title: Local retention of antibodies in vivo with an injectable film embedded with a fluorogen-activating protein.
abstract: Herein we report an injectable film by which antibodies can be localized in vivo. The system builds upon a bifunctional polypeptide consisting of a fluorogen-activating protein (FAP) and a β-fibrillizing peptide (βFP). The FAP domain generates fluorescence that reflects IgG binding sites conferred by Protein A/G (pAG) conjugated with the fluorogen malachite green (MG). A film is generated by mixing these proteins with molar excess of EAK16-II, a βFP that forms β-sheet fibrils at high salt concentrations. The IgG-binding, fluorogenic film can be injected in vivo through conventional needled syringes. Confocal microscopic images and dose-response titration experiments showed that loading of IgG into the film was mediated by pAG(MG) bound to the FAP. Release of IgG in vitro was significantly delayed by the bioaffinity mechanism; 26% of the IgG were released from films embedded with pAG(MG) after five days, compared to close to 90% in films without pAG(MG). Computational simulations indicated that the release rate of IgG is governed by positive cooperativity due to pAG(MG). When injected into the subcutaneous space of mouse footpads, film-embedded IgG were retained locally, with distribution through the lymphatics impeded. The ability to track IgG binding sites and distribution simultaneously will aid the optimization of local antibody delivery systems.
authors.affiliation: Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA 15282, United States.
authors.forename: Wen
authors.initials: W
authors.lastname: Liu
authors.affiliation: Molecular Biosensor and Imaging Center and Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Saunders
authors.affiliation: Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA 15282, United States.
authors.forename: Christina
authors.initials: C
authors.lastname: Bagia
authors.affiliation: College of Engineering, University of Georgia, Athens, GA 30602, United States.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Freeman
authors.affiliation: Institute of Cellular Therapeutics, Allegheny-Singer Research Institute, Pittsburgh, PA 15212, United States; Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, United States; McGowan Institute for Regenerative Medicine, Pittsburgh, PA 15213, United States.
authors.forename: Ellen S
authors.initials: ES
authors.lastname: Gawalt
authors.affiliation: Molecular Biosensor and Imaging Center and Carnegie Mellon University, Pittsburgh, PA 15213, United States; Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, United States.
authors.forename: Alan S
authors.initials: AS
authors.lastname: Waggoner
authors.affiliation: Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, PA 15282, United States. Electronic address: meng@duq.edu.
authors.forename: Wilson S
authors.initials: WS
authors.lastname: Meng
mesh_terms: D000818:Animals; D001665:Binding Sites; D016503:Drug Delivery Systems; D005260:Female; D005456:Fluorescent Dyes / Q000008:administration & dosage; D007074:Immunoglobulin G / Q000008:administration & dosage*; D007267:Injections; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000008:administration & dosage; D011485:Protein Binding; D012394:Rosaniline Dyes / Q000008:administration & dosage
chemical_list: D005456:Fluorescent Dyes; D007074:Immunoglobulin G; D010455:Peptides; D012394:Rosaniline Dyes; C005095:malachite green
keywords: Antibody formulation; Bioaffinity film; Controlled release; Dimerized light chain-5 (dL5); Draining lymph nodes; EAK16; Fluorescent imaging; Fluorogen-activating protein; Mathematical simulation; Self-assembling peptide; Single-chain variable fragment