title: Evaluation of cystamine-modified hyaluronic acid/chitosan polyplex as retinal gene vector.
abstract: OBJECTIVE
  A successful gene therapy approach can prevent or treat congenital and acquired diseases. However, there is still no ideal non-viral vector for gene delivery in a safe and timely manner. In this report the anionic polymer hyaluronic acid (HA) was investigated as a potential vector for gene therapy. Due to its intrinsic characteristics it constitutes an excellent candidate to deliver therapeutic genes, pending the modification of its surface charge.
  
  
  METHODS
  To modify its charge, HA was modified with cystamine. Several formulations were prepared using modified HA combined with sodium sulfate, sodium triphosphate, K-carrageenan and chitosan. Vectors were characterized with respect to size, charge, DNA load and its protection, and effect on cell viability. The better performing formulations were further evaluated in vitro for their transfection efficiency in HEK293T and ARPE-19 cells.
  
  
  RESULTS
  Cell viability assays showed low cytotoxicity for both polymers. Gene transfer efficiency depended on cell line and formulation, but no increased transfection efficiency was observed with the modified polymer.
  
  
  CONCLUSIONS
  HA has great potential as a gene therapy vector, but further optimization, including incorporation of a higher percentage of positive groups in HA, is needed before its use as a gene delivery vector.
authors.affiliation: Centre for Biomedical Research (CBMR), University of Algarve, Faro 8005-139, Portugal; Program in Biomedical Sciences, University of Algarve, Faro 8005-139, Portugal.
authors.forename: Ana V
authors.initials: AV
authors.lastname: Oliveira
authors.affiliation: Department of Biomedical Sciences and Medicine, University of Algarve, Faro 8005-139, Portugal.
authors.forename: Adriana
authors.initials: A
authors.lastname: Marcelo
authors.affiliation: Department of Chemistry and Pharmacy, University of Algarve, Faro 8005-139, Portugal; Algarve Chemistry Research Centre (CIQA), University of Algarve, Faro 8005-139, Portugal.
authors.forename: Ana M Rosa
authors.initials: AM
authors.lastname: da Costa
authors.affiliation: Centre for Biomedical Research (CBMR), University of Algarve, Faro 8005-139, Portugal; CEDOC, NOVA Medical School/Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo Mártires da Pátria 130, 1169-056 Lisboa, Portugal. Electronic address: gabriela.silva@fcm.unl.pt.
authors.forename: Gabriela A
authors.initials: GA
authors.lastname: Silva
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000737:chemistry*; D003538:Cystamine / Q000737:chemistry*; D005822:Genetic Vectors / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D011108:Polymers / Q000737:chemistry* / Q000633:toxicity; D011122:Polyphosphates / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry; D014162:Transfection
chemical_list: D011108:Polymers; D011122:Polyphosphates; D013431:Sulfates; C012036:sodium sulfate; D006820:Hyaluronic Acid; D048271:Chitosan; C005692:triphosphoric acid; D003538:Cystamine
keywords: Biocompatibility; Gene therapy; Hyaluronic acid; Polymer modification; Retina