Integrin [alpha]^sub v^[beta]^sub 3^ Targeted Gene Delivery Using RGD Peptidomimetic Conjugates with Copolymers of PEGylated Poly(ethylene imine)

• Published in: Bioconjugate chemistry Vol. 20; no. 6; p. 1270
• Main Authors: Merkel, Olivia M, Germershaus, Oliver, Wada, Carol K, Tarcha, Peter J, Merdan, Thomas, Kissel, Thomas
• Format: Journal Article
• Language: English
• Published: Washington American Chemical Society 17.06.2009
• Subjects: Binding sites; Biochemistry; Chemical synthesis; Copolymers; Peptides; Polyethylene glycol; Studies
• ISSN: 1043-1802; 1520-4812

This study describes the synthesis and characterization of five conjugates of poly(ethylene glycol) modified polyethylenimine (PEG-PEIs) coupled in two different synthesis routes to a nonpeptidic pentacyclic RDG-mimetic for integrin receptor-targeted gene delivery. Synthesis of this panel of different conjugates allowed for systematic analysis of structure-activity relationships. Conjugates were therefore characterized regarding molecular composition, DNA condensation, size, and zeta potential of self-assembled polyplexes. In vitro characterization included investigation of blood compatibility, binding affinity to receptor-positive and receptor-negative cells measured by flow cytometry, cellular uptake quantified by scintillation counting, and efficiency and specificity of transfection assayed by reporter gene expression. In a first synthetic approach, low molecular weight PEI (LMW-PEI) was PEGylated using a heterobifunctional PEG linker and coupling of the RGD-mimetic was achieved at the distal end of PEG chains. In a second synthesis route, the RGD-mimetic was directly coupled to AB-block-copolymers of PEI (25 kDa) and PEG (30 kDa). Interactions of RGD-PEG-LMW-PEI conjugates with DNA were strongly impaired, whereas PEG-PEI-RGD conjugates were more promising candidates due to their physicochemical properties and higher receptor specificity. The binding, uptake, and transfection efficiency in receptor-positive cells was strongly increased upon conjugation of the RGD-mimetic to AB-block-copolymers of PEG-PEI and depended on the degree of peptide substitution. The conjugates of PEG-PEI AB-block-copolymers with low ligand density of the RGD-mimetic appear to be promising candidates for in vivo cancer gene therapy. [PUBLICATION ABSTRACT]