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ABSTRACT: AimsThe study was designed to evaluate the mechanisms of cardiac regeneration after injury and to determine how to restore that capacity in aged individuals. The adult heart retains a small population of nascent cells that have myeloid, mesenchymal, and mesodermal capabilities, which play an essential role in the recovery of ventricular function after injury. In aged individuals, these cells are diminished and dysfunctional. We evaluated the derivation of some of these cardiac progenitors and a method to restore their number and function.Methods and resultsWe first demonstrated that aged mice have fewer progenitors in both the bone marrow (BM) and the myocardium, which correlated with the extent of cardiac dysfunction after injury. Bone marrow chimerism established in aged mice with young BM donors restored both myocardial progenitors and cardiac function, but neither was restored with aged BM donors. Cardiac micro-chimerism in aged mice was established with young BM cells, which restored cardiac function after injury, even with old peripheral BM cells. The young cardiac-resident BM-derived progenitor cells in the aged myocardium persisted for at least a year, and after myocardial infarction they actively proliferated and enhanced cardiac repair through paracrine mechanisms.Conclusion
Bone marrow reconstitution with young BM cells in aged recipients restored progenitors in both the BM and, most importantly, the myocardium. The number and function of cardiac-resident BM-derived progenitor cells in the aged myocardium prior to injury was the major determinant for successful recovery of cardiac function. The aged heart was rejuvenated with young BM cells.
European Heart Journal 04/2012; · 10.48 Impact Factor
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ABSTRACT: After a myocardial infarction, thinning and expansion of the fibrotic scar contribute to progressive heart failure. The loss of elastin is a major contributor to adverse extracellular matrix remodelling of the infarcted heart, and restoration of the elastic properties of the infarct region can prevent ventricular dysfunction. We implanted cells genetically modified to overexpress elastin to re-establish the elastic properties of the infarcted myocardium and prevent cardiac failure. A full-length human elastin cDNA was cloned, subcloned into an adenoviral vector and then transduced into rat bone marrow stromal cells (BMSCs). In vitro studies showed that BMSCs expressed the elastin protein, which was deposited into the extracellular matrix. Transduced BMSCs were injected into the infarcted myocardium of adult rats. Control groups received either BMSCs transduced with the green fluorescent protein gene or medium alone. Elastin deposition in the infarcted myocardium was associated with preservation of myocardial tissue structural integrity (by birefringence of polarized light; P < 0.05 versus controls). As a result, infarct scar thickness and diastolic compliance were maintained and infarct expansion was prevented (P < 0.05 versus controls). Over a 9-week period, rats implanted with BMSCs demonstrated better cardiac function than medium controls; however, rats receiving BMSCs overexpressing elastin showed the greatest functional improvement (P < 0.01). Overexpression of elastin in the infarcted heart preserved the elastic structure of the extracellular matrix, which, in turn, preserved diastolic function, prevented ventricular dilation and preserved cardiac function. This cell-based gene therapy provides a new approach to cardiac regeneration.
Journal of Cellular and Molecular Medicine 03/2012; 16(10):2429-39. · 4.13 Impact Factor
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ABSTRACT: We evaluated the hypothesis that uterine cells home to the heart after injury and improve cardiac outcomes. Premenopausal women have fewer cardiovascular complications than age-matched men, but the mechanisms responsible for this protection have not been conclusively identified. Hysterectomy was performed in young female rats (leaving the ovaries intact), and 7 days later the left coronary artery was ligated to produce a myocardial infarction (MI). Cardiac function at 28 days post-MI was measured using echocardiography. Fractional shortening was best in non-hysterectomized (non-Hx) females and lower in both Hx females and males. Uteri were then removed from GFP rats and heterotopically transplanted into non-GFP recipients to investigate homing of uterine cells to the infarcted myocardium. Seven days later, the uterine transplant recipients underwent coronary ligation. GFP(+) cells were found in the recipient hearts 7 days after MI and persisted for 6 months. Confocal analysis showed that homed uterine cells were located around blood vessels, suggesting their involvement in neovascularization. We then evaluated uterine cell transplantation by intravenously injecting GFP(+) uterine cells into Hx females immediately after MI. These GFP(+) cells were found to home to the injured myocardium, stimulate angiogenesis, improve cardiac function, and increase survival. This study demonstrates that uterine cells can home to the injured myocardium, enhance tissue repair, and prevent cardiac dysfunction. Uterine cells may play a role in the prevention of cardiovascular complications in females.
Journal of Molecular and Cellular Cardiology 03/2012; 52(6):1265-73. · 5.17 Impact Factor
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ABSTRACT: Cardiac cell therapy for older patients who experience a myocardial infarction may require highly regenerative cells from young, healthy (allogeneic) donors. Bone marrow mesenchymal stem cells (MSCs) are currently under clinical investigation because they can induce cardiac repair and may also be immunoprivileged (suitable for allogeneic applications). However, it is unclear whether allogeneic MSCs retain their immunoprivilege or functional efficacy late after myocardial implantation. We evaluated the effects of MSC differentiation on the immune characteristics of cells in vitro and in vivo and monitored cardiac function for 6 months after post-myocardial infarction MSC therapy.
In the in vitro experiments, inducing MSCs to acquire myogenic, endothelial, or smooth muscle characteristics (via 5-azacytidine or cytokine treatment) increased major histocompatibility complex-Ia and -II (immunogenic) expression and reduced major histocompatibility complex-Ib (immunosuppressive) expression, in association with increased cytotoxicity in coculture with allogeneic leukocytes. In the in vivo experiments, we implanted allogeneic or syngeneic MSCs into infarcted rat myocardia. We measured cell differentiation and survival (immunohistochemistry, real-time polymerase chain reaction) and cardiac function (echocardiography, pressure-volume catheter) for 6 months. MSCs (versus media) significantly improved ventricular function for at least 3 months after implantation. Allogeneic (but not syngeneic) cells were eliminated from the heart by 5 weeks after implantation, and their functional benefits were lost within 5 months.
The long-term ability of allogeneic MSCs to preserve function in the infarcted heart is limited by a biphasic immune response whereby they transition from an immunoprivileged to an immunogenic state after differentiation, which is associated with an alteration in major histocompatibility complex-immune antigen profile.
Circulation 12/2010; 122(23):2419-29. · 14.74 Impact Factor
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ABSTRACT: Stem cells exhibit long-term self-renewal by asymmetric division and multipotent differentiation. During embryonic development, cell fate is determined with predictable orientation, differentiation, and partitioning to form the organism. This includes the formation of a hemangioblast from which 2 derivative cell clusters commit to either a hematopoietic or an endothelial lineage. Frequently, it is not clear whether tissue resident stem cells in the adult originate from the bone marrow. Here, we show that blast colony-forming cells exhibiting bilineage (hematopoietic and vascular) potential and long-term self-renewal originate from the uterus in the mouse. This is the first in vitro and in vivo evidence of an adult hemangioblast retained from development in the uterus. Our findings offer new understanding of uterine cell renewal and turnover and may provide insights and opportunities for the study of stem cell maintenance.
Blood 10/2010; 116(16):2932-41. · 9.90 Impact Factor
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ABSTRACT: This study evaluated the capacity of ultrasound-targeted microbubble destruction (UTMD) to deliver angiogenic genes, improve perfusion, and recruit progenitor cells after a myocardial infarction (MI) in mice.
Angiogenic gene therapy after an MI may become a clinically relevant approach to improve the engraftment of implanted cells if targeted delivery can be accomplished noninvasively. The UTMD technique uses myocardial contrast echocardiography to target plasmid gene delivery to the myocardium and features low toxicity, limited immunogenicity, and the potential for repeated application.
Empty plasmids (control group) or those containing genes for vascular endothelial growth factor (VEGF), stem cell factor (SCF), or green fluorescent protein (to visualize gene delivery) were incubated with perflutren lipid microbubbles. The microbubble-deoxyribonucleic acid mixture was injected intravenously into C57BL/6 mice at 7 days after coronary artery ligation (MI). The UTMD technique facilitated transgene release into the myocardium. Twenty-one days after MI, myocardial perfusion and function were assessed by contrast echocardiography. Protein expression was quantified by Western blot and enzyme-linked immunosorbent assay. Flow cytometry quantified progenitor cell recruitment to the heart. Blood vessel density was evaluated immunohistochemically.
Green fluorescent protein expression in the infarcted myocardium demonstrated gene delivery. Myocardial VEGF and SCF levels increased significantly in the respective groups (p < 0.05). The physiologic impact of VEGF and SCF gene delivery was confirmed by increased myocardial recruitment of VEGF receptor 2- and SCF receptor (c-kit)-expressing cells, respectively (p < 0.05). Consequently, capillary and arteriolar density (Factor VIII and alpha-smooth muscle actin staining), myocardial perfusion, and cardiac function were all enhanced (p < 0.01 relative to control group) in recipients of VEGF or SCF.
Noninvasive UTMD successfully delivered VEGF and SCF genes into the infarcted heart, increased vascular density, and improved myocardial perfusion and ventricular function. The UTMD technique may be an ideal method for noninvasive, repeated gene delivery after an MI.
JACC. Cardiovascular imaging 07/2009; 2(7):869-79. · 14.29 Impact Factor
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Shu-Hong Li,
Teresa Y Y Lai, Zhuo Sun,
Mihan Han,
Eduardo Moriyama,
Brian Wilson,
Shafie Fazel,
Richard D Weisel,
Terrence Yau,
Joseph C Wu,
Ren-Ke Li
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ABSTRACT: Cell therapy improved cardiac function after a myocardial infarction in several preclinical studies; however, the functional benefits were limited in the initial clinical trials, perhaps because of inadequate cell engraftment. We used noninvasive molecular imaging to compare the distribution and myocardial retention of cells implanted by using clinical delivery routes.
Bone marrow stromal cells isolated from male rats and transfected with a firefly luciferase reporter gene were injected by using 3 increasingly invasive techniques (ie, intravenous, intra-aortic, and intramyocardial) into female rats 3 or 28 days after coronary ligation. Whole-body bioluminescence imaging was performed 2, 24, and 48 hours later; implanted cells were quantified at 48 hours in explanted organs by means of bioluminescence and real-time polymerase chain reaction.
Variations in cell distribution among groups were profound, with nearly complete trapping of the injected cells in the lungs after intravenous delivery. Cell delivery into the aortic root (with the distal aorta occluded) produced minimal cell retention in the heart. Direct intramyocardial injection facilitated the best early targeting of the cells (P < .05 vs intravenous and intra-aortic injection). Rapid signal loss over 48 hours indicated very poor cell survival in all 3 groups, although implanted cell retention was greater in mature compared with acute infarcts.
This is the first study to correlate live cell imaging with quantitative genetic and histologic techniques. Noninvasive molecular imaging tracked delivered cells and will permit the evaluation of new and improved delivery platforms designed to increase cell homing, retention, and engraftment.
The Journal of thoracic and cardiovascular surgery 06/2009; 137(5):1225-33.e1. · 3.41 Impact Factor
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ABSTRACT: We recently isolated angiogenic cell precursors (ACPs) from human blood, which can induce angiogenesis in vitro.
In the present study, we used a nude rat model of ischaemic cardiomyopathy to compare the efficacy of intramyocardial and intracoronary ACP implantation, and to evaluate effects on cardiac function, scar size and angiogenesis.
Adult nude rats underwent coronary artery ligation. Six days later, ACPs (characterized in vitro prior to implantation) or culture media were injected directly into the ischaemic myocardial region or into the coronary artery via the aorta. Cardiac function was measured by echocardiography prior to and at 2 and 4 weeks after implantation. Scar morphology, cell engraftment, and myocardial angiogenesis were evaluated at 4 weeks. Two and four weeks after implantation, cardiac function declined in both of the control groups but improved in both the intramyocardial and intracoronary ACP groups. Significant reductions in myocardial scar area were only observed in the intramyocardial ACP group, while increases in blood vessel density, which were observed in all ACP recipients, were greatest in the intracoronary ACP group.
Human ACPs, delivered via intramyocardial or intracoronary injection, engrafted into damaged cardiac tissue and improved cardiac function within 4 weeks through effects on scar morphology and blood vessel formation.
European Journal of Heart Failure 07/2008; 10(6):525-33. · 4.90 Impact Factor
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ABSTRACT: Accumulated evidence suggests that bone marrow stromal cells (BMSCs) are capable of regenerating damaged tissue. This study evaluated whether intravenously (noninvasively) administered, GFP-labeled BMSCs would migrate into damaged brain tissue and improve neurological function after a stroke. Wistar rats were subjected to middle cerebral artery occlusion and reperfusion. Twenty-four hours after injury, the rats received an i.v. injection of culture medium or BMSCs isolated from adult Wistar rats expressing green fluorescent protein (GFP). Two hours after injury and 1, 3, and 7 days after cell transplantation, neurological function was evaluated using a neurological severity scale. On day 7, the brain scar size was determined using tetrazolium chloride staining, and the implanted cells were identified using confocal microscopy. Immunohistochemistry was used to evaluate apoptosis and angiogenesis in the ischemic region, as well as the spatial distribution of the implanted BMSCs relative to the native neural cells. Implanted BMSCs migrated throughout the territory of the middle cerebral artery by 7 days after transplantation. Most implanted cells were located in the scar area and border zone of the ischemic region, and some expressed the neuronal marker NeuN. Rats receiving BMSC transplantation exhibited reduced scar size, limited apoptosis, and enhanced angiogenic factor expression and vascular density in the ischemic region relative to the control group, as well as significant improvements in the neurological severity scores. Intravenously administrated BMSCs facilitated the structural and functional recovery of neural tissue following ischemic injury, perhaps mediated by enhanced angiogenesis.
Cell Transplantation 02/2008; 16(10):993-1005. · 5.13 Impact Factor
