Non-Specific Endothelial Cell Interactions With the Substrate Result in Cell Activation and Angiogenesis In Vitro

Vascularization is critical for success of tissue engineering applications. Previous studies by us and others have shown that self-assembling peptide nanoscaffold RAD16-II promotes de novo capillary formation (angiogenesis) in vitro and neovascularization in vivo, and is a promising material for tissue engineering applications [1, 2]. However, the molecular mechanisms for cell interactions with this material are not known. Angiogenesis is mediated via interactions between integrins, which are expressed on the surface of activated endothelial cells (ECs), and extracellular matrix proteins. Among several integrins, α_vβ₃ is the most abundant and influential receptor regulating angiogenesis [3]. The α_vβ₃ integrin binds to its ligands via Arg-Gly-Asp (RGD) biding motif. However, there are no RGD motifs on RAD 16-II peptide. Instead, it contains three RAD motifs. Studies have shown that non-specific binding of α_vβ₃ with RAD can be retained through R and D sides [4]. The objective of this study, therefore, is to elucidate the underlying molecular mechanisms of RAD16-II nanoscaffold interactions with microvascular endothelial cells. We hypothesize that non-specific interactions between RAD16-II peptide nanoscaffold and α_vβ₃ integrin result in phosphorylations of β3 cytoplasmic domain, which then activate downstream angiogenic signaling pathways and promote angiogenesis.