When a vein or artery gets seriously blocked, a common course of action involves replacing it with part of another blood vessel harvested from elsewhere in the patient's body. While 3D-printed and lab-grown blood vessels show promise as alternatives, scientists from the Vienna University of Technology and Vienna Medical University have developed another option – polymer fabric vessels that transform into biological ones, once implanted.

The artificial blood vessels are made from biocompatible and biodegradable thermoplastic polyurethanes.

Liquid solutions of these polymers are spun in an electrical field, causing them to form into very fine threads. Those threads are then woven onto a long skinny spool, where they form the walls of the vessel. Once removed from the spool, an elongated tube of polymer fabric – the synthetic blood vessel – is the result.

The walls of the vessel are slightly porous, actually allowing some blood to initially permeate through. This is a good thing, though, as it lets host cells that are carried in the bloodstream migrate into the material. Over time, those cells multiply and replace the polymer, until nothing but natural tissue is left.

In tests on lab rats, the "vascular prostheses" were completely replaced by biological blood vessels within six months of being implanted. Additionally, no aneurysms, thromboses or inflammation were noted.

The technology is still under development, with human trials expected to begin within a few years.

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