Submitted April 24, 2006
Accepted August 5, 2006
Foamy virus-mediated gene transfer to canine repopulating cells
Hans-Peter Kiem*, James Allen, Grant Trobridge, Erik Olson, Kristin Keyser, Laura J. Peterson, and David W. Russell
Fred Hutchinson Cancer Research Center / University of Washington School of Medicine, Seattle, WA
Department of Medicine, University of Washington School of Medicine, Seattle, WA
Fred Hutchinson Cancer Center / University of Washington School of Medicine, Seattle, WA
Clinical Division, Fred Hutchinson Cancer Research Center, Seattle, WA
Departments of Medicine / Biochemistry, University of Washington School of Medicine, Seattle, WA
* Corresponding author; email: hkiem{at}fhcrc.org.
Foamy virus (FV) vectors are particularly attractive gene transfer vectors for stem cell gene therapy because they form a stable transduction intermediate in quiescent cells and can efficiently transduce hematopoietic stem cells. Here we studied the use of FV vectors to transduce long-term hematopoietic repopulating cells in the dog, a clinically relevant large animal model. Mobilized canine peripheral blood (PB) CD34+ cells were transduced with an enhanced green fluorescent protein (EGFP)-expressing FV vector in an 18-hour transduction protocol. All three dogs studied had rapid neutrophil engraftment to over 500/µl with a median of 10 days. Transgene expression was detected in all cell lineages (B-cells, T-cells, granulocytes, red blood cells and platelets) indicating multilineage engraftment of transduced cells. Up to 19% of blood cells were EGFP+, and this was confirmed at the DNA level by real-time PCR and Southern blot analysis. These transduction rates were higher than the best results we obtained previously with lentiviral vectors in a similar transduction protocol. Integration site analysis also demonstrated polyclonal repopulation and the transduction of multipotential hematopoietic repopulating cells. These data suggest that FV vectors should be useful for stem cell gene therapy, particularly for applications in which short transduction protocols are critical.
