Researchers print stent for fetuses

Researchers at the Federal Institute of Technology in Zurich (ETH) have developed a new method for producing malleable microstructures. By making tiny stents that are 40 times smaller than previously possible, the method could one day treat life-threatening constrictions of the urinary tract in fetuses in the womb. 

“We’ve printed the world’s smallest stent,” said researcher Carmela De Marco in a statement. With the method that she and her colleagues call “indirect 4D printing”, heat from a laser beam is first used to cut a three-dimensional template – a 3D negative – into a micromould layer that can be dissolved with a solvent. Next, the negative is filled with a shape-memory polymer and set using UV light. Finally, the template is dissolved in a solvent bath. 

The shape-memory polymer is suitable for treating urethral strictures, according to researcher Gaston De Bernardis. He explained: “When compressed, the stent can be pushed through the affected area. Then, once in place, it returns to its original shape and widens the constricted area of the urinary tract.”

Approximately one in every thousand children develops a urethral stricture, sometimes when they are still a fetus in the womb, writes the ETH. In such cases, surgeons have to remove the affected section of the urethra and sew the open ends of the tube back together again. Stents would be less damaging to the kidneys – but until now it has not been possible to produce them with small enough dimensions.  

Although the stents are still a long way from real-world application – and must first be tested in animals – the initial findings are promising. “We firmly believe that our results can open the door to the development of new tools for minimally invasive surgery,” said De Marco.