Background and Objectives: Although human-induced pluripotent stem cells (hiPSC) can be efficiently differentiated into cardiomyocytes (CMs), the heterogeneity of the hiPSC-CMs hampers their applications in research and regenerative medicine. Retinoic acid (RA)-mediated signaling pathway has been proved indispensable in cardiac development and differentiation of hiPSC toward atrial CMs. This study was aimed to test whether RA signaling pathway can be manipulated to direct the differentiation into sinoatrial node (SAN) CMs. Methods: and Results: Using the well-characterized GiWi protocol that cardiomyocytes are generated from hiPSC via temporal modulation of Wnt signaling pathway by small molecules, RA signaling pathway was manipulated during the differentiation of hiPSC-CMs on day 5 post-differentiation, a crucial time point equivalent to the transition from cardiac mesoderm to cardiac progenitor cells in cardiac development. The resultant CMs were characterized at mRNA, protein and electrophysiology levels by a combination of qPCR, immunofluorescence, flow cytometry, and whole-cell patch clamp. The results showed that activation of the RA signaling pathway biased the differentiation of atrial CMs, whereas inhibition of the signaling pathway biased the differentiation of sinoatrial node-like cells (SANLCs). Conclusions Our study not only provides a novel and simple strategy to enrich SANLCs but also improves our under-standing of the importance of RA signaling in the differentiation of hiPSC-CMs.

Background and Objectives: Manipulating different signaling pathways via small molecules could efficiently inducecardiomyocytes from human induced pluripotent stem cells (hiPSC). However, the effect of transcription factors on the hiPSC-directed cardiomyocytes differentiation remains unclear. Transcription factor, p53 has been demonstrated indispensable for the early embryonic development and mesendodermal differentiation of embryonic stem cells (ESC).We tested the hypothesis that p53 promotes cardiomyocytes differentiation from human hiPSC. Methods: and Results: Using the well-characterized GiWi protocol that cardiomyocytes are generated from hiPSC via temporal modulation of Wnt signaling pathway by small molecules, we demonstrated that forced expression of p53 in hiPSC remarkably improved the differentiation efficiency of cardiomyocytes from hiPSC, whereas knockdown endogenous p53 decreased the yield of cardiomyocytes. This p53-mediated increased cardiomyocyte differentiation was mediated through WNT3, as evidenced by that overexpression of p53 upregulated the expression of WNT3, and knockdown of p53 decreased the WNT3 expression. Mechanistic analysis showed that the increased cardiomyocyte differentiation partially depended on the amplified mesendodermal specification resulted from p53-mediated activation of WNT3-mediated Wnt signaling. Consistently, endogenous WNT3 knockdown significantly ameliorated mesendodermal specification and subsequent cardiomyocyte differentiation. Conclusions These results provide a novel insight into the potential effect of p53 on the development and differentiation of cardiomyocyte during embryogenesis.

Objective:To investigate the expression and clinical significance of F0 ATP synthase C subunit (Csub) in patients with ischemic heart disease (IHD).Methods:The 101 patients with chest pain admitted to the department of emergency of the People's Hospital of Yuhuan from May 2019 to December 2020 were enrolled, including 59 patients with acute myocardial infarction (AMI) and 42 patients with unstable angina pectoris (UAP). At the same time, 50 age-matched healthy subjects in the health examination center were selected as the healthy control (HC). All patients had completed blood sampling before the intervention of drugs or other intervention measures in the emergency room. The content of serum Csub was detected by enzyme linked immunosorbent assay (ELISA), and the relationship between Csub and clinical characteristics was analyzed. At the same time, the contents of hypersensitivity cardiac troponin T (hs-cTnT) and MB isoenzyme of creatine kinase (CK-MB) in blood were detected by electrochemical luminescence. The receiver operator characteristic curve (ROC curve) was drawn to evaluate the value of Csub, hs-cTnT, and CK-MB in the early diagnosis of IHD.Results:The baseline data such as age, gender, and history of the three groups were balanced. There were significant differences in low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), CK-MB, hs-cTnT and B-type natriuretic peptide (BNP), but there were no significant differences in other biochemical indexes. The Csub content in the AMI group and the UAP group were significantly higher than those in the HC group [8.96% (6.37%, 11.53%), 4.27% (3.23%, 6.49%) vs. 1.56% (1.07%, 2.33%), both P < 0.01]. Moreover, the Csub in the AMI group with more severe myocardial ischemia was higher than UAP group [8.96% (6.37%, 11.53%) vs. 4.27% (3.23%, 6.49%), P < 0.01]. A total of 59 patients with AMI were treated with percutaneous coronary intervention (PCI). According to the median of Csub, AMI patients were subdivided into above-median group (29 cases) and below-median group (30 cases). The results showed that there were no significant differences in the number of coronary artery lesion branches, the number of stent implantation and postoperative medication between the two groups. ROC curve analysis showed that the area under the curve (AUC) and 95% confidence interval (95% CI) of Csub, hs-cTnT and CK-MB in the diagnosis of IHD were 0.98 (0.95-1.00), 0.99 (0.99-1.00), 0.94 (0.89-0.99), respectively. The diagnostic efficacy of Csub was slightly lower than that of hs-cTnT but higher than that of CK-MB. When the cut-off value of Csub was 4.74%, the sensitivity and specificity for the diagnosis of IHD were 100% and 87.0%, respectively. Conclusions:Csub increased significantly in the serum of IHD patients, and further increased with the severity of ischemia. It can be used as a new diagnostic biomarker for the diagnosis and evaluation of the development of myocardial ischemia.