Paul Steels

Recovery of Regional but Not Global Contractile Function by the Direct Intramyocardial Autologous Bone Marrow Transplantation Results From a Randomized Controlled Clinical Trial

Background— Recent trials have shown that intracoronary infusion of bone marrow cells (BMCs) improves functional recovery after acute myocardial infarction. However, whether this treatment is effective in heart failure as a consequence of remodeling after organized infarcts remains unclear. In this randomized trial, we assessed the hypothesis that direct intramyocardial injection of autologous mononuclear bone marrow cells during coronary artery bypass graft (CABG) could improve global and regional left ventricular ejection fraction (LVEF) at 4-month follow-up. Methods and Results— Twenty patients (age 64.8±8.7; 17 male, 3 female) with a postinfarction nonviable scar, as assessed by thallium (Tl) scintigraphy and cardiac magnetic resonance imaging (MRI), scheduled for elective CABG, were included. They were randomized to a control group (n =10, CABG only) or a BMC group (CABG and injection of 60.106±31.106 BMC). Primary end points were global LVEF change and wall thickening changes in the infarct area from baseline to 4-month follow-up, as measured by MRI. Changes in metabolic activity were measured by Tl scintigraphy and expressed as a score with a range from 0 to 4, corresponding to percent of maximal myocardial Tl uptake (4 indicates <50%, nonviable scar; 3, 50% to 60%; 2, 60% to 70%; 1, 70% to 80%; 0>80%). Global LVEF at baseline was 39.5±5.5% in controls and 42.9±10.3% in the BMC group (P=0.38). At 4 months, LVEF had increased to 43.1±10.9% in the control group and to 48.9±9.5% in the BMC group (P=0.23). Systolic thickening had improved from −0.6±1.3 mm at baseline to 1.8±2.6 mm at 4 months in the cell-implanted scars, whereas nontreated scars remained largely akinetic (−0.5±2.0 mm at baseline compared with 0.4±1.7 mm at 4 months, P=0.007 control versus BMC-treated group at 4 months). Defect score decreased from 4 to 3.3±0.9 in the BMC group and to 3.7±0.4 in the control group (P=0.18). Conclusions— At 4 months, there was no significant difference in global LVEF between both groups, but a recovery of regional contractile function in previously nonviable scar was observed in the BMC group.

Abdominal Contributions to Cardiorenal Dysfunction in Congestive Heart Failure

Current pathophysiological models of congestive heart failure unsatisfactorily explain the detrimental link between congestion and cardiorenal function. Abdominal congestion (i.e., splanchnic venous and interstitial congestion) manifests in a substantial number of patients with advanced congestive heart failure, yet is poorly defined. Compromised capacitance function of the splanchnic vasculature and deficient abdominal lymph flow resulting in interstitial edema might both be implied in the occurrence of increased cardiac filling pressures and renal dysfunction. Indeed, increased intra-abdominal pressure, as an extreme marker of abdominal congestion, is correlated with renal dysfunction in advanced congestive heart failure. Intriguing findings provide preliminary evidence that alterations in the liver and spleen contribute to systemic congestion in heart failure. Finally, gut-derived hormones might influence sodium homeostasis, whereas entrance of bowel toxins into the circulatory system, as a result of impaired intestinal barrier function secondary to congestion, might further depress cardiac as well as renal function. Those toxins are mainly produced by micro-organisms in the gut lumen, with presumably important alterations in advanced heart failure, especially when renal function is depressed. Therefore, in this state-of-the-art review, we explore the crosstalk between the abdomen, heart, and kidneys in congestive heart failure. This might offer new diagnostic opportunities as well as treatment strategies to achieve decongestion in heart failure, especially when abdominal congestion is present. Among those currently under investigation are paracentesis, ultrafiltration, peritoneal dialysis, oral sodium binders, vasodilator therapy, renal sympathetic denervation and agents targeting the gut microbiota.

Cytokine-induced cell death in human oligodendroglial cell lines: I. Synergistic effects of IFN-γ and TNF-α on apoptosis

Multiple sclerosis is a chronic inflammatory disease of the central nervous system. Myelin and oligodendrocytes are considered the major targets of injury caused by a cell‐mediated immune response. There is circumstantial evidence that proinflammatory cytokines like tumor necrosis factor α (TNF‐α) and interferon γ (IFN‐γ) could have disease‐promoting roles in multiple sclerosis (MS). In the present study, the cytotoxic effects of IFN‐γ and TNF‐α on the human oligodendroglial cell lines human oligodendroglioma (HOG) and MO3.13 were analyzed. When the oligodendroglial cell lines were cultured in the presence of IFN‐γ or TNF‐α, apoptotic cell death was observed in both cell lines after >24 hr incubation. Apoptosis was evidenced by a decrease in cell viability, apoptotic changes in cell and nucleus morphology, and disruption of the membrane asymmetry. Our data show that TNF‐α and IFN‐γ induce apoptosis in a dose‐dependent fashion in both oligodendroglial cell lines and that their synergistic effect results in enhanced cell death. Understanding the regulation of cell death pathways in oligodendrocytes is critical for protecting myelin‐producing cells and their associated axons during injury in patients with MS.

Rafts in oligodendrocytes: Evidence and structure–function relationship

The plasma membrane of eukaryotic cells exhibits lateral inhomogeneities, mainly containing cholesterol and sphingomyelin, which provide liquid‐ordered microdomains (lipid “rafts”) that segregate membrane components. Rafts are thought to modulate the biological functions of molecules that become associated with them, and as such, they appear to be involved in a variety of processes, including signal transduction, membrane sorting, cell adhesion and pathogen entry. Although still a matter of ongoing debate, evidence in favor of the presence of these microdomains is gradually accumulating but a consensus on issues like their size, lifetime, composition, and biological significance has yet to be reached. Here, we provide an overview of the evidence supporting the presence of rafts in oligodendrocytes, the myelin‐producing cells of the central nervous system, and discuss their functional significance. The myelin membrane differs fundamentally from the plasma membrane, both in lipid and protein composition. Moreover, since myelin membranes are unusually enriched in glycosphingolipids, questions concerning the biogenesis and functional relevance of microdomains thus appear of special interest in oligodendrocytes. The current picture of rafts in oligodendrocytes is mainly based on detergent methods. The robustness of such data is discussed and alternative methods that may provide complementary data are indicated.

Unmasking of the Apical Electrogenic H Pump in Isolated Malpighian Tubules (Formica polyctena) by the Use of Barium

In the present study evidence is given for the presence of an electrogenic, vacuolar type ATPase (V type ATPase) in the apical membrane of malpighian tubules of Formica. Barium (6 m M

Hyponatremia in acute decompensated heart failure: depletion versus dilution.

Hyponatremia frequently poses a therapeutic challenge in acute decompensated heart failure (ADHF). Treating physicians should differentiate between depletional versus dilutional hyponatremia. The former is caused by diuretic agents, which enhance sodium excretion, often with concomitant potassium/magnesium losses. This can be treated with isotonic saline, whereas potassium/magnesium administration may be helpful if plasma concentrations are low. In contrast, as impaired water excretion, rather than sodium deficiency, is the culprit in dilutional hyponatremia, isotonic saline administration may further depress the serum sodium concentration. Because free water excretion is achieved by continuous sodium reabsorption in distal nephron segments with low water permeability, diuretic agents that impair this mechanism (e.g., thiazide-type diuretic agents and mineralocorticoid receptor antagonists) should be avoided, and proximally acting agents (e.g., acetazolamide and loop diuretic agents) are preferred. Vasopressin antagonists, which promote low water permeability in the collecting ducts and, hence, free water excretion, remain under investigation for dilutional hyponatremia in ADHF.

The kidney in congestive heart failure: ‘are natriuresis, sodium, and diuretics really the good, the bad and the ugly?’

This review discusses renal sodium handling in heart failure. Increased sodium avidity and tendency to extracellular volume overload, i.e. congestion, are hallmark features of the heart failure syndrome. Particularly in the case of concomitant renal dysfunction, the kidneys often fail to elicit potent natriuresis. Yet, assessment of renal function is generally performed by measuring serum creatinine, which has inherent limitations as a biomarker for the glomerular filtration rate (GFR). Moreover, glomerular filtration only represents part of the nephrons function. Alterations in the fractional reabsorptive rate of sodium are at least equally important in emerging therapy‐refractory congestion. Indeed, renal blood flow decreases before the GFR is affected in congestive heart failure. The resulting increased filtration fraction changes Starling forces in peritubular capillaries, which drive sodium reabsorption in the proximal tubules. Congestion further stimulates this process by augmenting renal lymph flow. Consequently, fractional sodium reabsorption in the proximal tubules is significantly increased, limiting sodium delivery to the distal nephron. Orthosympathetic activation probably plays a pivotal role in those deranged intrarenal haemodynamics, which ultimately enhance diuretic resistance, stimulate neurohumoral activation with aldosterone breakthrough, and compromise the counter‐regulatory function of natriuretic peptides. Recent evidence even suggests that intrinsic renal derangements might impair natriuresis early on, before clinical congestion or neurohumoral activation are evident. This represents a paradigm shift in heart failure pathophysiology, as it suggests that renal dysfunction—although not by conventional GFR measurements—is driving disease progression. In this respect, a better understanding of renal sodium handling in congestive heart failure is crucial to achieve more tailored decongestive therapy, while preserving renal function.

Cytokine-induced cell death in human oligodendroglial cell lines. II: Alterations in gene expression induced by interferon-γ and tumor necrosis factor-α

Cytokines, such as interferon‐γ (IFN‐γ) and tumor necrosis factor‐α (TNF‐α), can initiate dual effects resulting in either cell growth or cell death. In this study, the human oligodendroglial cell lines HOG and MO3.13 were used as a model to study the molecular mechanisms of cytokine‐induced cell death in human oligodendrocytes. We have previously shown that TNF‐α and IFN‐γ induce apoptosis in both oligodendroglial cell lines within 72 hr. In the present study, the cell death pathways operating within these cells were further investigated at the gene expression level. Both cell lines express a broad repertoire of caspases and apoptosis‐related genes. Some of these genes are specifically up‐regulated by cytokine treatment; e.g., caspase‐1 is up‐regulated by IFN‐γ. In addition to direct cytotoxic effects, IFN‐γ and TNF‐α also enhance the expression of Fas, TNFR1, and MHC class I molecules in both cell lines. This suggests that cytokines can make oligodendrocytes more vulnerable to different cell death pathways in an inflammatory environment. cDNA microarray analysis of the HOG cell line revealed that TNF‐α induces genes that regulate apoptosis, survival, inflammation, cell metabolism, and cell signaling. The data suggest that oligodendroglial cells activate both death and survival pathways upon cytokine challenges. However, the survival pathways seem to be unable to compete with the death signal after more than 24 hr of cytokine treatment. These results may contribute to the development of therapeutic strategies aimed at interfering with cytokine‐induced cell death of oligodendrocytes in patients with multiple sclerosis.

Glycine and glycine receptor signalling in non-neuronal cells

Glycine is an inhibitory neurotransmitter acting mainly in the caudal part of the central nervous system. Besides this neurotransmitter function, glycine has cytoprotective and modulatory effects in different non-neuronal cell types. Modulatory effects were mainly described in immune cells, endothelial cells and macroglial cells, where glycine modulates proliferation, differentiation, migration and cytokine production. Activation of glycine receptors (GlyRs) causes membrane potential changes that in turn modulate calcium flux and downstream effects in these cells. Cytoprotective effects were mainly described in renal cells, hepatocytes and endothelial cells, where glycine protects cells from ischemic cell death. In these cell types, glycine has been suggested to stabilize porous defects that develop in the plasma membranes of ischemic cells, leading to leakage of macromolecules and subsequent cell death. Although there is some evidence linking these effects to the activation of GlyRs, they seem to operate in an entirely different mode from classical neuronal subtypes.

The cardiac atrial appendage stem cell: a new and promising candidate for myocardial repair

AIMS Considerable shortcomings in the treatment of myocardial infarction (MI) still exist and therefore mortality remains high. Cardiac stem cell (CSC) therapy is a promising approach for myocardial repair. However, identification and isolation of candidate CSCs is mainly based on the presence or absence of certain cell surface markers, which suffers from some drawbacks. In order to find a more specific and reliable identification and isolation method, we investigated whether CSCs can be isolated based on the high expression of aldehyde dehydrogenase (ALDH). METHODS AND RESULTS An ALDH(+) stem cell population, the cardiac atrial appendage stem cells (CASCs), was isolated from human atrial appendages. CASCs possess a unique phenotype that is clearly different from c-kit(+) CSCs but that seems more related to the recently described cardiac colony-forming-unit fibroblasts. Based on immunophenotype and in vitro differentiation studies, we suggest that CASCs are an intrinsic stem cell population and are not mobilized from bone marrow or peripheral blood. Indeed, they possess a clonogenicity of 16% and express pluripotency-associated genes. Furthermore, compared with cardiosphere-derived cells, CASCs possess an enhanced cardiac differentiation capacity. Indeed, differentiated cells express the most important cardiac-specific genes, produce troponin T proteins, and have an electrophysiological behaviour similar to that of adult cardiomyocytes (CMs). Transplanting CASCs in the minipig MI model resulted in extensive cardiomyogenic differentiation without teratoma formation. CONCLUSION We have identified a new human CSC population able to differentiate into functional CMs. This opens interesting perspectives for cell therapy in patients with ischaemic heart disease.