Artificial Blood Vessels

Artificial blood vessels were first introduced during WWI when Alexis Carrel discovered a way to sew blood vessels together. Today, methods from the 1940s and 1950s are still used. Surgeons originally used transplants for arteries or veins. However, this method resulted in failure. The recipient’s body either rejected the vessels or arteriosclerosis (artery hardening) formed. To transplant vessels from the same body required two complicated surgeries and most patients with circulatory problems did not have vessels for transplantation.

Researchers began to develop artificial vessels to overcome this problem. Tubing materials included polyethylene (soft and waxy plastic) and siliconized rubber. Further research proved that vessels made from Teflon and Dacron were not rejected by the body. While the larger Dacron vessels worked well, the smaller ones formulated blood clots. Smoother interior walls would help prevent clots from forming.

In the 1980s, Donald Lyman synthesized a polymer that reduced clot formation. The elastic polymer also reduced the strain where the natural and artificial valves met. Human testing began in 1988. In 1990, the bio-research company Organogenesis implanted a hybrid vessel in animals made of natural and artificial materials. This artificial vessel features a smooth inner layer grown in the laboratory from human cadaver (dead body) artery cells and tubules strengthened with Dacron mesh. Stuart Williams at Jefferson Medical College, Philadelphia, Pennsylvania, uses cells from the patient's own inner blood vessel lining to grow a lining on the inside of Dacron synthetic vessels.

Researchers have already managed to make wider blood vessels from scratch, but the formation of the tiny diameter capillaries needed to create a blood supply within other tissues and organs is more challenging. However, through the “nanoscale” template, US scientists claim to have made progress using stem cells using endothelial progenitor. These cells detect the grooves and align themselves in the direction of the vessel. When a gel is added, the cells grow outward consequently forming tiny tubes. Even though these tubes are not ready to be placed inside the body, researchers cannot contain their enthusiasm for the potential results of this process.

http://www.discoveriesinmedicine.com/Apg-Ban/Artificial-Blood-Vessels.html

http://news.bbc.co.uk/2/hi/health/7152405.stm