Differentiation of myoblasts in serum-free media: Effects of modified media are cell line-specific

Myoblast cell lines are grown and differentiated readily in cell culture. T wo cell lines typically used for investigating the growth and differentiati on of muscle are the mouse cell line C2C12 and the rat cell line L6. The di fferentiation of these cells in vitro requires a switch from a serum-rich m edium to a less rich medium after the cells have reached confluence. Since the components present in serum are not well characterized, the use of a be tter defined medium for these studies was investigated. C2C12 and L6 myobla sts were differentiated in both serum-containing and serum-free media. The differentiation state of these cultures was then tested both microscopicall y and biochemically. Cultures were checked for myotube formation, the activ ity of creatine phosphokinase and the presence of sarcomeric actin. In C2C1 2 eel Is, the extent of differentiation was greater in the serum-free than in the serum-containing system. in both media types, the C2C12 cells produc ed sarcomeric actin, showing the presence of sarcomere structure in the myo tubes. In L6 cells, however, myotubes were readily formed in medium contain ing 2% horse serum, but not in the serum-free system. In addition, the abil ity of C2C12 cells to differentiate on substrates coated with extracellular matrix proteins was shown to be media-dependent. The presence of extracell ular matrix proteins did not enable L6 cells to form myotubes when cultured in serum-free media. Primary cultures of chick myoblasts were able to diff erentiate in both media tested, with Dulbecco's modified Eagle medium conta ining horse serum being a more efficient medium for cell fusion. This study shows a divergence in muscle cell line responses in th ree cell lines, two of which are typically used as 'model systems' for understanding muscle gr owth and development. Copyright (C) 2000 S. Karger AG,Basel.