Engineering a surface to enhance endothelial cell adhesion towards creating a 'roll-up' blood vessel prosthesis

This project investigated the technical feasibility of creating an adherent layer of endothelial cells with improved adhesive strength to produce a synthetic vascular graft using “cutting edge” technologies such as electrospinning and robotic free form fabrication (FFF). Firstly, cell adhesion on the modified surface of electrospun Polycaprolactone (PCL) fibers improved significantly, after verification using the centrifugation assisted cell adhesion assay. Human umbilical vein endothelial cell (HUVEC) adhesion was found to be highest on gelatin crosslinked to NaOH hydrolyzed electrospun PCL fibers before and after centrifugation, based on cell attachment observation under the fluorescent microscope and mitochondrial activity quantification using AlamarBlue®. Secondly, a specialized printing ink comprising of enzymatically crosslinked gelatin hydrogel was optimized for FFF controlled deposition of viable cells. The optimized gelatin “ink” allowed extended viability for the entrapped HUVECs and the drawn scaffold lines to retain their integrity whilst in growth media. Eventually, HUVECs entrapped in gelatin-polyethylene (PEO) ink were deposited by precise freeform fabrication (FFF), on the optimized 2-D PCL. The novel approach to fabricating 3-D small diameter tubular blood vessel by rolling-up the 2-D hydrogel laden film was also discussed in this report. This study demonstrated antecedent results with the fresh approach in forming small diameter vessels. However, there are still limitations to overcome including further characterization of the endothelialized surface using the flow setup. The hydrogel composition also requires optimization to compensate increased viscosity for the gel stability and to monitor the cell proliferation rate in this optimized gelatin by quantitative methods such as AlamarBlue®. To attain the target of a complete blood vessel with vasodilatory functions, incorporation of smooth muscles cells can be considered in the future.Bachelor of Engineering (Materials Engineering