title: Immunoliposomes for Targeted Delivery of an Antifibrotic Drug.
abstract: Excessive extracellular matrix formation in organs and tissues arises from an imbalance between the synthesis and degradation of matrix proteins, especially collagen. This condition interferes with proper wound healing and regeneration, and to date, no specific treatment is available. In the present study, we propose a targeted drug delivery system consisting of cell-specific immunoliposomes (ILs) loaded with deferoxamine (DFO) as an antifibrotic drug. ILs were functionalized with polyethylene glycol (PEG) to improve the steric stability and prolong their half-life. In addition, a single-chain Fv (scFv) antibody fragment that specifically targets fibroblast activation protein (FAP) was incorporated. An in vitro fibrosis model was employed to test this construct. This model consisted of highly activated pro-fibrotic fibroblasts with 2- to 6-fold induction of selected fibrosis markers: cell/matrix deposited collagen I, total soluble collagen, and α smooth muscle actin. The activation was accompanied by a significant and cell-specific elevation of FAP expression and activity, thereby confirming that FAP is an adequate target for antifibrotic drug delivery. Purified anti-FAP scFv was shown to bind specifically to these cells without influencing the FAP enzymatic activity. DFO was demonstrated to have a dose-dependent antifibrotic activity as quantified by collagen deposition. Specific binding and intracellular uptake of DiI-labeled ILs into the activated fibroblasts were shown by flow cytometry and microscopy. Finally, DFO-loaded ILs targeted to FAP caused a significant reduction in the collagen deposition, whereas no effect was observed using liposomes that lacked the targeting antibody fragment. These results suggest that the FAP-specific scFv-conjugated liposomes have considerable potential for cell-specific targeting applicable as a therapy for excessive collagen deposition during fibrosis. In general, through liposome encapsulation, bioactive molecules, such as DFO, that have broad effects and poor cell penetration can be converted into cell-specific composites for targeted drug delivery.
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstr. 55, 72770 Reutlingen, Germany.
authors.forename: Liane
authors.initials: L
authors.lastname: Schuster
authors.affiliation: Institute of Cell Biology and Immunology, University of Stuttgart , Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Seifert
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstr. 55, 72770 Reutlingen, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Vollmer
authors.affiliation: Institute of Cell Biology and Immunology, University of Stuttgart , Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: Roland E
authors.initials: RE
authors.lastname: Kontermann
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstr. 55, 72770 Reutlingen, Germany.
authors.forename: Burkhard
authors.initials: B
authors.lastname: Schlosshauer
authors.affiliation: NMI Natural and Medical Sciences Institute at the University of Tübingen , Markwiesenstr. 55, 72770 Reutlingen, Germany.
authors.forename: Hanna
authors.initials: H
authors.lastname: Hartmann
mesh_terms: D002478:Cells, Cultured; D003676:Deferoxamine / Q000008:administration & dosage*; D016503:Drug Delivery Systems; D010450:Endopeptidases; D005347:Fibroblasts / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D005354:Fibrosarcoma / Q000188:drug therapy* / Q000276:immunology / Q000473:pathology; D018093:Gelatinases / Q000037:antagonists & inhibitors* / Q000276:immunology; D006207:Half-Life; D006801:Humans; D007124:Immunoenzyme Techniques; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000276:immunology; D008081:Liposomes / Q000737:chemistry* / Q000276:immunology; D008168:Lung / Q000187:drug effects* / Q000276:immunology / Q000473:pathology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000276:immunology; D011092:Polyethylene Glycols / Q000737:chemistry; D012697:Serine Endopeptidases / Q000276:immunology; D017262:Siderophores / Q000008:administration & dosage; D057127:Single-Chain Antibodies / Q000008:administration & dosage* / Q000276:immunology; D000099167:Fibroblast Activation Protein Alpha
chemical_list: D003676:Deferoxamine; D010450:Endopeptidases; D018093:Gelatinases; D007128:Immunoglobulin Fragments; D008081:Liposomes; D008565:Membrane Proteins; D011092:Polyethylene Glycols; D012697:Serine Endopeptidases; D017262:Siderophores; D057127:Single-Chain Antibodies; D000099167:Fibroblast Activation Protein Alpha
keywords: antifibrotic therapy; cell-specific targeting; drug delivery system; fibroblast activation protein; immunoliposomes