Tissue-Engineered Blood Vessels

"Our results show that bone marrow is an excellent source of adult stem cells containing smooth muscle and endothelial cells, and that these stem cells can be used in regenerative medicine for cardiovascular applications," said Stelios T. Andreadis, Ph.D., associate professor in the University at Buffalo (UB) Department of Chemical and Biological Engineering in the School of Engineering and Applied Sciences.

The research demonstrates the potential for eventually growing tissue-engineered vessels out of stem cells harvested from the patients who need them, providing a desirable alternative to the venous grafts now routinely done in patients undergoing coronary bypass operations. Disadvantages with venous grafts include limited availability of vessels, pain and discomfort at the donor site and a high ten-year failure rate.

The UB researchers developed a novel method for isolating functional smooth muscle cells from bone marrow by using a fluorescent marker protein and a tissue-specific promoter for alpha-actin, a protein found in muscles that is responsible for their ability to contract and relax.

Although not yet strong enough for coronary applications, the UB group's tissue-engineered vessels (TEVs) performed similarly to native tissue in critical ways, including their morphology, their expression of several smooth muscle cell proteins, the ability to proliferate and the ability to contract in response to vasoconstrictors, one of the most important properties of blood vessels.

The TEVs also produced both collagen and elastin, which give connective tissue their strength and elasticity and are critical to the functioning of artificial blood vessels. "These are the first tissue-engineered vessels to demonstrate the ability to make elastin in vivo," said Andreadis. The TEVs were implanted into sheep and functioned normally for five weeks. Andreadis' group now is working on ways to make the TEVs stronger.

MEDICA.de; Source: University at Buffalo