The rapidly advancing world of regenerative medicine just got wilder as a team of researchers has reported a better technique for growing starter arteries for people with vascular disease who need replacements.

The synthetic blood vessels could eventually be used in patients undergoing heart surgery to have their hardened or blocked arteries removed and replaced with prosthetics or grafts that would allow the regeneration of a new artery.

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In recent years, specialists called tissue engineers have begun to figure out how to help patients grow new tissues and even entire organs to replace ailing and failing parts such as blood vessels, skin, cartilage, bone, stomachs, bladders and even hearts. The process involves seeding specially shaped artificial scaffolds with human cells such that the body eventually grows a functional new body part around the implant.

The trick with tissue engineering is to come up with synthetic parts that can withstand the mechanical strain of doing the body's work while also biodegrading slowly as the body rebuilds the real thing.

With blood vessels, experts already have shown that it is possible to make synthetic arteries that work in the lab.

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The new work is important because the team, at Virginia Commonwealth University, was able to create grafts that include elastin, which makes it so the cells seeded into the synthetic artery are much more likely to recognize and interact properly with the body. Elastin also makes the synthetic artery strong enough to work much more like our original blood vessels. The body's elastic fibers, found in nearly all organs and tissues, are made of elastin.

Patients with complete heart block, or disrupted electrical conduction in their hearts, are at risk for life-threatening rhythm disturbances and heart failure. The condition is currently treated by implanting a pacemaker in the patient's chest or abdomen, but these devices often fail over time, particularly in infants and small children who must undergo many re-operations. Researchers at Children's Hospital Boston have now taken preliminary steps toward using a patient's own cells instead of a pacemaker, marking the first time tissue-engineering methods have been used to create electrically conductive tissue for the heart.

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Cowan's team, including first author Yeong-Hoon Choi in Children's Department of Cardiac Surgery, obtained skeletal muscle from rats and isolated muscle precursor cells called myoblasts. They "seeded" the myoblasts onto a flexible scaffolding material made of collagen, creating a 3-dimensional bit of living tissue that could be surgically implanted in the heart.

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When the engineered tissue was implanted into rats, between the right atrium and right ventricle, the implanted cells integrated with the surrounding heart tissue and electrically coupled to neighboring heart cells. Optical mapping of the heart showed that in nearly a third of the hearts, the engineered tissue had established an electrical conduction pathway, which disappeared when the implants were destroyed. The implants remained functional through the animals' lifespan (about 3 years).