Embryonic Stem Cell-Derived CD166+ Precursors Develop into Fully Functional Sinoatrial-Like Cells
Rationale: A cell-based biological pacemaker is based on the differentiation of stem cells and the selection of a population displaying the molecular and functional properties of native sinoatrial node (SAN) cardiomyocytes. So far such selection has been hampered by the lack of proper markers. CD166 is specifically but transiently expressed in the mouse heart tube and sinus venosus, the prospective SAN.
Objective: We have explored the possibility to use CD166 expression for isolating SAN progenitors from differentiating embryonic stem cells (ESCs).
Methods and Results: We found that in E10.5 mouse hearts CD166 and HCN4, a marker of the pacemaker tissue, are co-expressed. Sorting ESCs for CD166 expression at differentiation day 8, selects a population of pacemaker precursors. CD166+ cells express high levels of genes involved in SAN development (Tbx18, Tbx3, Isl-1, Shox2) and function (Cx30.2, HCN4, HCN1, Cav1.3) and low levels of ventricular genes (Cx43, Kv4.2, HCN2, Nkx2.5). In culture, CD166+ cells form an autorhythmic syncytium composed of cells morphologically similar to and with the electrophysiological properties of murine SAN myocytes. Isoproterenol increase (+57%) and acetylcholine decreases (-23%) the beating rate of CD166-selected cells which indeed express the β-adrenergic and muscarinic receptors. In co-cultures, CD166-selected cells are able to pace neonatal ventricular myocytes at a rate faster than their own. Furthermore, CD166+ cells have lost pluripotency genes and do not form teratomas in vivo.
Conclusions: we demonstrated for the first time the isolation of a non-teratogenic population of cardiac precursors able to mature and form a fully functional SAN-like tissue.
- Received March 1, 2013.
- Revision received June 7, 2013.
- Accepted June 10, 2013.