Computer-designed customized regenerative heart valve. Source: Adapted from figure published in Science Translational Medicine

Growing replacement parts in the lab, also known as tissue engineering, is a key component of regenerative medicine research. Bioengineered tissues and cells can be used to restore functionality by replacing defective parts in the body. They offer significant advantages over the artificial implants currently in use: They can grow and regenerate themselves, and they do not cause immune reactions in the patient’s body.

Now, a milestone has been reached in terms of treating heart patients using valves cultured from human cells. A team led by Professor Simon P. Hoerstrup of the University of Zurich (UZH) in Switzerland has used computer simulations to successfully predict how well tissue-engineered heart valves (TEHVs) would grow, regenerate and function in large animal models (in this case, sheep). This is a significant step toward what could one day be a routine application of tissue engineering technology.

Although researchers have long explored using bioengineering approaches to create living heart valve replacements that can regenerate and remodel themselves to better accommodate the native circulatory system, none of the TEHVs under evaluation to date could continuously adapt to changes in blood flow over time. The UZH computer simulations are able to predict structural heart valve changes that occur during the dynamic regeneration process, including an estimation of the directions in which valves would stretch to compensate for later remodeling.

To underscore the significance of the research, one might consider the bigger picture of valvular heart disease, which is one of the major causes of mortality and morbidity worldwide. Employing artificial heart valve prostheses is a particularly unsatisfactory strategy when it comes to treating children with congenital heart defects. Such children often undergo surgery to replace defective heart valves or blood vessels, but the artificial parts they are given cannot grow along with their bodies. This means multiple reoperations, accompanied by an increased risk of complications and considerable psycho-social stress for both patients and families.

There are still a few hurdles to get over before the technology can be routinely used. "One of the biggest challenges for complex implants such as heart valves is that each patient's potential for regeneration is different,” Hoerstrup explained. “There is therefore no one-size-fits-all solution.”

Hoerstrup’s team has been among the pioneers of cardiovascular tissue engineering for more than 20 years. The new research appears in a recent issue of Science Translational Medicine.