A process using human stem cells may generate the cells that cover the external surface of the human heart — epicardium cells — according to a multidisciplinary team of researchers.

“In 2012, we discovered that if we treated human stem tissues with chemicals that sequentially activate and inhibit Wnt signaling pathway, they become myocardium muscle cells, inch said Xiaojun Lance Lian, assistant professor of biomedical engineering and biology, who is leading the study at Penn State. Myocardium, the middle of the heart’s three layers, could be the thick, muscular part that contracts to drive blood with the body.

The Wnt signaling pathway is really a group of signal transduction pathways made of proteins that move signals into a cell using cell-surface receptors.

“We needed to provide the cardiac progenitor cells with more information in order for them to generate into epicardium cells, but just before this study, we didn’t know what that information had been, ” said Lian. “Now, we know that if we activate the particular cells’ Wnt signaling pathway again, we can re-drive these types of cardiac progenitor cells to become epicardium cells, instead of myocardium cells. ”

The group’s results, released in Nature Biomedical Engineering , take them one step closer to regenerating an entire heart wall. Via morphological assessment and functional assay, the researchers discovered that the generated epicardium cells were similar to epicardium tissue in living humans and those grown in the laboratory.

“The last piece is turning cardiac progenitor cells to endocardium cells (the heart’s inner layer), and we are making progress on that, ” said Lian.

The group’s method of generating epicardium tissue could be useful in clinical applications, for patients who experience a heart attack. According to the Centers for Disease Control plus Prevention, every 43 seconds, someone in the United States has a myocardial infarction

“Heart attacks occur due to blockage associated with blood vessels, ” said Lian. “This blockage stops nutrition and oxygen from reaching the heart muscle, and muscle tissue cells die. These muscle cells cannot regenerate by themselves, so there is permanent damage, which can cause additional troubles. These epicardium cells could be transplanted to the patient plus potentially repair the damaged region. ”

During their study, the researchers engineered the human stem tissues to become reporter cells, meaning these cells expressed the fluorescent protein only when they became epicardium cells.

“We treated the cells with different cell signaling substances, and we found that when we treated them with Wnt signaling activators, they became fluorescent, ” said Lian.

Another finding, he said, is that in addition to producing the epicardium cells, the researchers also can keep them growing in the lab after treating these cells with a cell-signaling pathway Transforming Growth Factor Beta (TGF) inhibitor.

“After 50 days, our cells did not display any signs of decreased proliferation. However , the proliferation from the control cells without the TGF Beta inhibitor started to level after the tenth day, ” said Lian.

The team will continue working together to further their study on regenerating endocardium cells.

“We make progress on that inner layer, which will allow all of us to regenerate an entire heart wall that can be used in tissues engineering for cardiac therapy, ” said Lian.

Story Resource:

Materials provided by Penn State . Original written by Stefanie Tomlinson. Note: Content may be edited for style and duration.