Computer modeling improves life span of regenerative heart valve replacements in sheep

One year after implantation, the valves were still working and showed "remodeling comparable to native heart valves" in nine of the 11 sheep. (Manfred Richter)

Tissue-engineered heart valves are an attractive treatment for heart valve disease, but they tend to change shape and stop working after only a few months. To address this, a University of Zurich-led team used computational modeling to anticipate how engineered valves change in the body and then design a longer-lasting solution. The valves have demonstrated promising longevity in sheep.

“One of the biggest challenges for complex implants such as heart valves is that each patient’s potential for regeneration is different. There is therefore no one-size-fits-all solution,” said Simon Hoerstrup, a professor at the University of Zurich, in a statement. 

To customize the design and composition of regenerative valves, Hoerstrup's team used computer simulations that predicted how they would grow, regenerate and function in individual sheep. Their models included the directions in which the valves would stretch after they were implanted. 

Then they cultured "living" valves from blood vessel cells seeded on polymer mesh for four weeks and implanted them in 11 sheep. They checked the implanted valves each month, using MRI and intracardiac echocardiography. One year later, the valves were still working and showed "remodeling comparable to native heart valves" in nine of the 11 sheep, according to the statement.

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The benefits of an engineered "living" valve are obvious: Although artificial prosthetics last longer than valves made of animal tissue, they still wear out. They also require patients to take blood thinners to ward off blood clots. What's more, they do not grow with the patient, which makes them a bad choice for children, who end up needing multiple surgeries to replace a diseased valve. 

While there is more work ahead before the technology can be used in patients, the University of Zurich researchers hope their findings will help others translate new bioengineering approaches from the lab to the clinic. 

"It would be interesting to assess the functionality of our [tissue-engineered heart valves] beyond the study period to further investigate additional remodeling phenomena," the researchers wrote in their study, which appears in Science Translational Medicine.