Stem cell discovery brings regenerative heart therapy closer
to produce all three major heart tissue types brings heart tissue
regeneration after injury a step closer.
One of the major problems associated with using embryonic stem cells in heart regeneration is the danger of uncontrolled growth leading to cancer. By utilising these more developed master stem cell cultures uncontrolled growth is less likely to occur.
It had been believed that the heart's different cell types, including cardiac muscle, smooth muscle and endothelial cells that line blood vessels, originated from different embryonic precursors.
The new findings were researched and published independently in November issue of the journal Cell by the groups of Kenneth Chien, Massachusetts General Hospital and Harvard Medical School, and Stuart Orkin, Howard Hughes Medical Institute.
Chien's group traced the presence of an isl1 protein from an islet-1 cardiac muscle progenitor in mice through to cardiac muscle, smooth muscle, endothelial, pacemaker and non-muscle cell types. They also showed that these cells could develop from embryonic stem cells.
In the second study, Orkin's team isolated embryonic mouse cells that expressed the cardiac specific gene Nkx2.5+. They found that these cells differentiated into both cardiac muscle cells and the conduction system cells that carry the electrical impulses that tell the heart to beat. They also found that some of these cells expressed a second gene, c-kit, which had the ability to expand and produce both cardiac muscle and smooth muscle cells from a single cell.
"It's unknown what the relationship between these cells is, if any. One may be the predecessor of the other, or they might be quite separate," Orkin said and acknowledged that the precise relationship between the two types of cell was a question requiring further research.
"It's a surprise that a single cell can give rise to all of these tissues and structures in the heart," states Chien, "These studies document a developmental paradigm for cardiogenesis, where muscle and endothelial lineage diversification arises from a single cell-level decision"
The use of adult stem cells to treat a patient after a heart attack or other type of heart disease, is currently undergoing clinical trials in the US on patients waiting for heart transplants.
