Minicircle
Encyclopedia
Minicircles are small circular plasmid
Plasmid
In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular...

 derivatives that have been freed from all prokaryotic vector parts.

For uses as transgene
Transgene
A transgene is a gene or genetic material that has been transferred naturally or by any of a number of genetic engineering techniques from one organism to another....

 carriers for the genetic modification of mammalia cells, their preparation usually follows a two-step procedure:
  • production of a ´parental plasmid´ (bacterial plasmid with eukaryotic inserts) in 'E. coli'
  • induction of a site-specific recombinase at the end of this process but still in bacteria. These steps are followed by the
    • excision of prokaryotic vector parts via two recombinase-target sequences at both ends of the insert
    • recovery of the resulting minicircle (vehicle for the highly-efficient modification of the recipient cell) and the miniplasmid by capillary gel electrophoresis (CGE)


The purified minicircle can be transferred into the recipient cell by transfection
Transfection
Transfection is the process of deliberately introducing nucleic acids into cells. The term is used notably for non-viral methods in eukaryotic cells...

 or lipofection
Lipofection
Lipofection is a technique used to inject genetic material into a cell by means of liposomes, which are vesicles that can easily merge with the cell membrane since they are both made of a phospholipid bilayer. Lipofection generally uses a positively charged lipid to form an aggregate with the...

 and into a differentiated tissue, for instance, by jet injection.

A novel addition to the field are self-replicating minicircles, which owe this property to the presence of a S/MAR-Element (1). Self-replicating minicircles hold great promise for the systematic modification of stem cells the more as the feasibility of such an approach has recently been demonstrated with their precursor form (Ref.)
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