Enhancement of cardiomyocyte differentiation from human embryonic stem cells.

Several approaches have been used to encourage the differentiation of cardiomyocytes from human embryonic stem cells. However, the differentiation efficiency is low, and appropriate culture protocols are needed to produce adequate numbers of cardiomyocytes for therapeutic cell transplantation. This study investigated the effects of serum on cardiomyocyte differentiation in suspension culture medium during embryoid body (EB) formation by human embryonic stem cells. The addition of ascorbic acid, dimethylsulfoxide and 5-aza-2'-deoxycytidine during days 5-7 at the EB-forming stage resulted in an increase in the numbers of rhythmically contracting clusters of derived cardiomyocytes. Treatment with 0.1 mmol L(-1) ascorbic acid alone, or more notably in combination with 10 micromol L(-1) 5-aza-2'-deoxycytidine, induced the formation of beating cells within EBs. Most of the beating clusters had spontaneous contraction rates similar to those found in human adults, and their contractile activity lasted for up to 194 days.