Engineered heart tissue (EHT) made from human induced pluripotent stem cell-derived ventricular cardiomyocytes (hiPSC-VCMs) can be used as a promising tool for the cardiovascular therapeutics. Single ventricle heart defects are a class of congenital disorder where only a single ventricle properly develops. This can result in mixing of oxygen-rich blood and oxygen-poor blood during circulation, leading to inefficient oxygen supply to tissues of the body. Additionally, this class of defects places an increased strain on the single ventricle during contraction. Children born with this disease are commonly treated with the Fontan procedure to re-route blood flow from the superior and inferior vena cava directly into the pulmonary artery. Synthetic grafts lined with bone marrow derived stem cells have been used as vascular conduits to make the connection between the inferior vena cava and the pulmonary artery. However, these synthetic grafts cannot provide pumping activity to help circulate blood. The purpose of this project is to generate tissue engineered pulsatile conduits (TEPCs) to aid in circulation by producing contractile force, and thus an increased driving pressure, to aid in flow through the pulmonary system. The design strategy employed for TEPC production uses decellularized human umbilical artery as an acellular vascular scaffold because its mechanical characteristics allow it to maintain patent blood flow in the inferior vena cava. This scaffold is wrapped with hiPSC-VCM derived EHTs to provide contractile force for the conduit. Decellularized pig heart tissue is used as a scaffold for generating EHTs because it has an inherent fiber structure that allows for generation of controllable alignment of myocardial fibers within the tissue. Co-culture EHTs of hiPSC-VCMs and cardiac fibroblasts were made and tested for contractile force output. Preliminary data shows the introduction of fibroblasts into the tissue has a positive effect on contractile output. Microvascular networks will be generated to support thicker TEPC muscle layers and increase overall TEPC pressure generation. TEPCs will be subjected to an in vitro training regimen consisting of physical and electrical cues to enhance their contractility and electrical handling properties. A flow bioreactor will provide stretch within the TEPC lumen to give the tissue mechanical pressures that mimic what will be experienced in rat inferior vena cava. Electrodes placed within this bioreactor system will provide field stimulation that is intended to mimic the human developmental environment to coax out more mature electrical characteristics from the hiPSC- VCMs. To test for basic survival of the graft, a nude rat model will be used to assess basic parameters for successful engraftment as an inferior vena cava interposition graft. Refinement and optimization of this robust design strategy for producing TEPCs developed in this study will lay the groundwork for testing the construct?s therapeutic potential in the future. Ultimately, this work will make strides in developing improved treatment for patients with single ventricle defects.
This work will produce a suitable vascular conduit for the Fontan procedure used to treat patients with single ventricle cardiac anomalies. The ability of this conduit to produce pressure will aid in circulation and alleviate issues with associated with the poor circulation Fontan patients experience with traditional conduits. The successful development of this tissue engineered pulsatile conduit will pave the way for curative, rather than palliative, interventions for single ventricle cardiac anomalies.
