RESUMEN
<p><b>OBJECTIVE</b>To explore the feasibility of transfecting DHFR (human double-mutant dihydrofolate reductase) gene into mouse bone marrow cells and the effect of resistance to high dose MTX chemotherapy.</p><p><b>METHODS</b>After DHFR gene was transfected into mouse bone marrow cells with retroviral vector, the cells were treated with methotrexate (MTX) and then CFU-GM (granulocyte-macrophage colony-forming unit) assay was performed. Peripheral blood leucocytes and platelets, body weight and survival rate were observed. After treatment with high dose MTX, the expression of drug resistance gene was checked by RT-PCR in the transfected bone marrow cells.</p><p><b>RESULTS</b>SFG-F/S-NeoR gene-transfected mice bone marrow cells yielded drug-resistance colonies to MTX (donor mice: 15.8%, recipient mice: 18.0%, control: 0) The peripheral blood leucocytes and platelets, body weight recovered gradually and the survival rate was 83.3% at the 40th day, while 0 in controls in gene transfected mice after large dose MTX treatment. RT-PCR of transgenic mouse marrow cells showed the band of F/S gene (400 bp).</p><p><b>CONCLUSION</b>DHFR gene can not only be integrated and expressed in bone marrow cells but also improve their drug-resistence to MTX.</p>