DSpace Repository :: Browsing by Author "Conget, Paulette"

Browsing by Author "Conget, Paulette"

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A tetrameric peptide derived from bovine lactoferricin as a potential therapeutic tool for oral squamous cell carcinoma: A preclinical model
(PLoS, 2017) Solarte, Victor Alfonso; Conget, Paulette; Vernot, Jean-Paul; Rosas, Jaiver Eduardo; Rivera, Zuly Jenny; Garcia, Javier Eduardo; Arango-Rodríguez, Martha
Oral squamous cell carcinoma is the fifth most common epithelial cancer in the world, and its current clinical treatment has both low efficiency and poor selectivity. Cationic amphipathic peptides have been proposed as new drugs for the treatment of different types of cancer. The main goal of the present work was to determine the potential of LfcinB(20–25)4, a tetrameric peptide based on the core sequence RRWQWR of bovine lactoferricin LfcinB(20–25), for the treatment of OSCC. In brief, OSCC was induced in the buccal pouch of hamsters by applying 7,12-Dimethylbenz(a)anthracene, and tumors were treated with one of the following peptides: LfcinB(20–25)4, LfcinB(20–25), or vehicle (control). Lesions were macroscopically evaluated every two days and both histological and serum IgG assessments were conducted after 5 weeks. The size of the tumors treated with LfcinB(20–25)4 and LfcinB(20–25) was smaller than that of the control group (46.16±4.41 and 33.92±2.74 mm3 versus 88.77±10.61 mm3, respectively). Also, LfcinB(20–25)4 caused acellularity in the parenchymal tumor compared with LfcinB(20–25) and vehicle treatments. Furthermore, our results demonstrated that both LfcinB(20–25)4 and LfcinB(20–25) induced higher degree of apoptosis relative to the untreated tumors (75–86% vs 8%, respectively). Moreover, although the lowest inflammatory response was achieved when LfcinB(20–25)4 was used, this peptide appeared to induce higher levels of IgG antibodies relative to the vehicle and LfcinB(20–25). In addition the cellular damage and selectivity of the LfcinB(20–25)4 peptide was evaluated in vitro. These assays showed that LfcinB(20–25)4 triggers a selective necrotic effect in the carcinoma cell line. Cumulatively, these data indicate that LfcinB(20–25)4 could be considered as a new therapeutic agent for the treatment of OSCC.
Acellular derivatives of mesenchymal stem cells prevent peritoneal adhesions in an animal model
(2018) Rojo, Daniel; Conget, Paulette
Background: Peritoneal adhesions are nonanatomical connections that bind organs to the abdominal wall or among them. They arise after peritoneal injury, which triggers an inflammatory response followed by a healing process that leads to fibrotic tissue formation. Mesenchymal stem cells and their secretion products, also referred to as acellular derivatives (ACDs), have anti-inflammatory, fibrinolytic, and antifibrogenic properties. The aim of this study was to determine the effect of intraoperative administration of ACD on the appearance, severity, and progression of peritoneal adhesions, in an animal model. Materials and methods: Cecal erosions were mechanically induced in adult mice. Before closure, the vehicle, ACD, or Seprafilm was administered. Seven days later, the presence and grade of peritoneal adhesions were assessed macroscopically. One, 3, and 7 d after intervention, molecular and cellular markers of inflammation, fibrinolysis, and fibrogenesis were evaluated both locally and systemically. Results: ACDs avoided the appearance of clinically relevant peritoneal adhesions. The vehicle had no effect, and Seprafilm reduced them inconsistently. The antiadhesive effect of ACD was associated with an early reduction of proinflammatory cytokine (tumor necrosis factor-alpha and interferon-gamma) secretion and leukocyte (polymorphonuclears, mononuclears, and macrophages) infiltration. High levels of D-dimer, low fibrin deposits, low myofibroblasts infiltration, and less fibrosis were also observed. Conclusions: ACD administered at the end of abdominal surgeries prevents the formation of peritoneal adhesions due to the modulation of inflammatory, fibrinolytic, and fibrogenic processes.
Anterior cruciate ligament regeneration using mesenchymal stem cells and collagen type I scaffold in a rabbit model
(Springer, 2014) Figueroa, David; Espinosa, Maximiliano; Calvo, Rafael; Scheu, Maximiliano; Vaisman, Alex; Gallegos, Marcela; Conget, Paulette
Purpose: The objective of this study was to determine whether using mesenchymal stem cells (MSC) seeded in a collagen type I scaffold would be sufficient to regenerate the torn anterior cruciate ligament (ACL). Methods: Anterior cruciate ligament transection was performed on both knees in 10 New Zealand rabbits and then repaired with as follows: suture alone (suture-treated group, n = 6), suture associated with collagen type I scaffold (collagen type I scaffold-treated group, n = 8) or suture associated with autologous MSC seeded on collagen type I scaffold (MSC/collagen type I scaffold-treated group, n = 6). At 12-week post-intervention, the animals were killed and the ACLs were characterised macroscopically and histologically. Data of the 3 groups were against normal ACL (normal group, n = 10). Results: Macroscopic observation found that in MSC/collagen type I scaffold group, 33 % of specimens showed a complete ACL regeneration, with a tissue similar to the normal ACL. Regeneration was not observed in the group treated with suture alone or associated with collagen type I scaffold without cells. In the latter, only a reparative attempt at the ends was observed. Histological analysis of the regenerated ACL showed a tissue with organised collagen and peripheric vessels. Conclusions: These results provide evidence that the use of MSC seeded in a collagen type I scaffold in the treatment of ACL injuries is associated with an enhancement of ligament regeneration. This MSC-based technique is a potentially attractive tool for improving the treatment of ACL ruptures.
Assessment of Cell Viability of Fresh Osteochondral Allografts in N-Acetylcysteine-Enriched Medium
(Sage, 2018) Calvo, Rafael; Espinosa, Maximiliano; Figueroa, David; Pozo, Luz María; Conget, Paulette
Objective The purpose of this study was to evaluate the effect of N-acetylcysteine (NAC)-enriched storage medium on fresh osteochondral viability at 4°C. Our hypothesis was that the cell viability of chondrocytes obtained from human osteochondral tissue and stored at 4°C significantly improves in the presence of NAC. Design Controlled laboratory study. For this study, 8 samples of femoral condyle osteochondral tissue were obtained from patients undergoing total knee replacement. The samples were stored at either 4°C in phosphate-buffered saline (PBS) or at 3 different concentrations of NAC (NAC 1, 2, and 5 mM). Cell viability was analyzed at time 0 and 4 weeks by flow cytometry. The results of cell viability (median) were analyzed statistically using analysis of variance and Tukey's post hoc test. P values <0.05 were considered statistically significant. Results The viability at time 0 was 95.5% ± 3.7%. At 4 weeks, the cell viability was 56.8% ± 20.1% in the control group (PBS), 83.8% ± 11.9% in the group stored with NAC 1 mM, 73.4% ± 13.6% in the group stored with NAC 2 mM, and 66.4% ± 27.7% in the group stored with NAC 5 mM. A statistically significant difference from the baseline viability (time 0) was observed in the PBS control group ( P = 0.0018) but not in the other groups. A statistically significant difference was observed in the NAC 1 mM group compared with the PBS group ( P = 0.0255). Conclusion The use of NAC at 1 mM concentration improves cell viability after 4 weeks of storage in chondrocytes obtained from human osteochondral tissue.
Both quiescent and proliferating cells circulate in the blood of the invasive apple snail Pomacea canaliculata
(2020) Rodriguez, Cristian; Simon, Valeska; Conget, Paulette; Vega, Israel A
Gastropod hematopoiesis occurs at specialized tissues in some species, but the evidence also suggests that hemocyte generation is maybe widespread in the connective tissues or the blood system in others. In Ampullariidae (Caenogastropoda), both the kidney and the lung contain putative hematopoietic cells, which react to immune challenges. In the current study, we wanted to explore if hematopoiesis occurs in the blood of Pomacea canaliculata. Thus, we obtained circulating hemocytes from donor animals and tested their ability to proliferate in the blood of conspecific recipients. We tracked cell proliferation by labeling the donors' hemocytes with the fluorescent cell proliferation marker carboxyfluorescein diacetate succinimidyl ester (CFSE). Transferred CFSE-labeled hemocytes survived and proliferated into the recipients' circulation for at least 17 days. We also determined the cell cycle status of circulating hemocytes by using the propidium iodide (PI) and acridine orange (AO) staining methods. Flow cytometry analyses showed that most PI-stained hemocytes were in the G1 phase (~96%), while a lower proportion of cells were through the G2/S-M transition (~4%). When we instead used AO-staining, we further distinguished a subpopulation of cells (~5%) of low size, complexity-granularity, and RNA content. We regarded this subpopulation as quiescent cells. In separate experimental sets, we complemented these findings by assessing in circulating hemocytes two evolutionary conserved features of quiescent, undifferentiated cells. First, we used JC-1 staining to determine the mitochondrial membrane potential (Ψm) of circulating hemocytes, which is expected to be low in quiescent cells. Most hemocytes (~87%) showed high aggregation of JC-1, which indicates a high Ψm. Besides that, a small hemocyte subpopulation (~11%) showed low aggregation of the dye, thus indicating a low Ψm. It is known that the transition from a quiescent to a proliferating state associates with an increase of the Ψm. The specificity of these changes was here controlled by membrane depolarization with the Ψm disruptor CCCP. Second, we stained hemocytes with Hoechst33342 dye to determine the efflux activity of ABC transporters, which participate in the multixenobiotic resistance system characteristic of undifferentiated cells. Most hemocytes (>99%) showed a low dye-efflux activity, but a small proportion of cells (0.06-0.12%) showed a high dye-efflux activity, which was significantly inhibited by 100 and 500 μM verapamil, and thus is indicative of an undifferentiated subpopulation of circulating hemocytes. Taken together, our results suggest that, among circulating hemocytes, there are cells with the ability to proliferate or to stay in a quiescent state and behave as progenitor cells later, either in the circulation or the hematopoietic tissues/organs.
Cardiac stress test induced by dobutamine and monitored by cardiac catheterization in mice
(MYJoVE Corporation, 2013) Calligaris, Sebastian; Ricca, Micaela; Conget, Paulette
Dobutamine 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.
Could cancer and infection be adverse effects of mesenchymal stromal cell therapy?
(2015) Arango-Rodriguez, Martha L; Ezquer, Fernando; Ezquer, Marcelo; Conget, Paulette
Multipotent mesenchymal stromal cells [also referred to as mesenchymal stem cells (MSCs)] are a heterogeneous subset of stromal cells. They can be isolated from bone marrow and many other types of tissue. MSCs are currently being tested for therapeutic purposes (i.e., improving hematopoietic stem cell engraftment, managing inflammatory diseases and regenerating damaged organs). Their tropism for tumors and inflamed sites and their context-dependent potential for producing trophic and immunomodulatory factors raises the question as to whether MSCs promote cancer and/or infection. This article reviews the effect of MSCs on tumor establishment, growth and metastasis and also susceptibility to infection and its progression. Data published to date shows a paradoxical effect regarding MSCs, which seems to depend on isolation and expansion, cells source and dose and the route and timing of administration. Cancer and infection may thus be adverse or therapeutic effects arising form MSC administration.
Could donor multipotent mesenchymal stromal cells prevent or delay the onset of diabetic retinopathy?
(Wiley, 2014) Ezquer, Fernando; Ezquer, Marcelo; Arango-Rodríguez, Martha; Conget, Paulette
Diabetes mellitus is a complex metabolic disease that has become a global epidemic with more than 285 million cases worldwide. Major medical advances over the past decades have substantially improved its management, extending patients' survival. The latter is accompanied by an increased risk of developing chronic macro- and microvascular complications. Amongst them, diabetic retinopathy (DR) is the most common and frightening. Furthermore, during the past two decades, it has become the leading cause of visual loss. Irrespective of the type of diabetes, DR follows a well-known clinical and temporal course characterized by pericytes and neuronal cell loss, formation of acellular-occluded capillaries, occasional microaneurysms, increased leucostasis and thickening of the vascular basement membrane. These alterations progressively affect the integrity of retinal microvessels, leading to the breakdown of the blood-retinal barrier, widespread haemorrhage and neovascularization. Finally, tractional retinal detachment occurs leading to blindness. Nowadays, there is growing evidence that local inflammation and oxidative stress play pivotal roles in the pathogenesis of DR. Both processes have been associated with pericytes and neuronal degeneration observed early during DR progression. They may also be linked to sustained retinal vasculature damage that results in abnormal neovascularization. Currently, DR therapeutic options depend on highly invasive surgical procedures performed only at advanced stages of the disease, and which have proved to be ineffective to restore visual acuity. Therefore, the availability of less invasive and more effective strategies aimed to prevent or delay the onset of DR is highly desirable. Multipotent mesenchymal stromal cells, also referred to as mesenchymal stem cells (MSCs), are promising healing agents as they contribute to tissue regeneration by pleiotropic mechanisms, with no evidence of significant adverse events. Here, we revise the pathophysiology of DR to identify therapeutic targets for donor MSCs. Also, we discuss whether an MSC-based therapy could prevent or delay the onset of DR.
La creencia epistemológica constructivista sobre el conocimiento científico varía en función del año de formación en los estudiantes de Medicina pero no en los estudiantes de otras carreras de la salud
(2017) Lazcano, Ximena; Villalón, Francisco; Vera, Soledad; Conget, Paulette
Background: To optimize the teaching-learning process it is fundamental to know the representations that students have regarding knowledge. Epistemological beliefs are implicit theories that guide the practical actions of people. Aim: To characterize and compare epistemological beliefs regarding the nature and acquisition of scientific knowledge of health career students. Material and Methods: Between 2012 and 2013, 726 students coursing first, third or fifth year from six health careers answered a validated questionnaire that includes closed and open questions aimed to characterize their epistemological beliefs about scientific knowledge. Results: Irrespective of the career, when students had to select predefined answers, most of them appeared as constructivists (61%). On the other hand, when they had to argue, the majority seemed objectivist (47%). First-year medical students have the highest frequency of constructivist epistemological beliefs (56%). Paradoxically, the lowest percentage is found (34%) in the fifth year. The students of the health careers, in particular those of Medicine, recognize that knowledge is not acquired immediately (83%) and that its distribution is shared (92%). Conclusions: Discordance between selections and arguments suggests that epistemological sophistication is achieved declaratively but not practically. The lower proportion of students who presented constructivist beliefs in the fifth year compared to first year of Medicine could be associated with the pedagogical approaches used in the different cycles of the career.
Dexamethasone and rosiglitazone are sufficient and necessary for producing functional adipocytes from mesenchymal stem cells
(Society for Experimental Biology and Medicine by Sage, 2015) Contador, David; Ezquer, Fernando; Espinosa, Maximiliano; Arango-Rodríguez, Martha; Puebla, Carlos; Sobrevía, Luis; Conget, Paulette
The final product of adipogenesis is a functional adipocyte. This mature cell acquires the necessary machinery for lipid metabolism, loses its proliferation potential, increases its insulin sensitivity, and secretes adipokines. Multipotent mesechymal stromal cells have been recognized as a source of adipocytes both in vivo and in vitro. The in vitro adipogenic differentiation of human MSC (hMSC) has been induced up to now by using a complex stimulus which includes dexamethasone, 3-isobutyl-1-methylxanthine, indomethacin, and insulin (a classical cocktail) and evaluated according to morphological changes. The present work was aimed at demonstrating that the simultaneous activation of dexamethasone's canonical signaling pathways, through the glucocorticoid receptor and CCAAT-enhancer-binding proteins (C/EBPs) and rosiglitazone through peroxisome proliferator-activated receptor gamma (PPAR-gamma) is sufficient yet necessary for inducing hMSC adipogenic differentiation. It was also ascertained that hMSC exposed just to dexamethasone and rosiglitazone (D&R) differentiated into cells which accumulated neutral lipid droplets, expressed C/EBP-alpha, PPAR-gamma, aP2, lipoprotein lipase, acyl-CoA synthetase, phosphoenolpyruvate carboxykinase, adiponectin, and leptin genes but did not proliferate. Glucose uptake was dose dependent on insulin stimulus and high levels of adipokines were secreted (i.e. displaying not only the morphology but also expressing mature adipocytes' specific genes and functional characteristics). This work has demonstrated that (i) the activating C/EBPs and PPAR-gamma signaling pathways were sufficient to induce adipogenic differentiation from hMSC, (ii) D&R producing functional adipocytes from hMSC, (iii) D&R induce adipogenic differentiation from mammalian MSC (including those which are refractory to classical adipogenic differentiation stimuli). D&R would thus seem to be a useful tool for MSC characterization, studying adipogenesis pathways and producing functional adipocytes.
Diseño y validación de un cuestionario para evaluar oportunidades de práctica pedagógica, metacognición y lifelong learning, brindadas por los programas de formación inicial docente
(2021) Matsumoto-Royo, Kiomi; Conget, Paulette; Ramírez-Montoya, María Soledad
El objetivo del estudio fue diseñar y validar un cuestionario para recoger información respecto de las oportunidades que brindan los programas de formación inicial docente de aproximarse a la práctica pedagógica, de desarrollar habilidades de procesamiento metacognitivo y de adoptar el lifelong learning. El instrumento fue diseñado conforme a la literatura y validado usando el método Delphi. Fue aplicado en una muestra de 198 estudiantes de Pedagogía. Luego de ajustes en función de los resultados de un análisis factorial confi rmatorio, se obtuvo una versión de alta validez y confi abilidad. El cuestionario está organizado en tres dimensiones y 24 reactivos y permite estudiar desde la perspectiva de los estudiantes las acciones de los programas de formación docente, constituyendo un marco referencial para orientar las decisiones de ajuste e innovación en este ámbito de formación.
Evidence of hysteresis in propofol pharmacodynamics
(John Wiley & Sons, 2017) Sepúlveda, Pablo; Carrasco, E; Tapia, Luis; Ramos, Mario; Cruz, F; Conget, Paulette; Olivares, Q; Cortinez, I
It is commonly assumed that loss of responsiveness and recovery of responsiveness occur at similar concentrations of propofol. However, the 'conscious' and 'anaesthetised' conditions produced by general anaesthetics may behave as two bistable states. We hypothesised that loss of responsiveness and recovery of responsiveness occur at different propofol concentrations. Propofol was administered to 19 healthy volunteers by effect-site target-controlled infusion using increasing and decreasing stable concentration steps of 7 min. Propofol serum concentrations were measured from venous blood samples at the end of each 7-min step. A long step of 14 min was performed at loss of responsiveness. At this step, propofol concentrations were measured at 7 and 14 min. Propofol concentrations measured at loss of responsiveness and recovery of responsiveness were 2.6 (1.2-4.7) μg.ml-1 and 1.6 (0.6-3.3) μg.ml-1 , respectively (p < 0.001). Propofol plasma concentration and the corresponding bispectral index values measured at minute 7 and minute 14 of the long step performed at loss of responsiveness were 2.6 (1.2-4.7) vs. 2.6 (1.3-4.3) at recovery of responsiveness, (p = 0.96) and 61.2 (49.0-77.0) vs. 58.4 (45.0-74.0), (p = 0.058), respectively. Loss of responsiveness and recovery of responsiveness appear to occur at different propofol concentrations. However, it is possible that, if equilibration was not achieved between plasma and effect-sites at the end of each 7-min step, the higher concentrations found at loss of responsiveness compared with those observed during recovery of responsiveness could be explained by a possible bias in estimations of the effect-site concentrations of propofol by the Schnider model, rather than neural inertia.
Feedback as an opportunity to promote lifelong learning in pre-service teachers: a mixed methods study
(2023) Matsumoto-Royo, Kiomi; Conget, Paulette; Ramírez-Montoya, María Soledad
The aim of this study was to investigate whether, within a practice-based curriculum, feedback on the assessment tasks provided during campus coursework offers opportunities to promote lifelong learning dispositions in pre-service teachers. For this, pre-service teachers (n = 231) completed a validated questionnaire regarding lifelong learning dispositions. Then, feedback from assessment tasks (n = 14) was analyzed to identify claims related to curiosity, motivation, perseverance, and self-regulation of learning. Finally, in-depth interviews were conducted with preservice teachers (n = 8) to explore their perspectives on feedback and lifelong learning dispositions. Data triangulation was used to confirm and add depth to the findings. Feedback on assessment tasks provided during campus course work promotes lifelong learning dispositions when: (i) tied to authentic tasks, (ii) is provide not only by teacher educators but also by peers, (iii) incorporates both positive and negative comments, along with practical advice. The implication of findings for teacher education is discussed.
Identification of a Patient Cohort with Relapsing Diffuse Large B-Cell Lymphoma with a Low International Prognostic Index in PET/CT Using a 2-Gene (LMO2/TNFRSF9) Scoring System
(2020) Omidvar, Nader; Bruna, Flavia; Tekin, Nilgun; Conget, Paulette; Timar, Botond; Gagyi, Eva; Basak, Ranjan; Auewarakul, Chirayu; Sritana, Narongrit; Cerci, Juliano Julio; Dimamay, Mark Pierre; Gyorke, Tamas; Redondo, Francisca; Nair, Reena; Gorospe, Charity; Páez, Diana; Fanti, Stefano; Ozdag, Hilal; Padua, Rose Ann; Carr, Robert
Letter to the Editor
Insulin is secreted upon glucose stimulation by both gastrointestinal enteroendocrine K-cells and L-cells engineered with the preproinsulin gene
(2011) Encina Silva, Gonzalo; Ezquer, Fernando; Conget, Paulette; Israel, Yedy
Transgenic mice carrying the human insulin gene driven by the K-cell glucose-dependent insulinotropic peptide (GIP) promoter secrete insulin and display normal glucose tolerance tests after their pancreatic beta-cells have been destroyed. Establishing the existence of other types of cells that can process and secrete transgenic insulin would help the development of new gene therapy strategies to treat patients with diabetes mellitus. It is noted that in addition to GIP secreting K-cells, the glucagon-like peptide 1 (GLP-1) generating L-cells share/many similarities to pancreatic p-cells, including the peptidases required for proinsulin processing, hormone storage and a glucose-stimulated hormone secretion mechanism. In the present study, we demonstrate that not only K-cells, but also L-cells engineered with the human preproinsulin gene are able to synthesize, store and, upon glucose stimulation, release mature insulin. When the mouse enteroendocrine STC-1 cell line was transfected with the human preproinsulin gene, driven either by the K-cell specific GIP promoter or by the constitutive cytomegalovirus (CMV) promoter, human insulin co-localizes in vesicles that contain GIP (GIP or CMV promoter) or GLP-1 (CMV promoter). Exposure to glucose of engineered STC-1 cells led to a marked insulin secretion, which was 7-fold greater when the insulin gene was driven by the CMV promoter (expressed both in K-cells and L-cells) than when it was driven by the GIP promoter (expressed only in K-cells). Thus, besides pancreatic beta-cells, both gastrointestinal enteroendocrine K-cells and L-cells can be selected as the target cell in a gene therapy strategy to treat patients with type 1 diabetes mellitus.
Intraarticular administration of dexamethasone after mesenchymal stem cells implantation does not improve significantly the treatment of preestablished full-thickness chondral defect in a rabbit model
(Sage Publications, 2013) Espinosa, Maximiliano; Vaisman, Alex; Nazal, Nicolas; Figueroa, David; Gallegos, Marcela; Conget, Paulette
Objective: The aim of this study was to evaluate the contribution to hyaline cartilage regeneration of dexamethasone intraarticular administration after autologous mesenchymal stem cells (MSCs) implantation into a preestablished knee full-thickness chondral defect. Design: Full-thickness chondral defects of 4.5 × 4.5 mm2 were surgically made in both medial femoral condyles of adult male New Zealand rabbits. Two weeks later, autologous ex vivo expanded bone marrow–derived MSCs were embedded in hyaluronic acid and implanted into the chondral defects. Immediately and every week after the intervention, dexamethasone 0.25 mg/kg was intraarticularly administered (MSC/dexa-treated group). Six weeks after MSC transplantation, the animals were euthanized and condyles were characterized molecularly according to aggrecan, collagen type II, and collagen type I gene expression (quantitative reverse transcriptase-polymerase chain reaction) and histologically (hematoxylin–eosin staining). Data of MSC/dexa-treated condyles were compared with untreated, dexa-treated, MSCtreated, or normal unlesioned condyles. Results: The ratio between collagen type II expression versus collagen type I expression in MSC/dexa-treated condyles was higher than one, even though the group mean value was not statistically different from that of untreated defects. Histological changes were observed between MSC/dexa-treated and untreated defects mainly in surface regularity and in hyaline matrix abundance. However, International Cartilage Repair Society score analysis did not support robust differences between those groups. Conclusion: Intraarticular administration of dexamethasone after autologous MSC implantation into a preestablished full-thickness chondral defect does not contribute significantly to the regeneration of a tissue with molecular and histological characteristics identical to hyaline cartilage.
Intravenous administration of bone marrow-derived multipotent mesenchymal stromal cells has a neutral effect on obesity-induced diabetic cardiomyopathy
(Sociedad de Biología de Chile, 2013) Calligaris, Sebastián; Conget, Paulette
Obesity is a major global health issue. Obese patients develop metabolic syndrome, which is a cluster of clinical features characterized by insulin resistance and dyslipidemia. Its cardiac manifestation, diabetic cardiomyopathy, leads to heart failure. Bone marrow-derived multipotent mesenchymal stromal cells, also referred to as mesenchymal stem cells (MSC) are envisioned as a therapeutic tool not only for cardiovascular diseases but also for other degenerative conditions. Our aim was to evaluate whether the intravenous administration of MSC modifies cardiac dysfunction in obese mice. To this end, C57BL/6 mice were fed a regular (normal) or high-fat diet (obese). Obese animals received the vehicle (obese), a single dose (obese + 1x MSC) or three doses (obese + 3x MSC) of 0.5x106 syngeneic MSC. Two to three months following MSC administration, cardiac function was assessed by cardiac catheterization, at basal condition and after a pharmacological stress. Compared to normal mice, obese mice presented hyperglycemia, hyperinsulinemia, hypercholesterolemia and cardiac dysfunction after stress condition. Exogenous MSC neither improved nor impaired this cardiac dysfunction. Thus, intravenous administration of MSC has neutral effect on obesity-induced diabetic cardiomyopathy
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, Paulette
Background & 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.
Intravitreal administration of multipotent mesenchymal stromal cells triggers a cytoprotective microenvironment in the retina of diabetic mice
(BioMed Central, 2016) Ezquer, Marcelo; Urzúa, Cristhian; Montecino, Scarleth; Leal, Karla; Conget, Paulette; Ezquer, Fernando
Diabetic retinopathy is a common complication of diabetes and the leading cause of irreversible vision loss in the Western world. The reduction in color/contrast sensitivity due to the loss of neural cells in the ganglion cell layer of the retina is an early event in the onset of diabetic retinopathy. Multipotent mesenchymal stromal cells (MSCs) are an attractive tool for the treatment of neurodegenerative diseases, since they could differentiate into neuronal cells, produce high levels of neurotrophic factors and reduce oxidative stress. Our aim was to determine whether the intravitreal administration of adipose-derived MSCs was able to prevent the loss of retinal ganglion cells in diabetic mice. METHODS: Diabetes was induced in C57BL6 mice by the administration of streptozotocin. When retinal pro-damage mechanisms were present, animals received a single intravitreal dose of 2 × 10(5) adipose-derived MSCs or the vehicle. Four and 12 weeks later we evaluated: (a) retinal ganglion cell number (immunofluorescence); (b) neurotrophic factor levels (real-time quantitative polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA)); (c) retinal apoptotic rate (TUNEL); (d) retinal levels of reactive oxygen species and oxidative damage (ELISA); (e) electrical response of the retina (electroretinography); (f) pro-angiogenic and anti-angiogenic factor levels (RT-qPCR and ELISA); and (g) retinal blood vessels (angiography). Furthermore, 1, 4, 8 and 12 weeks post-MSC administration, the presence of donor cells in the retina and their differentiation into neural and perivascular-like cells were assessed (immunofluorescence and flow cytometry). RESULTS: MSC administration completely prevented retinal ganglion cell loss. Donor cells remained in the vitreous cavity and did not differentiate into neural or perivascular-like cells. Nevertheless, they increased the intraocular levels of several potent neurotrophic factors (nerve growth factor, basic fibroblast growth factor and glial cell line-derived neurotrophic factor) and reduced the oxidative damage in the retina. Additionally, MSC administration has a neutral effect on the electrical response of the retina and did not result in a pathological neovascularization. CONCLUSIONS: Intravitreal administration of adipose-derived MSCs triggers an effective cytoprotective microenvironment in the retina of diabetic mice. Thus, MSCs represent an interesting tool in order to prevent diabetic retinopathy.
Mice long-term high-fat diet feeding recapitulates human cardiovascular alterations: an animal model to study the early phases of diabetic cardiomyopathy
(PLoS, 2013) Calligaris, Sebastian; Lecanda, Manuel; Solis, Felipe; Ezquer, Marcelo; Gutierrez, Jaime; Brandan, Enrique; Leiva, Andrea; Sobrevia, Luis; Conget, Paulette
BACKGROUND/AIM: Hypercaloric diet ingestion and sedentary lifestyle result in obesity. Metabolic syndrome is a cluster of clinical features secondary to obesity, considered as a pre-diabetic condition and recognized as an independent risk factor for cardiovascular diseases. To better understand the relationship between obesity, metabolic syndrome and cardiovascular disease as well as for the development of novel therapeutic strategies, animal models that reproduce the etiology, course and outcomes of these pathologies are required. The aim of this work was to characterize the long-term effects of high-fat diet-induced obesity on the mice cardiovascular system, in order to make available a new animal model for diabetic cardiomyopathy. METHODS/RESULTS: Male C57BL/6 mice were fed with a standardized high-fat diet (obese) or regular diet (normal) for 16 months. Metabolic syndrome was evaluated testing plasma glucose, triglycerides, cholesterol, insulin, and glucose tolerance. Arterial pressure was measured using a sphygmomanometer (non invasive method) and by hemodynamic parameters (invasive method). Cardiac anatomy was described based on echocardiography and histological studies. Cardiac function was assessed by cardiac catheterization under a stress test. Cardiac remodelling and metabolic biomarkers were assessed by RT-qPCR and immunoblotting. As of month eight, the obese mice were overweight, hyperglycaemic, insulin resistant, hyperinsulinemic and hypercholesterolemic. At month 16, they also presented normal arterial pressure but altered vascular reactivity (vasoconstriction), and cardiac contractility reserve reduction, heart mass increase, cardiomyocyte hypertrophy, cardiac fibrosis, and heart metabolic compensations. By contrast, the normal mice remained healthy throughout the study. CONCLUSIONS: Mice fed with a high-fat diet for prolonged time recapitulates the etiology, course and outcomes of the early phases of human diabetic cardiomyopathy.

Browsing by Author "Conget, Paulette"

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