Functional Characterization of Ca2+ and K+ Channels in Human Embryonic Stem Cells

Abstract

Human embryonic stem cell (hESC) expansion involves both self‐renewal and differentiation. Physiological properties of cell motility, migration and proliferation all require cytoplasmic Ca2+ and are regulated by a) membrane potential; b) spatial and temporal variations of intracellular Ca2+; and c) spatially‐ and temporally‐regulated expression of plasmalemmal receptors. Functional adaptation of Ca2+ and K+ channels in the plasma membrane may thus be an important prerequisite for hESCs to self‐renew, migrate into special niches or microenvironments and to differentiate into specific lineages. Using H9 hESC, changes in the voltage‐gated K+ (Kv) channels were closely related with the ability of hESC to differentiate into a smooth muscle like cell phenotype. The ion channel profile changed from a predominantly "A" type rapidly inactivating current to a delayed rectifier type current and correlated with an increase in expression of the Kv1 family of delayed rectifier K+ channels and a decrease in pluripotency markers OCT‐4 and NANOG. In addition, hESC express multiple transient receptor potential (TRP) channel subunits and passive depletion of Ca2+ from intracellular stores activated store‐operated Ca2+ entry. These data confirm that function and expression of certain ion channels in hESC differ from those in differentiated cell phenotypes such as smooth muscle cells and neurons, and the changes in channel activity are necessary for hESC to differentiate into functionally matured cells.Funded by the NIH/NHLBI and CIRM.