Development of donor heart valve that grows with the body

In the Netherlands, 1 in 100 children are born with a heart defect. A quarter of them have an abnormality of the aortic or pulmonary artery valve. They often have to undergo major surgery in the first year of life to replace the diseased valve with a donor valve to prevent heart failure. The problem is that the donor heart valve does not grow with the child and is also often rejected by the immune system. This requires multiple, high-risk surgeries with new donor heart valves during life, severely limiting the quality of life of these patients.

Mats Vervoorn, heart-lung surgeon in training, Bram van Wijk, pediatric heart surgeon at UMC Utrecht and Marijn Peters, biomedical researcher are now joining forces to work together to develop a heart valve that grows with them and is not rejected. “The problem with donor valves is that they have to be frozen until they are used in surgery,” explains Vervoorn. “This freezing kills the cells, preventing the valve from growing. We want to develop a small bioreactor to give the heart valve oxygen and nutrients. In this way, we want to keep the heart valve alive for a few weeks to bridge the period between removing the heart valve from the donor body and transplanting it into the child with the congenital heart defect.

One donor heart valve

If researchers succeed, the heart valve can grow with the child, requiring only one donor heart valve and one operation. At least, if the valve is not rejected. Our immune system protects us from dangerous outside influences. Unfortunately, the immune system recognizes a donor heart valve as a danger because it comes from another body. As a result, the valve is rejected. This is where the researchers came up with something clever. Peters: “We copied the art of the body itself. There is a well-known situation in which something is not rejected, namely a baby in the womb. We discovered that there are special cells in the placenta that ensure that the mother’s body regards the baby as safe, even though the baby consists of 50% of the father’s genetic material. We will investigate whether we can use properties of these cells to ensure that the heart valve is also seen as safe.”

Improve quality of life

The research is made possible by a Dekker Team Science grant from the Heart Foundation. The collaboration between Utrecht and Eindhoven brings together different areas of expertise. The project could not only provide lifelong functioning heart valves, but also be a breakthrough for other transplants such as heart, lung, liver and kidney transplants, where patients currently have to take heavy medication to prevent rejection. Reducing rejection would be a huge breakthrough because the drugs can cause serious infections and cancer. With the new technology, patients would need fewer heavy drugs, which would significantly improve the length and quality of life of these patients.