The mechanical properties of tissue-engineered heart valves still need to be improved to enable their implantation in the systemic circulation. The aim of this study is to develop a tissue-engineered valve for the aortic position - the BioTexValve - by exploiting a bio-inspired composite textile scaffold to confer native-like mechanical strength and anisotropy to the leaflets. This is achieved by multifilament fibers arranged similarly to the collagen bundles in the native aortic leaflet, fixed by a thin electrospun layer directly deposited on the pattern. The textile-based leaflets are positioned into a 3D mould where the components to form a fibrin gel containing human vascular smooth muscle cells are introduced. Upon fibrin polymerization, a complete valve is obtained. After 21 d of maturation by static and dynamic stimulation in a custom-made bioreactor, the valve shows excellent functionality under aortic pressure and flow conditions, as demonstrated by hydrodynamic tests performed according to ISO standards in a mock circulation system. The leaflets possess remarkable burst strength (1086 mmHg) while remaining pliable; pronounced extracellular matrix production is revealed by immunohistochemistry and biochemical assay. This study demonstrates the potential of bio-inspired textile-reinforcement for the fabrication of functional tissue-engineered heart valves for the aortic position.

One step to enable long-term use of extracorporeal membrane oxygenation devices or even the development of an artificial fully implantable lung is the endothelialization of oxygenator membranes in order to present a physiological and anti-thrombogenic surface to the blood flow. Since cell seeding decreases the gas transfer of oxygenation devices, a way to reincrease gas exchange performance by other means has to be found. In this study membrane assemblies suitable for endothelialization were developed, which profit from a secondary flow arrangement to increase gas transfer rates, the so-called Bellhouse effect. Therefore textiles that allow a homogeneous gas flow between the membranes and provide a structure that can be used as mold for hollow imprinting onto the membrane surfaces are combined with flat membranes to a sandwich structure. On top of that two approaches for hollow imprinting are generated and their results compared. The furrowed membrane assemblies are seeded with HUVECs and regularly inspected over 3 days cultivation. A surface characterization of the applied membranes is performed by contact angle measurement to identify reasons for inhomogeneous cell growth. In general first important results to develop a biohybrid lung assist device could be achieved in this study.

State-of-the-art lung support systems are limited to short time application because of a lack of long term hemocompatibility and protein absorption on the membrane surfaces. In a highly interdisciplinary project at RWTH Aachen University a biohybrid lung assist system with endothelialised gas exchange flat membranes is developed to improve long term compatibility of oxygenators. To increase the gas exchange performance of flat membranes hollows are imprinted in the membrane surfaces. This approach is based on the research of B. J. Bell-house et al. [1], who discovered this effect, now known as Bellhouse-effect, around 1960. In this paper a processes to manufacture membrane assemblies for oxygenation with imprinted hollows on the flat membrane surfaces is reviewed.

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