Interaction between Vascular Endothelial Cells and Surface Textured Biomaterials

Abstract

A promising approach to overcome thrombus and neointima formation on vascular grafts is to create a functional, quiescent monolayer of endothelial cells on the surface of implants. Surface topography of these implants is proven to enhance cell attachment and to reduce the inflammation associated with a smooth surface. Photoembossing is a relatively new, simple, environment-friendly and cost-effective technique to create surface topographies, since there is no etching step or mould needed. In this study, photopolymer films are photoembossed through contact mask photoembossing, while fibres are photoembossed through holographic lithography. Surface relief textures of ridges and grooves with various pitch sizes and heights are successfully obtained through both methods. Furthermore, we introduce this technique to fabricate, for the first time, reproducible surface textures on electrospun fibres. Human umbilical vein endothelial cells (HUVECs) are used in the study. Three different systems are investigated: non-degradable PMMA-TPETA, semi-degradable PLGA-TPETA and fully degradable PLGA-PEGDA-DTT, for different applications and therapeutic requirements. Both non-degradable PMMA-TPETA photopolymer and semi-degradable PLGA-TPETA photopolymer are shown to improve biocompatibility compared to PMMA and PLGA, respectively. Photoembossed films made from these two photopolymers show significantly improved cell attachment and proliferation, IV with a water contact angle around 70º. It is shown that the pitch size of surface topographies affects cell adhesion and migration in the wound healing assay study. Interaction between HUVECs and fibres shows that cells grow from their initial locations at fibre crossings. Focal adhesions are seen to be more aggregated on the surface textured fibres, while those on the glass cover slips are more dispersed near the edge of the cell membrane. The appearance of F-actin in the cytoplasm is also seen to be influenced by the surface topography, where changes in the diameter of the fibre and its surface texture result in F-actin rearrangement. Our study shows that a surface textured, fully degradable, gel-like photopolymer PLGA-PEGDA-DTT has great potential to be further developed for tissue engineering applications.