title: Bioreducible crosslinked polyelectrolyte complexes for MMP-2 siRNA delivery into human vascular smooth muscle cells.
abstract: OBJECTIVE
  Bioreducible crosslinked polyplexes were prepared via disulfide bond formation after siRNA condensation with polyethylenimine-modified by deoxycholic acid (PEI-DA) to stabilize polyplex structure in an extracellular environment and to promote transfection efficiency in human smooth muscle cells (hSMCs).
  
  
  METHODS
  The PEI-DA/siRNA polyplexes were further modified by crosslinking the primary amines of PEI with thiol-cleavable crosslinkers. The effect of disulfide crosslinked PEI-DA/siRNA (Cr PEI-DA/siRNA) polyplexes on target gene silencing was investigated by transfecting hSMCs with matrix metalloproteinase-2 (MMP-2) siRNA under serum conditions. The MMP-2 levels in the conditioned medium were examined using gelatin zymography.
  
  
  RESULTS
  The Cr PEI-DA/siRNA polyplexes showed increased stability against heparin exchange reactions, while their disulfide linkages were successfully cleaved under reducing conditions. The polyplex crosslinking reaction led to a slight decrease in MMP-2 gene silencing activity in hSMCs due to the insufficient redox potential. However, the gene silencing efficiency of the Cr PEI-DA/siRNA polypexes was gradually improved in response to increasing intracellular reduction potential. The increased serum stability of the Cr PEI-DA/siRNA polyplexes resulted in significant enhancement of the intracellular delivery efficiency especially under serum conditions.
  
  
  CONCLUSIONS
  The Cr PEI-DA/siRNA polyplex formulation may be a promising siRNA delivery system for the treatment of incurable genetic disorders.
authors.affiliation: Severance Integrative Research Institute for Cerebral and Cardiovascular Disease, Yonsei University Health System, 250 Seongsanno, Seodaemun-gu, Seoul, 120-752, South Korea.
authors.forename: Dokyoung
authors.initials: D
authors.lastname: Lee
authors.forename: Dongkyu
authors.initials: D
authors.lastname: Kim
authors.forename: Hyejung
authors.initials: H
authors.lastname: Mok
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Jeong
authors.forename: Donghoon
authors.initials: D
authors.lastname: Choi
authors.forename: Sun Hwa
authors.initials: SH
authors.lastname: Kim
mesh_terms: D002460:Cell Line; D003840:Deoxycholic Acid / Q000737:chemistry* / Q000378:metabolism; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D020778:Matrix Metalloproteinase 2 / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D010084:Oxidation-Reduction; D011094:Polyethyleneimine / Q000737:chemistry* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000235:genetics / Q000378:metabolism; D044967:Serum / Q000378:metabolism; D014162:Transfection
chemical_list: D004220:Disulfides; D034741:RNA, Small Interfering; D003840:Deoxycholic Acid; D011094:Polyethyleneimine; D020778:Matrix Metalloproteinase 2