Showcase of Undergraduate Research and Creative Endeavors (SOURCE)

Developing and Optimizing Recellularization of Porcine Internal Thoracic Artery Scaffolds

Cardiovascular disease remains a global challenge, even for most developed nations. An important part of meeting this challenge includes the search for graft alternatives for use in bypass procedures on candidate patients. Tissue-engineered blood vessels show promise in this regard since they eliminate the need for patient-derived grafts and reduce the risk of re-intervention. In our search for a graft source, we chose porcine internal thoracic artery (PITA) scaffolds because they are the most biologically and mechanically similar to patient small-diameter vasculature. Decellularization of PITAs via detergents and DNase treatment generates non-immunogenic acellular scaffolds. In this study, we examined the effects of varying detergent concentrations used in decellularization on scaffold ultrastructure and cell seeding efficiency using endothelial cells. Additionally, the use of adipose derived stem cells was introduced as a candidate for scaffold re-cellularization. Stem cells grown in the presence of transformation growth factor beta 1 were also analyzed for their potential use as a population of pre-differentiated smooth muscle cells during scaffold re-cellularization. We observed that higher detergent concentration did not have a significant effect of PITA porosity, but that it did affect re-cellularization. We also showed that aortic endothelial cells can be cultured on PITA scaffolds when the detergent is fully cleared from the scaffolds. Gene expression analysis revealed that stem cells upregulated expression of genes associated with smooth muscle cells in control conditions. These results necessitate further investigation and explanation to optimize a protocol for inducing smooth muscle cell differentiation.