title: Hepatic cell-to-cell transmission of small silencing RNA can extend the therapeutic reach of RNA interference (RNAi).
abstract: OBJECTIVE
  RNA interference (RNAi), a sequence-specific gene silencing technology triggered by small interfering RNA (siRNA), represents promising new avenues for treatment of various liver diseases including hepatitis C virus (HCV) infection. In plants and invertebrates, RNAi provides an important mechanism of cellular defence against viral pathogens and is dependent on the spread of siRNA to neighbouring cells. A study was undertaken to investigate whether vector-delivered RNAi can transfer between hepatic cells in vitro and in mice, and whether this exchange could extend the therapeutic effect of RNAi against HCV infection.
  
  
  METHODS
  Transmission of RNAi was investigated in culture by assessing silencing of HCV replication and expression of viral entry receptor CD81 using a human hepatic cell line and primary B lymphocytes transduced with siRNA-expressing vectors. In vivo transmission between hepatic cells was investigated in NOD/SCID mice. Involvement of exosomes was demonstrated by purification, uptake and mass spectrometric analysis.
  
  
  RESULTS
  Human and mouse liver cells, as well as primary human B cells, were found to have the ability to exchange small RNAs, including cellular endogenous microRNA and delivered siRNA targeting HCV or CD81. The transmission of RNAi was largely independent of cell contact and partially mediated by exosomes. Evidence of RNAi transmission in vivo was observed in NOD/SCID mice engrafted with human hepatoma cells producing CD81 siRNA, causing suppression of CD81 expression in mouse hepatocytes.
  
  
  CONCLUSIONS
  Both human and mouse hepatic cells exchange small silencing RNAs, partially mediated by shuttling of exosomes. Transmission of siRNA potentially extends the therapeutic reach of RNAi-based therapies against HCV as well as other liver diseases.
authors.affiliation: Department of Gastroenterology and Hepatology, Erasmus MC-University Medical Center, Rotterdam, The Netherlands.
authors.forename: Qiuwei
authors.initials: Q
authors.lastname: Pan
authors.forename: Vedashree
authors.initials: V
authors.lastname: Ramakrishnaiah
authors.forename: Scot
authors.initials: S
authors.lastname: Henry
authors.forename: Suomi
authors.initials: S
authors.lastname: Fouraschen
authors.forename: Petra E
authors.initials: PE
authors.lastname: de Ruiter
authors.forename: Jaap
authors.initials: J
authors.lastname: Kwekkeboom
authors.forename: Hugo W
authors.initials: HW
authors.lastname: Tilanus
authors.forename: Harry L A
authors.initials: HL
authors.lastname: Janssen
authors.forename: Luc J W
authors.initials: LJ
authors.lastname: van der Laan
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D055354:Exosomes / Q000502:physiology; D005455:Fluorescent Antibody Technique; D016174:Hepacivirus / Q000502:physiology; D006526:Hepatitis C / Q000235:genetics / Q000378:metabolism* / Q000628:therapy; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D013058:Mass Spectrometry; D051379:Mice; D016513:Mice, SCID; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000378:metabolism* / Q000627:therapeutic use; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D014162:Transfection; D014779:Virus Replication
chemical_list: D034741:RNA, Small Interfering