HIGH EXPRESSION OF HUMAN CLOTTING FACTOR-IX CDNA IN MYOBLASTS C2C12 CELLS AND C3H MICE

Mouse myoblast C2C12 cell was used as target cell for gene transfer st udy of human clotting factor IX (hFIX) cDNA. In addition to the previo usly constructed retroviral vectors XLIX, LNCIX and G1NaCIX, G1NaMCIX with hFIX driven by muscle creatine kinase (MCK) enhancer and human cy tomegalovirus (CMV) was constructed, based on the retroviral vector G1 Na. These four retroviral vectors were used to transduce mouse myoblas ts C2C12. With ELISA assays, it has been found that the expression lev els of human clotting factor IX detected in those transduced C2C12 cel ls are G1NaMCIX > G1NaCIX > LNCIX > XLIX. Mixed colonal cells transduc ed with G1NaMCIX expressed hFIX protein at the level of 640 ng/10(6) c ell every 24 h. The modified C2C12 cells transduced with G1NaMCIX were implanted into skeletal muscle of the hindlegs of C3H mice; a stable expression of hFIX was detected and lasted for 35 d, with a maximum le vel of 206 ng/mL plasma. The regulation of hFIX cDNA expression in myo blasts was discussed and it was strongly suggested that a myoblast-med iated gene delivery system had the potential to be optimized as a safe and effective therapeutic modality for hemophilia B.