Hyosook Hwang

The small molecule Wnt signaling modulator ICG-001 improves contractile function in chronically infarcted rat myocardium.

The adult mammalian heart has limited capability for self-repair after myocardial infarction. Therefore, therapeutic strategies that improve post-infarct cardiac function are critically needed. The small molecule ICG-001 modulates Wnt signaling and increased the expression of genes beneficial for cardiac regeneration in epicardial cells. Lineage tracing experiments, demonstrated the importance of β-catenin/p300 mediated transcription for epicardial progenitor contribution to the myocardium. Female rats given ICG-001 for 10 days post-occlusion significantly improved ejection fraction by 8.4%, compared to controls (P<0.05). Taken together, Wnt modulation via β-catenin/CBP inhibition offers a promising therapeutic strategy towards restoration of myocardial tissues and an enhancement of cardiac functions following infarction.

Improving regenerating potential of the heart after myocardial infarction: factor-based approach.

The emerging evidence that the heart has the potential to regenerate, albeit not ideally, has stimulated considerable interest in the field of cardiac regenerative medicine. Several lines of research demonstrated that factor-based therapy is feasible and effective, whether it is used independently or as an adjunct to cell therapy. The ultimate goal of the factor-based approach is to improve the regenerating potential of the heart as a means to treat patients with cardiovascular disease. This article reviews recent approaches involving factor-based therapy for cardiac repair and regeneration including some of the advantages of this type of therapy as well as some of the hurdles that must be overcome before this therapeutic approach becomes a standard part of clinical medicine.

Ranolazine as a Cardioplegia Additive Improves Recovery of Diastolic Function in Isolated Rat Hearts

Background— Ranolazine (Ran), an antianginal agent, inhibits late Na+ current. The purpose of this study was to determine whether there was an added benefit of adding Ran to cardioplegia (CP) in a model of global ischemia/reperfusion. Methods and Results— Isolated rat hearts were Langendorff-perfused and exposed to 40-minute normothermic, cardioplegic global ischemia and 30 minutes of reperfusion. Before ischemia and during reperfusion, hearts were treated with no drug (control) or with the late Na+ current inhibitors Ran (5 &mgr;mol/L) or tetrodotoxin (1 &mgr;mol/L). Ischemic cardioplegic arrest led to an increase of left ventricular end-diastolic pressure (LVEDP) by ≥20 mm Hg (ie, cardiac contracture). Ten out of 11 hearts treated with CP alone developed contracture, whereas 6 out of 11 hearts treated with CP plus Ran developed contracture. Ran added to CP reduced LVEDP at the end of ischemia from 41±5 mm Hg in CP alone to 26±3 mm Hg in CP plus Ran (P=0.024). Area under the curve for LVEDP during the entire ischemic period was also smaller in CP plus Ran versus CP alone. The percent increase (from baseline) of LVEDP measured at the end of 30-minute reperfusion was smaller for CP plus Ran (66±18%) versus CP alone (287±90%; P=0.035). The area under the curve for LVEDP during reperfusion was smaller in CP plus Ran versus CP alone. Tetrodotoxin (1 &mgr;mol/L) also reduced cardiac contracture during ischemia/reperfusion, compared to CP alone. Conclusions— Our results suggest that Ran may have therapeutic potential as an adjunct to CP and further support a protective role of Na+ current inhibition during ischemia/reperfusion.

The effect of mannosylation of liposome-encapsulated indocyanine green on imaging of sentinel lymph node

Abstract The imaging of sentinel lymph nodes (SLN) has been researched for its role in assessing cancer progression and postsurgical lymphedema. Indocyanine green (ICG) is a near-infrared (NIR) optical dye that has been approved by the Food and Drug Administration. It is known that liposome-encapsulated ICG (LP-ICG) has improved stability and fluorescence signal compared with ICG. We designed mannosylated liposome-encapsulated ICG (M-LP-ICG) as an optical contrast agent for SLN. M-LP-ICG has a higher UV absorbance spectrum and fluorescence intensity than LP-ICG. The stability of M-LP-ICG measured in 50% fetal bovine serum solution by a dialysis method was better than that of LP-ICG. M-LP-ICG demonstrated a high uptake in RAW 264.7 macrophage cell because the density of mannose is high. There were differences between M-LP-ICG and glucosylated liposome-encapsulated ICG (G-LP-ICG), which are geometrical isomers. The result of an inhibition study of M-LP-ICG showed a statistically significant decrease in uptake in RAW 264.7 cells after either co-treatment or pre-treatment with d-(+)-mannose as an inhibitor. Results from an in vitro experiment demonstrated that M-LP-ICG was specifically taken up by macrophage cells through the mannose receptor on its surface. The time-series images acquired from a normal mouse model after subcutaneous injection showed that the signal from M-LP-ICG in SLN and other organs appeared early and disappeared quickly in comparison with signals from LP-ICG. Not only the sentinel but also the draining lymph nodes were observed partly in M-LP-ICG. M-LP-ICG appears to increase the specificity of uptake and retention in macrophages, making it a good candidate contrast agent for an optic imaging system for SLN and the lymphatic system.

New Insights Into the Open Artery Hypothesis

See related article, pages 98–106 Early coronary artery reperfusion is clearly the most important therapy for acute ST segment elevation myocardial infarcts. Early reperfusion reduces myocardial infarct size and in so doing helps to prevent or minimize deleterious consequences of a large myocardial infarction, including infarct expansion (thinning and dilation of the infarct), subsequent eccentric hypertrophy and dilation of the noninfarcted ventricular muscle, and global dilation of the left ventricle.1–4 These processes encompass the phenomenon of ventricular remodeling. One of the major determinants of death at 1 year after a myocardial infarction is the degree of dilation of the left ventricle (LV).5 However, suppose early reperfusion is not available. A number of manipulations and pharmacological therapies can be administered beyond the time frame of reducing myocardial infarct size and still reduce the extent of infarct expansion and LV remodeling (Table 1). Angiotensin converting enzyme inhibitors6 and angiotensin receptor blockers7 have been shown to reduce LV dilation and remodeling and in some studies reduce major cardiovascular events. Cell therapy and even some noncellular therapies (collagen, alginate) may thicken the infarct scar and prevent ventricular wall dyskinesis.8–10 Aneurysmectomy and certain suturing techniques have been attempted to prevent infarct expansion and remodeling.11 Late reperfusion—too late to reduce myocardial infarct size, but early enough to favorably affect infarct healing1—also appears to limit infarct expansion and limit LV remodeling, and is the subject of the accompanying article.12 View this table: Table 1. Table 1. Factors That May Improve or Lessen Post-MI LV Remodeling Certain features are associated with worse LV remodeling (Table 2), including a large myocardial infarct, lack of any reperfusion,1 a large zone of no reflow,13 and certain antiinflammatory agents14 (such as steroids and a host of nonsteroidal antiinflammatory agents) introduced early enough to inhibit …

Effect of blue light emitting diodes on melanoma cells: Involvement of apoptotic signaling

The present study was undertaken to examine whether blue LED irradiation induces cellular apoptosis in B16-F10 cells and whether it blocks the early growth of melanoma cells in mice. Irradiation with blue LED was observed to reduce cell viability and to induce apoptotic cell death, as accompanied by exposure of phosphatidylserine on the plasma outside membrane and an accumulation of a sub-G1 population. Furthermore, the mitochondrial membrane potential increased, and mitochondria-related apoptotic proteins (cytochrome c, caspase 3, and PARP) were observed. In addition, the level of intracellular superoxide anion (O2(-)) gradually increased. Interestingly the phosphorylation of p53 increased at earlier times under blue LED irradiation, but reduced after exposure for a longer time. Additionally, the thickness of the mice footpad injected with B16-F10 cells decreased significantly until the 9th day of blue LED irradiation, indicating the inhibition of the early growth rate of the melanoma cells. Our data demonstrate that blue LED irradiation induces apoptotic cell death by activating the mitochondria-mediated pathway and reduces the early growth rate of melanoma cells. Further studies are needed to elucidate the precise mechanism of blue LED in melanoma cells.

Peptide-loaded Nanoparticles and Radionuclide Imaging for Individualized Treatment of Myocardial Ischemia

PURPOSE To determine whether chitosan hydrogel nanoparticles loaded with vascular endothelial growth factor (VEGF) peptides (81-91 fragments) capable of targeting the ischemic myocardium enhance angiogenesis and promote therapeutic effects and whether radionuclide image-guided dosage control is feasible. MATERIALS AND METHODS Experimental procedures and protocols were approved by the Institutional Animal Care and Use Committee. Rats (n = 32, eight per group) were subjected to myocardial ischemia (control group) and received chitosan hydrogel nanoparticles with VEGF165 proteins (chitosan VEGF) or VEGF81-91 peptides (chitosan peptides) via apical puncture. Ischemic hearts receiving chitosan without angiogenic factors served as the chitosan control. Myocardial perfusion was examined 7 days after surgery by using technetium 99m ((99m)Tc) tetrofosmin (37 MBq) autoradiography, and changes in vascular density with immunohistochemical staining were reviewed. Kruskal-Wallis test and Bonferroni corrected Mann-Whitney U test were used for multiple comparisons. Wilcoxon signed rank test was used to compare myocardial retention of (99m)Tc chitosan. RESULTS Thirty minutes of myocardial ischemia resulted in perfusion defects (median, 54%; interquartile range [IQR], 41%-62%). Chitosan VEGF decreased perfusion defect extent (median, 68%; IQR, 63%-73%; P = .006 vs control) and increased vascular density (median, 81 vessels per high-power field; IQR, 72-100; P = .009 vs control). Administration of chitosan peptides reduced the degree of perfusion defects (median, 66%; IQR, 62%-73%; P = .006 vs control) and increased vascular density (median, 82 vessels; IQR, 78-92; P = .006 vs control). The effects of chitosan peptides on perfusion and vascular density were comparable to those seen with chitosan VEGF proteins (P = .713 and P = .833, respectively). Chitosan radiolabeled with (99m)Tc was administered twice at reperfusion with a 1-hour interval to determine whether image-guided dosage control is feasible. The hearts initially retained 4.6% (IQR, 4.1%-5.0%) of (99m)Tc chitosan administered and 9.2% (IQR, 6.6%-12.7%; P = .068) with subsequent injection. CONCLUSION VEGF peptides have angiogenic potential and resulted in therapeutic effectiveness. Adjunct use of single photon emission computed tomography was also demonstrated for individualized treatment of myocardial ischemia by further tailoring the therapeutic dosing. Online supplemental material is available for this article.

Blue light emitting diode induces apoptosis in lymphoid cells by stimulating autophagy.

The present study was performed to examine the induction of apoptotic cell death and autophagy by blue LED irradiation, and the contribution of autophagy to apoptosis in B cell lymphoma A20 and RAMOS cells exposed to blue LED. Irradiation with blue LED reduced cell viability and induced apoptotic cell death, as indicated by exposure of phosphatidylserine on the plasma outside membrane and fragmentation of DNA. Furthermore, the mitochondrial membrane potential increased, and apoptotic proteins (PARP, caspase 3, Bax, and bcl-2) were observed. In addition, the level of intracellular superoxide anion (O2(-)) gradually increased. Interestingly the formation of autophagosomes and level of LC3-II were increased in blue LED-irradiated A20 and RAMOS cells, but inhibited after pretreatment with 3-methyladenine (3-MA), widely used as an autophagy inhibitor. Inhibition of the autophagic process by pretreatment with 3-MA blocked blue LED irradiation-induced caspase-3 activation. Moreover, a significant reduction of both the early and late phases of apoptosis after transfection with ATG5 and beclin 1 siRNAs was shown by the annexin V/PI staining, indicating a crucial role of autophagy in blue LED-induced apoptosis in cells. Additionally, the survival rate of mice irradiated with blue LED after injection with A20 cells increased compared to the control group. Our data demonstrate that blue LED irradiation induces apoptosis via the mitochondrial-mediated pathway, in conjunction with autophagy. Further studies are needed to elucidate the precise mechanism of blue LED-induced immune cell death.

Ranolazine as an Adjunct to Cardioplegia: A Potential New Therapeutic Application

The purpose of this study was to examine the therapeutic potential of ranolazine, a novel antianginal drug, as an adjunctive therapy to hyperkalemic cardioplegia. Rat hearts were Langendorff-perfused and exposed to 40 minutes of ischemia and 30 minutes of reperfusion without (control) or with cardioplegia or cardioplegia with 50 µmol/L ranolazine. During ischemia, cardioplegia prolonged time to contracture, defined as the time to reach an intraventricular pressure of 20 mm Hg, from 12 + 1 minute (control) to 25 + 2 minutes (P < .05). Ranolazine supplement further lengthened the time to contracture to 34 + 2 minutes (P < .05). Ischemia/reperfusion caused a dramatic elevation in left ventricular end diastolic pressure (LVEDP) during reperfusion. Cardioplegia lessened the LVEDP elevation measured at 30 minutes of reperfusion from 76 + 3 mm Hg (control) to 32 + 3 mm Hg (P < .05). The increase in LVEDP was reduced even further to 17 + 2 mm Hg in hearts receiving cardioplegia plus ranolazine (P < .05). These results suggest that addition of ranolazine during hyperkalemic ischemic cardioplegic arrest is beneficial and provides further protection against contracture.

Direct and Acute Cardiotoxic Effects of Ultrafine Air Pollutants in Spontaneously Hypertensive Rats and Wistar–Kyoto Rats

It is hypothesized that preexisting cardiovascular disease could affect the susceptibility to direct and acute cardiotoxic effects of ultrafine air pollutants. Ultrafine particles (UFP) isolated from 12.5 mg of diesel particulate matter (National Institute of Standards and Technology) were infused into isolated Langendorffperfused hearts obtained from spontaneously hypertensive rats (SHR) and normotensive control Wistar— Kyoto rats (WKY). Perfusion for 30 minutes with UFP reduced cardiac function in both groups—but to a greater extent in WKY. In SHR, developed pressure was reduced by 24.1 ± 4.4% of baseline and maximal dP/dt was reduced by 19.8 ± 4.9%; in WKY, developed pressure was reduced by 43.5 ± 7.3% and maximal dP/dt by 41.8 ± 8.2% (P < .05 for maximal dP/dt in SHR vs WKY). Coronary flow was decreased by 30.3% versus 53.7% in SHR versus WKY ( P < .05). The results of this study suggest that although UFP depress myocardial contractile response and coronary flow in both SHR and WKY the underlying hypertension does not necessarily worsen the response.