Browsing by Author "Ricca, Micaela"
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Item Cardiac stress test induced by dobutamine and monitored by cardiac catheterization in mice(MYJoVE Corporation, 2013) Calligaris, Sebastian; Ricca, Micaela; Conget, PauletteDobutamine is a β-adrenergic agonist with an affinity higher for receptor expressed in the heart (β1) than for receptors expressed in the arteries (β2). When systemically administered, it increases cardiac demand. Thus, dobutamine unmasks abnormal rhythm or ischemic areas potentially at risk of infarction. Monitoring of heart function during a cardiac stress test can be performed by either echocardiography or cardiac catheterization. The latter is an invasive but more accurate and informative technique that the former. Cardiac stress test induced by dobutamine and monitored by cardiac catheterization accomplished as described here allows, in a single experiment, the measurement of the following hemodynamic parameters: heart rate (HR), systolic pressure, diastolic pressure, end-diastolic pressure, maximal positive pressure development (dP/dtmax) and maximal negative pressure development (dP/dtmin), at baseline conditions and under increasing doses of dobutamine. As expected, in normal mice we observed a dobutamine dose-related increase in HR, dP/dtmax and dP/dtmin. Moreover, at the highest dose tested (12 ng/g/min) the cardiac decompensation of high fat diet-induced obese mice was unmasked.Item Intravenous administration of multipotent stromal cells prevents the onset of non-alcoholic steatohepatitis in obese mice with metabolic syndrome(2011) Ezquer, Marcelo; Ezquer, Fernando; Ricca, Micaela; Allers, Carolina; Conget, PauletteBackground & Aims: Metabolic syndrome is secondary to obesity and characterized by dyslipidemia, insulin resistance, and hypertension. Non-alcoholic fatty liver disease is its hepatic manifestation, whose progression-limiting step is non-alcoholic steatohepatitis (NASH). The latter is characterized by lipid accumulation, hepatocyte damage, leukocyte infiltration, and fibrosis. NASH is a prodrome to cirrhosis and hepatocellular carcinoma. Multipotent stromal cells (MSCs) have been shown to be immunomodulatory and contribute to liver regeneration in acute failure conditions. Our aim was to evaluate whether MSC administration prevents the onset of NASH in obese mice with metabolic syndrome. Methods: C57BL/6 mice were chronically fed with high-fat diet. At week 33, mice received intravenously either the vehicle (obese untreated) or two doses of 0.5 x 10(6) syngeneic MSCs (obese MSC-treated). Four months later, liver function and structure, and metabolic syndrome markers were assessed. The persistence of donor MSCs(GFP) in obese mice was evaluated 17 weeks after their administration. Results: Obese untreated mice presented high plasma levels of hepatic enzyme, hepatomegaly, liver fibrosis, inflammatory cell infiltration, and hepatic triglyceride accumulation. Furthermore, they showed high expression levels of fibrosis markers and pro-inflammatory cytokines. By contrast, obese MSC-treated mice only presented steatosis. Mice kept obese, hypercholesterolemic, hyperglycemic, and insulin resistant irrespective of whether they received MSCs or not. Donor MSCs(GFP) were found in liver, bone marrow, heart, and kidney of obese mice. Conclusions: MSC administration prevents the onset of NASH in obese mice. Observed hepatoprotection is not related to a reversion of the metabolic syndrome but to the preclusion of the inflammatory process. (C) 2011 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.Item The Antidiabetic Effect of Mesenchymal Stem Cells Is Unrelated to Their Transdifferentiation Potential But to Their Capability to Restore Th1/Th2 Balance and to Modify the Pancreatic Microenvironment(2012) Ezquer, Fernando; Ezquer, Marcelo; Contador, David; Ricca, Micaela; Simón, Valeska; Conget, PauletteType 1 diabetes mellitus (T1DM) is a chronic metabolic disease that results from cell-mediated autoimmune destruction of insulin-producing cells. In T1DM animal models, it has been shown that the systemic administration of multipotent mesenchymal stromal cells, also referred as to mesenchymal stem cells (MSCs), results in the regeneration of pancreatic islets. Mechanisms underlying this effect are still poorly understood. Our aims were to assess whether donor MSCs (a) differentiate into pancreatic b-cells and (b) modify systemic and pancreatic pathophysiologic markers of T1DM. After the intravenous administration of 5 3 105 syngeneic MSCs, we observed that mice with T1DM reverted their hyperglycemia and presented no donor-derived insulin-producing cells. In contrast, 7 and 65 days post-transplantation, MSCs were engrafted into secondary lymphoid organs. This correlated with a systemic and local reduction in the abundance of autoaggressive T cells together with an increase in regulatory T cells. Additionally, in the pancreas of mice with T1DM treated with MSCs, we observed a cytokine profile shift from proinflammatory to antinflammatory. MSC transplantation did not reduce pancreatic cell apoptosis but recovered local expression and increased the circulating levels of epidermal growth factor, a pancreatic trophic factor. Therefore, the antidiabetic effect of MSCs intravenously administered is unrelated to their transdifferentiation potential but to their capability to restore the balance between Th1 and Th2 immunological responses along with the modification of the pancreatic microenvironment. Our data should be taken into account when designing clinical trials aimed to evaluate MSC transplantation in patients with T1DM since the presence of endogenous precursors seems to be critical in order to restore glycemic control.