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For four decades, the Homograft Valve Bank at the University of the Free State (UFS) – also known as the UFS Tissue Lab – has played a life-changing role in South African cardiac care. The lab continues to process, store and distribute donated human heart valves for patients nationwide, offering a vital lifeline to infants born with heart defects and adults requiring valve replacement surgery.

Today, the lab is also shaping the future of heart surgery. Its latest research focuses on developing advanced biological replacement tissues designed to last longer and reduce complications such as calcification and tissue degeneration. Dr Hans van den Heever, Medical Scientist and Director of the UFS Tissue Lab, which is situated in the Department of Cardiothoracic Surgery within the Faculty of Health Sciences, says they aim to make biological implants available to patients that offer better durability and requires less frequent reoperation surgeries. Dr Van den Heever joined the team in 1987 and has led the facility since 2000.

Early days

The Tissue Lab began in 1984 under visionary cardiac surgeons at the University of the Free State including Prof Hannes Meyer, the then Head of the Department, Dr Japie Hough, consultant paediatric cardiac surgeon and Prof Leon Neethling, medical scientist and former manager. Inspired by new developments in the UK, Dr Hough wanted to establish South Africa’s first programme using donor heart valves in repairing of congenital heart abnormalities in young children and replacement of diseased valves in older patients. Since then, the lab has harvested more than 3 350 donor heart valves and vessels from nearly 2 300 donors, with almost 2 000 homografts successfully transplanted in hospitals across the country.

These valves do not require any anticoagulation therapy after implantation, allowing patients a much easier, healthy life. The homograft bank is currently the only tissue bank in Southern Africa that processes and distributes donated human heart valves for transplantation, but severe shortages in donor numbers are having a major impact on the availability of valves of various sizes for recipient patients.

The lab is a key contributor to the South African Tissue Banking Association (SATIBA) and collaborates closely with national and international partners, including the Netcare Transplant Division.

Research

“Our valve and large vessel research in the circulatory system of the sheep model has grown in stature, and soft tissue processing to obtain the best results after implantation in patients has become a major focus of the lab’s research. Peer review publications and numerous presentations at local and international congresses have resulted from the activities of the lab,” says Dr Van den Heever.

While still affiliated to the UFS-Tissue Lab as a special professor, Prof Neethling from the Fremantle Heart Institute and Admedus Institute in Australia, high quality research resulted in the development of a pericardial patch for use in cardiac reconstructive surgery that is currently used worldwide. Says Dr Van den Heever “We are currently working on the implantation of locally decellularised and treated pericardium in a primate model to evaluate immunogenicity response of the recipient. We are also evaluating differently processed pericardial tissues in a transcathether valve in the right ventricular outflow tract of young sheep as well as the evaluation of decellularised and treated bovine jugular veins with valves (Contegra conduits) in the circulatory system of young sheep as replacement tissue alternatives.”

Preparing for regulatory approval for future clinical use

Very positive results were obtained using decellularised donor homograft heart valves and bovine pericardium in bioprosthetic valves (transcathether valves) in sheep, as it proved a treatment option with great potential to mitigate tissue calcification and degradation. The next step, explains Dr Van den Heever, will be to approach the regulatory authorities for possible use in human implants.