A Heart is Born

by Lehanna Sanders from Hatzopoulos Hub Site 11

How many people do you know were born with some sort of heart defect, or have had a heart attack? Heart defects are one of the most common types of birth defects and heart disease remains the most prominent contributor to deaths worldwide. Knowing how the heart develops and regenerates could help generate therapies for people that suffer from such defects as well as those that have suffered from a heart attack. Despite the fact that how cells assemble to form the heart has been extensively studied over the last decades, the identity of every cell type that is responsible for building heart muscles has remained elusive.

In June of this year, scientists at the PCBC Hub at the University of Pennsylvania published work that was featured on the cover of Science, which includes discoveries that made huge strides in improving the understanding of heart muscle stem cells. This paper by the group of Jonathan Epstein describes how a protein called Hopx has a unique way of regulating two signaling pathways that are critical for heart development; activates BMP signaling and inhibits Wnt signaling. This leads to the generation of a newly discovered population of progenitor cells that are committed to becoming exclusively heart muscle cells. This new cell population has never been previously characterized and therefore given a new name, the “cardiomyoblast” [see model image, R. Jain et al., Science 348, aaa6071 (2015)].

The discovery of this Hopx mediated stem cell commitment is exciting because it includes a novel mode of interaction between two signaling pathways that have previously been known to interact in several other important processes, including cancer. Understanding this molecular interaction could have the potential to pave the way for future therapies, particularly in regenerative medicine. As a young scientist working in the field of cardiac recovery, I found the research presented in this paper enlightening, and I am especially excited about this new founder cell for heart muscle. I feel that far too often, the developmental processes that have previously been established are taken for granted, and feel that it is important to challenge those concepts, to allow for new discoveries such as this one. Now the question is, what can the cardiomyoblast do for you? Glad to hear your comments.