IN VITRO STUDY ON THE CLONING AND TRANSDUCTION OF HUMAN O^6-METHYLGUANINE-DNA-METHYLTRANS cDNA INTO HUMAN UMBILICAL CORD BLOOD CD34^+ CELLS

摘要

Objective: To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human O^6-methylguanine-DNA-methyltrans (MGMT) gene could increase resistance to 1,3-Bis(2- Chloroethyl)-1-Nitrosourea (BCNU). Methods: The cDNA encoding the MGMT was isolated by using RT- PCR method from total RNA of fresh human liven the fragment was cloned into PGEM-T vector and further subcloned into GINa retrovirus vector. Then the GINaMGMT was transduced into the packaging cell lines GP+E86 and PA317 by LipofectAMINE. By using the medium containing BCNU for cloning selection and ping-ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, high titer amphotropic PA317 producer clone with the highest titer up to 5.8x105 CFU/ml was obtained. Cord blood CD34+ cells were transfected repeatedly with supernatant of retrovirus containing human MGMT- cDNA under stimulation of hemopoietic growth factors. Results: The retrovirus vector construction was verified by restriction endonuclease analysis and DNA sequencing. PCR, RT-PCR, Southern Blot, Western Blot and MTT analyses showed that MGMT drug resistance gene has been integrated into the genomic DNA of cord blood CD34+ cells and expressed efficiently. The transgene cord blood CD34+ cells conferred 4-folds stronger resistance to BCNU than untransduced cells. Conclusion: The retrovirus vector-mediated transfer of MGMT drug resistance gene into human cord blood CD34+ cells and its expression provided an experimental foundation for gene therapy in clinical trial.