Multivalent Vesicles of Stimuli-Responsive Elastin- and Resilin-Based Block Copolypeptides with an Anti-Angiogenic Peptide

Self-assembled nanostructures of stimuli-responsive block copolypeptides fused with a variety of functional peptides have been of growing interest because they can present multivalent functionalities and show biocompatibility and biodegradability for advanced drug delivery systems, biosensing and bioimaging applications. In this study, we developed multivalent vesicles of stimuli-responsive elastin- and resilin-based diblock copolypeptides (EBP-RBP) with the anti-angiogenic peptide, a vascular endothelial growth factor receptor 1 (VEGFR1, fms-like tyrosine kinase-1, Flt1) antagonist known as anti-Flt1 peptide, to control over migration and tube formation of human umbilical vein endothelial cells (HUVECs) because it competitively binds to the VEGFR1 in the presence of VEGF for anti-angiogenesis. The anti-Flt1-EBP-RBPs were molecularly cloned, over-expressed in <i>E. coli</i> and non-chromatographically purified with high yield by inverse transition cycling. The anti-Flt1-EBP-RBPs were self-assembled into vesicles under physiological conditions by thermal trigger due to aggregated RBP block below the UCST (upper critical solution temperature) and soluble EBP block below the LCST (lower critical solution temperature). In contrast to EBP-RBPs, the anti-Flt1-EBP-RBPs showed decrease in LCST and an increase in UCST because of hydrophobicity of the anti-Flt1 peptide (GNQWFI). The vesicles of the anti-Flt1-EBP-RBPs showed concentration and incubation dependent intracellular localization in HUVECs through molecular interactions of multivalent anti-Flt1s against the VEGFR1. Especially, migration and tube formation of HUVECs was largely inhibited in a dose-dependent manner by the vesicles with multivalent anti-Flt1s on the condition of VEGF-triggered angiogenesis signaling. Therefore, the self-assembled block copolypeptide-based vesicles with multivalent VEGFR1 antagonists would be of great potential as targeted drug delivery systems for anti-angiogenesis such as treatment of retinal and choroidal neovascularization.