The Medical Technology Blog

German researchers look at materials to keep stents secure

Welcome back to the Medical Technology Blog, we have a great post today provided by our medical newsletters team-leader, Lawrence Miller, Lawrence is the editor for Cardiovascular Device Business, please read on…

Researchers from the Fraunhofer Institute in Germany are working on the development of a special surface coating that keeps the stent in place.

When coronary blood vessels are constricted, cardiologists try to prevent a heart attack by widening them with stent implants that stabilise the veins and arteries, improve the flow of blood and prevent vascular obliteration. These stents can be used to treat pathological constriction of the windpipe. This kind of respiratory stenosis, which may be caused by tumours, chronic infections or congenital deformities, can be life-threatening. In such cases, the metal or plastic stents are designed to enlarge the trachea and prevent it from closing up altogether. However, the stent implant can slip out of position, closing off the windpipe altogether. Bacteria can also colonise the stents and trigger pneumonia. The reason for this is that the stents have no barrier-forming cells of the kind usually present in the respiratory system, whose task is to fend off bacteria and inhaled substances such as particulate.

Dr Martina Hampel, a scientist at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart, working with Professor Thorsten Walles, head of the department of thoracic surgery at the University Hospital of Würzburg and a visiting scientist at the IGB, participated  in the “REGiNA” project, the goal of which was to develop surface coatings that enable the stents to be incorporated in the surrounding tissue, thereby reducing the risk that they will move. REGiNA, a German acronym for Regenerative Medicine in the Neckar-Alb and Stuttgart Region, is funded by the German Federal Ministry of Education and Research (BMBF).

The scientists used stents lined with a polyurethane (PU) film, which were produced by Aachen-based Leufen Medical. In the subsequent tests, a wide variety of different coatings were applied to the PU film. In addition to synthetic polymers composed of organic acids, the researchers also tried out biological proteins such as fibronectin and type-I collagen. The coating was modified again using plasma technology, with vacuum-ionised gas being used to treat the surface. The experts used an untreated PU film for control purposes.

In order to find out which of the surface coatings was the most suitable, the researchers brought both lab-cultivated cell lines and human primary tracheal epithelial cells into contact with the films in cell culture vessels. The primary goal was for the primary respiratory cells from human tissue to attach themselves to the film. The researchers achieved their best results with the protein-coated film, on which the primary tracheal epithelial cells grew particularly well and multiplied. The team found that whilst respiratory cells proved to be more vital on bioactive films rather than on ones treated with plasma, polymer-coated film turned out to be “completely useless.”

The laboratory tests have since been completed, and animal tests are currently being prepared. If the lab results are confirmed in these tests, the next step will be to conduct clinical trials of the modified stents at the Schillerhöhe specialist lung clinic, a part of the Robert Bosch Hospital. The hope is that, within a few years, well-tolerated, cell-compatible surface coatings will be available for use in other biomedical prostheses, such as pacemaker leads, tooth implants and replacement joints.

Article Source: Cardiovascular Device Business


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