Decreased homing of retrovirally transduced human bone marrow CD34+ cells in the NOD/SCID mouse model.
OBJECTIVE
Many clinical gene therapy trials have described poor engraftment of retrovirally transduced CD34(+) cells. Because engraftment is dependent upon successful homing of graft cells to the bone marrow (BM), we examined whether retroviral-mediated gene transfer (RMGT) induces a homing defect in CD34(+) cells.


METHODS
Homing of fluorescently labeled human BM CD34(+) cells transduced with three separate retroviral vectors (MFG-eGFP, LNC-eGFP, and LXSN) was assessed in nonobese diabetic/severe combined immunodeficient mice.


RESULTS
Homing of transduced CD34(+) cells was significantly decreased 20 hours after transplantation compared with freshly isolated control and cultured untransduced control cells. Specifically, homing of GFP(+) cells in the graft was preferentially decreased thus skewing the contribution of transduced cells to engraftment. Transduced cells were not selectively trapped in other organs and BM-homed transduced cells did not undergo apoptosis at a higher rate than untransduced cells. Adhesion molecule expression and binding activity was not altered by RMGT. This homing defect was reversed when transduced cells were cultured over CH-296 for 2 additional days with SCF only.


CONCLUSIONS
These data suggest that RMGT of hematopoietic cells may compromise their homing potential and implicate transduction-induced reduced homing in the observed low engraftment of retrovirally transduced CD34(+) cells. These results may have a direct clinical application in gene therapy protocols.
Department of Microbiology and Immunology, Division of Hematology/Oncology, Indian University School of Medicine, Indianapolis, 46202, USA.
Kristin M
KM
Hall
Tamara L
TL
Horvath
Rafat
R
Abonour
Kenneth
K
Cornetta
Edward F
EF
Srour
D000818:Animals; D018952:Antigens, CD34; D017209:Apoptosis / Q000502:physiology; D001853:Bone Marrow / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D015316:Genetic Therapy / Q000379:methods; D006085:Graft Survival; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008954:Models, Biological; D012190:Retroviridae; D014161:Transduction, Genetic
D018952:Antigens, CD34; D015815:Cell Adhesion Molecules