Atherosclerosis is one of the major causes of death in the Western World. Based on an intimal (part of the vessel wall) hyperplasia, narrowing or occlusion of the vessel appears, often resulting in an infarct. More and more people get a stent angioplasty as a treatment. By the use of this procedure the occlusive vessel will be expanded by a balloon catheter and kept open by a stent holding the plaque aside. However more cells will grow into the lumen, leading to restenosis and cause thrombosis. The vessel will occlude again and another operation is necessary. The aim of the project is to stop restenosis and thrombosis after stent angioplasty. From crucial relevance is the endothelial cell layer on the inner surface of the blood vessel. If this layer is undamaged, it prevents thrombosis,tissue outgrowth and infiltration of leucocytes in the vessel wall. Leucocytes release growth factors which increase the proliferation rate of smooth muscle.
In his main structure, the BioStent is a self expandable stent made of nitinol, structurally like usual bare metal stents (BMS). This supporting structure is then covered by autologous tissue. Smooth muscle cells and fibrin gel are used to mould the stent, followed by a endothelial cell lining of the stent lumen. In a bioreactor system the BioStent will be cultivated for stabilization.
In figure 1 the potential advantages of the covered stent are shown. At first, there is a total exclusion of the atherosclerotic plaque because the mesh is filled up with tissue. This will also hinder the cells to grow through the mesh. Furthermore there will be no immune responses due to the coverage. And above all, there is also a new functional endothelial cell layer in the damaged region.
In cooperation with the Institut für Textiltechnik of the RWTH Aachen (ITA) the stent structure will be optimized. Our group is engaged with the optimization of the cell layer, for a tough and thin tissue.