Continuous Erythropoietin Delivery by Muscle-Targeted Gene Transfer Using in Vivo Electroporation

It has been demonstrated that gene transfer by in vivo electroporation of mouse muscle increases the level of gene expression by more than 100-fold over simple plasmid DNA injection. We tested continuous rat erythropoietin (Epo) delivery by this method in normal rats, using plasmid DNA expressing rat Epo (pCAGGSEpo) as the vector. A pair of electrodes was inserted into the thigh muscles of rat hind limbs and 100 mug of pCAGGS-Epo was injected between the electrodes. Eight 100-V, 50-msec electric pulses were delivered through the electrodes. Each rat was injected with a total of 400 mug of pCAGGS-Epo, which was delivered to the medial and lateral sides of each thigh. The presence of vector-derived Epo mRNA at the DNA injection site was confirmed by RT-PCR. The serum Epo levels peaked at 122.2 ± 33.0 mU/ml on day 7 and gradually decreased to 35.9 ± 18.2 mU/ml on day 32. The hematocrit levels increased continuously, from the preinjection level of 49.5 ± 1.1 to 67.8 ± 2.2% on day 32 (p<0.001). In pCAGGS-Epo t...