Fluorescent staining for the cytoskeleton of atrial cardiac cells (red) and ventricular cardiac cells (green) shows that stem cell cardiac patches consist of heterogeneous cell types. Cell nuclei are stained blue.

The Beat Goes On

Stem cells show promise in regulating arrhythmia

issue 17 | fall/winter 2012

For those suffering from heart disease, stem cell biology represents a new medical frontier. A cutting-edge method developed at the University of Michigan Center for Arrhythmia Research uses stem cells to create human heart muscle patches capable of mimicking the heart's crucial squeezing action.

The cardiac patches displayed activity similar to most people's resting heart rate. At 60 beats per minute, the rhythmic electrical impulse transmission of the engineered cells in the U-M study is 10 times faster than in most other reported stem cell studies.

Stem cell therapy could help the 2.5 million people with an arrhythmia, an irregularity in the heart's electrical impulses that can impair the heart's ability to pump blood.

"To date, the majority of studies using induced pluripotent stem-cell-derived cardiac muscle cells have focused on single cell functional analysis," says Todd J. Herron, Ph.D., assistant research professor in the departments of Internal Medicine and Molecular & Integrative Physiology at U-M. "For potential stem-cell-based cardiac regeneration therapies for heart disease, however, it is critical to develop multicellular tissue-like constructs that beat as a single unit."

The research team's objectives included developing a bioengineering approach using stem cells generated from skin biopsies to create large numbers of cardiac muscle cells that can transmit uniform electrical impulses and function as a unit.

"Action potential and calcium wave impulse propagation trigger each normal heart beat, so it is imperative to record each parameter in bioengineered human cardiac patches," Herron says.

The velocity of the engineered cardiac cells, while faster than previous reports, is still slower than the velocity observed in the beating adult heart. Still, the velocity is comparable to commonly used rodent cells, and researchers suggest human cardiac patches could be used rather than rodent systems for research purposes.

In October, U-M celebrated a new collaboration of heart researchers who will work together in the Cardiovascular Research Center laboratories at the North Campus Research Complex. The bioengineering method created at U-M can be readily applied in most cardiac research laboratories and opens the door for the use of cardiac stem cell patches in disease research, testing of new drug treatments and therapies to repair damaged heart muscle.

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