Donor chimerism and stem cell function in a murine congenic transplantation model after low-dose radiation conditioning: effects of a retroviral-mediated gene transfer protocol and implications for gene therapy.
OBJECTIVE
We investigated low-dose radiation conditioning for the transplantation of retrovirus-transduced cells in a C57Bl6/J murine model.


METHODS
The effect of low-dose radiation on stem cell function was investigated using a competitive repopulation assay. Stem cell function of marrow cells that underwent a retroviral-mediated gene transfer (RMGT) protocol was examined by this assay, and donor chimerism of these cells when transplanted into 160-cGy conditioned syngeneic hosts was compared to fresh marrow.


RESULTS
Irradiation with 300 or 160 cGy substantially decreased stem cell function as measured by competitive repopulation. Animals conditioned with 160 cGy and transplanted with 20 x 10(6) fresh marrow cells permitted donor cell engraftment of 53.6% +/- 11.4% 6 months after transplant compared to 100% donor cell engraftment after 1100 cGy irradiation. Lymphoid and myeloid engraftment did not significantly differ from total engraftment in submyeloablated hosts. When transplanted into lethally irradiated hosts, the competitive repopulating activity of marrow treated with a single dose of 5-fluorouracil followed by ex vivo culture according to a standard RMGT protocol was equal to 5-fluorouracil-only treated marrow. However, cells treated with 5-fluorouracil or 5-fluorouracil plus ex vivo culture for RMGT repopulated less well than fresh marrow cells in 160 cGy conditioned hosts.


CONCLUSIONS
Low-dose irradiation decreases host stem cell function, allowing engraftment of both fresh and RMGT protocol-treated marrow, although the engraftment of 5-fluorouracil-treated cells was reduced at least two-fold, and 5-fluorouracil plus RMGT protocol-treated cells at least three-fold, compared to fresh marrow. Modification of current RMGT protocols may be important for optimizing engraftment under these conditions.
Goebel
W Scott
WS
Herman B. Wells Center for Pediatric Research and Department of Pediatrics, Hematology/Oncology, James Whitcomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis, IN, USA.
Yoder
Mervin C
MC
Pech
Nancy K
NK
Dinauer
Mary C
MC
D000818:Animals; D020296:Animals, Congenic; D001853:Bone Marrow / Q000187:drug effects / Q000528:radiation effects*; D016026:Bone Marrow Transplantation; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured / Q000187:drug effects / Q000528:radiation effects / Q000637:transplantation; D004307:Dose-Response Relationship, Radiation; D005240:Feasibility Studies; D005472:Fluorouracil / Q000633:toxicity; D017930:Genes, Reporter; D005822:Genetic Vectors / Q000235:genetics*; D006085:Graft Survival / Q000528:radiation effects*; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000528:radiation effects*; D015850:Interleukin-6 / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D011828:Radiation Chimera; D011829:Radiation Dosage; D011994:Recombinant Proteins / Q000494:pharmacology; D013047:Specific Pathogen-Free Organisms; D019089:Stem Cell Factor / Q000494:pharmacology; D014019:Tissue Donors; D020858:Tissue and Organ Harvesting / Q000379:methods*; D014162:Transfection; D019172:Transplantation Conditioning / Q000379:methods*; D014916:Whole-Body Irradiation / Q000379:methods*
D015850:Interleukin-6; D011994:Recombinant Proteins; D019089:Stem Cell Factor; D005472:Fluorouracil