Embryonic Blood Vessels that Give Rise to Blood Stem Cells can be Manipulated to Create Beating Heart Muscle Cells

Findings May Lead to a New Understanding of How to Better Make Heart Cells for Regenerative Medicine

Scientists led by Dr. Hanna Mikkola of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA have found for the first time a surprising and unexpected plasticity in the embryonic endothelium, the place where blood stem cells are made in early development. The two-year study is published Aug. 3, 2012 in the peer-reviewed journal Cell.

The stem cell scientists found that the lack of one transcription factor, a type of gene that controls cell fate by regulating other genes, allows the precursors that normally generate blood stem and progenitor cells in blood forming tissues to become something very unexpected - beating cardiomyocytes, or heart muscle cells.

The finding is important because it suggests that the endothelium can serve as a source of heart muscle cells. The discovery may provide new understanding of how to make cardiac stem cells for use in regenerative medicine, said Mikkola, study senior author and a UCLA associate professor of molecular, cell and developmental biology in Life Sciences.

“It was absolutely unbelievable. These findings went beyond anything that we could have imagined,” Mikkola said. “The microenvironment in the embryonic vasculature that normally gives rise to blood cells can generate cardiac cells when only one factor, Scl, is removed, essentially converting a hematopoietic organ into a cardiogenic organ.”