1887

Abstract

Abstract

The implementation of the sinuses of Valsalva in both the aortic and the pulmonary position is a crucial step towards the development of functional tissue engineered heart valves with optimal hemodynamic performance and reduced risk of thrombi formation. However, the implementation of these features is not standard in tissue engineered heart valves. In our laboratory we aim at the realization of autologous heart valves starting from materials isolated from the patient (fibrinogen and cells) and shaped into 3D geometries by moulding techniques. We present two new fabrication methods that result in the realization of heart valve scaffolds reproducing the complex geometry of semilunar valves. The first concept consists of a mould in two parts: a ventricular part and a vascular part which contains three removable bulbs representing the sinuses of Valsalva; in the second concept the vascular part features three flexible protrusions shaped as the sinuses of Valsalva which can be collapsed when a vacuum is applied. The moulds were designed with the 3D CAD software Pro/Engineer (PTC, Needham, MA, USA) and manufactured by rapid prototyping. The cell embedded fibrin gel valves were produced by polymerizing a fibrinogen solution in TBS (10 mg/ml) with CaCl2, thrombin and ovine umbilical cord derived fibroblasts (10x106 /ml) suspended in TBS. Afterwards, the obtained construct was placed in a static bioreactor to be cultured on the mould for 14 days in order to avoid cell-mediated tissue contraction before transferring it to a bioreactor for dynamic cultivation of a duration of 2 weeks. To release the fibrin scaffold from the mould after static cultivation the vascular part and subsequently the three removable sinuses of Valsalva were removed (first approach), or the vascular part was collapsed and taken out as one part (second approach). The constructs were successfully released without any tearing with both approaches despite the poor mechanical properties of the fibrin gel. Valved conduits including the sinuses of Valsalva were obtained without the need for suturing any of the parts together. After static and dynamic cultivation the conduits demonstrated good compliance. The tissue development was evaluated by histology (hematoxylin, eosin and immunohistochemistry) hydroxyproline assay and DNA assay. The presence of the sinuses of Valsalva in the aortic and the pulmonary root is fundamental for the correct functioning of semilunar heart valves. The implementation of the sinuses in tissue engineered valves will lead to an improvement of the valve function and an increased durability. Ongoing research focuses on the optimization of the cell source and of the conditioning protocol as to achieve optimal extracellular matrix synthesis and mechanical properties and minimize cell mediated tissue contraction.

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/content/papers/10.5339/qproc.2012.heartvalve.4.16
2012-05-01
2019-08-17
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http://instance.metastore.ingenta.com/content/papers/10.5339/qproc.2012.heartvalve.4.16
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  • Accepted: 29 May 2012
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