Plasma and Patterning: The New Focus for the Development of Nanocomposite Vascular Grafts

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Introduction: The concept of surface modulation holds much promise for the future development of vascular grafts. Our aim is to enhance a nanocomposite material using surface modification techniques such as plasma technology and surface patterning to augment both surface chemistry and topography with a view towards endothelialisation. Methods: Polyhedral oligomeric silsesquioxane (POSS) was combined with polycarbonate urea urethane (PCU) to produce a Nanocomposite polymer. Microgrooves with pitch size of 25 μm was created using photolithography. Fidelity was verified with scanning electron microscopy (SEM) and atomic force microscopy (AFM). The polymer was then exposed to pure O2 plasma and contact angles were measured. Human umbilical vein endothelial cells (HUVECs) were then seeded onto POSS-PCU. The metabolic activity of the cells was assessed and immunostaining was used and subsequently visualised with confocal microscopy. Results: Contact angle results (mean: 85°) show the increase hydrophilicity of the polymer surface and both AFM and SEM confirm the high replication of the microgrooves within the surface of the polymer using photolithography. Metabolic activity of HUVECs on the surface modified polymer was significantly increased compared with control (p < 0.05). Further immunostaining further confirms the adhesive nature of the cells as well as the migratory potential. Conclusion: Using a combination of plasma technology and surface patterning to augment both surface chemistry and topography on a nanocomposite polymer promotes increased endothelial cell adhesion, migration and proliferation. The ordered microgrooves were seen to enhance cellular adhesion and spreading. Plasma technology and micro-grooving is a promising methodology to optimise luminal endothelisation and the prospect for ‘self-endothelisation.’