Non-slip tracheal implants

July 3, 2012

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 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

The scientists used stents lined with a polyurethane (PU) film, which were produced by Aachen-based Leufen Medical GmbH. In the ensuing 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-ionized 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, we brought both lab-cultivated cell lines and human primary tracheal epithelial cells into contact with the films in cell culture vessels. What we wanted, of course, was for the primary respiratory cells from human tissue to attach themselves to the film,” explains Hampel. The researchers achieved their best results with the protein-coated film, on which the primary tracheal epithelial cells grew particularly well and multiplied. “The respiratory cells proved to be more vital on bioactive films rather than on ones treated with plasma. By contrast, polymer-coated film turned out to be completely useless,” says Hampel.

The laboratory tests have since been completed, and animal tests are in preparation. If the good 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, part of the Robert Bosch Hospital. “We hope that, within just a few years, our well-tolerated, cell-compatible surface coatings will be used for other biomedical prostheses such as pacemaker leads, tooth implants and replacement joints,” says Hampel.

Explore further: Stents may reduce heart attacks by delivering downstream medication

Related Stories

Stents may reduce heart attacks by delivering downstream medication

September 15, 2011
Researchers at Cleveland Clinic have discovered that cardiac patients receiving medicated stents -- a procedure that occurs often when blood vessels are blocked -- have a lower likelihood of suffering heart attacks or developing ...

A new stent design may put patients at risk

November 17, 2011
Some stents that keep blood vessels open to treat heart disease are poorly designed to resist shortening, according to publications in the Journal of Interventional Cardiology. A case report published in the journal by Dr. ...

Recommended for you

Lactation hormone also helps a mother's brain

September 26, 2017
The same hormone that stimulates milk production for lactation, also acts in the brain to help establish the nurturing link between mother and baby, University of Otago researchers have revealed for the first time.

Image ordering often based on factors other than patient need: study

September 25, 2017
Do you really need that MRI?

Bone marrow concentrate improves joint transplants

September 25, 2017
Biologic joint restoration using donor tissue instead of traditional metal and plastic may be an option for active patients with joint defects. Although recovery from a biologic joint repair is typically longer than traditional ...

Researchers describe mechanism that underlies age-associated bone loss

September 22, 2017
A major health problem in older people is age-associated osteoporosis—the thinning of bone and the loss of bone density that increases the risk of fractures. Often this is accompanied by an increase in fat cells in the ...

Researchers develop treatment to reduce rate of cleft palate relapse complication

September 22, 2017
Young people with cleft palate may one day face fewer painful surgeries and spend less time undergoing uncomfortable orthodontic treatments thanks to a new therapy developed by researchers from the UCLA School of Dentistry. ...

Exosomes are the missing link to insulin resistance in diabetes

September 21, 2017
Chronic tissue inflammation resulting from obesity is an underlying cause of insulin resistance and type 2 diabetes. But the mechanism by which this occurs has remained cloaked, until now.

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

bishop
not rated yet Jul 03, 2012
Great strategy which needs a new generation product.
Have a look to the auto extending stent that a small french company is producing and selling since a few months: Stentys.
http://www.stenty...hp?lg=us

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.