title: Non-viral episomal modification of cells using S/MAR elements.
abstract: BACKGROUND
  The early potential of gene therapy is slowly becoming realized following the recent treatment of patients with severe combined immunodeficiency and ocular diseases. However at present the field of gene therapy is tempered by the toxicity issues, mainly that of the integrated retroviral vector used in most trials which led to oncogenesis in several of the treated patients. The development of safer, alternative vectors is therefore vital for further progress in this field, in particular vectors which remain episomal and are therefore less genotoxic. One such unique class of vectors are those based on scaffold matrix attachment regions (S/MARs) elements, which are maintained extra-chromosomally and replicate in vitro and in vivo.
  
  
  METHODS
  The overview here describes the most relevant studies utilizing the S/MAR element to episomally modify mammalian cells and tissues with a particular focus on liver tissue, as well as the brain, the muscle, the eye, cancer cells, embryonic cells and neonatal mice. For this purpose, recently published data in these areas (mainly articles published between 2000 and 2010) are reviewed.
  
  
  CONCLUSIONS
  The utilisation of vectors harbouring an S/MAR element is an efficient, safe and cost-effective way to episomally modify mammalian cells.
authors.affiliation: Imperial College London, Gene Therapy Research Group, Sir Alexander Fleming Building, National Heart and Lung Institute, South Kensington, London SW7 2AZ, UK. o.argyros@imperial.ac.uk
authors.forename: Orestis
authors.initials: O
authors.lastname: Argyros
authors.forename: Suet-Ping
authors.initials: SP
authors.lastname: Wong
authors.forename: Richard P
authors.initials: RP
authors.lastname: Harbottle
mesh_terms: D000818:Animals; D002477:Cells / Q000378:metabolism*; D004261:DNA Replication; D015870:Gene Expression; D015316:Genetic Therapy; D005822:Genetic Vectors / Q000235:genetics* / Q000627:therapeutic use; D006801:Humans; D045170:Matrix Attachment Regions / Q000235:genetics*; D051379:Mice; D010957:Plasmids / Q000378:metabolism*