title: Histological Quantification of Gene Silencing by Intratracheal Administration of Dry Powdered Small-Interfering RNA/Chitosan Complexes in the Murine Lung.
abstract: OBJECTIVE
  The use of small-interfering RNA (siRNA) as an inhalation therapy has recently received much attention. Some reports have confirmed the suppression of gene expression in whole lungs following intratracheal administration of dry powdered siRNA; however, the anatomical location in the lung where gene silencing occurs has not been precisely identified. Here, we aimed to histologically evaluate gene silencing efficacy in murine lungs by intratracheal administration of an siRNA/chitosan complex as a dry powder.
  
  
  METHODS
  Enhanced green fluorescence protein (EGFP)-specific siRNA (EGFP-siRNA)/chitosan powder was prepared and administered intratracheally to EGFP transgenic mice or mice carrying metastatic lung tumors consisting of Lewis lung carcinoma (LLC) cells stably expressing EGFP (EGFP-LLCs). Thereafter, green fluorescence intensities were quantified in the airways, parenchyma, and lung tumors.
  
  
  RESULTS
  Intratracheal administration of the EGFP-siRNA/chitosan powder suppressed EGFP expression in the bronchi, bronchioles, and alveolar walls of EGFP transgenic mice. Additionally, EGFP-siRNA/chitosan effectively silenced EGFP expression in lung tumors consisting of EGFP-LLC cells.
  
  
  CONCLUSIONS
  Pulmonary administration of siRNA/chitosan powder suppressed gene expression throughout the lung and in lung tumors. Therefore, this may become a powerful strategy to target genes expressed in a wide range of respiratory diseases involving the airways, parenchyma, and lung tumors.
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ihara
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan. nhattori@hiroshima-u.ac.jp.
authors.forename: Noboru
authors.initials: N
authors.lastname: Hattori
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Horimasu
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Masuda
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Senoo
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iwamoto
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Fujitaka
authors.affiliation: Department of Drug Delivery Research, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya, 468-8503, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Okamoto
authors.affiliation: Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan.
authors.forename: Nobuoki
authors.initials: N
authors.lastname: Kohno
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D045744:Cell Line, Tumor; D048271:Chitosan / Q000737:chemistry*; D005260:Female; D049452:Green Fluorescent Proteins / Q000235:genetics; D008168:Lung / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure*; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000556:secondary; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011208:Powders; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000737:chemistry / Q000235:genetics; D014132:Trachea / Q000378:metabolism
chemical_list: D011208:Powders; D034741:RNA, Small Interfering; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D048271:Chitosan
keywords: airway epithelium; alveolar wall; dry powdered siRNA/chitosan complex; intratracheal administration; metastatic lung tumor