gene therapy
- Germline transmission
- Lentiviral vector
- Real-time PCR