Single ventricle congenital heart defects, in which one ventricle fails to develop leading to mixing of oxygenated
and deoxygenated blood, affect approximately 1 in 1,000 live births and have a 70% mortality rate. The Fontan
operation is the standard surgical treatment, where venous blood is diverted directly to the pulmonary artery via
synthetic or tissue-engineered vascular conduits (TEVCs). TEVCs are of great interest and promise due to their
ability to remodel and grow with children. However, an unexpectedly high incidence of graft stenosis was reported
in a prior TEVC clinical trial, leading to termination. It is likely that overt inflammatory responses caused by graft
material degradation and pre-seeded bone marrow cells may have led to over-proliferation of repopulated host
cells and graft stenosis. By replacing bone marrow cells with human induced pluripotent cell-derived endothelial
cells (hiPSC-ECs) and substituting biodegradable synthetic grafts with native decellularized human umbilical
arteries (dHUAs), we generated TEVCs via coating the lumen of dHUAs with hiPSC-ECs under physiological
shear stress in a flow bioreactor. TEVCs prevented luminal stenosis and clotting after implantation as inferior
vena cava (IVC) interposition grafts in nude rats, a validated model for studying grafts for Fontan procedures. To
make TEVCs immunocompatible to any patient, we have generated hypoimmunogenic universal hiPSC-ECs via
ablation of human leukocyte antigens (HLAs) using the CRISPR gene editing. The therapeutic efficacy and
immunocompatibility of universal TEVCs will be investigated via IVC implantation in immune-humanized rats.
Graft patency and blood flow will be monitored by ultrasound, and grafts will be harvested for histological analysis
within 3 months post-implantation. Expanding on using universal, endothelialized vascular conduits, the PI’s
group will also develop a contractile Fontan conduit as a generation 2 therapy to assist blood flow from IVC to
the pulmonary artery, as none of the conduits now in use provide pumping activity, leading to insufficient tissue
perfusion, heart failure, and pulmonary vascular disease. We have recently developed a tissue-engineered
pulsatile conduit (TEPC) by deriving engineered heart tissues (EHTs) made by seeding hiPSC-derived
cardiomyocytes into decellularized native heart matrices and then wrapping the EHTs around a dHUA. We will
develop an immunocompatible TEPC by wrapping EHTs based on universal hiPSC-derived cardiomyocytes and
cardiac fibroblasts around the above vascular conduits. TEPCs will be matured under electro-mechanical training
conditions in bioreactors to achieve enhanced contractile output to make a strong Fontan conduit that assists
pulmonary circulation. The PI will test the hypothesis that universal TEPCs are immunocompatible and maintain
contractility in the IVC graft model in immune-humanized rats. Ultrasound will be employed to monitor the
patency and pulsatility of TEPCs, and TEPCs will be explanted for histological analysis. Universal hiPSC-TEPCs
will establish the foundation for generating readily available, mechanically active Fontan conduits, providing a
curative therapeutic for patients born with single ventricle congenital heart defects.