title: Fluorescence- and computed tomography for assessing the biodistribution of siRNA after intratracheal application in mice.
abstract: Pulmonary delivery of nucleic acids opens the possibility for direct treatment of lung diseases, like fibrosis, cancer, and infections. Lung retention and biodistribution of nucleic acids remain important issues for the development of suitable therapeutic approaches. Moreover, monitoring the dynamic biodistribution processes of siRNA after aerosol delivery can help in identifying bottlenecks and optimizing therapeutic concepts. We investigated dynamic biodistribution events after intratracheal application of chemically stabilized siRNA labelled with near infrared emitting dye AlexaFluor750 (AF750). Epifluorescence imaging was combined with spectral unmixing to improve the signal to noise ratio. Transillumination imaging has been utilized for quantitative fluorescence imaging tomography (FLIT) together with contrast agent enhanced X-ray absorption computed tomography (CT). Spectral unmixing allowed unambiguous detection of AF750 signals, which could be clearly distinguished from food derived autofluorescence. After successful delivery to the lung, fluorescent signals were also observed in kidneys and bladder, indicating renal excretion of AF750-siRNA. Gel electrophoresis of urine samples showed presence of intact siRNA, at least to a considerable extent. FLIT/CT allowed signal quantification and precise allocation to anatomical structures.
authors.affiliation: Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Antonia
authors.initials: A
authors.lastname: Geyer
authors.affiliation: Division of Medicinal Chemistry, Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Lorenzer
authors.affiliation: Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Gehrig
authors.affiliation: Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Manuela
authors.initials: M
authors.lastname: Simlinger
authors.affiliation: Division of Medicinal Chemistry, Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Winkler
authors.affiliation: Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria. Electronic address: haider.sami@univie.ac.at.
authors.forename: Haider
authors.initials: H
authors.lastname: Sami
authors.affiliation: Laboratory of MacroMolecular Cancer Therapeutics (MMCT), Center of Pharmaceutical Sciences, Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Ogris
mesh_terms: D000818:Animals; D005260:Female; D007668:Kidney / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D061848:Optical Imaging; D034741:RNA, Small Interfering / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed; D001743:Urinary Bladder / Q000378:metabolism
chemical_list: D034741:RNA, Small Interfering
keywords: Aerosolization; Biodistribution; Fluorescence tomography; Near infrared imaging; Pulmonary delivery; siRNA delivery