If a person's windpipe is constricted, an operation in which the surgeon inserts a stent to enlarge the trachea is often the only way to relieve their respiratory distress. But this grid-like implant can slip out of position, closing off the windpipe altogether. Researchers are working on a special surface coating for the stents to keep them in place.
When coronary blood vessels are constricted, cardiologists try to prevent a heart attack by widening them with small grid-like implants called stents, which stabilize the veins and arteries, improve the flow of blood and prevent vascular obliteration. A lesser known fact is that stents can be used to treat pathological constriction of the windpipe. This kind of respiratory stenosis, which may be caused by tumors, chronic infections or congenital deformities, can be life-threatening. The metal or plastic stents are designed to enlarge the trachea and prevent it from closing up altogether.
But complications can arise when the implants are inserted. Firstly, there is the danger that the stents will shift, thus partially or completely obstructing the respiratory tract. Secondly, bacteria can colonize 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. "The windpipe has an important barrier function, with goblet and cilia cells purifying the inhaled air. It is very important that cells like these can adhere to the stents so as to maintain the air-purifying effect of the damaged section of the windpipe and to promote incorporation of the stents in the surrounding tracheal tissue," says Dr. Martina Hampel, a scientist at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart. Together with Prof. Dr. Thorsten Walles, head of the department of thoracic surgery at the University Hospital of Würzburg and a visiting scientist at the IGB, Dr. Hampel and her team took part in the "REGiNA" project, the goal of which was to develop surface coatings that enable the stents to be incorporated in the surrounding tissue, thus 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.
Bioactive coatings lower the risk for patients