Publications by authors named "Fiona See"

14 Publications

  • Page 1 of 1

Isolation and characterization of embryonic stem cell-derived cardiac Purkinje cells.

Stem Cells 2015 Apr;33(4):1102-12

Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, New York, USA.

The cardiac Purkinje fiber network is composed of highly specialized cardiomyocytes responsible for the synchronous excitation and contraction of the ventricles. Computational modeling, experimental animal studies, and intracardiac electrical recordings from patients with heritable and acquired forms of heart disease suggest that Purkinje cells (PCs) may also serve as critical triggers of life-threatening arrhythmias. Nonetheless, owing to the difficulty in isolating and studying this rare population of cells, the precise role of PC in arrhythmogenesis and the underlying molecular mechanisms responsible for their proarrhythmic behavior are not fully characterized. Conceptually, a stem cell-based model system might facilitate studies of PC-dependent arrhythmia mechanisms and serve as a platform to test novel therapeutics. Here, we describe the generation of murine embryonic stem cells (ESC) harboring pan-cardiomyocyte and PC-specific reporter genes. We demonstrate that the dual reporter gene strategy may be used to identify and isolate the rare ESC-derived PC (ESC-PC) from a mixed population of cardiogenic cells. ESC-PC display transcriptional signatures and functional properties, including action potentials, intracellular calcium cycling, and chronotropic behavior comparable to endogenous PC. Our results suggest that stem-cell derived PC are a feasible new platform for studies of developmental biology, disease pathogenesis, and screening for novel antiarrhythmic therapies.
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http://dx.doi.org/10.1002/stem.1921DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4418548PMC
April 2015

Early and delayed tranilast treatment reduces pathological fibrosis following myocardial infarction.

Heart Lung Circ 2013 Feb 15;22(2):122-32. Epub 2012 Sep 15.

Department of Epidemiology & Preventive Medicine, Centre of Cardiovascular Research & Education in Therapeutics, Monash University, Melbourne, Victoria 3004, Australia.

Background: Tranilast has been shown to inhibit TGFβ1-related fibrosis and organ failure in various disease models. We sought to examine the effects of tranilast on left ventricular (LV) remodelling post-MI.

Methods: Following coronary artery ligation, Sprague Dawley rats were randomised to receive tranilast (300mg/kg/d, p.o.) or vehicle control over one of two treatment periods: (1) from 24h until seven days post-MI, (2) from seven days to 28 days post-MI. Cardiac tissue was harvested for molecular, immunohistochemical and cell culture analyses.

Results: Tranilast treatment of MI rats from 24h until seven days post-MI reduced myocardial collagen content, α1 (I) procollagen, TGFβ1 and CTGF mRNA transcripts, monocyte/macrophage infiltration and exacerbated infarct expansion compared with vehicle-treatment. Delaying the commencement of tranilast treatment to seven days post-MI attenuated myocardial fibrosis, gene expression of α1(I) procollagen, α1(III) procollagen, fibronectin, TGFβ1 and CTGF mRNA transcripts, and monocyte/macrophage infiltration at 28d compared to vehicle-treatment, without detriment to infarct healing. Extended post-MI also preserved LV infarct size. In cultures of rat cardiac fibroblasts, tranilast attenuated TGFβ1-stimulated fibrogenesis.

Conclusion: Tranilast inhibits myocardial TGFβ1 expression, fibrosis in rat post-MI and collagen production in cardiac fibroblasts. While tranilast intervention from 24h post-MI exacerbated infarct expansion, delaying the commencement of treatment to seven days post-MI impeded LV remodelling.
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http://dx.doi.org/10.1016/j.hlc.2012.08.054DOI Listing
February 2013

Therapeutic effects of human STRO-3-selected mesenchymal precursor cells and their soluble factors in experimental myocardial ischemia.

J Cell Mol Med 2011 Oct;15(10):2117-29

The University of Melbourne, St Vincent's Hospital, Department of Medicine, Melbourne, Victoria, Australia.

Stromal precursor antigen (STRO)-3 has previously been shown to identify a subset of adult human bone marrow (BM)-derived mesenchymal lineage precursors, which may have cardioprotective potential. We sought to characterize STRO-3-immunoselected and culture-expanded mesenchymal precursor cells (MPCs) with respect to their biology and therapeutic potential in myocardial ischemia. Immunoselection of STRO-3(+) MPCs enriched for fibroblastic colony forming units from unfractionated BM mononuclear cells (MNCs). Compared to mesenchymal stem cells conventionally isolated by plastic adherence, MPCs demonstrated increased proliferative capacity during culture expansion, expressed higher levels of early 'stem cell' markers and various pro-angiogenic and cardioprotective cytokines, and exhibited greater trilineage developmental efficiency. Intramyocardial injection of MPCs into a rat model of myocardial infarction (MI) promoted left ventricular recovery and inhibited left ventricular dilatation. These beneficial effects were associated with cardioprotective and pro-angiogenic effects at the tissue level, despite poor engraftment of cells. Treatment of MI rats with MPC-conditioned medium (CM) preserved left ventricular function and dimensions, reduced myocyte apoptosis and fibrosis, and augmented neovascularization, involving both resident vascular cells and circulating endothelial progenitor cells (EPCs). Profiling of CM revealed various cardioprotective and pro-angiogenic factors, which had biological activity in cultures of myocytes, tissue-resident vascular cells and EPCs. Prospective immunoselection of STRO-3(+) MPCs from BM MNCs conferred advantage in maintaining a population of immature MPCs during ex vivo expansion. Transplantation of culture-expanded MPCs into the post-MI heart resulted in therapeutic benefit, attributable at least in part to paracrine mechanisms of action. Thus, MPCs represent a promising therapy for myocardial ischemia.
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http://dx.doi.org/10.1111/j.1582-4934.2010.01241.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3092801PMC
October 2011

Alternatively spliced RAGEv1 inhibits tumorigenesis through suppression of JNK signaling.

Cancer Res 2010 Jul 22;70(13):5628-38. Epub 2010 Jun 22.

Division of Surgical Science, Department of Surgery, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.

Receptor for advanced glycation end products (RAGE) and its ligands are overexpressed in multiple cancers. RAGE has been implicated in tumorigenesis and metastasis, but little is known of the mechanisms involved. In this study, we define a specific functional role for an alternate splice variant termed RAGE splice variant 1 (RAGEv1), which encodes a soluble endogenous form of the receptor that inhibits tumorigenesis. RAGEv1 was downregulated in lung, prostate, and brain tumors relative to control matched tissues. Overexpressing RAGEv1 in tumor cells altered RAGE ligand stimulation of several novel classes of genes that are critical in tumorigenesis and metastasis. Additionally, RAGEv1 inhibited tumor formation, cell invasion, and angiogenesis induced by RAGE ligand signaling. Analysis of signal transduction pathways underlying these effects revealed marked suppression of c-jun-NH(2)-kinase (JNK) pathway signaling, and JNK inhibition suppressed signaling through the RAGE pathway. Tumors expressing RAGEv1 were significantly smaller than wild-type tumors and displayed prominently reduced activation of JNK. Our results identify RAGEv1 as a novel suppressor, the study of which may offer new cancer therapeutic directions.
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http://dx.doi.org/10.1158/0008-5472.CAN-10-0595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2919303PMC
July 2010

Islet grafting and imaging in a bioengineered intramuscular space.

Transplantation 2009 Nov;88(9):1065-74

Department of Surgery, Columbia University Medical College, New York, NY, USA.

Background: Because the hepatic portal system may not be the optimal site for islet transplantation, several extrahepatic sites have been studied. Here, we examine an intramuscular transplantation site, bioengineered to better support islet neovascularization, engraftment, and survival, and we demonstrate that at this novel site, grafted beta cell mass may be quantitated in a real-time noninvasive manner by positron emission tomography (PET) imaging.

Methods: Streptozotocin-induced rats were pretreated intramuscularly with a biocompatible angiogenic scaffold received syngeneic islet transplants 2 weeks later. The recipients were monitored serially by blood glucose and glucose tolerance measurements and by PET imaging of the transplant site with [11C] dihydrotetrabenazine. Parallel histopathologic evaluation of the grafts was performed using insulin staining and evaluation of microvasularity.

Results: Reversal of hyperglycemia by islet transplantation was most successful in recipients pretreated with bioscaffolds containing angiogenic factors when compared with those who received no bioscaffolds or bioscaffolds not treated with angiogenic factors. PET imaging with [11C] dihydrotetrabenazine, insulin staining, and microvascular density patterns were consistent with islet survival, increased levels of angiogenesis, and with reversal of hyperglycemia.

Conclusions: Induction of increased neovascularization at an intramuscular site significantly improves islet transplant engraftment and survival compared with controls. The use of a nonhepatic transplant site may avoid intrahepatic complications and permit the use of PET imaging to measure and follow transplanted beta cell mass in real time. These findings have important implications for effective islet implantation outside of the liver and offer promising possibilities for improving islet survival, monitoring, and even prevention of islet loss.
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http://dx.doi.org/10.1097/TP.0b013e3181ba2e87DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3076663PMC
November 2009

A DNA enzyme against plasminogen activator inhibitor- type 1 (PAI-1) limits neointima formation after angioplasty in an obese diabetic rodent model.

J Cardiovasc Pharmacol 2007 Dec;50(6):633-40

Department of Surgery, Columbia University, College of Surgeons and Physicians, New York, New York, USA.

We investigated whether targeted cleavage of PAI-1 mRNA might prevent post-angioplasty neointima formation in diabetic JCR:LA-cp/cp rats with naturally elevated PAI-1 levels. Catalytic DNA enzymes targeting rat PAI-1 mRNA (PAI-1 DNA enzyme, n = 12) or a random sequence as control (scrambled DNA enzyme, n = 12) were infused at the site of arterial damage. Control animals demonstrated prominent PAI-1 protein expression in the arterial endothelium at 48 hours, and robust neointimal proliferation by two weeks, with 60 +/- 10% mean occlusion of the artery lumen. The neointimal lesion consisted of dense fibrin deposition and numerous proliferating smooth muscle cells, as determined by dual alpha-smooth muscle actin/Ki67 expression. Treatment with PAI-1 DNA enzyme resulted in marked early (48 hour) reduction of endothelial PAI-1 protein expression, which persisted for the next two weeks as well as a two fold reduction of expression of PAI-1 mRNA by RT-PCR at the same time point, (P < 0.05). By two weeks, PAI-1 DNA enzyme treated animals demonstrated significantly reduced levels of fibrin deposition and 5-fold lower levels of proliferating smooth muscle cells at the site of arterial injury compared to controls (P < 0.01), and a 2-fold lower neointima/media ratio (0.67 +/- 0.11 vs 1.39 +/- 0.12) (P < 0.05). Treatment with a catalytic PAI-1 DNA enzyme successfully prevents neointimal proliferation after balloon injury in diabetic animals.
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http://dx.doi.org/10.1097/FJC.0b013e318150d6b3DOI Listing
December 2007

Mesenchymal lineage precursor cells induce vascular network formation in ischemic myocardium.

Nat Clin Pract Cardiovasc Med 2006 Mar;3 Suppl 1:S18-22

Division of Cardiothoracic Surgery, Columbia University, New York, NY, USA.

Mesenchymal lineage precursors can be reproducibly isolated from adult mammalian bone marrow and grown in culture. Immunoselection with monoclonal antibodies against STRO-1 and vascular-cell-adhesion molecule 1 (VCAM1/CD106) prior to expansion results in a 1,000-fold enrichment of mesenchymal precursors compared to standard isolation techniques. Intramyocardial injection of human STRO-1-selected precursors in an athymic rat model of acute myocardial infarction results in induction of vascular network formation and arteriogenesis coupled with global functional cardiac recovery.
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http://dx.doi.org/10.1038/ncpcardio0404DOI Listing
March 2006

Catalytic degradation of vitamin D up-regulated protein 1 mRNA enhances cardiomyocyte survival and prevents left ventricular remodeling after myocardial ischemia.

J Biol Chem 2005 Nov 19;280(47):39394-402. Epub 2005 Sep 19.

Department of Surgery, Columbia University Medical Center, New York, New York 10032, USA.

Vitamin D3 up-regulated protein 1 (VDUP1) is a key mediator of oxidative stress on various cellular processes via downstream effects on apoptosis signaling kinase 1 (ASK1) and p38 mitogen-activated protein kinase (MAPK). Here, we report that VDUP1 expression is significantly increased in rat hearts following acute myocardial ischemia, suggesting it may have important regulatory effects on cardiac physiological processes during periods of oxidative stress. Transfection of H9C2 cardiomyoblasts with a sequence-specific VDUP1 DNA enzyme to down-regulate VDUP1 mRNA expression significantly reduced apoptosis and enhanced cell survival under conditions of H(2)O(2) stress, and these effects involved inhibition of ASK1 activity. Direct intracardiac injection of the DNA enzyme at the time of acute myocardial infarction reduced myocardial VDUP1 mRNA expression and resulted in prolonged reduction in cardiomyocyte apoptosis and ASK1 activity. Moreover, down-regulation of VDUP1 was accompanied by significant reduction in cardiac expression of pro-collagen type I alpha2 mRNA level, as well as marked reduction in myocardial scar formation. These features were accompanied by significant improvement in cardiac function. Together, these results suggest a direct role for VDUP1 in the adverse effects of ischemia and oxidative stress on cardiomyocyte survival, left ventricular collagen deposition, and cardiac function. Strategies to inhibit VDUP1 expression and/or function during acute ischemic events may be beneficial to cardiac functional recovery and prevention of left ventricular remodeling.
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http://dx.doi.org/10.1074/jbc.M502966200DOI Listing
November 2005

Fibrosis as a therapeutic target post-myocardial infarction.

Curr Pharm Des 2005 ;11(4):477-87

National Health & Medical Research Council of Australia Centre of Clinical Research Excellence in Therapeutics, Monash University, Alfred Hospital, Melbourne Victoria 3004, Australia.

The extracellular matrix (ECM) is a dynamic microenvironment and a major contributor to the adverse ventricular remodelling that follows myocardial infarction (MI), via activation of both direct pro-fibrotic pathways and matrix metalloproteinases (MMPs) that enhance collagenase activity. Reactive fibrosis, i.e. deposition of ECM materials remote from the region of the MI is clearly detrimental to ventricular function and contributory to adverse outcomes post-MI. Therefore, reversal of this process represents an important therapeutic target in post-MI management and treatment of established heart failure. A number of existing agents exert their beneficial effects in part via reductions in ECM deposition. Furthermore, specific anti-fibrotic drugs have been developed and are currently being explored for these and other cardiac conditions where pathological ECM deposition is felt to be contributory to disease progression.
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http://dx.doi.org/10.2174/1381612053382098DOI Listing
March 2005

Tranilast attenuates cardiac matrix deposition in experimental diabetes: role of transforming growth factor-beta.

Cardiovasc Res 2005 Feb;65(3):694-701

University of Melbourne, Department of Medicine, St. Vincent's Hospital, Victoria, Australia.

Objective: The pathological accumulation of extracellular matrix is a characteristic feature of diabetic cardiomyopathy that is directly related to a loss of function. Tranilast (n-[3,4-anthranilic acid), used for the treatment of fibrotic skin diseases, has also been shown to inhibit transforming growth factor-beta (TGF-beta)-induced matrix production in kidney epithelial cells.

Methods: To investigate the effects of tranilast in the diabetic heart, we examined its effects in cultured cardiac fibroblasts and then assessed its effects in (mRen-2)27 diabetic rats with established disease (8 weeks after streptozotocin).

Results: In vitro studies demonstrated a 58% reduction in TGF-beta1-induced 3[H]-hydroxyproline incorporation with tranilast 30 microM (p<0.01). At 16 weeks, diabetes in the Ren-2 rat was associated with increased cardiac fibrosis and evidence of TGF-beta1 activation, as measured by the abundance of phosphorylated Smad2. Despite persistent hyperglycaemia and hypertension, tranilast attenuated cardiac fibrosis by 37% (p<0.05) in association with reduction in phospho-Smad2 (p<0.01).

Conclusion: These findings indicate that tranilast has antifibrotic actions in the Ren-2 model of experimental diabetic cardiac disease by mechanisms that might attributable to reduced TGF-beta activity.
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http://dx.doi.org/10.1016/j.cardiores.2004.10.041DOI Listing
February 2005

p38 mitogen-activated protein kinase inhibition improves cardiac function and attenuates left ventricular remodeling following myocardial infarction in the rat.

J Am Coll Cardiol 2004 Oct;44(8):1679-89

National Health and Medical Research Council Center of Clinical Research Excellence in Therapeutics, Department of Medicine, Monash University, Alfred Hospital, Commercial Road, Prahran, Victoria 3181, Australia.

Objectives: The aim of this study was to examine the effect of the p38 mitogen-activated protein kinase (MAPK) inhibitor, RWJ-67657 (RWJ), on left ventricular (LV) dysfunction and remodeling post-myocardial infarction (MI) in rats.

Background: p38 MAPK signaling has been implicated in the progression of chronic heart failure.

Methods: From day 7 post-MI (coronary artery ligation), rats received either RWJ (50 mg/day, by gavage, n = 8, MI+RWJ) or vehicle (by gavage, n = 8, MI+V) for 21 days. Echocardiography was performed on day 6, before the commencement of treatment, and on day 27. In vivo hemodynamic measurements were made on day 28. Sham-operated rats served as controls.

Results: The LV end-diastolic pressure and lung/body weight ratio were reduced, whereas the maximum rate of rise of LV pressure was increased towards sham levels in MI+RWJ compared with MI+V. Baseline echocardiographic studies demonstrated uniform LV remodeling and dysfunction in MI rats. Fractional shortening (FS) further deteriorated in MI+V, whereas FS was preserved in MI+RWJ. Progressive LV dilation and infarct expansion observed in MI+V were inhibited in MI+RWJ. MI+RWJ also demonstrated increased myocyte hypertrophy in the peri-infarct and non-infarct zones, and reduced myocardial collagen and alpha-smooth muscle actin (SMA) immunoreactivity compared with MI+V. The antifibrotic effects of RWJ in vivo may reflect direct effects on cardiac fibroblasts, because RWJ attenuated transforming growth factor beta-1-stimulated collagen synthesis and alpha-SMA expression in isolated cardiac fibroblasts. RWJ also protected cultured myocytes from hydrogen peroxide-induced apoptosis.

Conclusions: RWJ-67657 treatment post-MI had beneficial effects on LV remodeling and dysfunction, supporting a key role for p38 MAPK in pathologic cell signaling in these processes and its inhibition as a novel therapy.
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http://dx.doi.org/10.1016/j.jacc.2004.07.038DOI Listing
October 2004

Cardiovascular role of urotensin II: effect of chronic infusion in the rat.

Peptides 2004 Oct;25(10):1783-8

NHMRC Centre of Clinical Research Excellence in Therapeutics, Departments of Medicine and Epidemiology & Preventive Medicine, Central and Eastern Clinical School, Monash University, Alfred Hospital, Commercial Road, Prahran, Vic. 3181, Australia.

Urotensin II (UII) is a potent vaso-active peptide thought to have multiple roles in the regulation of cardiovascular physiology and pathophysiology. The actions of UII are complex and difficult to interpret given its systemic hemodynamic effects and variable action on different vascular beds and isolated vessels. Direct effects of UII on the myocardium, include myocyte hypertrophy, extracellular matrix deposition and contractility. These observations, together with elevated plasma levels found in disease, are common traits reported in other pathophysiologically implicated neurohormonal systems. In this review, we include original data obtained from chronic infusion of UII in rats. We report a reduction in first derivative of left ventricular pressure (+dP/dt), as well as an increase in the ratio of left ventricular collagen I:III, that may contribute to the reduced myocardial contractility observed in these animals.
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http://dx.doi.org/10.1016/j.peptides.2004.03.029DOI Listing
October 2004

Direct actions of urotensin II on the heart: implications for cardiac fibrosis and hypertrophy.

Circ Res 2003 Aug 3;93(3):246-53. Epub 2003 Jul 3.

NHMRC Centre of Clinical Research Excellence in Therapeutics, Department of MedicineEpidemiology and Preventive Medicine, Monash University Medical School, Prahran, Victoria, Australia.

Urotensin II (UII) is a somatostatin-like peptide recently identified as a potent vasoconstrictor. In this study, we examined whether UII promotes cardiac remodeling through nonhemodynamic effects on the myocardium. In a rat model of heart failure after myocardial infarction (MI), increased UII peptide and UII receptor protein expression was observed in both infarct and noninfarct regions of the left ventricle compared with sham. Moreover, post-MI remodeling was associated with a significant 75% increase in UII receptor gene expression in the heart (P<0.05 versus sham controls), with this increase noted in both regions of the left ventricle. In vitro, UII (10-7 mol/L) stimulation of neonatal cardiac fibroblasts increased the level of mRNA transcripts for procollagens alpha1(I), alpha1(III), and fibronectin by 139+/-15% (P<0.01), 59+/-5% (P<0.05), and 141+/-14% (P<0.01), respectively, with a concomitant 23+/-2% increase in collagen peptide synthesis as determined by 3H-proline incorporation (P<0.01). UII had no effect on cellular hypertrophy, as determined by changes in total protein content in isolated neonatal cardiomyocytes. However, expression of recombinant rat UII receptor in neonatal cardiomyocytes resulted in significant UII-dependent activation of hypertrophic signaling as demonstrated by increased total protein content (unstimulated, 122.4+/-4.0 microg/well; rat UII, 147.6+/-7.0 microg/well; P<0.01) and activation of the hypertrophic phenotype through Galpha(q)- and Ras-dependent pathways. These results indicate that, in addition to potent hemodynamic effects, UII may be implicated in myocardial fibrogenesis through increased collagen synthesis by cardiac fibroblasts and may also be an important determinant of pathological cardiac hypertrophy in conditions characterized by UII receptor upregulation.
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http://dx.doi.org/10.1161/01.RES.0000084382.64418.BCDOI Listing
August 2003
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