Improving the Re-endothelialization of Vascular Substitutes via Peptide-based Endothelial Progenitor Cells Recruitment

PURPOSE: The lack of adequate surface endothelialization of vascular substitutes contributes to complications such as neo-intimal hyperplasia and in-stent thrombosis. Biomimetic surfaces that recruit circulating endothelial... [ view full abstract ]

PURPOSE: The lack of adequate surface endothelialization of vascular substitutes contributes to complications such as neo-intimal hyperplasia and in-stent thrombosis. Biomimetic surfaces that recruit circulating endothelial progenitor cells (EPCs) could promote re endothelialisation and increase the probability of vascular healing. In this work, we investigated the potential of surfaces modified with a novel fluorophore-tagged RGD peptide (CGK(PEG3-TAMRA)GGRGDS, referred to as “RGD-TAMRA”) to induce the adhesion and expansion of EPCs.
METHODS: Peripheral blood mononuclear cells were seeded on RGD-TAMRA modified polystyrene surfaces or on control collagen-coated surfaces under static conditions. The formation of late outgrowth endothelial colonies consisting of endothelial colony-forming cells (ECFCs) was observed over the course of 30 days. The resulting ECFCs were characterized based on surface marker expression, tube formation in Matrigel®, as well as cell alignment in the presence of laminar flow.
RESULTS: ECFCs appeared between the second and the 4th week of culture on both RGD-TAMRA and collagen-coated surfaces. As expected, the ECFCs obtained on both surfaces expressed CD31, CD105, CD144, and CD146 but not CD14 or CD45. The cells formed tubular networks 4 hours after seeding onto Matrigel®. Furthermore, preliminary results suggest that exposure to 25 dyn/cm2 wall shear stress led to cellular and actin filament alignment in the direction of flow.
CONCLUSION: Surface modification with the novel RGD peptide described in this work is a promising avenue to engineer vascular scaffolds that promote EPC adhesion and expansion.