The project investigated a novel aortic valve replacement concept that combines a biologically derived, cell‑free pericardial matrix with an expandable nitinol stent. The aim was to create a haemodynamically competent valve that could be implanted in a minimally invasive manner while avoiding the long‑term complications that have limited current transcatheter aortic valve replacement (TAVR) devices, such as paravalvular leakage and structural valve deterioration.

In a large‑animal study using sheep, the valve prostheses were implanted under cardiopulmonary bypass. Post‑operative monitoring revealed that the valves maintained normal function on echocardiography and Doppler imaging. The mean transvalvular pressure gradient remained within physiological limits and the valve opening area was preserved, indicating that the prosthesis did not impose an excessive afterload on the left ventricle. Doppler studies showed only minimal regurgitation, and no significant paravalvular leaks were detected. Histological examination of explanted valves after the observation period showed an intact collagen matrix, absence of calcific deposits, and no evidence of structural degradation. Hematoxylin‑eosin staining revealed occasional host cell nuclei within the matrix, suggesting mild cellular infiltration, while Masson‑Trichrome staining confirmed the preservation of collagen fibers. Alizarin‑red staining did not reveal calcium deposition, supporting the absence of early calcification. A small number of neutrophils and macrophages were present, indicating a mild foreign‑body reaction that did not lead to acute rejection of the xenograft.

Despite these encouraging functional results, the study encountered several technical challenges. The prostheses migrated distally or into the left‑ventricular outflow tract in a subset of animals, and paravalvular leaks occurred in some cases. Ventricular fibrillation and thrombus formation were the main causes of peri‑operative mortality, underscoring the need for meticulous anticoagulation and rhythm management. The size of the distal stent segment proved too long for the relatively short ascending aorta of the sheep, and the lack of a suitable fixation technique prevented the use of a purely transcatheter approach. Consequently, all implantations required an open surgical route with cardiopulmonary bypass, limiting the translational potential of the design until a reliable minimally invasive delivery system can be developed.

The research was carried out within a multi‑partner consortium that included German universities, research institutes, and industry collaborators. Each partner contributed specific expertise: material scientists developed the decellularized pericardial matrix and optimized the stent‑valve interface; surgical teams performed the implantation and peri‑operative care; cardiologists and imaging specialists conducted the functional assessments; and pathologists performed the detailed histological analyses. The project spanned several years and was supported by national research agencies and European Union funding programmes, reflecting the high priority placed on advancing valve technology for younger patients who would otherwise require repeated surgical interventions.

In summary, the study demonstrates that a cell‑free pericardial matrix combined with an expandable stent can produce a haemodynamically competent aortic valve that resists calcification and maintains structural integrity in a large‑animal model. However, technical hurdles related to valve positioning, delivery, and peri‑operative complications must be addressed before the concept can be translated into a clinically viable transcatheter device. The collaborative effort across multiple disciplines and institutions provides a solid foundation for further refinement and eventual clinical testing.