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Differentiation of human embryonic stem cells to cardiomyocytes by coculture with endoderm in serum-free medium.

Many of the applications envisaged for human embryonic stem cells (hESC) undergoing cardiomyogenesis require that the differentiation procedure is robust and high yield. For many hESC lines currently available this is a challenge; beating areas are often obtained but subsequent analysis shows only few (<1%) cardiomyocytes actually present. Here the authors provide a protocol based on serum-free coculture with a mouse endoderm-like cell line (END2), which yields cultures containing on average 25% cardiomyocytes for two widely available hESC lines, hES2 and hES3. The authors also provide a variant on the protocol based on growth of hESC aggregates/embryoid bodies in END2-conditioned medium and a method for dissociating beating aggregates without compromising cardiomyocyte viability so that they can be used for transplantation into animals or further (electrophysiological) analysis.