The first is a complete heart replacement using advances in bioengineering of an implantable, artificial device. Next is sufficient understanding of the biology of xenotransplantation with the ability to manipulate the biology for permanent acceptance of a replacement heart from an animal source. The third strategy is the topic of this presentation, which is engineering of living structures toward replacement of the component parts of a heart and, eventually, the possibility of a complete living heart replacement. Component structures can be envisioned as replacement of heart muscle toward improved cardiac pumping action, replacement of portions of or complete heart valves, and complete blood vessel replacement either of the coronary vasculature or the major outflow tracts. Systems of stem cell replacement to improve myocardial repair, regeneration, and pump function are being evaluated worldwide.
Human trials are underway in a few centers.
The design and fabrication of living heart valve and blood vessel replacements likewise are underway and include progenitor and stem cell populations added to scaffolding and incubated in dynamic flow bioreactors. Finally, the problem of replacement of large portions of cardiac muscle or the potential for full replacement is being investigated. Some envision the complete morphogenesis of an organ using stem cells. Our approach has been the design and fabrication of a complete vascular circulation using microfabrication technologies. The addition of the muscle layer is then envisioned as the fundamental tissue structure toward a permanent living replacement.