(117c) Guided Cardiogenic Commitment of Human Embryonic Stem Cells for Heart Tissue Engineering

Heart disease is a major cause of morbidity and mortality worldwide. In the US, heart failure is top ranked as a cause of death, afflicting over 5 million people and with more than 500,000 new cases each year. Although significant progress has been made in mechanical devices and pharmacological interventions, more than half of the patients with heart failure die within 5 years of initial diagnosis. Wide application of heart transplantation is severely hindered by the limited availability of donor organs. To this end, cell therapies may provide an attractive alternative to current treatments of heart failure.

Stem cells can be used to generate functional cells for repairing the damaged myocardium but most differentiation protocols reported to date involve the formation of embryoid bodies within which control of stem cell commitment is challenging. Moreover, clinical applications of stem cell-derived cardiac cells will require the use of defined media. We developed a method for directing the commitment of human embryonic stem cells (hESCs) in monolayers to heart muscle cells with developmentally relevant factors. Human ESCs were guided through the mesendoderm, mesoderm, early cardiac and cardiac stages in ~15-20 days. The cells expressed stage-specific markers during their differentiation. The hESC-derived cardiomyocyte-like cells expressed heart muscle-specific genes including atrial natriuretic factor (ANF), NKX2.5, GATA4, β-myosin heavy chain (MHC) as assessed by quantitative PCR. These cells also showed immunoreactivity for NKX2.5, α-actinin, MHC and cardiac troponin I. Using flow cytometry, the differentiation efficiency of this scheme was found to be higher compared to that of typical embryoid body-based protocols. Furthermore, the resulting cardiac-like cells responded physiologically to chronotropic agents. Current investigations on further functional characterization of the hESC cardiac progeny and scaling up the production of cardiomyocytes from stem cells will also be presented.