pEPIto: a significantly improved non-viral episomal expression vector for mammalian cells

HAASE, R.; ARGYROS, O.; WONG, S-P.; HARBOTTLE, R. P.; LIPPS, H.J.; OGRIS, M.; MAGNUSSON, T.; VIZOSO PINTO, M. G.; HAAS, J.; BAIKER, A.

BMC BIOTECHNOLOGY

BIOMED CENTRAL LTD

Año: 2010 vol. 10 p. 1 - 14

1472-6750

Background: The episomal replication of the prototype vector pEPI-1 depends on a transcription unit starting from the constitutively expressed Cytomegalovirus immediate early promoter (CMV-IEP) and directed into a 2000 bp long matrix attachment region sequence (MARS) derived from the human β-interferon gene. The original pEPI-1 vector contains two mammalian transcription units and a total of 305 CpG islands, which are located predominantly within the vector elements necessary for bacterial propagation and known to be unterproductive for persistent long-term transgene expression.Results: Here, we report the development of a novel vector pEPito, which is derived from the pEPI-1 plasmid replicon but has considerably improved efficacy both in vitro and in vivo. The pEPito vector is significantly reduced in size, contains only one transcription unit and 60% less CpG motives in comparison to pEPI-1. It exhibits major advantagescompared to the original pEPI-1 plasmid, including higher transgene expression levels and increased colony-forming efficiencies in vitro, as well as more persistent transgene expression profiles in vivo. The performance of pEPito-based vectors was further improved by replacing the CMV-IEP with the human CMV enhancer/human elongation factor 1 alpha promoter  hCMV/EF1P) element that is known to be less affected by epigenetic silencing events.Conclusions: The novel vector pEPito can be considered suitable as an improved vector for  biotechnological applications in vitro and for non-viral gene delivery in vivo.