Project description:Apical resection in 1-day-old mice results in complete regenerated heart and normal cardiac function, which is characterized by significant cardiomyocyte proliferation with minimal fibrosis. Local damage on hearts of 1-day-old mice can amplify cardiomyocyte proliferation located in the whole ventricle rather than limited damage area. This response provides a reasonable screening model to identify novel genes involved in endogenous cardiac regeneration
Project description:We use spatial transcriptomics to establish regional transcriptional profile of neonatal heart tissue obtained at indicated timpoints after apical resection surgery.
Project description:The mammalian heart has generally been considered nonregenerative, but recent progress suggests that neonatal mouse hearts have a genuine capacity to regenerate following apex resection (AR). However, in this study, we performed AR or sham surgery on 400 neonatal mice from inbred and outbred strains and found no evidence of complete regeneration. Ideally, new functional cardiomyocytes, endothelial cells, and vascular smooth muscle cells should be formed in the necrotic area of the damaged heart. Here, damaged hearts were 9.8% shorter and weighed 14% less than sham controls. In addition, the resection border contained a massive fibrotic scar mainly composed of nonmyocytes and collagen disposition. Furthermore, there was a substantial reduction in the number of proliferating cardiomyocytes in AR hearts. Our results thus question the usefulness of the AR model for identifying molecular mechanisms underlying regeneration of the adult heart after damage.
Project description:Since the proliferative capacity of cardiomyocytes is extremely limited in the adult mammalian hearts, the irreversible loss of cardiomyocytes following cardiac injury markedly reduces cardiac function, leading to cardiac remodeling and heart failure. However, the early neonatal mice have a strong ability in cardiomyocyte proliferation and cardiac regeneration after heart damage such as apical resection. Besides of cardiomyocytes, non-myocytes in heart tissue also play important roles in the regeneration process. Previous studies showed that cardiac macrophages, regulatory T cells and CD4+ T cells are all involved in regulating the myocardial regeneration process. However, the roles of other cardiac immune cells in cardiac regeneration remains to be elucidated. B cells is a prominent immune cell in injured heart; here we discovered the indispensable function of cardiac B cells in improving cardiomyocyte proliferation and heart regeneration in neonatal mice.
Project description:The neonatal mammalian heart is able to regenerate after injury by inducing cardiomyocyte proliferation. However, this regenerative capacity is virtually lost in the adult mammalian heart. Extracellular vesicles (EVs) have been shown to play an important cardioprotective role in heart repair. Here, we performed proteomic analysis of EVs from neonatal mouse heart tissues (Neo-EVs), EVs regenerated from neonatal heart tissues after apicoectomy (AR-Neo-EVs), and EVs from adult mouse hearts (Adu-EVs), to compare the differential changes in proteins among them.
Project description:To investigate the transcriptional response to proteotoxic stress from CRYAB-R120G mutation in the heart with age, RNA sequencing of the heart apex was performed.
Project description:Myocardial infarction results in compromised myocardial function with heart failure due to insufficient cardiomyocyte self-renewal. Unlike lower vertebrates, mammalian hearts only have a transient neonatal renewal capacity. Reactivating the primitive reparative ability in the fully mature heart requires an intimate knowledge of the molecular mechanisms promoting early heart repair. Here we identified a novel factor that can sufficiently promote heart muscle repair. By screening an established Hippo-deficient heart regeneration model for renewal promoting factors, we found that PITX2 protein expression in ventricles was induced after cardiomyocyte injury. Moreover, Pitx2-deficient neonatal hearts failed to repair after apex resection. Pitx2-gain-of-function in ventricular cardiomyocytes conferred reparative ability to the adult mouse heart after myocardial infarction. Integrated genomic analyses indicated that Pitx2 activated genes encoding electron transport chain components and reactive oxygen species scavengers. Pitx2 mutant myocardium had elevated reactive oxygen species levels while supplement of antioxidants suppressed the Pitx2-loss-of-function phenotype. Furthermore, PITX2 directly binds NFE2L2 and translocates from cytoplasm to nucleus upon oxidative stress.
Project description:Cy3-labeled cDNA obtained from four pools of three hearts of neonatal C57BL Cx43 null mice were compared to Cy3-labeled cDNA obtained from four pools of three hearts of neonatal C57BL wildtype mice through Cy5-labeled sample reference prepared at once for the entire experiment from aorta, brain, heart, kidney, liver, lung, ovary/testicles, spleen, and stomach - equal amounts from adult male and female C57BL mice. Keywords = Cx32 null vs wildtype neonatal mouse heart