Comparative evaluation of different modalities for measuring in vivo carnosine levels.

Carnosine is an endogenous di-peptide (ß-alanine -L- histidine) involved in maintaining tissue homeostasis. It is most abundant in skeletal muscle where its concentration has been determined in biopsy samples using tandem mass spectrometry (MS-MS). Carnosine levels can also be assessed in intact leg muscles by proton magnetic resonance spectroscopy (1H-MRS) or in blood and urine samples using mass spectrometry. Nevertheless, it remains uncertain how carnosine levels from these distinct compartments are correlated with each other when measured in the same individual. Furthermore, it is unclear which measurement modality might be most suitable for large-scale clinical studies. Hence, in 31 healthy volunteers, we assessed carnosine levels in skeletal muscle, via 1H-MRS, and in erythrocytes and urine by MS-MS. While muscle carnosine levels were higher in males (C2 peak, p = 0.010; C4 peak, p = 0.018), there was no sex-associated difference in urinary (p = 0.433) or erythrocyte (p = 0.858) levels. In a linear regression model adjusted for age, sex, race, and diet, there was a positive association between erythrocyte and urinary carnosine. However, no association was observed between 1H-MRS and erythrocytes or urinary measures. In the relationship between muscle versus urinary and erythrocyte measures, females had a positive association, while males did not show any association. We also found that 1H-MRS measures were highly sensitive to location of measurement. Thus, it is uncertain whether 1H-MRS can accurately and reliably predict endogenous carnosine levels. In contrast, urinary and erythrocyte carnosine measures may be stable and in greater synchrony, and given financial and logistical concerns, may be a feasible alternative for large-scale clinical studies.

Association of electronic cigarette use with circulating angiogenic cell levels in healthy young adults: Evidence for chronic systemic injury.

BACKGROUND: Circulating angiogenic cells (CACs) are indicative of vascular health and repair capacity; however, their relationship with chronic e-cigarette use is unclear. This study aims to assess the association between e-cigarette use and CAC levels. METHODS: We analyzed CAC levels in 324 healthy participants aged 21-45 years from the cross-sectional Cardiovascular Injury due to Tobacco Use study in four groups: never tobacco users (n = 65), sole e-cigarette users (n = 19), sole combustible cigarette users (n = 212), and dual users (n = 28). A total of 15 CAC subpopulations with four cell surface markers were measured using flow cytometry: CD146 (endothelial), CD34 (stem), CD45 (leukocyte), and AC133 (early progenitor/stem). Generalized linear models with gamma distribution and log-link were generated to assess association between CACs and smoking status. Benjamini-Hochberg were used to adjust p-values for multiple comparisons. RESULTS: The cohort was 47% female, 51% Black/African American, with a mean (± SD) age of 31 ± 7 years. Sole cigarette use was significantly associated with higher levels of two endothelial marker CACs (Q ⩽ 0.05). Dual users had higher levels of four endothelial marker CACs and one early progenitor/stem marker CAC (Q ⩽ 0.05). Sole e-cigarette users had higher levels of one endothelial and one leukocyte marker CAC (Q ⩽ 0.05). CONCLUSION: Dual use of e-cigarettes and combustible cigarettes was associated with higher levels of endothelial origin CACs, indicative of vascular injury. Sole use of e-cigarettes was associated with higher endothelial and inflammatory CACs, suggesting ongoing systemic injury. Distinct patterns of changes in CAC subpopulations suggest that CACs may be informative biomarkers of changes in vascular health due to tobacco product use.

The Epigenetic Regulator HDAC1 Modulates Transcription of a Core Cardiogenic Program in Human Cardiac Mesenchymal Stromal Cells Through a p53-Dependent Mechanism.

Histone deacetylase (HDAC) regulation is an essential process in myogenic differentiation. Inhibitors targeting the activity of specific HDAC family members have been shown to enhance the cardiogenic differentiation capacity of discrete progenitor cell types; a key property of donor cell populations contributing to their afforded benefits in cardiac cell therapy applications. The influence of HDAC inhibition on cardiac-derived mesenchymal stromal cell (CMC) transdifferentiation or the role of specific HDAC family members in dictating cardiovascular cell lineage specification has not been investigated. In the current study, the consequences of HDAC inhibition on patient-derived CMC proliferation, cardiogenic program activation, and cardiovascular differentiation/cell lineage specification were investigated using pharmacologic and genetic targeting approaches. Here, CMCs exposed to the pan-HDAC inhibitor sodium butyrate exhibited induction of a cardiogenic transcriptional program and heightened expression of myocyte and endothelial lineage-specific markers when coaxed to differentiate in vitro. Further, shRNA knockdown screens revealed CMCs depleted of HDAC1 to promote the induction of a cardiogenic transcriptional program characterized by enhanced expression of cardiomyogenic- and vasculogenic-specific markers, a finding which depended on and correlated with enhanced acetylation and stabilization of p53. Cardiogenic gene activation and elevated p53 expression levels observed in HDAC1-depleted CMCs were associated with improved aptitude to assume a cardiomyogenic/vasculogenic cell-like fate in vitro. These results suggest that HDAC1 depletion-induced p53 expression alters CMC cell fate decisions and identify HDAC1 as a potential exploitable target to facilitate CMC-mediated myocardial repair in ischemic cardiomyopathy. Stem Cells 2016;34:2916-2929.

Rapid Extracorporeal Membrane Oxygenation Overcomes Fulminant Myocarditis Induced by 5­Fluorouracil.

Fulminant myocarditis is a rare but potentially life-threatening illness caused by 5-fluorouracil cardiotoxicity. Data supporting the use of extracorporeal membrane oxygenation for the treatment of fulminant myocarditis are limited. A 49-year-old, previously healthy white man, recently diagnosed with anal squamous cell carcinoma, developed severe chest pain hours after completing his first 96-hour intravenous 5-fluorouracil treatment. Over a period of 3 days from onset of symptoms, the patient developed cardiogenic shock secondary to fulminant myocarditis induced by 5-fluorouracil cardiotoxicity. This required emergency initiation of extracorporeal membrane oxygenation. The patient's systolic function recovered by day 5, and on the 17th day he was discharged in hemodynamically stable condition, without symptoms of heart failure. This case shows the importance of prompt recognition of cardiogenic shock secondary to 5-fluorouracil-induced myocarditis and how the immediate initiation of extracorporeal membrane oxygenation can restore adequate tissue perfusion, leading to myocardial recovery and ultimately the survival of the patient.

Effect of the stop-flow technique on cardiac retention of c-kit positive human cardiac stem cells after intracoronary infusion in a porcine model of chronic ischemic cardiomyopathy.

It is commonly thought that the optimal method for intracoronary administration of cells is to stop coronary flow during cell infusion, in order to prolong cell/vascular wall contact, enhance adhesion, and promote extravasation of cells into the interstitial space. However, occlusion of a coronary artery with a balloon involves serious risks of vascular damage and/or dissection, particularly in non-stented segments such as those commonly found in patients with heart failure. It remains unknown whether the use of the stop-flow technique results in improved donor cell retention. Acute myocardial infarction was produced in 14 pigs. One to two months later, pigs received 10 million indium-111 oxyquinoline (oxine)-labeled c-kit(pos) human cardiac stem cells (hCSCs) via intracoronary infusion with (n = 7) or without (n = 7) balloon inflation. Pigs received cyclosporine to prevent acute graft rejection. Animals were euthanized 24 h later and hearts harvested for radioactivity measurements. With the stop-flow technique, the retention of hCSCs at 24 h was 5.41 ± 0.80 % of the injected dose (n = 7), compared with 4.87 ± 0.62 % without coronary occlusion (n = 7), (P = 0.60). When cells are delivered intracoronarily in a clinically relevant porcine model of chronic ischemic cardiomyopathy, the use of the stop-flow technique does not result in greater myocardial cell retention at 24 h compared with non-occlusive infusion. These results have practical implications for the design of cell therapy trials. Our observations suggest that the increased risk of complications secondary to coronary manipulation and occlusion is not warranted.