In Tissue Engineered Vascular Grafts (TEVGs) of small diameter, chronic inflammation is a common failure cause mainly due to induction of thrombogenesis, and development of hyperplasia intima and atherosclerosis. Contrary to fibrinogen, some authors have suggested that albumin-coated surfaces reduce the leukocyte interaction, thereby, reducing the inflammatory and thrombogenic responses. To develop bioactive surfaces on TEVGs, we intended to avoid thrombogenesis and control inflammatory responses using organoselenium compounds and adhesive peptides for endothelial cell adhesion surface modifications on carboxylated Polyester Urethane Urea (PEUU-COOH). Herein, we aim to study in silico and experimentally albumin adsorption under pulsatile flow conditions in surface-modified tubular PEUU-COOH structures. Briefly, a two-way Fluid-Structure Interaction model in ANSYS Fluent 2019R3® and ANSYS Transient Structural® software was linked to kinetic models in COMSOL Multiphysics5.5® for albumin adsorption on PEUU-COOH tubular structures modified superficially with seleno-L-cystine, 4-arm PEG 20.000 or heparin. Physiological pulsatile pressures were introduced as boundary conditions to gain insights into the effects of wall deformation and their associated velocity profiles on albumin adsorption patterns. For the in vitro validation, successful fluorescent labeling of albumin with rhodamine B was performed via EDC/NHS conjugation. Polymeric tubular structures with the three different surface modifications were placed into a previously designed and tested fluidic device under pulsatile flow conditions with equal volumes of the fluorescent albumin. The protein adsorption was investigated as a function of time to validate the in silico model. Surface protein concentration and distribution over the modified surfaces were evaluated by confocal microscopy. The models showed time-spatial and chemistry-dependent albumin concentration and saturation, demonstrating the influence of surface chemistry and flow over protein adsorption. Confocal images confirmed this data. Our in vitro and in silico models showed that the PEUU-COOH scaffold superficially modified with seleno-L-cystine favors albumin adsorption compared with the other surface modifications. This more profound understanding of albumin adsorption indicates that surface modifications might play a significant impact on modulating the inflammatory response and ultimately, the regenerative potential of TEVGs.

Albumin adsorption over surface modified Tubular PEUU-COOH scaffolds: In silico and in vitro approaches

ACS Fall 2021

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Albumin adsorption over surface modified T</i><i>ubular PEUU-COOH scaffolds: In silico and in vitro approaches