Investigation Of The Therapeutic Effects Of Human Pluripotent Stem Cell-Derived Ventricular And Atrial Cardiomyocytes On Myocardial Infarction

The adult human heart lacks the ability to regenerate.Once myocardial infarction occurs,a large number of cardiomyocytes die,and it is difficult to activate endogenous repair.Traditional treatment can only alleviate the deterioration of ventricular function and delay the occurrence of heart failure,however,it is difficult to fundamentally solve the problem of cardiomyocyte regeneration.Transplantation of human pluripotent stem cell-derived cardiomyocytes can effectively replace necrotic cardiomyocytes and improve heart function.It has great potential to cure myocardial infarction in the future.However,pluripotent stem cell-derived cardiomyocytes are heterogeneous,including ventricular and atrial myocytes.It is not clear whether there are difference between these two in the treatment of myocardial infarction.This subject is designed to investigate the differences in the efficacy of pluripotent stem cell-derived ventricular myocytes,atrial myocytes and unsorted mixed cardiomyocytes in the treatment of myocardial infarction.CRISPR/Cas9 technology is exploited to knock in eGFP to trace ventricular and atrial in the human embryonic stem cell line H7.After identification of the differentiation potential,the above-mentioned cells were directional differentiated into ventricular and atrial myocytes.After cell enrichment and functional identification,cardiomyocytes of each type were injected to mice after myocardial infarction.Mice were divided into four groups randomly:PBS control group,ventricular myocyte group,atrial myocyte group and mixed cardiomyocyte group.The differences among these four groups in the therapeutic effects on myocardial infarction were investigated through continuous monitoring of cardiac function,analysis of the structural changes of the heart,and a series of molecular experiments.The echocardiographic results showed that,compared with the PBS control group,the ejection fraction(EF)and fractional shortening(FS)of the mouse heart were improved with varying degrees after cardiomyocyte injection.The values of EF and FS in the ventricular myocyte group were significantly higher than that in the atrial myocyte group,but was similar to that in the mixed cardiomyocyte group.Masson staining exhibited similar tendency.Cardiomyocyte transplantation can significantly reduce the area of fibrosis in the heart of mice with myocardial infarction.The degree of fibrosis in the ventricular myocyte group were significantly lower than that in the atrial myocyte group,but was similar to that in the mixed cardiomyocyte group.With the development of myocardial infarction(28 days after myocardial infarction),the heart size in different experimental groups also showed differences.According to Masson and statistical analysis of immunofluorescence staining,the hearts of mice receiving cell therapy were significantly smaller than the PBS control group.Among them,the degree of cardiac hypertrophy of the mice in the ventricular myocyte group was significantly weaker than that of the mice in the atrial myocyte group,but there was no significant difference in the heart of the mice in the mixed cardiomyocyte transplantation group.As to myocardial infarction treatment,we found that the effect of ventricular myocyte was significantly better than that of atrial myocyte and exists no significant difference with that of mixed cardiomyocytes,which may be due to the greater proportion of ventricular myocytes in mixed cardiomyocytes.The heart-friendly effect of cardiomyocyte transplantation is achieved through improving cardiac function,reducing cardiac fibrosis,and inhibiting myocardial hypertrophy.This study provides a new method and perspective for further optimization and refinement of cell therapy strategies for myocardial infarction.