New insight into cardiac stem cell therapies

A new study provides useful insight into the behaviour of stem cell-derived heart muscle cells which have interested researchers for many years as potential replacement for damaged cardiac tissue following a heart attack.

Researchers Yvonne Aratyn-Schaus and Francesco Pasqualini from Harvard University found that stem cell-derived heart muscle cells were unable to effectively replace damaged cardiac tissue because they did not contract strongly enough, thus making therapies based on them less potent.

The study, published in the Journal of Cell Biology, said one possible explanation for this could be that mechanical forces are not transmitted properly between the new, stem cell-derived cardiomyocytes and the old, surviving heart cells.

The researchers led by professor Kit Parker developed a simplified, in-vitro system in which single heart cells isolated from mice were combined with individual, stem cell-derived cardiomyocytes to form a two-cell "microtissue" that they called a "muscle on-a-chip".

Using this approach, the team found that stem cell-derived cardiomyocytes could structurally couple and synchronously beat with mouse cardiomyocytes. Stem cell-derived myocytes contracted less strongly than their partners,

however, and this imbalance resulted in the cells transmitting mechanical forces to their surroundings, instead of to each other. Computer simulations suggests that human cardiomyocytes were likely to behave similarly, the authors noted.