Feasibility Studies on Using a Thermoplastic Polyurethane Scaffold for Hybrid Tissue-Engineered Heart Valves

ABSTRACT OF THE THESISFeasibility Studies on Using a Thermoplastic Polyurethane Scaffold for Hybrid Tissue-Engineered Heart ValvesBySamuel David ZukeMaster of Science in Biomedical EngineeringUniversity of California, Irvine, 2017Professor Arash Kheradvar, ChairHeart valve replacement procedures currently use either mechanical or bioprosthetic valves made from animal tissue. This thesis examined the use of polymers as the scaffold material for novel hybrid tissue-engineered heart valves and as the leaflet material for polymer heart valves. The concept of a polymeric heart valve was also examined when testing material durability and functionality with accelerated wear testing and a pulsatile flow simulator. Human aortic smooth muscle cells (HASMC), normal human lung fibroblasts (NHLF), and umbilical vein endothelial cells (HUVEC) were examined on a thermoplastic polyurethane, Aromatic Carbothane. Each cell type was seeded on individual pieces of both fibronectin-treated and untreated Carbothane to test biocompatibility. Samples were stained using Cell Tracker Red CMTPX and imaged using fluorescence microscopy. Fluorescence imaging confirmed HASMC and NHLF adhesion and viability on the polyurethane substrate. HUVECs initially attached on both fibronectin-treated and untreated substrate, but they began to detach and clump together within 24 hours. Trilayered tissue samples were successfully grown on a lasercut Carbothane mesh scaffold using the three cell types. A Carbothane heart valve was sewn and placed in a heart flow simulator to examine geometric orifice area. The valve opened to about 49% of the calculated orifice area, but it showed very symmetrical coaptation as it closed. The valve showed no signs of damage after 20 million cycles in the AWT. Carbothane exhibited excellent biocompatibility, and its durability, ease of manufacturing, and flexibility make it a promising candidate for future studies in the field of heart valve engineering.