Daisuke Ihara1, Noboru Hattori2, Yasushi Horimasu1, Takeshi Masuda1, Taku Nakashima1, Tadashi Senoo1, Hiroshi Iwamoto1, Kazunori Fujitaka1, Hirokazu Okamoto3, Nobuoki Kohno1. 1. Department of Molecular and Internal Medicine, Institute of Biomedical & Health Sciences, Hiroshima University, Kasumi 1-2-3 Minami-ku, Hiroshima, 734-8551, Japan. 2. 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. 3. Department of Drug Delivery Research, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya, 468-8503, Japan.
Abstract
PURPOSE: 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.
PURPOSE: 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: Myla Manser; Blair A Morgan; Xueya Feng; Rod G Rhem; Myrna B Dolovich; Zhou Xing; Emily D Cranston; Michael R Thompson Journal: Pharm Res Date: 2022-07-19 Impact factor: 4.580