When someone has chronic venous insufficiency, it means that because of faulty valves in their leg veins, oxygen-poor blood isn't able to be pumped back to their heart. The George Washington University's Dr. Narine Sarvazyan has created a possible solution, however – a beating "mini heart" that's wrapped around the vein, to help push the blood through.
The mini heart takes the form of a cuff of rhythmically-contracting heart tissue, made by coaxing the patient's own adult stem cells into becoming cardiac cells. When one of those cuffs is placed around a vein, its contractions aid in the unidirectional flow of blood, plus it helps keep the vein from becoming distended. Additionally, because it's grown from the patient's own cells, there's little chance of rejection.
So far, the cuffs have been grown in the lab, where they've also been tested. Soon, however, Sarvazyan hopes to conduct animal trials, in which the cuffs are actually grown on the vein, in the body.
"We are suggesting, for the first time, to use stem cells to create, rather than just repair damaged organs," she said. "We can make a new heart outside of one’s own heart, and by placing it in the lower extremities, significantly improve venous blood flow."
Scientists at Germany's Fraunhofer Institute for Manufacturing Engineering and Automation are also working on a treatment for chronic venous insufficiency, although their approach has been to create artificial venous valves that could be used to replace the defective natural ones.
A paper on Sarvazyan's research was recently published in the Journal of Cardiovascular Pharmacology and Therapeutics. One of the mini hearts can be seen beating away, in the video below.
Source: The George Washington University
To answer the question of why not valves it likely is due to the complexity of building a vavle that doesn't destroy the blood cells and inserting them into the veins. Wrapping veins in muscle without killing the patient is easy. Opening a major vein and installing anything is scary.