Researchers have demonstrated a new method of implanting artificial blood vessel structures to guide regrowth of tissue, leading to regeneration of a functional biological blood vessel:
Blocked blood vessels can quickly become dangerous. It is often necessary to replace a blood vessel - either by another vessel taken from the body or even by artificial vascular prostheses. Researchers have developed artificial blood vessels made from a special elastomer material, which has excellent mechanical properties. Over time, these artificial blood vessels are replaced by endogenous material. At the end of this restorative process, a natural, fully functional vessel is once again in place. The most important thing is to find a suitable material. The artificial materials that have been used so far are not ideally compatible with body tissue. The blood vessel can easily become blocked, especially if it is only small in diameter. Researchers have therefore developed new polymers. "These are so-called thermoplastic polyurethanes. By selecting very specific molecular building blocks we have succeeded in synthesizing a polymer with the desired properties."
To produce the vascular prostheses, polymer solutions were spun in an electrical field to form very fine threads and wound onto a spool. The wall of these artificial blood vessels is very similar to that of natural ones. The polymer fabric is slightly porous and so, initially, allows a small amount of blood to permeate through and this enriches the wall with growth factors. This encourages the migration of endogenous cells. The new method has already proved very successful in experiments with rats. "The rats' blood vessels were examined six months after insertion of the vascular prostheses. We did not find any aneurysms, thromboses or inflammation. Endogenous cells had colonized the vascular prostheses and turned the artificial constructs into natural body tissue." In fact, natural body tissue re-grew much faster than expected so that the degradation period of the plastic tubes can be made even shorter.