Núria Solanes

Allogeneic adipose stem cell therapy in acute myocardial infarction.

Stem cell therapy offers a promising approach to reduce the long‐term mortality rate associated with heart failure after acute myocardial infarction (AMI). To date, in vivo translational studies have not yet fully studied the immune response to allogeneic adipose tissue‐derived mesenchymal stem cells (ATMSCs). We analysed the immune response and the histological and functional effects of allogeneic ATMSCs in a porcine model of reperfused AMI and determine the effect of administration timing.

Effects of cyclosporine, tacrolimus and sirolimus on vascular changes related to immune response.

BACKGROUND Despite the use of newer immunosuppressors such as sirolimus (SRL) and tacrolimus (TRL) in heart transplantation, the rate of humoral rejection has remained unchanged. The aim of this study was to analyze the immunologic and histologic effects of cyclosporine (CsA), SRL, and TRL in a porcine model of arterial transplantation. METHODS Each transplant recipient animal (n = 49) received an autograft and an allograft and was then allocated to one of four treatment groups and a 7- or 30-day follow-up period, as follows: a WOT group (without immunosuppressor treatment), 7 days (n = 6) and 30 days (n = 5); a CsA group, 7 days (n = 5) and 30 days (n = 6); an SRL group, 7 days (n = 7) and 30 days (n = 8); and a TRL group, 7 days (n = 6) and 30 days (n = 6). The presence of donor-specific antibodies (DSA) was tested at the end of the follow-up period. Morphometric parameters and inflammatory infiltration were analyzed in the explanted grafts. RESULTS At 30-day follow-up, SRL was the only treatment capable of suppressing DSA formation (0 of 7 vs 4 of 5 in the WOT group; p < 0.05). SRL completely prevented aneurismal dilation and reduced the number of macrophages in the allografts. TRL treatment achieved a greater reduction of T lymphocytes. CsA did not prevent the reduction in total vascular area at 7 days that was achieved with the SRL and TRL groups. Animals treated with CsA had the largest number of T lymphocytes and macrophages in both follow-up periods. CONCLUSIONS SRL prevented DSA formation and reduced the number of macrophages as compared with TRL and CsA.

Hemosiderin Deposits Confounds Tracking of Iron-Oxide-Labeled Stem Cells: An Experimental Study

BACKGROUND The aim of the present research was to study the possible interference of hemosiderin deposits with the histological detection of dextran-coated, iron-labeled, mesenchymal stem cells after intracoronary administration in a porcine model of myocardial infarction. MATERIALS AND METHODS A myocardial infarction was induced in six animals that received intracoronary iron-labeled autologous mesenchymal stem cells (group 1; n = 2) or placebo (group 2; n = 4). Six control animals without myocardial infarction underwent direct intramyocardial injections of iron-labeled autologous mesenchymal stem cells (group 3; n = 2) or placebo (group 4; n = 4). Histological sections from explanted hearts were stained with Prussian blue to identify dextran-coated, iron-labeled, mesenchymal stem cells. RESULTS After Prussian blue staining, granular blue labeling in the tissue was observed in both groups of animals with infarcts. Similar granular blue labeling was detected in hearts from control animals without infarction that had received iron-labeled mesenchymal stem cells. However, hearts from control animals without infarction that received placebo did not have any granular blue labeling in the tissue. CONCLUSIONS Hemosiderin from infarction hemorrhage interferes with detection of dextran-coated iron-labeled mesenchymal stem cells after intracoronary administration, suggesting that this marker is not useful to detect mesenchymal stem cells in a porcine model of myocardial infarction.

Histological basis of the porcine femoral artery for vascular research.

The similarities between the porcine and human cardiovascular systems make the pig a useful animal model for the study of vascular biology. However, a standardized method is needed to describe the normal histological properties of porcine arteries in order to evaluate pathologic lesions in future studies. Descriptive and morphometric analyses were done on 16 porcine femoral arteries. For these purposes, three histological stains (haematoxylin eosin, Massons trichrome, and orcein), four immunohistochemical methods (using antibodies anti‐α‐actin, anti‐CD3, anti‐L1 and anti‐lysozyme), and a glycohistochemical method (using Dolichos biflorus lectin) were performed. The porcine femoral arteries evaluated had a mean total area of 6.25 ± 1.99 mm2 and a diameter of 2.79 ± 0.41 mm. The majority of the total area was occupied by the medial layer (42.97 ± 5.38%) and was mainly constituted by smooth muscle cells (94.58 ± 2.65%). All the cell markers used reacted with porcine paraffin‐embedded tissue. However, the anti‐lysozyme antibody was excluded from this histological analysis because of cytoplasmatic reactivity in smooth muscle cells. In summary, this study proposes histological methods to describe the normal characteristics of the porcine femoral artery and raises the possibility of applying this methodology in future studies on porcine vascular research.

Development of a Swine Model of Left Bundle Branch Block for Experimental Studies of Cardiac Resynchronization Therapy

Animal models that mimic human electrical and mechanical dyssynchrony often associated with chronic heart failure would provide an essential tool to investigate factors influencing response to cardiac resynchronization therapy. A standardized closed-chest porcine model of left bundle branch block (LBBB) was developed using 16 pigs. Radiofrequency applications were performed to induce LBBB, which was confirmed by QRS widening, a surface electrocardiogram pattern concordant with LBBB, and a prolonged activation time from endocardial. Echocardiography confirmed abnormal motion of the septum, which was not present at the baseline echocardiogram. High susceptibility of pigs to ventricular fibrillation during the endocardial ablation was overcome by applying high-rate pacing during radiofrequency applications. This is the first study to devise a closed-chest porcine model of LBBB that closely reproduces abnormalities found in patients with electrical and mechanical cardiac dyssynchrony, and provides a useful tool to investigate the basic mechanisms underlying cardiac resynchronization therapy benefits in heart failure.

El estradiol potencia la vasodilatación dependiente del endotelio a través del óxido nítrico

Introduccion y objetivo El mecanismo por el cual el estradiol lleva a cabo su efecto vasodilatador sobre la pared arterial es todavia controvertido. El objetivo de este estudio fue evaluar si el estradiol potencia la vasodilatacion dependiente del endotelio en un modelo experimental humano in vitro y si este efecto se halla mediado por el oxido nitrico. Metodos Estudiamos 18 anillos arteriales procedentes de arterias mamarias internas de pacientes sometidos a cirugia de revascularizacion miocardica utilizando una camara de bano de organos. Se evaluo la respuesta a la acetilcolina en situacion basal y tras la adicion de 10–6 mol/l de estradiol al medio, en presencia o no de un inhibidor de la oxido nitrico sintetasa (L-NNA, 10–4 mol/l). Resultados El estradiol potencio de manera significativa la relajacion de los anillos arteriales en respuesta a la acetilcolina (52 ± 20% con estradiol frente a 42 ± 22% en situacion basal; n = 10; p = 0,02). Esta mejoria en la relajacion dependiente del endotelio mediada por acetilcolina tras la adicion de estradiol al medio no se demostro en presencia de L-NNA (47 ± 25% con estradiol frente a 38 ± 22% sin estradiol; n = 8; p = NS). Conclusiones El estradiol produce in vitro un aumento de la vasodilatacion dependiente del endotelio en los anillos arteriales de la arteria mamaria interna humana, efecto que disminuye al anadir al medio un inhibidor de la sintesis de oxido nitrico. Por tanto, el efecto vasodilatador del estradiol a las dosis utilizadas esta mediado por la liberacion de oxido nitrico.

Intracoronary Administration of Allogeneic Adipose Tissue–Derived Mesenchymal Stem Cells Improves Myocardial Perfusion But Not Left Ventricle Function, in a Translational Model of Acute Myocardial Infarction

Background Autologous adipose tissue–derived mesenchymal stem cells (ATMSCs) therapy is a promising strategy to improve post–myocardial infarction outcomes. In a porcine model of acute myocardial infarction, we studied the long‐term effects and the mechanisms involved in allogeneic ATMSCs administration on myocardial performance. Methods and Results Thirty‐eight pigs underwent 50 minutes of coronary occlusion; the study was completed in 33 pigs. After reperfusion, allogeneic ATMSCs or culture medium (vehicle) were intracoronarily administered. Follow‐ups were performed at short (2 days after acute myocardial infarction vehicle‐treated, n=10; ATMSCs‐treated, n=9) or long term (60 days after acute myocardial infarction vehicle‐treated, n=7; ATMSCs‐treated, n=7). At short term, infarcted myocardium analysis showed reduced apoptosis in the ATMSCs‐treated animals (48.6±6% versus 55.9±5.7% in vehicle; P=0.017); enhancement of the reparative process with up‐regulated vascular endothelial growth factor, granulocyte macrophage colony‐stimulating factor, and stromal‐derived factor‐1α gene expression; and increased M2 macrophages (67.2±10% versus 54.7±10.2% in vehicle; P=0.016). In long‐term groups, increase in myocardial perfusion at the anterior infarct border was observed both on day‐7 and day‐60 cardiac magnetic resonance studies in ATMSCs‐treated animals, compared to vehicle (87.9±28.7 versus 57.4±17.7 mL/min per gram at 7 days; P=0.034 and 99±22.6 versus 43.3±14.7 22.6 mL/min per gram at 60 days; P=0.0001, respectively). At day 60, higher vascular density was detected at the border zone in the ATMSCs‐treated animals (118±18 versus 92.4±24.3 vessels/mm2 in vehicle; P=0.045). Cardiac magnetic resonance–measured left ventricular ejection fraction of left ventricular volumes was not different between groups at any time point. Conclusions In this porcine acute myocardial infarction model, allogeneic ATMSCs‐based therapy was associated with increased cardioprotective and reparative mechanisms and with better cardiac magnetic resonance–measured perfusion. No effect on left ventricular volumes or ejection fraction was observed.

Enalaprilat, losartan and LU 135252 in coronary blood flow regulation

Background High plasma levels of angiotensin II are found in several pathologies such as hypertension, heart failure and myocardial infarction. The effect of high concentrations of angiotensin II on coronary circulation is not well defined. The aim of the present study was to assess coronary blood flow regulation during tachycardia in the presence of elevated coronary plasma levels of angiotensin II, and the changes induced by ACE inhibition and blockade of angiotensin II and endothelin‐A receptors.

ALLOGENEIC ADIPOSE STEM CELL THERAPY REDUCES APOPTOSIS AND PROMOTES ANTI-INFLAMMATORY MACROPHAGES PHENOTYPE IN A PORCINE MODEL OF ACUTE MYOCARDIAL INFARCTION

Adipose stem cells (ATMSCs) therapy offers a promising approach to promoting myocardial regeneration and preventing ventricular remodelling after an acute myocardial infarction (AMI). AMI was induced in 20 pigs by occlusion of coronary artery for 50 minutes. After reperfusion, pigs received culture

INTRACORONARY ADMINISTRATION OF ALLOGENEIC ADIPOSE TISSUE-DERIVED STEM CELLS IN A PORCINE MODEL OF ACUTE MYOCARDIAL INFARCTION: STUDY OF IMMUNE RESPONSE AND TIMING OF ADMINISTRATION

Methods: ADSCs were isolated from 6 donor pigs and labeled by transfection. AMI was induced by occlusion of the left anterior descending artery. Animals that survived the AMI induction (24/26) received: culture medium on the same day of AMI (n = 6); ADSCs on the same day of AMI (n = 6), culture medium 7 days after AMI (n = 6), or ADSCs 7 days after AMI (n = 6). At three weeks follow-up, cardiac function and alloantibodies formation were tested. Histological analysis was performed to study ADSCs implantation and differentiation, vascular density,T cells and vascular endothelial growth factor expression.