Cell-free heart valve offers promise of normal life
EU-funded researchers have developed and tested a way to make human heart valve implants more tolerable and longer lasting, enabling recipients of all ages to avoid follow-up surgery and live largely normal lives, cutting hospital stays and healthcare costs.
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Heart disease is the leading cause of death in the EU and takes many forms. Treatment for some of these conditions including congenital heart defects that impact one in every 100 babies born in the European Union today are pulmonary heart-valve replacements.
Currently, such replacements involve the use of either mechanical or biological heart-valve substitutes. Both are problematic, however, with mechanical valves made from artificial materials requiring a lifetime intake of blood thinners that can be dangerous for children and pregnant women.
Biological heart valves derived from either human donors or animals degenerate within 10-15 years after coming under attack from the recipients immune system, requiring further transplants. That time frame drops dramatically for children and young people whose active immune systems could mean repeat surgery as often as every two years. And each additional transplant brings greater risks.
The ESPOIR project set out to solve this problem. The result is a new type of cell-free heart valve that can last a lifetime.
Multiple heart operations due to recurrent valvular heart disease are the other side of the coin in the success story of congenital heart defect repair, says clinical trial director Samir Sarikouch from the Hannover Medical School in Germany, which led the project consortium. Within ESPOIR, a new type of biological heart valve a decellularised human heart valve was tested and brought on to the market.
The researchers built upon and tested an innovative technique they had previously developed to remove biological material from human heart valves available for transplantation, essentially ridding them of all traces of the donor. This results in a so-called extracellular matrix, non-cellular connective tissue solely responsible for providing structure and biochemical support for surrounding cells.
Most importantly for transplantation, this decellularised heart valve is not seen as a threat by a recipients immune system. Instead, the patients cells actually populate the valve and eventually make it part of the body.
The cells of the body invade this matrix and sit there, says Sarikouch. The hope is that they do what they do normally they maintain the extracellular matrix and, with time, this valve becomes more the patients own valve.
Since extensive animal studies have shown such valves to be well tolerated, the main objective of ESPOIR was to promote their widespread clinical use.
Corlife OHG, a small biotech company and spin-off of the Hannover Medical School, currently offers decellularisation to any interested tissue bank or hospital meeting certain EU requirements.
However, getting to this point was not easy. ESPOIR only obtained regulatory approval for the ground-breaking technique after a pioneering cross-border effort that took several years.
What followed was a clinical trial involving some 120 patients at seven centres around Europe. The project has also created a registry of 240 patients worldwide who have received a decellularised homograft for pulmonary valve replacement to enable proper monitoring and a 10-year follow-up.
The results are impressive: 99 % of those who have received the mostly cell-free heart valves have not needed follow-up surgery so far.
A drawback, however, is that the procedure requires human donations, which are not that easy to come by. In fact, according to Sarikouch, there are many more people eager to try the new treatment than there are valves available.
We sometimes have to wait for donor tissue, he says, adding that not all are suitable for transplantation since size and length have to match the recipients anatomy. Four major heart valve banks contributed to ESPOIR, he says, underscoring the highly important work of tissue banks in Europe.
Looking forward, the researchers expect a major breakthrough once humanised valves of animal origin are available for decellularisation, possibly in five to 10 years, with ESPOIR laying the foundations for communicating with regulatory authorities and carrying out clinical studies.
The project results will feed into the new EU-funded ARISE project, which runs until 2019. ARISE will develop a clinical trial to show that cell-free aortic heart valves are safe and effective for young patients.