title: Displaying high-affinity ligands on adeno-associated viral vectors enables tumor cell-specific and safe gene transfer.
abstract: Gene transfer vectors derived from the adeno-associated virus (AAV) have recently received increasing attention due to substantial therapeutic benefit in several clinical trials. Nevertheless, their great potential for in vivo gene therapy can only be partially exploited owing to their broad tropism. Current cell surface targeting strategies expanded vector tropism towards transduction of cell types that are inefficiently infected naturally, but failed to restrict or fully re-direct AAV's tropism. Hypothesizing that this limitation can be overcome by equipping natural receptor-blinded AAV vectors with high-affinity ligands, we displayed designed ankyrin repeat proteins (DARPin) as VP2 fusion proteins on AAV capsids ablated for natural primary receptor binding. These second generation targeting vectors demonstrated an as of yet unachieved efficiency to discriminate between target and non-target cells in mono- and mixed cultures. Moreover, DARPin-AAV vectors delivered a suicide gene precisely to tumor tissue and substantially reduced tumor growth without causing fatal liver toxicity. The latter caused death in animals treated with conventional AAV vectors with unmodified capsids, which accumulated in liver tissue and failed to affect tumor growth. This novel targeting platform will be key to translational approaches requiring restricted and cell type-specific in vivo gene delivery.
authors.affiliation: Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, Langen, Germany.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Münch
authors.forename: Hanna
authors.initials: H
authors.lastname: Janicki
authors.forename: Iris
authors.initials: I
authors.lastname: Völker
authors.forename: Anke
authors.initials: A
authors.lastname: Rasbach
authors.forename: Michael
authors.initials: M
authors.lastname: Hallek
authors.forename: Hildegard
authors.initials: H
authors.lastname: Büning
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Buchholz
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D000229:Dependovirus / Q000235:genetics*; D004797:Enzyme-Linked Immunosorbent Assay; D018014:Gene Transfer Techniques; D005822:Genetic Vectors; D008024:Ligands; D008854:Microscopy, Electron
chemical_list: D008024:Ligands