Bogdan Preda | Romanian Academy of Science (original) (raw)

Papers by Bogdan Preda

Open Research Europe

Soft skills are the elementary management, personal, and interpersonal abilities that are vital f... more Soft skills are the elementary management, personal, and interpersonal abilities that are vital for an individual to be efficient at workplace or in their personal life. Each work place requires different set of soft skills. Thus, in addition to scientific/technical skills that are easier to access within a short time frame, several key soft skills are essential for the success of a researcher in today’s international work environment. In this paper, the trainees and trainers of the EU-CardioRNA COST Action CA17129 training school on soft skills present basic and advanced soft skills for early career researchers. Here, we particularly emphasize on the importance of transferable and presentation skills, ethics, literature reading and reviewing, research protocol and grant writing, networking, and career opportunities for researchers. All these skills are vital but are often overlooked by some scholars. We also provide tips to ace in aforementioned skills that are crucial in a day-to-...

Romanian Journal of Cardiology, 2021

Mesenchymal stromal cells (MSC) are nonhematopoietic cells with fibroblast-like morphology and mu... more Mesenchymal stromal cells (MSC) are nonhematopoietic cells with fibroblast-like morphology and multipotent capacity that are widely used in pre-clinical and clinical investigations. Unfortunately, the efficiency of MSC treatment is hindered by the poor survival rate after transplantation at the damaged tissue. The goal of this study was to investigate the fate of MSC exposed to various stimuli mimicking the in vivo microenvironment post transplantation. To this aim, murine bone marrow–derived MSC were stimulated with IFNγ and TNFα under low oxygen (hypoxia) or atmospheric (normoxia) conditions for 24 to 72 hours, in order to better mimic an ischemic injury. The results showed that MSC pre-stimulation with TNFα and IFNγ enhanced immunosuppressive pathways by over-expression of NOS2, IDO, COX2 and production of NO. However, MSC viability was affected by these two cytokines in dose-dependent and time-dependent manners. Besides, priming with TNFα and/or IFNγ under low oxygen concentrati...

Frontiers in Cardiovascular Medicine, 2022

Deregulation of microRNA (miRNA) profile has been reportedly linked to the aging process, which i... more Deregulation of microRNA (miRNA) profile has been reportedly linked to the aging process, which is a dominant risk factor for many pathologies. Among the miRNAs with documented roles in aging-related cardiac diseases, miR-18a, -21a, -22, and -29a were mainly associated with hypertrophy and/or fibrosis; however, their relationship to aging was not fully addressed before. The purpose of this paper was to evaluate the variations in the expression levels of these miRNAs in the aging process. To this aim, multiple organs were harvested from young (2–3-months-old), old (16–18-months-old), and very old (24–25-months-old) mice, and the abundance of the miRNAs was evaluated by quantitative real-time (RT)-PCR. Our studies demonstrated that miR-21a, miR-22, and miR-29a were upregulated in the aged heart. Among them, miR-29a was highly expressed in many other organs, i.e., the brain, the skeletal muscle, the pancreas, and the kidney, and its expression was further upregulated during the natural...

Hybrid Organic-Inorganic Interfaces, 2017

Stem Cell Research & Therapy, 2021

Background Mesenchymal stem/stromal cells (MSC) represent adult cells with multipotent capacity. ... more Background Mesenchymal stem/stromal cells (MSC) represent adult cells with multipotent capacity. Besides their capacity to differentiate into multiple lineages in vitro and in vivo, increasing evidence points towards the immunomodulatory capacity of these cells, as an important feature for their therapeutic power. Although not included in the minimal criteria established by the International Society for Cellular Therapy as a defining MSC attribute, demonstration of the immunomodulatory capacity of MSC can be useful for the characterization of these cells before being considered MSC. Methods Here we present a simple and reliable protocol by which the immunosuppressive effect of mouse bone marrow-derived MSC can be evaluated in vitro. It is based on the measuring of the proliferation of activated T cells cultured in direct contact with irradiated MSC. Results Our results showed that mouse MSC have a dose-dependent inhibitory effect on activated T cell proliferation, which can be quant...

Journal of Cellular and Molecular Medicine, 2020

Subcutaneous transplantation of mesenchymal stromal cells (MSC) emerged as an alternative to intr... more Subcutaneous transplantation of mesenchymal stromal cells (MSC) emerged as an alternative to intravenous administration because it avoids the pulmonary embolism and prolongs post‐transplantation lifetime. The goal of this study was to investigate the mechanisms by which these cells could affect remote organs. To this aim, murine bone marrow–derived MSC were subcutaneously transplanted in different anatomical regions and the survival and behaviour have been followed. The results showed that upon subcutaneous transplantation in mice, MSC formed multicellular aggregates and did not migrate significantly from the site of injection. Our data suggest an important role of hypoxia‐inducible signalling pathways in stimulating local angiogenesis and the ensuing modulation of the kinetics of circulating cytokines with putative protective effects at distant sites. These data expand the current understanding of cell behaviour after subcutaneous transplantation and contribute to the development of a non‐invasive cell‐based therapy for distant organ protection.

International Journal of Molecular Sciences, 2021

Mesenchymal stromal cells (MSC) are promising candidates for regenerative therapy of the infarcte... more Mesenchymal stromal cells (MSC) are promising candidates for regenerative therapy of the infarcted heart. However, poor cell retention within the transplantation site limits their potential. We hypothesized that MSC benefits could be enhanced through a dual-cell approach using jointly endothelial colony forming cells (ECFC) and MSC. To assess this, we comparatively evaluated the effects of the therapy with MSC and ECFC versus MSC-only in a mouse model of myocardial infarction. Heart function was assessed by echocardiography, and the molecular crosstalk between MSC and ECFC was evaluated in vitro through direct or indirect co-culture systems. We found that dual-cell therapy improved cardiac function in terms of ejection fraction and stroke volume. In vitro experiments showed that ECFC augmented MSC effector properties by increasing Connexin 43 and Integrin alpha-5 and the secretion of healing-associated molecules. Moreover, MSC prompted the organization of ECFC into vascular networks...

Cardiovascular diseases are the leading cause of death worldwide and one of the most important cl... more Cardiovascular diseases are the leading cause of death worldwide and one of the most important clinical manifestations of these is represented by ischemic heart disease. This pathological condition of the heart is characterized by reduced coronary flow in a certain region of the heart, which results in the appearance of myocardial necrosis due to ischemia. The development of heart failure after myocardial infarction is strongly related to alterations in the geometry, function and structure of heart, that are collectively called "ventricular remodeling". The current treatment of heart failure can only improve symptoms but can not reverse the loss of myocardial tissue by replacing dead cells with new contracting cardiomyocytes (CMC). The only current alternative to the more severe pathological manifestations of heart failure is heart transplantation, but this therapeutic intervention is limited, not only because of the high costs that are involved, but also due to unavailabi...

There is continuing interest in therapeutic applications of bone marrow-derived mesenchymal strom... more There is continuing interest in therapeutic applications of bone marrow-derived mesenchymal stromal cells (MSC). Unlike human counterparts, mouse MSC are difficult to propagate in vitro due to their contamination with adherent hematopoietic cells that overgrow the cultures. Here we investigated the properties of these contaminating cells, referred to as bone marrow-derived proliferating hematopoietic cells (BM-PHC). The results showed that both BM-PHC and MSC had strong immunomodulatory properties on T cells in vitro, with PGE2 and NO involved in this mechanism. However, BM-PHC were stronger immunomodulators than MSC, with CCL-6 identified as putative molecule responsible for superior effects. In vivo studies showed that, in contrast to BM-PHC, MSC endorsed a more rapid xenograft tumor rejection, thus indicating a particular context in which only MSC therapy would produce positive outcomes. In conclusion, bone marrow contains two cell populations with immunomodulatory properties, wh...

Background and aim. The intrapancreatic injection of mesenchymal stromal cells may be a viable de... more Background and aim. The intrapancreatic injection of mesenchymal stromal cells may be a viable delivery route for experimental therapy in type 1 diabetes. Adequate in vivo cell imaging is important to evaluate the treatment efficiency, the fate of the transplanted cells, and the mechanisms of the effects observed. Here, we present a technique for delivering these cells into the mouse pancreas and tracking them using fluorescent near-infrared quantum dots and in vivo imaging. Methods and results. Bone marrow-derived mesenchymal stromal cells isolated from NOD mice were cultured and labeled with Qdots 800 nanocrystals, before being injected in the pancreas of pre-diabetic mice. In vivo analysis (IVIS Spectrum system) showed that the cells were successfully injected and remained localized in the pancreas for at least 24 hours. Conclusions. Labeling of mesenchymal stromal cells with Qdots 800 nanocrystals is a reliable method for in vivo cell tracking, after local delivery in the pancreas.

Aging determines a multilevel functional decline and increases the risk for cardiovascular pathol... more Aging determines a multilevel functional decline and increases the risk for cardiovascular pathologies. MicroRNAs are recognized as fine tuners of all cellular functions, being involved in various cardiac diseases. The heart is one of the most affected organs in aged individuals, however little is known about the extent and robustness to which miRNA profiles are modulated in cardiac cells during aging. This paper provides a comprehensive characterization of the aging-associated miRNA profile in the murine cardiac fibroblasts, which are increasingly recognized for their active involvement in the cardiac physiology and pathology. Next-generation sequencing of cardiac fibroblasts isolated from young and old mice revealed that an important fraction of the miRNAs generated by the Meg3-Mirg locus was downregulated during aging. To address the specificity of this repression, four miRNAs selected as representative for this locus were further assessed in other cells and organs isolated from ...

Comparative medicine, 2010

This paper evaluates the modifications induced by ischemia and ischemia-reperfusion in mice after... more This paper evaluates the modifications induced by ischemia and ischemia-reperfusion in mice after permanent or transient, respectively, ligation of the left coronary artery and establishes a correlation among the extent of ischemia, electrocardiograph features, and infarct size. The left coronary artery was ligated 1 mm distal from the tip of the left auricle. Histologic analysis revealed that 30-min ischemia (n = 9) led to infarction involving 9.7% ± 0.5% of the left ventricle, whereas 1-h ischemia (n = 9) resulted in transmural infarction of 16.1% ± 4.6% of the left ventricle. In contrast, 24-h ischemia (n = 8) and permanent ischemia (n = 8) induced similarly sized infarcts (33% ± 2% and 31.8% ± 0.7%, respectively), suggesting ineffective reperfusion after 24-h ischemia. Electrocardiography revealed that ligation of the left coronary artery led to ST height elevation (204 compared with 14 μV) and QTc prolongation (136 compared with 76 ms). Both parameters rapidly normalized on rep...

Stem Cells and Development, 2013

Stem cell-based therapy for myocardial regeneration has reported several functional improvements ... more Stem cell-based therapy for myocardial regeneration has reported several functional improvements that are attributed mostly to the paracrine effects stimulating angiogenesis and cell survival. This study was conducted to comparatively evaluate the potential of factors secreted by mesenchymal stem cells (MSCs) in normoxic and hypoxic conditions to promote tissue repair by sustaining endothelial cell (EC) adhesion and proliferation and conferring protection against apoptosis. To this aim, a conditioned medium (CM) was generated from MSCs after 24-h incubation in a serum-free normal or hypoxic environment. MSCs exhibited resistance to hypoxia, which induced increased secretion of vascular endothelial growth factor (VEGF) and decreased levels of other cytokines, including stromal-derived factor-1 (SDF). The CM derived from normal (nMSC-CM) and hypoxic cells (hypMSC-CM) induced similar protective effects on H9c2 cells in hypoxia. Minor differences were noticed in the potential of normal versus hypoxic CM to promote angiogenesis, which were likely connected to SDFa and VEGF levels: the nMSC-CM was more effective in stimulating EC migration, whereas the hypMSC-CM had an enhanced effect on EC adhesion. However, the factors secreted by MSCs in normoxic or hypoxic conditions supported adhesion, but not proliferation, of ECs in vitro, as revealed by impedance-based dynamic assessments. Surprisingly, factors secreted by other stem/progenitor cells, such as endothelial progenitor cells (EPCs), had complementary effects to the MSC-CM. Thus, the EPC-CM, in either a normal or hypoxic environment, supported EC proliferation, but did not sustain EC adhesion. Combined use of the MSC-CM and EPC-CM promoted both EC adhesion and proliferation, suggesting that the local angiogenesis at the site of ischemic injury might be better stimulated by simultaneous releasing of factors secreted by multiple stem/progenitor cell populations.

Frontiers in Immunology

Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were p... more Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were phenotypically classified into pro-inflammatory N1 and anti-inflammatory N2 sub-populations, but the functional differences between the two subtypes are not completely understood. We aimed to investigate the phenotypic and functional differences between N1 and N2 neutrophils, and to identify the potential contribution of the S100A9 alarmin in neutrophil polarization. We describe distinct transcriptomic profiles and functional differences between N1 and N2 neutrophils. Compared to N2, the N1 neutrophils exhibited: i) higher levels of ROS and oxidative burst, ii) increased activity of MPO and MMP-9, and iii) enhanced chemotactic response. N1 neutrophils were also characterized by elevated expression of NADPH oxidase subunits, as well as activation of the signaling molecules ERK and the p65 subunit of NF-kB. Moreover, we found that the S100A9 alarmin promotes the chemotactic and enzymatic ac...

Cell Death & Disease

Mesenchymal stromal cells (MSC) are attractive tools for cell-based therapy, yet the mechanisms u... more Mesenchymal stromal cells (MSC) are attractive tools for cell-based therapy, yet the mechanisms underlying their migration and survival post-transplantation are unclear. Accumulating evidence indicates that MSC apoptosis modulates both innate and adaptive immune responses which impact on MSC therapeutic effects. Using a dual tracking system, namely the Luciferase expression and VivoTrack680 labelling, and in vivo optical imaging, we investigated the survival and migration of MSC transplanted by various routes (intravenous, subcutaneous, intrapancreatic and intrasplenic) in order to identify the best delivery approach that provides an accumulation of therapeutic cells to the injured pancreas in the non-obese diabetic (NOD) mouse. The results showed that transplanted MSC had limited migration capacity, irrespective of the administration route, and were short-lived with almost total disappearance at 7 days after transplantation. Within one day after transplantation, cells activated hyp...

Nature Communications

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Nature Communications

We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG ... more We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O2 in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its bi...

Open Research Europe

Soft skills are the elementary management, personal, and interpersonal abilities that are vital f... more Soft skills are the elementary management, personal, and interpersonal abilities that are vital for an individual to be efficient at workplace or in their personal life. Each work place requires different set of soft skills. Thus, in addition to scientific/technical skills that are easier to access within a short time frame, several key soft skills are essential for the success of a researcher in today’s international work environment. In this paper, the trainees and trainers of the EU-CardioRNA COST Action CA17129 training school on soft skills present basic and advanced soft skills for early career researchers. Here, we particularly emphasize on the importance of transferable and presentation skills, ethics, literature reading and reviewing, research protocol and grant writing, networking, and career opportunities for researchers. All these skills are vital but are often overlooked by some scholars. We also provide tips to ace in aforementioned skills that are crucial in a day-to-...

Romanian Journal of Cardiology, 2021

Mesenchymal stromal cells (MSC) are nonhematopoietic cells with fibroblast-like morphology and mu... more Mesenchymal stromal cells (MSC) are nonhematopoietic cells with fibroblast-like morphology and multipotent capacity that are widely used in pre-clinical and clinical investigations. Unfortunately, the efficiency of MSC treatment is hindered by the poor survival rate after transplantation at the damaged tissue. The goal of this study was to investigate the fate of MSC exposed to various stimuli mimicking the in vivo microenvironment post transplantation. To this aim, murine bone marrow–derived MSC were stimulated with IFNγ and TNFα under low oxygen (hypoxia) or atmospheric (normoxia) conditions for 24 to 72 hours, in order to better mimic an ischemic injury. The results showed that MSC pre-stimulation with TNFα and IFNγ enhanced immunosuppressive pathways by over-expression of NOS2, IDO, COX2 and production of NO. However, MSC viability was affected by these two cytokines in dose-dependent and time-dependent manners. Besides, priming with TNFα and/or IFNγ under low oxygen concentrati...

Frontiers in Cardiovascular Medicine, 2022

Deregulation of microRNA (miRNA) profile has been reportedly linked to the aging process, which i... more Deregulation of microRNA (miRNA) profile has been reportedly linked to the aging process, which is a dominant risk factor for many pathologies. Among the miRNAs with documented roles in aging-related cardiac diseases, miR-18a, -21a, -22, and -29a were mainly associated with hypertrophy and/or fibrosis; however, their relationship to aging was not fully addressed before. The purpose of this paper was to evaluate the variations in the expression levels of these miRNAs in the aging process. To this aim, multiple organs were harvested from young (2–3-months-old), old (16–18-months-old), and very old (24–25-months-old) mice, and the abundance of the miRNAs was evaluated by quantitative real-time (RT)-PCR. Our studies demonstrated that miR-21a, miR-22, and miR-29a were upregulated in the aged heart. Among them, miR-29a was highly expressed in many other organs, i.e., the brain, the skeletal muscle, the pancreas, and the kidney, and its expression was further upregulated during the natural...

Hybrid Organic-Inorganic Interfaces, 2017

Stem Cell Research & Therapy, 2021

Background Mesenchymal stem/stromal cells (MSC) represent adult cells with multipotent capacity. ... more Background Mesenchymal stem/stromal cells (MSC) represent adult cells with multipotent capacity. Besides their capacity to differentiate into multiple lineages in vitro and in vivo, increasing evidence points towards the immunomodulatory capacity of these cells, as an important feature for their therapeutic power. Although not included in the minimal criteria established by the International Society for Cellular Therapy as a defining MSC attribute, demonstration of the immunomodulatory capacity of MSC can be useful for the characterization of these cells before being considered MSC. Methods Here we present a simple and reliable protocol by which the immunosuppressive effect of mouse bone marrow-derived MSC can be evaluated in vitro. It is based on the measuring of the proliferation of activated T cells cultured in direct contact with irradiated MSC. Results Our results showed that mouse MSC have a dose-dependent inhibitory effect on activated T cell proliferation, which can be quant...

Journal of Cellular and Molecular Medicine, 2020

Subcutaneous transplantation of mesenchymal stromal cells (MSC) emerged as an alternative to intr... more Subcutaneous transplantation of mesenchymal stromal cells (MSC) emerged as an alternative to intravenous administration because it avoids the pulmonary embolism and prolongs post‐transplantation lifetime. The goal of this study was to investigate the mechanisms by which these cells could affect remote organs. To this aim, murine bone marrow–derived MSC were subcutaneously transplanted in different anatomical regions and the survival and behaviour have been followed. The results showed that upon subcutaneous transplantation in mice, MSC formed multicellular aggregates and did not migrate significantly from the site of injection. Our data suggest an important role of hypoxia‐inducible signalling pathways in stimulating local angiogenesis and the ensuing modulation of the kinetics of circulating cytokines with putative protective effects at distant sites. These data expand the current understanding of cell behaviour after subcutaneous transplantation and contribute to the development of a non‐invasive cell‐based therapy for distant organ protection.

International Journal of Molecular Sciences, 2021

Mesenchymal stromal cells (MSC) are promising candidates for regenerative therapy of the infarcte... more Mesenchymal stromal cells (MSC) are promising candidates for regenerative therapy of the infarcted heart. However, poor cell retention within the transplantation site limits their potential. We hypothesized that MSC benefits could be enhanced through a dual-cell approach using jointly endothelial colony forming cells (ECFC) and MSC. To assess this, we comparatively evaluated the effects of the therapy with MSC and ECFC versus MSC-only in a mouse model of myocardial infarction. Heart function was assessed by echocardiography, and the molecular crosstalk between MSC and ECFC was evaluated in vitro through direct or indirect co-culture systems. We found that dual-cell therapy improved cardiac function in terms of ejection fraction and stroke volume. In vitro experiments showed that ECFC augmented MSC effector properties by increasing Connexin 43 and Integrin alpha-5 and the secretion of healing-associated molecules. Moreover, MSC prompted the organization of ECFC into vascular networks...

Cardiovascular diseases are the leading cause of death worldwide and one of the most important cl... more Cardiovascular diseases are the leading cause of death worldwide and one of the most important clinical manifestations of these is represented by ischemic heart disease. This pathological condition of the heart is characterized by reduced coronary flow in a certain region of the heart, which results in the appearance of myocardial necrosis due to ischemia. The development of heart failure after myocardial infarction is strongly related to alterations in the geometry, function and structure of heart, that are collectively called "ventricular remodeling". The current treatment of heart failure can only improve symptoms but can not reverse the loss of myocardial tissue by replacing dead cells with new contracting cardiomyocytes (CMC). The only current alternative to the more severe pathological manifestations of heart failure is heart transplantation, but this therapeutic intervention is limited, not only because of the high costs that are involved, but also due to unavailabi...

There is continuing interest in therapeutic applications of bone marrow-derived mesenchymal strom... more There is continuing interest in therapeutic applications of bone marrow-derived mesenchymal stromal cells (MSC). Unlike human counterparts, mouse MSC are difficult to propagate in vitro due to their contamination with adherent hematopoietic cells that overgrow the cultures. Here we investigated the properties of these contaminating cells, referred to as bone marrow-derived proliferating hematopoietic cells (BM-PHC). The results showed that both BM-PHC and MSC had strong immunomodulatory properties on T cells in vitro, with PGE2 and NO involved in this mechanism. However, BM-PHC were stronger immunomodulators than MSC, with CCL-6 identified as putative molecule responsible for superior effects. In vivo studies showed that, in contrast to BM-PHC, MSC endorsed a more rapid xenograft tumor rejection, thus indicating a particular context in which only MSC therapy would produce positive outcomes. In conclusion, bone marrow contains two cell populations with immunomodulatory properties, wh...

Background and aim. The intrapancreatic injection of mesenchymal stromal cells may be a viable de... more Background and aim. The intrapancreatic injection of mesenchymal stromal cells may be a viable delivery route for experimental therapy in type 1 diabetes. Adequate in vivo cell imaging is important to evaluate the treatment efficiency, the fate of the transplanted cells, and the mechanisms of the effects observed. Here, we present a technique for delivering these cells into the mouse pancreas and tracking them using fluorescent near-infrared quantum dots and in vivo imaging. Methods and results. Bone marrow-derived mesenchymal stromal cells isolated from NOD mice were cultured and labeled with Qdots 800 nanocrystals, before being injected in the pancreas of pre-diabetic mice. In vivo analysis (IVIS Spectrum system) showed that the cells were successfully injected and remained localized in the pancreas for at least 24 hours. Conclusions. Labeling of mesenchymal stromal cells with Qdots 800 nanocrystals is a reliable method for in vivo cell tracking, after local delivery in the pancreas.

Aging determines a multilevel functional decline and increases the risk for cardiovascular pathol... more Aging determines a multilevel functional decline and increases the risk for cardiovascular pathologies. MicroRNAs are recognized as fine tuners of all cellular functions, being involved in various cardiac diseases. The heart is one of the most affected organs in aged individuals, however little is known about the extent and robustness to which miRNA profiles are modulated in cardiac cells during aging. This paper provides a comprehensive characterization of the aging-associated miRNA profile in the murine cardiac fibroblasts, which are increasingly recognized for their active involvement in the cardiac physiology and pathology. Next-generation sequencing of cardiac fibroblasts isolated from young and old mice revealed that an important fraction of the miRNAs generated by the Meg3-Mirg locus was downregulated during aging. To address the specificity of this repression, four miRNAs selected as representative for this locus were further assessed in other cells and organs isolated from ...

Comparative medicine, 2010

This paper evaluates the modifications induced by ischemia and ischemia-reperfusion in mice after... more This paper evaluates the modifications induced by ischemia and ischemia-reperfusion in mice after permanent or transient, respectively, ligation of the left coronary artery and establishes a correlation among the extent of ischemia, electrocardiograph features, and infarct size. The left coronary artery was ligated 1 mm distal from the tip of the left auricle. Histologic analysis revealed that 30-min ischemia (n = 9) led to infarction involving 9.7% ± 0.5% of the left ventricle, whereas 1-h ischemia (n = 9) resulted in transmural infarction of 16.1% ± 4.6% of the left ventricle. In contrast, 24-h ischemia (n = 8) and permanent ischemia (n = 8) induced similarly sized infarcts (33% ± 2% and 31.8% ± 0.7%, respectively), suggesting ineffective reperfusion after 24-h ischemia. Electrocardiography revealed that ligation of the left coronary artery led to ST height elevation (204 compared with 14 μV) and QTc prolongation (136 compared with 76 ms). Both parameters rapidly normalized on rep...

Stem Cells and Development, 2013

Stem cell-based therapy for myocardial regeneration has reported several functional improvements ... more Stem cell-based therapy for myocardial regeneration has reported several functional improvements that are attributed mostly to the paracrine effects stimulating angiogenesis and cell survival. This study was conducted to comparatively evaluate the potential of factors secreted by mesenchymal stem cells (MSCs) in normoxic and hypoxic conditions to promote tissue repair by sustaining endothelial cell (EC) adhesion and proliferation and conferring protection against apoptosis. To this aim, a conditioned medium (CM) was generated from MSCs after 24-h incubation in a serum-free normal or hypoxic environment. MSCs exhibited resistance to hypoxia, which induced increased secretion of vascular endothelial growth factor (VEGF) and decreased levels of other cytokines, including stromal-derived factor-1 (SDF). The CM derived from normal (nMSC-CM) and hypoxic cells (hypMSC-CM) induced similar protective effects on H9c2 cells in hypoxia. Minor differences were noticed in the potential of normal versus hypoxic CM to promote angiogenesis, which were likely connected to SDFa and VEGF levels: the nMSC-CM was more effective in stimulating EC migration, whereas the hypMSC-CM had an enhanced effect on EC adhesion. However, the factors secreted by MSCs in normoxic or hypoxic conditions supported adhesion, but not proliferation, of ECs in vitro, as revealed by impedance-based dynamic assessments. Surprisingly, factors secreted by other stem/progenitor cells, such as endothelial progenitor cells (EPCs), had complementary effects to the MSC-CM. Thus, the EPC-CM, in either a normal or hypoxic environment, supported EC proliferation, but did not sustain EC adhesion. Combined use of the MSC-CM and EPC-CM promoted both EC adhesion and proliferation, suggesting that the local angiogenesis at the site of ischemic injury might be better stimulated by simultaneous releasing of factors secreted by multiple stem/progenitor cell populations.

Frontiers in Immunology

Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were p... more Neutrophils have been classically viewed as a homogenous population. Recently, neutrophils were phenotypically classified into pro-inflammatory N1 and anti-inflammatory N2 sub-populations, but the functional differences between the two subtypes are not completely understood. We aimed to investigate the phenotypic and functional differences between N1 and N2 neutrophils, and to identify the potential contribution of the S100A9 alarmin in neutrophil polarization. We describe distinct transcriptomic profiles and functional differences between N1 and N2 neutrophils. Compared to N2, the N1 neutrophils exhibited: i) higher levels of ROS and oxidative burst, ii) increased activity of MPO and MMP-9, and iii) enhanced chemotactic response. N1 neutrophils were also characterized by elevated expression of NADPH oxidase subunits, as well as activation of the signaling molecules ERK and the p65 subunit of NF-kB. Moreover, we found that the S100A9 alarmin promotes the chemotactic and enzymatic ac...

Cell Death & Disease

Mesenchymal stromal cells (MSC) are attractive tools for cell-based therapy, yet the mechanisms u... more Mesenchymal stromal cells (MSC) are attractive tools for cell-based therapy, yet the mechanisms underlying their migration and survival post-transplantation are unclear. Accumulating evidence indicates that MSC apoptosis modulates both innate and adaptive immune responses which impact on MSC therapeutic effects. Using a dual tracking system, namely the Luciferase expression and VivoTrack680 labelling, and in vivo optical imaging, we investigated the survival and migration of MSC transplanted by various routes (intravenous, subcutaneous, intrapancreatic and intrasplenic) in order to identify the best delivery approach that provides an accumulation of therapeutic cells to the injured pancreas in the non-obese diabetic (NOD) mouse. The results showed that transplanted MSC had limited migration capacity, irrespective of the administration route, and were short-lived with almost total disappearance at 7 days after transplantation. Within one day after transplantation, cells activated hyp...

Nature Communications

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Nature Communications

We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG ... more We hereby provide the initial portrait of lincNORS, a spliced lincRNA generated by the MIR193BHG locus, entirely distinct from the previously described miR-193b-365a tandem. While inducible by low O2 in a variety of cells and associated with hypoxia in vivo, our studies show that lincNORS is subject to multiple regulatory inputs, including estrogen signals. Biochemically, this lincRNA fine-tunes cellular sterol/steroid biosynthesis by repressing the expression of multiple pathway components. Mechanistically, the function of lincNORS requires the presence of RALY, an RNA-binding protein recently found to be implicated in cholesterol homeostasis. We also noticed the proximity between this locus and naturally occurring genetic variations highly significant for sterol/steroid-related phenotypes, in particular the age of sexual maturation. An integrative analysis of these variants provided a more formal link between these phenotypes and lincNORS, further strengthening the case for its bi...