Mild preconditioning and low-level engraftment confer methotrexate resistance in mice transplanted with marrow expressing drug-resistant dihydrofolate reductase activity.

摘要: Effective engraftment of hematopoietic cells targeted for gene transfer is facilitated by cytoreductive preconditioning such as high-dose total body irradiation (TBI). To minimize the adverse side effects associated with TBI, experiments were conducted to determine whether sublethal doses TBI would allow sufficient MTX-resistant confer survival on recipient mice administered MTX. FVB/N animals 1, 2, or 4 Gy (lethal dose, 8.5 Gy), transplanted 107 transgenic marrow expressing an dihydrofolate reductase (DHFR) transgene, and then MTX daily 60 days. Control 1 without subsequent transplantation normal succumbed toxicity day 45. In contrast, nearly all survived administration, regardless dose used preconditioning. The donor DHFR level was proportional but surprisingly reduced in given 2 subsequently when compared control phosphate-buffered saline. Animals preconditioned also protected from amounts (5 × 106 cells) marrow, resulting low-level (approximately 1%) engraftment. conclusion, very mild allows genetically modified stem vivo manifestation phenotype, suggesting usefulness regimens human therapy trials targeting cells.