Stem Cells Used for 'Biological Pacemaker'

July 24 -- WEDNESDAY, July 22 (HealthDay News) -- Stem cells from a type of human fat tissue may one day be able to reverse the electrical problems in the heart that pacemakers now correct, Japanese scientists report.

Researchers grew "beating" cells with properties similar to the heart's conductive tissue from stem cells taken from the brown fat tissue of mice. They then injected them into rodents with reduced heart rates caused by electrical signaling problems known as atrioventricular (AV) block.

After a week, the AV block was completely reversed or partially reversed in half of the test mice, according to the report scheduled to be presented Wednesday at the American Heart Association's Basic Cardiovascular Sciences Conference in Dallas. No change was observed in the control mice, they said.

The beating cells, which researchers colored green so they would be easy to see, were found to have attached near the section of the heart that manages its electrical conduction systems.

"Electronic pacemakers are often used as palliative therapy (helpful but not curative treatment) for people who have conduction problems with the electrical signals that govern the heart beat. However, that therapy has several shortcomings, including possible malfunction and the need for repeated replacement of the device's power packs and electrodes," study lead author Dr. Toshinao Takahashi, a research fellow at Chiba University Graduate School of Medicine in Chiba, Japan, said in an American Heart Association news release. "Cell therapy could overcome those problems and provide a possible cure for conductive disease. Our goal is to create a biological pacemaker."

Brown fat tissue is a source of mesenchymal stem cells, which previous studies have shown can develop into many different types of cells, such as bone, neuron, muscle, liver and fat cells. After isolating these cells in a laboratory, the Japanese team managed to grow groups of spontaneously beating cells. One tube-like group of cells resembled the heart's fine muscle fiber, while all contained two proteins, chemical markers and other similarities to the heart's own pacemaker-like cells.