Ligand-regulatable erythropoietin production by plasmid injection and in vivo electroporation.
BACKGROUND: The development of an in vivo gene transfer approach to deliver physiologic levels of recombinant proteins to the systemic circulation would represent a significant advance in the treatment of protein deficiency disorders. However, the ability to regulate transgene expression is of paramount importance for safe and effective gene transfer therapy. METHODS: We developed two plasmids, one encoder of chimeric GeneSwitch protein, and the other an inducible transgene for human erythropoietin ( Epo). The level of secretion of Epo into the serum was modulated by intraperitoneal administration of mifepristone (MFP). Rats were divided into four groups: one group administered Epo plasmid with MFP for 50 days, a second group administered Epo plasmid with MFP for 15 days and then again from day 30 to day 50, a third group administered Epo plasmid without MFP, and a fourth group administered control plasmid. A pair of electrodes was inserted into the muscle of the right thigh, 100 mg of each plasmid was injected, and in vivo electroporation (8 pulses at 100 V for 50 msec) was performed. RESULTS: The presence of vector-derived Epo mRNA was detected by RT-PCR only in the Epo plasmid and MFP(+) groups. The hematocrit levels increased continuously, from the pre-injection level of 41.2% to 55.0% on day 30 and 53.8% on day 50 in the Epo plasmid and MFP(+) groups. In the MFP re-challenged group, the hematocrit levels rose up to day 15, fell after 20 to 30 days, and then rose again after MFP re-administration. The serum Epo levels increased only in the Epo plasmid and MFP(+) groups. There were no significant changes in hematocrit levels and Epo levels in the Epo plasmid and MFP(-) group. CONCLUSION: Epo gene transfer with the GeneSwitch system by in vivo electroporation is a useful procedure for efficient drug-regulated delivery of Epo.[1]References
- Ligand-regulatable erythropoietin production by plasmid injection and in vivo electroporation. Terada, Y., Tanaka, H., Okado, T., Shimamura, H., Inoshita, S., Kuwahara, M., Akiba, T., Sasaki, S. Kidney Int. (2002) [Pubmed]
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