Requirement of TCTG(G/C) Direct Repeats and Overlapping GATA Site for Maintaining the Cardiac-Specific Expression of Cardiac troponin T in Developing and Adult Mice

MicroRNA-1 Regulates the Differentiation of Adipose-Derived Stem Cells into Cardiomyocyte-Like Cells

Stem cell transplantation is one of most valuable methods in the treatment of myocardial infarction, and adipose-derived stem cells (ASCs) are becoming a hot topic in medical research. Previous studies have shown that ASCs can be differentiated into cardiomyocyte-like cells, but the efficiency and survival rates are low. We investigated the role and mechanism of microRNA-1 (miR-1) in the differentiation of ASCs into cardiomyocyte-like cells. ASCs and cardiomyocytes were isolated from neonatal rats. We constructed lentivirus for overexpressing miR-1 and used DAPT, an antagonist of the Notch1 pathway, for in vitro analyses. We performed cocultures with ASCs and cardiomyocytes. The differentiation efficiency of ASCs was detected by cell-specific surface antigens. Our results showed that miR-1 can promote the expression of Notch1 and reduce the expression of Hes1, a Notch pathway factor, and overexpression of miR-1 can promote the differentiation of ASCs into cardiomyocyte-like cells, which may occur by regulating Notch1 and Hes1.

Increased High-Sensitivity Troponin-T Levels Are Associated with Mortality After Ischemic Stroke

Biomarkers for diagnosis, treatment, and outcome prediction after stroke are lacking. Therefore, we aimed to evaluate the association between increased serum troponin, stroke severity, and mortality. Unselected patients with acute ischemic stroke assessed for troponin levels were included over the span of 1 year. Risk-factor profile, stroke etiology, stroke severity, and mortality during acute admission were recorded. The study included 212 patients, and 35 had increased troponin levels. Elevated troponin levels were associated with older age (82.1 ± 10.7 vs. 72.2 ± 12.6, p < 0.001), poor kidney function (calculated GFR 58.7 ± 29.8 vs. 82.7 ± 28.4, p < 0.001), and known ischemic heart disease (51.4% vs. 33.9%, p = 0.049). Patients with increased troponin had increased stroke severity on admission (National Institutes of Health Stroke Scale (NIHSS) 16.0 ± 9.4 vs. 10.4 ± 8.0, p < 0.001). This association remained significant after multivariate analysis but was nonlinear. Mortality rates were significantly higher in patients with increased troponin (37.1 vs. 5.6%, p < 0.001). On multivariate analysis, elevated troponin (odds ratio [OR] 22.57, 95% CI 4.4-116.6), absence of ischemic heart disease (OR 10.3, 95% CI 1.8-57.6), and admission NIHSS score (OR 1.59 for every 5 points, 95% CI 1.1-2.4) were associated with mortality. This study indicates that elevated troponin is an independent marker for severe deficits on presentation and for mortality in stroke patients.

Discontinuous thoracic venous cardiomyocytes and heart exhibit synchronized developmental switch of troponin isoforms

Cardiomyocyte-like cells have been reported in thoracic veins of rodents and other mammals, but their differentiation state and relationship to the muscle mass in the heart remain to be characterized. Here we investigated the distribution, ultrastructure, expression and developmental regulation of myofilament proteins of mouse and rat pulmonary and azygos venous cardiomyocytes. Tracing cardiomyocytes in transgenic mouse tissues using a lacZ reporter gene driven by a cloned rat cardiac troponin T promoter demonstrated scattered distribution of cardiomyocytes discontinuous from the atrial sleeves. The longitudinal axis of venous cardiomyocytes is perpendicular to that of the vessel. These cells contain typical sarcomere structures and intercalated discs as shown in electron microscopic images, and express cardiac isoforms of troponin T, troponin I and myosin. The expression of troponin I isoform genes and the alternative splicing of cardiac troponin T in thoracic venous cardiomyocytes are regulated during postnatal development in precise synchrony with that in the heart. However, the patterns of cardiac troponin T splicing in adult rat thoracic venous cardiomyocytes are slightly but clearly distinct from those in the atrial and ventricular muscles. The data indicate that mouse and rat thoracic venous cardiomyocytes residing in extra-cardiac tissue possess a physiologically differentiated state and an intrinsically pre-set developmental clock, which are apparently independent of the very different hemodynamic environments and functional features of the vessels and heart.

Promoter-specific lentivectors for long-term, cardiac-directed therapy of Fabry disease

In Fabry disease a deficiency of α-galactosidase A (α-gal A) activity leads to accumulation of globotriaosylceramide (Gb3) in various tissues including the heart. A specific cardiac variant of Fabry disease has also been described. Previously we have demonstrated the feasibility of gene therapy for Fabry disease. Here, to provide efficient transfer and increased specificity of transgene expression, we synthesized lentiviral vectors (LVs) with myocardial-specific promoters including: α-myosin heavy chain (α-MHC), myosin light chain (MLC2v), and cardiac troponin T (cTnT). Initially, neonatal Balb/c mice were injected with such LV constructs engineering expression of luciferase. One month post-injection, we found specific expression of luciferase in hearts of recipient animals when compared with transgene expression driven by the standard EF1-α promoter. To examine the feasibility of long-term therapy specifically targeting the heart, recombinant LV/α-gal A therapeutic vectors with analogous cardiac promoters were generated and injected into numerous neonatal Fabry mice. No immune response against the corrective α-gal A hydrolase was observed in the treated mice. Serum α-gal A activity of 10-week-old Fabry mice was increased in LV/α-gal A-injected animals compared to controls. In 28-week-old Fabry mice we observed significantly decreased Gb3 accumulation. Neonatal injections with LVs harboring cardiac-specific promoters may thus be an effective long-term treatment strategy for heart manifestations and cardiac variant Fabry disease. These results can be also extended to other progressive pathologies of the heart.