Myogenic Differentiation of iPS Cells Shows Different Efficiency in Simultaneous Comparison of Protocols

Induced pluripotent stem (iPS) cells constitute a perfect tool to study human embryo development processes such as myogenesis, thanks to their ability to differentiate into three germ layers. Currently, many protocols to obtain myogenic cells have been described in the literature. They differ in many aspects, such as media components, including signaling modulators, feeder layer constituents, and duration of culture. In our study, we compared three different myogenic differentiation protocols to verify, side by side, their efficiency. Protocol I was based on embryonic bodies differentiation induction, ITS addition, and selection with adhesion to collagen I type. Protocol II was based on strong myogenic induction at the embryonic bodies step with BIO, forskolin, and bFGF, whereas cells in Protocol III were cultured in monolayers in three special media, leading to WNT activation and TGF-β and BMP signaling inhibition. Myogenic induction was confirmed by the hierarchical expression of myogenic regulatory factors MYF5, MYOD, MYF6 and MYOG, as well as the expression of myotubes markers MYH3 and MYH2, in each protocol. Our results revealed that Protocol III is the most efficient in obtaining myogenic cells. Furthermore, our results indicated that CD56 is not a specific marker for the evaluation of myogenic differentiation.