Objective:To investigate the effect of the titin gene and its influence on the contraction protein gene such as β-MHC and cTnI in the procession of MSCs differentiating into cardiomyocytes in vitro.Methods:MSCs were isolated from bilateral thighbones and tibias of Wistar rats

purified、expanded and then exposed to 5-aza.we observed the morphology of MSCs with phase-contrast microscope at 1st

4th 7th

14th day after induction.Then we transfected the recombination plasmid vector(including pSITITIN and pSIACTIN)into MSCs after induction.detected the expression of titin、β-MHC and cTnI at interval times by RT-PCR.Results:1.we obtained the mild expression of titin、β-MHC and cTnI gene before 5-aza treament

but the expression of them increased after induction.2.After recombination plasmid were transfected into MSCs which have been induced by 5-aza

the expression of titin gene was decreased 3.The expression of β-MHC gene kept invariant

while the expression of cTnI gene was weakened after the interference.Conclusion:1.titin gene probably play an important role in the procession of MSCs differentiating into cardiomyocytes in vitro.2.titin gene may regulate the expression of cTnI.