Gene electro-transfer of an improved erythropoietin plasmid in mice and non-human primates

Abstract

The modified EPO gene yields higher levels of circulating transgene product and a more significant biological effect than the wild-type gene in all the species tested, thus showing great potential in clinically developable gene therapy approaches for EPO delivery.

Minimal doses of a sequence-optimized transgene mediate high-level and long-term EPO expression in vivo: challenging CpG-free gene design

“…Notably, EGT of EPO pDNA into skeletal muscle of small animals has been reported to boost EPO expression up to 100-fold compared with pDNA alone. 8,33,40 However, clinical application of EGT in larger animals or humans might be more challenging due to large pDNA quantities required to achieve therapeutic effects, 41 thus necessitating further improvement of the delivered pDNA.…”

“…Most work published to date regarding pDNA-based EPO gene transfer has been focused on the optimization of EPO secretion, 41 promoter choice, 39 DNA dose effects 39,40,42 or application routes, 38,39,[41][42][43] whereas the contribution of gene design has received less attention. Although several in vivo studies have been performed using either wild type 8,28,43,44 or codon-optimized EPO genes 41 for EGT, no direct comparison of gene-specific long-term EPO expression has been reported.…”

“…Although several in vivo studies have been performed using either wild type 8,28,43,44 or codon-optimized EPO genes 41 for EGT, no direct comparison of gene-specific long-term EPO expression has been reported.…”

“…In this context, it has been shown that serum EPO content is rather limited by the saturation of the cellular secretion machinery than by expression limitations, as cell-associated protein levels were still increased at elevated pDNA amounts, although serum EPO levels reached a plateau. 41 Even a further increase of EPO secretion, which can be achieved using improved leader sequences, would not boost HCT or hemoglobin values beyond a biologically acceptable level. Finally, one must bear in mind that the EPO-specific regulation is highly complex and overexpression of exogenous EPO has been shown to downregulate endogenous EPO via a negative feedback loop, 40 which might contribute to the lack of dose response at high pDNA amounts.…”

DNA immunization using constant-current electroporation affords long-term protection from autochthonous mammary carcinomas in cancer-prone transgenic mice

“…This feature allows the device to maintain a true constant-current and a square wave through the muscle tissue during electroporation, preventing heating of a tissue 5 and consequently reducing tissue damage and pain, as well as contributing to the overall increase in plasmid uptake and expression. 4,6 There have been numerous reviews of the advantages and disadvantages of various models of cancer vaccine, therapeutic versus prophylactic vaccines and transplantable versus autochthonous tumors 7 as well as the current tools such as adjuvants that have been used to enhance the immune responses generated by the vaccines. 8 Furthermore, there has been a recent surge in interest in using electroporation to enhance the delivery of plasmids or drugs with anti-tumor effects, as reviewed by Gothelf et al 9 and Heller et al 10 Female BALB/c mice transgenic for the transforming rat neu 664VÀE oncogenes (BALB-neuT 664VÀE mice) display p185 neu , the protein product of rat neu oncogene, on the surface of the cells of their rudimentary mammary glands at 3 weeks of age.…”