A novel approach to studying transformation of human stem cells into cardiac cells in vivo.

Stem cell transplantation has been proposed as a novel means of regenerating new myocardium following cardiac damage. Many laboratories have demonstrated that stem cells from different sources have the potential to transform into cardiomyocytes. Human peripheral blood CD34+ cells were transplanted into the hearts of mice with severe combined immune deficiency syndrome, and it was demonstrated that human stem cells could transform into cardiomyocytes, endothelial cells and smooth muscle cells. Using single cell preparation, cell sorting and fluorescent in situ hybridization, human peripheral blood CD34+ cells were transformed into cardiomyocytes mainly through cell fusion, whereas endothelial cells were derived through direct differentiation of the transplanted stem cells. This analytical method should provide a novel approach to identifying the mechanisms of stem cell transformation into cardiomyocytes in vivo.