Transduction of MYOD and EV lentiviruses to hAFS cells. (a) MYOD mRNA expression in hAFS cells infected with empty or MYOD lentivirus was analyzed. Morphology of hAFS cells infected with EV lentivirus at day 3 and MYOD lentivirus at days 3 and 10 is shown. Myotube-like morphology was clearly detected in hAFS cells transduced with MYOD at day 10. (b) and (c) mRNA expression of myogenic genes. hAFS cells were cultured for one, three, and seven days in myogenic differentiation medium. (b) Myogenic marker genes were analyzed using RT-PCR. (c) Expression of pre-myogenic marker genes was analyzed. (d) Levels of myogenic proteins during myogenic differentiation of hAFS cells. hAFS cells differentiated for one, three, seven and ten days in myogenic medium. The protein levels were analyzed with antibodies specific to each myogenic protein (Scale bar = 20 μm). EV, empty vector; hAFS, human amniotic fluid stem.