BACKGROUND:It has been proved that induced pluripotent stem cells can differentiate into cardiomyocytes,but there are few reports on the maturity of differentiated cardiomyocytes.OBJECTIVE:To explore the effect of prolonging the induced differentiation time on the morphology,sarcomere length,binuclear cell content,cardiac gene expression,cardiac protein expression,and mitochondrial function of cardiomyocytes derived from induced pluripotent stem cells.METHODS:Bone morphogenetic protein 4,CH IR 99021,and IWR1 were used to induce pluripotent stem cells to differentiate into cardiomyocytes,and differentiated cardiomyocytes were collected on days 20 and 40 respectively.The expression levels of cardiac genes and proteins in differentiated cardiomyocytes were detected by RT-PCR and immunofluorescence,respectively.LAS X image analysis software was used to analyze the morphology and sarcomere length of differentiated cardiomyocytes.MitoTracker Green FM mitochondrial staining was used to detect total mitochondria.JC-1 mitochondrial staining was used to detect mitochondrial membrane potential.RESULTS AND CONCLUSION:Differentiated card io myocytes on day 40 had longer cell circumference and sarcomere length,and larger cell area than those on day 20(P＜0.05).The proportion of multinucleated cells rose sharply from about 16％on day 20 to about 29％on day 40(P＜0.05).Differentiated cardiomyocytes on day 40 had gene expression levels that were more similar to those of the primary cardiomyocytes,and the expression levels of SERCA2A,Cx-43,and α-MHC genes were significantly higher than on day 20(P＜0.05).Compared with the differentiated cardiomyocytes on day 20,the expression density of TNNT2 and α-MHC protein was relatively higher,the distribution density of mitochondria was larger,and the number of functional mitochondria was greater on day 40(P＜0.05).The results show that prolonging the induced differentiation time can increase the maturity of differentiated cardiomyocytes by increasing the length of sarcomere and the number of functional mitochondria,as well as improving the expression levels of cardiac genes and proteins.

BACKGROUND:It has been proved that induced pluripotent stem cells can differentiate into cardiomyocytes,but there are few reports on the maturity of differentiated cardiomyocytes.OBJECTIVE:To explore the effect of prolonging the induced differentiation time on the morphology,sarcomere length,binuclear cell content,cardiac gene expression,cardiac protein expression,and mitochondrial function of cardiomyocytes derived from induced pluripotent stem cells.METHODS:Bone morphogenetic protein 4,CH IR 99021,and IWR1 were used to induce pluripotent stem cells to differentiate into cardiomyocytes,and differentiated cardiomyocytes were collected on days 20 and 40 respectively.The expression levels of cardiac genes and proteins in differentiated cardiomyocytes were detected by RT-PCR and immunofluorescence,respectively.LAS X image analysis software was used to analyze the morphology and sarcomere length of differentiated cardiomyocytes.MitoTracker Green FM mitochondrial staining was used to detect total mitochondria.JC-1 mitochondrial staining was used to detect mitochondrial membrane potential.RESULTS AND CONCLUSION:Differentiated card io myocytes on day 40 had longer cell circumference and sarcomere length,and larger cell area than those on day 20(P＜0.05).The proportion of multinucleated cells rose sharply from about 16％on day 20 to about 29％on day 40(P＜0.05).Differentiated cardiomyocytes on day 40 had gene expression levels that were more similar to those of the primary cardiomyocytes,and the expression levels of SERCA2A,Cx-43,and α-MHC genes were significantly higher than on day 20(P＜0.05).Compared with the differentiated cardiomyocytes on day 20,the expression density of TNNT2 and α-MHC protein was relatively higher,the distribution density of mitochondria was larger,and the number of functional mitochondria was greater on day 40(P＜0.05).The results show that prolonging the induced differentiation time can increase the maturity of differentiated cardiomyocytes by increasing the length of sarcomere and the number of functional mitochondria,as well as improving the expression levels of cardiac genes and proteins.