Adult Stem Cells Act as Pacemaker

U.S. News & World Report, July 22, 2009

Scientists at the Chiba University Graduate School of Medicine in Japan have announced their discovery of a natural "biological pacemaker" in adult stem cells derived from adipose (fat) tissue. Specifically, the adult stem cells are mesenchymal stem cells (MSCs), and their naturally occurring "pacemaker" qualities may someday be useful in correcting electrical problems in the heart.

According to Dr. Toshinao Takahashi of the Chiba University, "Electronic pacemakers are often used as palliative therapy 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. Cell therapy could overcome those problems and provide a possible cure for conductive disease. Our goal is to create a biological pacemaker."

The researchers harvested MSCs from the adipose tissue of mice which were then differentiated into beating cells which resembled heart cells in all features including cell surface proteins that serve as cardiac chemical markers. The new cells were then injected into mice who suffered from atrioventricular (AV) block, an electrical signaling problem of the heart which results in an abnormally reduced heart rate. Within a week after treatment with the new cells, the AV block was reversed to some extent, either completely or partially, in half of the mice who received the stem cell transplant.

Adipose tissue is known to be a rich source of MSCs which have been shown in numerous studies to differentiate into a wide variety of tissue types such as bone, muscle, liver, neuron and cardiac cells, among others. As the name implies, MSCs possess qualities of the "mesenchyme" - the unspecialized matrix cells that are found in the early embryo - which is in fact derived from all 3 germ layers, so one would therefore logically expect MSCs to be able to differentiate into most if not all cell and tissue types of the adult human body. Additionally, adipose tissue is known to exhibit a number of unique immunomodulatory properties which would also prove to be especially beneficial in the treatment of a variety of diseases and injuries (as recently reported by N.H. Riordan et al. in a publication in the April 24, 2009 issue of the Journal of Translational Medicine entitled, "Non-expanded adipose stromal vascular fraction cell therapy for multiple sclerosis").

In the particular treatment of disorders stemming from problems in cardiac electrical conduction and signaling, Dr. Takahashi has concluded that, "Our findings suggest that brown-fat-derived mesenchymal stem cells may become a useful cell source for antiarrhythmic therapy."

The results were presented at the American Heart Association's Basic Cardiovascular Sciences Conference in Dallas.