title: Fluorescent chloride indicators to assess the efficacy of CFTR cDNA delivery.
abstract: Cl(-)-sensitive fluorescent indicators have been used extensively in cell culture systems to measure the Cl(-)-transporting function of the cystic fibrosis transmembrane conductance regulator protein CFTR. These indicators have been used in establishing a surrogate end point to assess the efficacy of CFTR cDNA delivery in human gene therapy trials. The ability to measure Cl- transport with high sensitivity in small and heterogeneous tissue samples makes the use of Cl- indicators potentially attractive in gene delivery studies. In this review article, the important technical aspects of Cl- transport measurements by fluorescent indicators such as SPQ are described, applications of Cl- indicators to assay CFTR function are critically evaluated, and new methodological developments are discussed. The available Cl- indicators have been effective in quantifying Cl- transport rates in cell culture models and in vitro systems such as isolated membrane vesicles and liposomes. However, the imperfect photophysical properties of existing Cl- indicators limit their utility in performing measurements in airway tissues, where gene transfer vectors are delivered in CF gene therapy trials. The low efficiency of gene transfer and the cellular heterogeneity in airway samples pose substantial obstacles to functional measurements of CFTR expression. Significant new developments in generating long-wavelength and dual-wavelength halide indicators are described, and recommendations are proposed for the use of the indicators in gene therapy trials.
authors.affiliation: National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Mansoura
authors.forename: J
authors.initials: J
authors.lastname: Biwersi
authors.forename: M A
authors.initials: MA
authors.lastname: Ashlock
authors.forename: A S
authors.initials: AS
authors.lastname: Verkman
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D002712:Chlorides / Q000737:chemistry*; D002986:Clinical Trials as Topic; D003550:Cystic Fibrosis / Q000628:therapy*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics*; D018076:DNA, Complementary / Q000008:administration & dosage*; D005456:Fluorescent Dyes / Q000737:chemistry*; D015316:Genetic Therapy; D006801:Humans; D017136:Ion Transport
chemical_list: C505032:CFTR protein, human; D002712:Chlorides; D018076:DNA, Complementary; D005456:Fluorescent Dyes; D019005:Cystic Fibrosis Transmembrane Conductance Regulator