carbocyanines and Myocardial-Infarction

Timely diagnosis of acute myocardial infarction (AMI) strongly impacts the survival rate of patients. The authors report the development of a two-shell hollow silica contrast agent useful for ultrasound (US) imaging, which is able to provide ultra-early diagnosis of AMI. To target the characterization of fast blood flow and high blood pressure in the heart, two shells of hollow silica are adopted with opposite polarities, which assemble based on amino and perfluorodecyl silanes. The external amino silane facilitates the attachment of disease-targeted groups, while the internal perfluorodecyl silane provides great US imaging contrast. The material also possesses superior water dispersity, controllable morphology, low toxicity, and biodegradability both in vitro and in vivo, thus promoting its applications in the ultra-early diagnosis of AMI in rats, and is particularly useful for delineation of myocardial necrosis sites.

Topics: Animals; Carbocyanines; Cell Line; Cell Survival; Contrast Media; Early Diagnosis; Female; Fluorescein-5-isothiocyanate; Hemolysis; Male; Mice; Microscopy, Electron, Transmission; Myocardial Infarction; Nanospheres; Rats, Sprague-Dawley; Silicon Dioxide; Spectroscopy, Fourier Transform Infrared; Ultrasonography

Assessment of the coronary microcirculation remains challenging.. we explored the feasibility of evaluating the coronary microvasculature in rats with myocardial infarction (MI) using a three-dimensional visualization technique.. Animals were divided into the sham operation group (S), MI 45 min group (M45), and MI 180 min group (M180). Opened microvessels were labelled with the fluorescent dye DiI (1, 1'-dioctadecyl-3, 3, 3'3'-tetramethylindo carbocyanine perchlorate) using a heart perfusion method. The microvascular distribution and opening status were observed under laser scanning confocal microscopy, which was adjusted to facilitate evaluation of subjects around 6 to 20 μm.. Microvascular vessels (6-20 μm) were successfully labelled by DiI. Intact and clear three-dimensional microvascular structures were observed in myocardium of sham rats and remote non-infarct myocardial tissue of MI rats, while there was almost no microvascular structure in the infarct area of the M45 group, and only a small amount of microvascular visualization was visualized in the infarct area of the M180 group. The microvascular area and microvascular density in M45 group and M180 group in the infarct border zone were significantly lower than corresponding area in S group.. Three-dimensional visualization of opened coronary microvascular vessels is feasible in DiI-labelled myocardium in this rat MI model. This novel technique might be useful for defining the underlying mechanisms of coronary microvascular diseases and observe the efficacy of various therapy strategies on coronary microvessels.

Topics: Animals; Carbocyanines; Coronary Vessels; Disease Models, Animal; Feasibility Studies; Fluorescent Dyes; Imaging, Three-Dimensional; Microscopy, Confocal; Microscopy, Fluorescence; Microvessels; Myocardial Infarction; Predictive Value of Tests; Rats, Sprague-Dawley

Nucleic acid (NA)-based therapy is proposed to address serious diseases such as cardiovascular diseases (CVDs). Powerful NA delivery vehicles are essential for effective gene therapy. Herein, a novel type of delivery vehicle, an unlockable core-shell nanocomplex (Hep@PGEA) with self-accelerating NA release, is structurally designed. Hep@PGEA is composed of disulfide-bridged heparin nanoparticle (HepNP) core and low-toxicity PGEA cationic shell. In comparison with NA, heparin, a negatively charged polysaccharide macromolecule, exhibits stronger interactions with cationic species. Upon the breakdown of redox-responsive HepNP cores, unlocked heparin would interact with the outer cationic shells and replace the condensed NA to facilitate NA release. Such unique Hep@PGEA is successfully explored for effective miRNA-pDNA staged gene therapy of myocardial infarction (MI), one of the most serious CVDs. With the progression of MI, glutathione amounts in heart tissues increase. MiR-499 (for the inhibition of cardiomyocyte apoptosis) and plasmid encoding vascular endothelial growth factor (for the promotion of angiogenesis) are sequentially delivered for systemic treatment of MI. Such treatment produces impressive results in restoring heart function and suppressing cardiac hypertrophy. Due to the wide existence of redox agents in cells, the proposed unlockable delivery nanovehicle and staged therapy strategy can provide new methods to effectively treat different serious diseases.

Topics: Animals; Carbocyanines; DNA; Genetic Therapy; Glutathione; Heparin; Mice; MicroRNAs; Microscopy, Atomic Force; Microscopy, Confocal; Myocardial Infarction; Nanoparticles; Particle Size; Polymethacrylic Acids; Vascular Endothelial Growth Factor A

Topics: Animals; Arrhythmias, Cardiac; Bone Marrow; Bone Marrow Cells; Bone Marrow Transplantation; Carbocyanines; Cell Differentiation; Coronary Vessels; Disease Models, Animal; Dogs; Myocardial Infarction; Myocardium; Transplantation, Autologous

Mesenchymal stem cells (MSCs) have been shown to improve cardiac electrophysiology when administered in the setting of acute myocardial infarction. However, the electrophysiological phenotype of MSCs in situ is not clear. We hypothesize that MSCs delivered intramyocardially to cryoinjured myocardium can engraft, but will not actively generate, action potentials. Cryoinjury-induced scar was created on the left ventricular epicardial surface of adult rat hearts. Within 30 min, hearts were injected with saline (sham, n = 11) or bone marrow-derived MSCs (2 × 10(6)) labeled with 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocarbocyanine percholate (DiI; n = 16). At 3 wk, optical mapping and cell isolation were used to measure optical action potentials and calcium transients, respectively. Histological analysis confirmed subepicardial scar thickness and the presence of DiI-positive cells that express connexin-43. Optical action potential amplitude within the scar at MSC-positive sites (53.8 ± 14.3%) was larger compared with sites devoid of MSCs (35.3 ± 14.2%, P < 0.05) and sites within the scar of shams (33.5 ± 6.9%, P < 0.05). Evidence of simultaneous action potential upstroke, the loss of action potential activity following ablation of adjacent viable myocardium, and no rapid calcium transient response in isolated DiI+ cells suggest that the electrophysiological influence of engrafted MSCs is electrotonic. MSCs can engraft when directly injected into a cryoinjury and are associated with evidence of action potential activity. However, our results suggest that this activity is not due to generation of action potentials, but rather passive influence coupled from neighboring viable myocardium.

Topics: Action Potentials; Animals; Calcium Signaling; Carbocyanines; Cell Communication; Connexin 43; Cryosurgery; Disease Models, Animal; Fluorescent Dyes; Heart Conduction System; Heart Ventricles; Male; Mesenchymal Stem Cell Transplantation; Myocardial Infarction; Myocardium; Rats; Rats, Inbred Lew; Regeneration; Time Factors; Voltage-Sensitive Dye Imaging

During tissue healing, the primary role of myofibroblasts involves the synthesis and deposition of collagen. However, it has also been reported that selective populations of myofibroblasts can acquire the phenotype and/or differentiate to other cells types. The present study tested the hypothesis that myofibroblasts isolated from the scar of the ischemically damaged rat heart can recapitulate an endothelial cell-like response when plated in a permissive in vitro environment. Scar myofibroblasts, neonatal and adult ventricular fibroblasts express smooth muscle α-actin, collagen α(1) type 1 and a panel of pro-fibrotic and pro-angiogenic peptide growth factor mRNAs. Myofibroblasts plated alone on matrigel led to the self assembly of lumen-like structures whereas neonatal and adult rat ventricular fibroblasts were unresponsive. Myofibroblasts labeled with the fluorescent cell tracker CM-DiI were injected in the viable myocardium of 3-day post-myocardial infarcted Sprague-Dawley rats and sacrificed 7 days later. Injected CM-DiI-labeled myofibroblasts were detected predominantly in the peri-infarct/infarct region, highlighting their migration to the damaged region. However, engrafted myofibroblasts in the peri-infarct/infarct region were unable to adopt an endothelial cell-like phenotype or lead to the de novo formation of CM-DiI-labeled blood vessels. The non-permissive nature of the infarct region may be attributed at least in part to the presence of growth-promoting stimuli as TGF-β and the β-adrenergic agonist isoproterenol inhibited the self assembly of lumen-like structures by myofibroblasts. Thus, when plated in a permissive in vitro environment, scar myofibroblasts can self assemble and form lumen-like structures providing an additional novel phenotype distinguishing this population from normal ventricular fibroblasts.

Topics: Actins; Animals; Carbocyanines; Cell Culture Techniques; Cell Differentiation; Cell Separation; Cells, Cultured; Cicatrix; Collagen; Collagen Type I; Collagen Type I, alpha 1 Chain; Drug Combinations; Endothelial Cells; Fibroblasts; Heart Ventricles; Intercellular Signaling Peptides and Proteins; Isoproterenol; Laminin; Male; Myocardial Infarction; Myocardial Ischemia; Myocardium; Myofibroblasts; Phenotype; Proteoglycans; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transforming Growth Factor beta

Using molecular imaging techniques, we examined interstitial alterations during postmyocardial infarction (MI) remodeling and assessed the efficacy of antiangiotensin and antimineralocorticoid intervention, alone and in combination.. The antagonists of the renin-angiotensin-aldosterone axis restrict myocardial fibrosis and cardiac remodeling after MI and contribute to improved survival. Radionuclide imaging with technetium-99m-labeled Cy5.5 RGD imaging peptide (CRIP) targets myofibroblasts and indirectly allows monitoring of the extent of collagen deposition post-MI.. CRIP was intravenously administered for gamma imaging after 4 weeks of MI in 63 Swiss-Webster mice and in 6 unmanipulated mice. Of 63 animals, 50 were treated with captopril (C), losartan (L), spironolactone (S) alone, or in combination (CL, SC, SL, and SCL), 8 mice received no treatment. Echocardiography was performed for assessment of cardiac remodeling. Hearts were characterized histopathologically for the presence of myofibroblasts and thick and thin collagen fiber deposition.. Acute MI size was similar in all groups. The quantitative CRIP percent injected dose per gram uptake was greatest in the infarct area of untreated control mice (2.30 +/- 0.14%) and decreased significantly in animals treated with 1 agent (C, L, or S; 1.71 +/- 0.35%; p = 0.0002). The addition of 2 (CL, SC, or SL 1.31 +/- 0.40%; p < 0.0001) or 3 agents (SCL; 1.16 +/- 0.26%; p < 0.0001) demonstrated further reduction in tracer uptake. The decrease in echocardiographic left ventricular function, strain and rotation parameters, as well as histologically verified deposition of thin collagen fibers, was significantly reduced in treatment groups and correlated with CRIP uptake.. Radiolabeled CRIP allows for the evaluation of the efficacy of neurohumoral antagonists after MI and reconfirms superiority of combination therapy. If proven clinically, molecular imaging of the myocardial healing process may help plan an optimal treatment for patients susceptible to heart failure.

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Animals; Captopril; Carbocyanines; Cardiovascular Agents; Disease Models, Animal; Drug Therapy, Combination; Echocardiography; Fibrillar Collagens; Fibroblasts; Fibrosis; Losartan; Mice; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Myocardium; Oligopeptides; Predictive Value of Tests; Spironolactone; Technetium; Tomography, Emission-Computed, Single-Photon; Ventricular Function, Left; Ventricular Remodeling

Topics: Angiotensin II Type 1 Receptor Blockers; Angiotensin-Converting Enzyme Inhibitors; Carbocyanines; Cardiovascular Agents; Drug Therapy, Combination; Echocardiography; Fibrillar Collagens; Fibroblasts; Fibrosis; Heart Failure; Humans; Mineralocorticoid Receptor Antagonists; Myocardial Infarction; Myocardium; Oligopeptides; Predictive Value of Tests; Technetium; Tomography, Emission-Computed, Single-Photon; Ventricular Function, Left; Ventricular Remodeling

The aim of the current study is to test the ability to label and detect murine embryonic stem cell-derived cardiovascular progenitor cells (ES-CPC) with cardiac magnetic resonance (CMR) using the novel contrast agent Gadofluorine M-Cy3 (GdFM-Cy3).. Cell therapy shows great promise for the treatment of cardiovascular disease. An important limitation to previous clinical studies is the inability to accurately identify transplanted cells. GdFM-Cy3 is a lipophilic paramagnetic contrast agent that contains a perfluorinated side chain and an amphiphilic character that allows for micelle formation in an aqueous solution. Previous studies reported that it is easily taken up and stored within the cytosol of mesenchymal stem cells, thereby allowing for paramagnetic cell labeling. Investigators in our laboratory have recently developed techniques for the robust generation of ES-CPC. We reasoned that GdFM-Cy3 would be a promising agent for the in vivo detection of these cells after cardiac cell transplantation.. ES-CPC were labeled with GdFM-Cy3 by incubation. In vitro studies were performed to assess the impact of GdFM-Cy3 on cell function and survival. A total of 500,000 GdFM-Cy3-labeled ES-CPC or control ES-CPC were injected into the myocardium of mice with and without myocardial infarction. Mice were imaged (9.4-T) before and over a 2-week time interval after stem cell transplantation. Mice were then euthanized, and their hearts were sectioned for fluorescence microscopy.. In vitro studies demonstrated that GdFM-Cy3 was easily transfectable, nontoxic, stayed within cells after labeling, and could be visualized using CMR and fluorescence microscopy. In vivo studies confirmed the efficacy of the agent for the detection of cells transplanted into the hearts of mice after myocardial infarction. A correspondence between CMR and histology was observed.. The results of the current study suggest that it is possible to identify and potentially track GdFM-Cy3-labeled ES-CPC in murine infarct models via CMR.

Topics: Animals; Carbocyanines; Cell Line; Cell Proliferation; Cell Survival; Contrast Media; Disease Models, Animal; Embryonic Stem Cells; Female; Fluorescent Dyes; Fluorocarbons; Magnetic Resonance Imaging; Mesenchymal Stem Cell Transplantation; Mice; Mice, SCID; Microscopy, Fluorescence; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Organometallic Compounds; Staining and Labeling; Time Factors

Topics: Animals; Carbocyanines; Cell Proliferation; Cell Survival; Contrast Media; Fluorescent Dyes; Fluorocarbons; Humans; Magnetic Resonance Imaging; Mice; Microscopy, Fluorescence; Myocardial Infarction; Myocardium; Myocytes, Cardiac; Organometallic Compounds; Staining and Labeling; Stem Cell Transplantation; Stem Cells; Time Factors

A novel dual-contrast molecular MRI technique to image both cardiomyocyte apoptosis and necrosis in vivo within 4 to 6 hours of ischemia is presented. The technique uses the annexin-based nanoparticle AnxCLIO-Cy5.5 (apoptosis) and simultaneous delayed-enhancement imaging with a novel gadolinium chelate, Gd-DTPA-NBD (necrosis).. Mice with transient coronary ligation were injected intravenously at the onset of reperfusion with AnxCLIO-Cy5.5 (n=7) or the control probe Inact_CLIO-Cy5.5 (n=6). T2*-weighted MR images (9.4 T) were acquired within 4 to 6 hours of reperfusion. The contrast-to-noise ratio between injured and uninjured myocardium was measured. The mice were then injected with Gd-DTPA-NBD, and delayed-enhancement imaging was performed within 10 to 30 minutes. Uptake of AnxCLIO-Cy5.5 was most prominent in the midmyocardium and was significantly greater than that of Inact_CLIO-Cy5.5 (contrast-to-noise ratio, 8.82+/-1.5 versus 3.78+/-1.1; P<0.05). Only 21+/-3% of the myocardium with accumulation of AnxCLIO-Cy5.5 showed delayed-enhancement of Gd-DTPA-NBD. Wall thickening was significantly reduced in segments with delayed enhancement and/or transmural accumulation of AnxCLIO-Cy5.5 (P<0.001). Fluorescence microscopy of AnxCLIO-Cy5.5 and immunohistochemistry of Gd-DTPA-NBD confirmed the presence of large numbers of apoptotic but potentially viable cardiomyocytes (AnxCLIO-Cy5.5 positive, Gd-DTPA-NBD negative) in the midmyocardium.. A novel technique to image cardiomyocyte apoptosis and necrosis in vivo within 4 to 6 hours of injury is presented and reveals large areas of apoptotic but viable myocardium in the midmyocardium. Strategies to salvage the numerous apoptotic but potentially viable cardiomyocytes in the midmyocardium in acute ischemia should be investigated.

Topics: 4-Chloro-7-nitrobenzofurazan; Analysis of Variance; Animals; Annexin A5; Annexins; Apoptosis; Carbocyanines; Contrast Media; Flow Cytometry; Gadolinium DTPA; Image Processing, Computer-Assisted; In Situ Nick-End Labeling; Magnetic Resonance Imaging; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Myocardial Infarction; Myocytes, Cardiac; Nanoparticles; Nanotechnology; Necrosis; Organometallic Compounds; Pentetic Acid; Statistics, Nonparametric

Basic and clinical studies have shown that bone marrow cell therapy can improve cardiac function following infarction. In experimental animals, reported stem cell-mediated changes range from no measurable improvement to the complete restoration of function. In the clinic, however, the average improvement in left ventricular ejection fraction is around 2% to 3%. A possible explanation for the discrepancy between basic and clinical results is that few basic studies have used the magnetic resonance (MR) imaging (MRI) methods that were used in clinical trials for measuring cardiac function. Consequently, we employed cine-MR to determine the effect of bone marrow stromal cells (BMSCs) on cardiac function in rats. Cultured rat BMSCs were characterized using flow cytometry and labeled with iron oxide particles and a fluorescent marker to allow in vivo cell tracking and ex vivo cell identification, respectively. Neither label affected in vitro cell proliferation or differentiation. Rat hearts were infarcted, and BMSCs or control media were injected into the infarct periphery (n = 34) or infused systemically (n = 30). MRI was used to measure cardiac morphology and function and to determine cell distribution for 10 wk after infarction and cell therapy. In vivo MRI, histology, and cell reisolation confirmed successful BMSC delivery and retention within the myocardium throughout the experiment. However, no significant improvement in any measure of cardiac function was observed at any time. We conclude that cultured BMSCs are not the optimal cell population to treat the infarcted heart.

Topics: Animals; Bone Marrow Cells; Bone Marrow Transplantation; Carbocyanines; Cell Differentiation; Cell Movement; Cell Proliferation; Cell Survival; Cells, Cultured; Disease Models, Animal; Ferric Compounds; Flow Cytometry; Fluorescent Dyes; Green Fluorescent Proteins; Immunohistochemistry; Magnetic Resonance Imaging, Cine; Male; Myocardial Contraction; Myocardial Infarction; Myocardium; Rats; Rats, Wistar; Staining and Labeling; Stroke Volume; Stromal Cells; Time Factors; Ventricular Function, Left

The purpose of this study was to evaluate interstitial alterations in myocardial remodeling using a radiolabeled Cy5.5-RGD imaging peptide (CRIP) that targets myofibroblasts.. Collagen deposition and interstitial fibrosis contribute to cardiac remodeling and heart failure after myocardial infarction (MI). Evaluation of myofibroblastic proliferation should provide indirect evidence of the extent of fibrosis.. Of 46 Swiss-Webster mice, MI was induced in 41 by coronary artery occlusion, and 5 were unmanipulated. Of the 41 mice, 6, 6, and 5 received intravenous technetium-99m labeled CRIP for micro-single-photon emission computed tomography imaging 2, 4, and 12 weeks after MI, respectively; 8 received captopril or captopril with losartan up to 4 weeks after MI. Scrambled CRIP was used 4 weeks after MI in 6 mice; the remaining 10 of 46 mice received unradiolabeled CRIP for histologic characterization.. Maximum CRIP uptake was observed in the infarct area; quantitative uptake (percent injected dose/g) was highest at 2 weeks (2.75 +/- 0.46%), followed by 4 (2.26 +/- 0.09%) and 12 (1.74 +/- 0.24%) weeks compared with that in unmanipulated mice (0.59 +/- 0.19%). Uptake was higher at 12 weeks in the remote areas. CRIP uptake was histologically traced to myofibroblasts. Captopril alone (1.78 +/- 0.31%) and with losartan (1.13 +/- 0.28%) significantly reduced tracer uptake; scrambled CRIP uptake in infarct area (0.74 +/- 0.17%) was similar to CRIP uptake in normal myocardium.. Radiolabeled CRIP allows for noninvasive visualization of interstitial alterations during cardiac remodeling, and is responsive to antiangiotensin treatment. If proven clinically feasible, such a strategy would help identify post-MI patients likely to develop heart failure.

Topics: Animals; Carbocyanines; Collagen; Coronary Artery Disease; Endomyocardial Fibrosis; Feasibility Studies; Fibroblasts; Heart Failure; Integrins; Male; Mice; Models, Animal; Myocardial Infarction; Myocardium; Radiopharmaceuticals; Time Factors; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed; Ultrasonography; Ventricular Remodeling

Fluorescence imaging of the heart is currently limited to invasive ex vivo or in vitro applications. We hypothesized that the adaptation of advanced transillumination and tomographic techniques would allow noninvasive fluorescence images of the heart to be acquired in vivo and be coregistered with in vivo cardiac magnetic resonance images.. The uptake of the magnetofluorescent nanoparticle CLIO-Cy5.5 by macrophages in infarcted myocardium was studied. Ligation of the left coronary artery was performed in 12 mice and sham surgery in 7. The mice were injected, 48 hours after surgery, with 3 to 20 mg of iron per kilogram of CLIO-Cy5.5. Magnetic resonance imaging and fluorescence molecular tomography were performed 48 hours later. An increase in magnetic resonance imaging contrast-to-noise ratio, indicative of myocardial probe accumulation, was seen in the anterolateral walls of the infarcted mice but not in the sham-operated mice (23.0+/-2.7 versus 5.43+/-2.4; P<0.01). Fluorescence intensity over the heart was also significantly greater in the fluorescence molecular tomography images of the infarcted mice (19.1+/-5.2 versus 5.3+/-1.4; P<0.05). The uptake of CLIO-Cy5.5 by macrophages infiltrating the infarcted myocardium was confirmed by fluorescence microscopy and immunohistochemistry.. Noninvasive imaging of myocardial macrophage infiltration has been shown to be possible by both fluorescence tomography and magnetic resonance imaging. This could be of significant value in both the research and clinical settings. The techniques developed could also be used to image other existing fluorescent and magnetofluorescent probes and could significantly expand the role of fluorescence imaging in the heart.

Topics: Animals; Carbocyanines; Disease Models, Animal; Macrophages; Magnetic Resonance Imaging; Mice; Mice, Inbred C57BL; Microscopy, Fluorescence; Myocardial Infarction; Myocardium; Tomography, Optical