Hugo Sondermeijer

University of Melbourne, Melbourne, Victoria, Australia

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Publications (14)43.96 Total impact

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    ABSTRACT: 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.
    Journal of Cellular and Molecular Medicine 09/2011; 15(10):2117 - 2129. · 4.75 Impact Factor
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    ABSTRACT: Although adequate numbers of hematopoietic progenitor cells reside in the human bone marrow, the extent of endogenous neovascularization after myocardial infarction remains insufficient. The aim of this study was to identify the role of the CXC chemokine receptor 4/stromal cell-derived factor 1 axis in the mobilization and homing of hematopoietic progenitor cells in the ischemic heart. Human bone marrow-derived hematopoietic progenitor cells or saline were injected systemically into athymic nude rats 48 hours after myocardial infarction. Myocardial and bone marrow expression of stromal cell-derived factor 1 and chemotaxis of hematopoietic progenitor cells were measured in vitro in the presence or absence of stromal cell-derived factor 1. The role of the CXC chemokine receptor 4/stromal cell-derived factor 1 axis was investigated by means of antibody blockade or systemic administration of granulocyte colony-stimulating factor. Morphologic analysis included measurement of the infarct area, capillary density, and apoptosis, whereas left ventricular function was measured by means of echocardiographic analysis. Expression of postinfarct stromal cell-derived factor 1 was increased by 67% in the bone marrow and decreased by 43% in myocardium. Disruption of bone marrow stromal cell-derived factor 1/CXC chemokine receptor 4 interactions by antibody blockade resulted in a redirection of human hematopoietic progenitor cells from the bone marrow to the ischemic heart and augmented neovascularization and cardiomyocyte survival. Similarly, systemic administration of granulocyte colony-stimulating factor to block CXC chemokine receptor 4/stromal cell-derived factor 1 interaction resulted in increased mobilization and homing of hematopoietic progenitor cells to the ischemic heart, which translated to augmented myocardial neovascularization, prevention of apoptosis, and improved cardiac function. Bone marrow stromal cell-derived factor 1 upregulation after myocardial ischemia prevents mobilization of endogenous hematopoietic progenitor cells. We provide evidence that disruption of stromal cell-derived factor 1/CXC chemokine receptor 4 interactions allows redirection of hematopoietic progenitor cells to ischemic myocardium and enhances recovery of left ventricular function.
    The Journal of thoracic and cardiovascular surgery 03/2011; 142(3):687-96, 696.e1-2. · 3.41 Impact Factor
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    ABSTRACT: 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. 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. 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. 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.
    Transplantation 11/2009; 88(9):1065-74. · 3.78 Impact Factor
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    World Journal of Surgery 10/2009; 34(4):625-7. · 2.23 Impact Factor
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    ABSTRACT: The presence of complement fixing anti-human leukocyte antigen (HLA) antibodies in the circulation of organ transplant recipients may result in heart allograft rejection. Here, we assessed the clinical impact of pre- and post-transplantation allosensitization on long-term survival of heart allografts. Sequential samples of sera from heart allograft recipients were screened pretransplantation for panel reactive antibodies using the complement-dependent cytotoxicity test. Patients were monitored post-transplantation for donor specific anti-HLA class I and class II antibodies. Kaplan-Meier graft survival plots were generated to analyze the effect of anti-HLA antibodies on transplantation outcomes. Statistical analysis showed that the post-transplantation development of alloantibodies was a significant risk factor that was associated with low long-term survival rates; in contrast, recipients' gender, age, previous transplantations, and degree of HLA matching with the donor had no effect on long-term survival. The presence in pretransplantation sera of antibodies against more than 10% of the HLA reference panel (PRA >10%) was associated with AMR and with a relatively lower rate of graft survival after 1 year but did not affect 10-year survival. The present data underline the importance of monitoring the development of anti-HLA antibodies as a tool for early diagnosis and treatment of AMR.
    Human immunology 07/2009; 70(10):825-9. · 2.55 Impact Factor
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    ABSTRACT: Allogeneic hematopoietic cell transplantation represents an important therapy for certain malignant and nonmalignant diseases. However, graft-versus-host disease (GVHD) is a major cause of mortality and morbidity. The search for agents that can efficiently suppress GVHD has been going on for more than half a century. GVHD is particularly strong in xenogeneic donor-recipient combinations, given the unlimited number of potentially immunogenic antigens donor lymphocytes encounter in the host. Using a hu-nonobese diabetic/severe combined immunodeficiency (hu-NOD/SCID) gamma-null model of xenogeneic GVHD, we have demonstrated that treatment with recombinant immunoglobulin-like transcript 3-Fc protein induces the differentiation of CD8(+) T suppressor cells and blocks the cellular and humoral arm of the GVH reaction.
    Human immunology 07/2009; 70(9):663-9. · 2.55 Impact Factor
  • Human Immunology - HUM IMMUNOL. 01/2009; 70.
  • Human Immunology - HUM IMMUNOL. 01/2009; 70.
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    ABSTRACT: Hematopoietic progenitor cells are able to induce neovascularization of ischemic myocardium, inhibit apoptosis, and prevent heart failure. They express functional CC chemokine-binding receptor 3 (CCR3) and CXC chemokine-binding receptor 4 (CXCR4); however, the role of those receptors in migration of progenitor cells into the ischemic myocardium is unknown. Myocardial infarction was surgically induced in athymic nude rats, and human bone marrow-derived CD34+ cells or saline was injected into the tail vein. Cell chemotaxis was studied in vitro using chemotaxis chambers with or without concomitant stimulation with eotaxin or stromal cell-derived factor-1. Cell migration into ischemic myocardium was evaluated by immunohistochemistry. CCR3 and CXCR4 antibodies or local injections of stromal cell-derived factor-1 were used to investigate the role of chemokine expression in the migration capacity of the injected cells. Morphologic analysis included evaluation of apoptosis and capillary density in the ischemic myocardium. Ischemic rat myocardium demonstrated induced messenger RNA expression for the CCR3-binding chemokines eotaxin, RANTES (regulated on activation, normal T expressed and secreted), and monocyte chemotactic protein-3, but not the CXCR4-binding chemokine stromal cell-derived factor-1. Migration of human angioblasts to ischemic rat myocardium was inhibited by a blocking anti-CCR3 monoclonal antibody, but not by a blocking anti-CXCR4 monoclonal antibody, which instead inhibited migration to bone marrow. Finally, intramyocardial injection of stromal cell-derived factor-1 redirected migration of human angioblasts to ischemic rat hearts, resulting in augmented neovascularization, enhanced cardiomyocyte survival, and functional cardiac recovery. CCR3-dependent chemokine interactions regulate endogenous migration of CD34+ progenitors from bone marrow to ischemic but not to normal myocardium. Manipulating CXCR4-dependent interactions could enhance the efficacy of cell therapy after myocardial infarction.
    The Journal of thoracic and cardiovascular surgery 11/2008; 136(4):1044-53. · 3.41 Impact Factor
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    ABSTRACT: 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.
    Journal of Cardiovascular Pharmacology 12/2007; 50(6):633-40. · 2.38 Impact Factor
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    ABSTRACT: We describe the case of a 45-year-old man with mitral and aortic prosthetic valve replacement who presented with symptoms of subacute bacterial endocarditis. Bartonella quintana was grown from blood after prolonged culture. The course of the disease was complicated by splenic infarction, glomerulonephritis resulting in progressive renal insufficiency, and cerebroventricular hemorrhage. Notably, cardiac ultrasonography showed no extensive vegetations but a strand-like lesion. Culture-positive B. quintana prosthetic valve endocarditis in a formerly healthy subject represents a newly observed entity. It should be added to the differential diagnosis of prosthetic valve endocarditis, especially when it presents with features suggesting subacute bacterial endocarditis.
    European Journal of Internal Medicine 11/2006; 17(6):441-3. · 2.05 Impact Factor
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    ABSTRACT: In the adult, new blood vessel formation can occur either through angiogenesis from pre-existing mature endothelium or vasculogenesis mediated by bone marrow-derived endothelial precursors. We recently isolated endothelial progenitor cells, or angioblasts, in human adult bone marrow which have selective migratory properties for ischemic tissues, including myocardium, to where they home and induce vasculogenesis. Here we show that myocardial production of the IL-8/Gro-alpha CXC chemokine family is significantly increased after acute ischemia, and that this provides a chemoattractant gradient for bone marrow-derived endothelial progenitors, or angioblasts. This chemokine-mediated homing of bone marrow angioblasts to the ischemic heart regulates their ability to induce myocardial neovascularization, protection against cardiomyocyte apoptosis, and functional cardiac recovery. Together, our results indicate that CXC chemokines play a central role in regulating vasculogenesis in the adult, and suggest that manipulation of interactions between chemokines and their receptors on autologous human bone marrow-derived angioblasts could augment neovascularization of ischemic myocardial tissue.
    Journal of Molecular and Cellular Cardiology 05/2006; 40(4):455-64. · 5.15 Impact Factor
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    ABSTRACT: 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.
    Nature Clinical Practice Cardiovascular Medicine 04/2006; 3 Suppl 1:S18-22. · 7.04 Impact Factor
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    ABSTRACT: 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.
    Journal of Biological Chemistry 12/2005; 280(47):39394-402. · 4.65 Impact Factor