We developed a strategy to capture cardiovascular progenitor cells during the cardiac reprogramming from mouse fibroblasts and expand these CPCs for a long term in a chemically defined condition. Overall design: To study the process of cardiac transdifferentiation, we collected cells at different stages of cardiac reprogramming, including initial 2nd MEFs, MEFs at day9 of reprogramming, ieCPCs, and their derivatives after further cardiac differentiation. To learn the characteristics of ieCPCs during their long-term expansion, we collected ieCPCs at both early and late passages.