HSC were harvested from transgenic mice expressing green fluorescent protein (GFP) and injected in the region bordering the infarct, 3-5 hours after coronary artery occlusion in mice. A band of closely packed cells was identified 7 to 17 days later in nearly 50% of HSC injected hearts, between the endocardial and epicardial surface of the infarcted ventricle. This band occupied 50 75% of the damaged portion of the wall. c-kit/GFP positive HSC were found in the infarcted area shortly after coronary ligation and were still detectable at 7 days. c-kit stained HSC were not labeled by markers of myocytes, a-sarcomeric actin and myosin, endothelial cells, factor VIII, and smooth muscle cells, smooth muscle actin. The band of tissue included in the infarcted zone was constituted 75% by GFP, a-sarcomeric actin, myosin and a-actinin positive cardiac muscle cells. Other GFP-positive cell populations were endothelial cells and smooth muscle cells, organized in nascent capillary structures and arterioles. Proliferating myocytes were small with partially aligned myofibrils and resembled late fetal-neonatal cells. GFP-positive replicating myocytes, endothelial cells and smooth muscle cells were c-kit negative. Infarcted mice were injected with BrdU, once a day for 4 days, to establish the extent of cell proliferation in the regenerating myocardium: 28% myocytes, 17% endothelial cells and 12% smooth muscle cells were BrdU positive. These three levels of BrdU labeling were statistically different. Additionally, the percentages of cells positive to Ki67 were measured to evaluate the fraction of cycling cells at this stage of repair: 18% myocytes, 10% endothelial cells and 8% smooth muscle cells were in G1-G2M. In conclusion, HSC, when injected in the heart, rapidly differentiate into myocardium resulting in significant recovery of muscle mass after infarction.

Background— Despite widespread clinical use as a prognostic marker in ischemic heart disorders, the actual pathogenetic role of the short pentraxin, C-reactive protein, has not undergone stringent genetic testing because of evolutionary divergence between mouse and humans. The long pentraxin PTX3 is conserved in evolution, is expressed in the heart under inflammatory conditions, and is a candidate prognostic marker in acute myocardial infarction. It was therefore important to assess whether PTX3 plays a pathogenetic role in acute myocardial infarction. Methods and Results— In a model of acute myocardial infarction caused by coronary artery ligation and reperfusion, tissue mRNA expression and circulating levels of PTX3 increased. The interleukin-1R–MyD88 pathway plays a pivotal role in the induction of PTX3 transcript after ischemia. ptx3 -deficient mice showed exacerbated heart damage (33% larger infarcts in null mice; P =0.0047). Increased myocardial damage in ptx3 -deficient mice was associated with a greater no-reflow area, increased neutrophil infiltration, decreased number of capillaries, and increased number of apoptotic cardiomyocytes. In addition, ptx3 -deficient mice with acute myocardial infarction showed higher circulating levels of interleukin-6 and increased C3 deposition in lesional tissue. The phenotype was reversed by exogenous PTX3. Conclusions— Thus, PTX3 plays a nonredundant, regulatory, cardioprotective role in acute myocardial infarction in mice. Our results suggest that modulation of the complement cascade contributes to the cardioprotective function of PTX3.

Among the cardiovascular pathologies, ischemic heart disease is the leading cause of congestive heart failure as well as permanent premature disabilities. Reperfusion of a previously ischemic heart is a standard clinical procedure. Even if beneficial, reperfusion triggers an inflammatory response that contributes to the acute extension of ischemic injury and later participates in the reparative processes of the damaged myocardium. Occlusion of a major coronary artery in small rodents, followed or not followed by reperfusion, has proven to be a good model to assess the relevance of pathophysiological processes and drug effects in the setting of myocardial ischemia. Models involving reperfusion appear to be particularly suitable to study the inflammatory response, which is much more marked than with permanent ischemia. Ischemia/reperfusion of the myocardium in wild-type and transgenic animals (mostly mice) allows the possibility of testing the vast array of mediators that orchestrate the sequelae of inflammation, including tumor necrosis factor (TNF). Moreover, this model allows testing of the protective effects of anti-inflammatory drugs in experimental myocardial infarction.

Cardiac myocytes have been traditionally regarded as terminally differentiated cells that adapt to increased work and compensate for disease exclusively through hypertrophy. However, in the past few years, compelling evidence has accumulated suggesting that the heart has regenerative potential. Recent studies have even surmised the existence of resident cardiac stem cells, endothelial cells generating cardiomyocytes by cell contact or extracardiac progenitors for cardiomyocytes, but these findings are still controversial. We describe the isolation of undifferentiated cells that grow as self-adherent clusters (that we have termed “cardiospheres”) from subcultures of postnatal atrial or ventricular human biopsy specimens and from murine hearts. These cells are clonogenic, express stem and endothelial progenitor cell antigens/markers, and appear to have the properties of adult cardiac stem cells. They are capable of long-term self-renewal and can differentiate in vitro and after ectopic (dorsal subcutaneous connective tissue) or orthotopic (myocardial infarction) transplantation in SCID beige mouse to yield the major specialized cell types of the heart: myocytes (ie, cells demonstrating contractile activity and/or showing cardiomyocyte markers) and vascular cells (ie, cells with endothelial or smooth muscle markers).

Myocardial infarction leads to loss of tissue and impairment of cardiac performance. The remaining myocytes are unable to reconstitute the necrotic tissue, and the post-infarcted heart deteriorates with time 1 . Injury to a target organ is sensed by distant stem cells, which migrate to the site of damage and undergo alternate stem cell differentiation 2 , 3 , 4 , 5 ; these events promote structural and functional repair 6 , 7 , 8 . This high degree of stem cell plasticity prompted us to test whether dead myocardium could be restored by transplanting bone marrow cells in infarcted mice. We sorted lineage-negative (Lin - ) bone marrow cells from transgenic mice expressing enhanced green fluorescent protein 9 by fluorescence-activated cell sorting on the basis of c- kit expression 10 . Shortly after coronary ligation, Lin - c- kit POS cells were injected in the contracting wall bordering the infarct. Here we report that newly formed myocardium occupied 68% of the infarcted portion of the ventricle 9?days after transplanting the bone marrow cells. The developing tissue comprised proliferating myocytes and vascular structures. Our studies indicate that locally delivered bone marrow cells can generate de novo myocardium, ameliorating the outcome of coronary artery disease.

We compared the effects of an ACE inhibitor, captopril, with those of a DA 2 -dopaminergic/α 2 -adrenergic receptor agonist (CHF-1024) on neuroendocrine activation and cardiac fibrosis in a model of pressure-overload hypertrophy. Interrenal aortic stenosis was performed in 89 rats, treated with CHF-1024 (0.33, 2 or 6 mg kg −1 day −1 ), or captopril (1 g/L). Hemodynamic variables were recorded. Cardiac and renal weights, plasma aldosterone, renin activity and urinary catecholamine excretion were measured, as well as cardiac collagen. Blood pressure was lower in stenotic animals treated with CHF-1024 compared to vehicle (161 ± 10 vs 219 ± 10 mmHg, p < 0.01), but LV weight was similar. CHF-1024 elicited a marked dose-dependent attenuation of urinary norepinephrine excretion (1.80 ± 0.18 in controls compared to 0.40 ± 0.14 μg/24 h at the highest dose, p < 0.01) and of LV perivascular fibrosis. Captopril provoked a marked hypotension, reduced cardiac and body weights, plasma aldosterone concentration, dopamine excretion and perivascular collagen. The DA 2 /α 2 agonist CHF-1024 effectively blunts adrenergic drive and cardiac fibrosis in a rat model of pressure overload.

HomeCirculationVol. 102, No. 21Exogenous Hematopoietic Stem Cells Can Regenerate Infarcted Myocardium Free AccessOtherPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessOtherPDF/EPUBExogenous Hematopoietic Stem Cells Can Regenerate Infarcted Myocardium Donald Orlic, Jan Kajstura, Stefano Chimenti, Baosheng Li, Stacie Anderson, David Bodine, James Pickel, Annarosa Leri, Bernardo Nadal-Ginard, and Piero Anversa Donald OrlicDonald Orlic New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Jan KajsturaJan Kajstura New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Stefano ChimentiStefano Chimenti New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Baosheng LiBaosheng Li New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Stacie AndersonStacie Anderson New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , David BodineDavid Bodine New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , James PickelJames Pickel New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Annarosa LeriAnnarosa Leri New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , Bernardo Nadal-GinardBernardo Nadal-Ginard New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author , and Piero AnversaPiero Anversa New York Medical College, Valhalla, NY; NHGRI/NIH, Bethesda, MD Search for more papers by this author Originally published21 Nov 2000https://doi.org/10.1161/01.CIR.102.21.2672-gCirculation. 2000;102:2672To determine whether hematopoietic stem cells (HSC) can transform into cardiomyocytes with the potential to repair dead myocardium after infarction, Lin/c-kitI-II HSC were harvested from transgenic mice expressing green fluorescent protein (GFP) and injected in the region bordering the infarct, 3–5 hours after coronary artery occlusion in mice. A band of closely packed cells was identified 7 to 17 days later in nearly 50% of HSC injected hearts, between the endocardial and epicardial surface of the infarcted ventricle. This band occupied 50 75% of the damaged portion of the wall. c-kit/GFP positive HSC were found in the infarcted area shortly after coronary ligation and were still detectable at 7 days. c-kit stained HSC were not labeled by markers of myocytes, α-sarcomeric actin and myosin, endothelial cells, factor VIII, and smooth muscle cells, smooth muscle actin. The band of tissue included in the infarcted zone was constituted 75% by GFP, α-sarcomeric actin, myosin and α-actinin positive cardiac muscle cells. Other GFP-positive cell populations were endothelial cells and smooth muscle cells, organized in nascent capillary structures and arterioles. Proliferating myocytes were small with partially aligned myofibrils and resembled late fetal-neonatal cells. GFP-positive replicating myocytes, endothelial cells and smooth muscle cells were c-kit negative. Infarcted mice were injected with BrdU, once a day for 4 days, to establish the extent of cell proliferation in the regenerating myocardium: 28% myocytes, 17% endothelial cells and 12% smooth muscle cells were BrdU positive. These three levels of BrdU labeling were statistically different. Additionally, the percentages of cells positive to Ki67 were measured to evaluate the fraction of cycling cells at this stage of repair: 18% myocytes, 10% endothelial cells and 8% smooth muscle cells were in G1-G2M. In conclusion, HSC, when injected in the heart, rapidly differentiate into myocardium resulting in significant recovery of muscle mass after infarction. Previous Back to top Next FiguresReferencesRelatedDetails November 21, 2000Vol 102, Issue 21Article InformationMetrics Download: 26 Copyright © 2000 by American Heart Associationhttps://doi.org/10.1161/01.CIR.102.21.2672-g Originally publishedNovember 21, 2000 PDF download