Scientists Grow Blood Vessels from Human Donor Tissue
Someday soon, surgeons may go to a refrigerator to select the blood vessels they need for heart bypass surgery. Researchers announce they have grown blood vessels using human donor tissue, and that these new veins could replace artificial ones now often used.
New human blood vessels are grown on a scaffold
Coronary bypass surgery is one of the most common surgical procedures performed in the United States. Currently, the procedure involves taking arteries or veins from other parts of the patient’s body—typically a vein from the leg or an artery from the chest or wrist--and attaching it above and below the clogged area, which allows blood to bypass the blockage. Some patients require more than one bypass.
Patients who do not have suitable veins or arteries for this procedure can be given artificial blood vessels. These vessels, however, tend to clog easily and can result in infection.
The new technique for making blood vessels involves harvesting random donor cells from human tissue. These cells are used to grow collagen (a protein) on a biodegradable infrastructure or “scaffold” composed of a polymer. Once the scaffold dissolves, it leaves behind fully developed blood vessels.
The original human cells are washed away from these vessels so they are unlikely to be rejected by the recipient. These new blood vessels can be safely stored in refrigeration in a saline solution for up to one year without becoming clogged or losing their elasticity or strength.
Experiments using these new blood vessels in baboons have revealed that not only are they capable of fully restoring blood flow, they also showed no sign of thickening or clogging six months after they were implanted, which indicates they could be effective for the long term.
Using current methods, 5 to 10 percent of coronary artery bypass graft surgeries fail within one year. Over the long term, symptoms recur in 3 to 4 percent of patients per year. Five-year survival expectancy is 90 percent, at 10 years it is 85 percent, and at 20 years, about 40 percent.
According to Dr. Alan Kypson at East Carolina University and a co-author of the new study, although grafting a patient’s own veins is still the gold standard for coronary bypass, “harvesting a vein from the patient’s leg can lead to complications, and for patients who don’t have suitable veins, the bioengineered veins could serve as an important new way to provide a coronary bypass.”
Introduction of these new blood vessels made from donor human tissue “could serve as an important new way to provide a coronary bypass,” noted Kypson. They may also prove to be useful in kidney dialysis patients whose blood vessels become damaged by treatment. Much research, including clinical trials, remains to be done before these new blood vessels find their way to a refrigerator in a hospital near you.
American Heart Association
Dahl SLM et al. Science Translational Medicine 2011 Feb 2; 3(68): 68ra9