Shorter Is Better: The α-(l)-Threofuranosyl Nucleic Acid Modification Improves Stability, Potency, Safety, and Ago2 Binding and Mitigates Off-Target Effects of Small Interfering RNAs.

Chemical modifications are necessary to ensure the metabolic stability and efficacy of oligonucleotide-based therapeutics. Here, we describe analyses of the α-(l)-threofuranosyl nucleic acid (TNA) modification, which has a shorter 3'-2' internucleotide linkage than the natural DNA and RNA, in the context of small interfering RNAs (siRNAs). The TNA modification enhanced nuclease resistance more than 2'-O-methyl or 2'-fluoro ribose modifications. TNA-containing siRNAs were prepared as triantennary N-acetylgalactosamine conjugates and were tested in cultured cells and mice. With the exceptions of position 2 of the antisense strand and position 11 of the sense strand, the TNA modification did not inhibit the activity of the RNA interference machinery. In a rat toxicology study, TNA placed at position 7 of the antisense strand of the siRNA mitigated off-target effects, likely due to the decrease in the thermodynamic binding affinity relative to the 2'-O-methyl residue. Analysis of the crystal structure of an RNA octamer with a single TNA on each strand showed that the tetrose sugar adopts a C4'-exo pucker. Computational models of siRNA antisense strands containing TNA bound to Argonaute 2 suggest that TNA is well accommodated in the region kinked by the enzyme. The combined data indicate that the TNA nucleotides are promising modifications expected to increase the potency, duration of action, and safety of siRNAs.

Post-Synthetic Nucleobase Modification of Oligodeoxynucleotides by Sonogashira Coupling and Influence of Alkynyl Modifications on the Duplex-Forming Ability.

Recently, it was reported that the alkynyl modification of nucleobases mitigates the toxicity of antisense oligonucleotides (ASO) while maintaining the efficacy. However, the general effect of alkynyl modifications on the duplex-forming ability of oligonucleotides (ONs) is unclear. In this study, post-synthetic nucleobase modification by Sonogashira coupling in aqueous medium was carried out to efficiently evaluate the physiological properties of various ONs with alkynyl-modified nucleobases. Although several undesired reactions, including nucleobase cyclization, were observed, various types of alkynyl-modified ONs were successfully obtained via Sonogashira coupling of ONs containing iodinated nucleobases. Evaluation of the stability of the duplex formed by the synthesized alkynyl-modified ONs showed that the alkynyl modification of pyrimidine was less tolerated than that of purine, although both the modifications occurred in the major groove of the duplex. These results can be attributed to the bond angle of the alkyne on the pyrimidine and the close proximity of the alkynyl substituents to the phosphodiester backbone. The synthetic method developed in this study may contribute to the screening of the optimal chemical modification of ASO because various alkynyl-modified ONs that are effective in reducing the toxicity of ASO can be easily synthesized by this method.

Identification of nucleobase chemical modifications that reduce the hepatotoxicity of gapmer antisense oligonucleotides.

Currently, gapmer antisense oligonucleotide (ASO) therapeutics are under clinical development for the treatment of various diseases, including previously intractable human disorders; however, they have the potential to induce hepatotoxicity. Although several groups have reported the reduced hepatotoxicity of gapmer ASOs following chemical modifications of sugar residues or internucleotide linkages, only few studies have described nucleobase modifications to reduce hepatotoxicity. In this study, we introduced single or multiple combinations of 17 nucleobase derivatives, including four novel derivatives, into hepatotoxic locked nucleic acid gapmer ASOs and examined their effects on hepatotoxicity. The results demonstrated successful identification of chemical modifications that strongly reduced the hepatotoxicity of gapmer ASOs. This approach expands the ability to design gapmer ASOs with optimal therapeutic profiles.

A case of endomyocardial biopsy-proven early stage cardiac involvement in heterozygous Fabry disease.

BACKGROUND: Fabry disease is a lysosomal disorder caused by a deficiency in α-galactosidase A. Heterozygous female patients remain free of serious complications, including cardiovascular symptoms, until late in life. This often makes it difficult to decide on the best time to initiate treatment in female patients. Still, it is important to initiate treatment before the disease progresses too far. CASE SUMMARY: We report the case of a 39-year-old asymptomatic female patient with Fabry disease [heterozygous p.Arg301Pro (c.902 G>C) variant in the 6th exon of α-galactosidase A (NM_000169.3)]. After 8 years of follow-up, increased QRS voltage and strain T waves developed in the left precordial electrocardiogram leads in the absence of hypertension, left ventricular hypertrophy or ischemia. Echocardiography, cardiac magnetic resonance, and coronary angiography showed normal findings. Through endomyocardial biopsy, the patient was ultimately diagnosed with early stage cardiac involvement of her Fabry disease, and chaperon therapy was initiated. Follow-up after one year revealed reduction of both the electrocardiogram abnormality and microalbuminuria, suggesting disease progression was halted. CONCLUSION: This case highlights importance of prompt diagnosis of asymptomatic Fabry disease through endomyocardial biopsy as well as the potential benefit of chaperon therapy.

Synthesis of Sugar and Nucleoside Analogs and Evaluation of Their Anticancer and Analgesic Potentials.

Chemical modification of sugars and nucleosides has a long history of producing compounds with improved selectivity and efficacy. In this study, several modified sugars (2-3) and ribonucleoside analogs (4-8) have been synthesized from α-d-glucose in a total of 21 steps. The compounds were tested for peripheral anti-nociceptive characteristics in the acetic acid-induced writhing assay in mice, where compounds 2, 7, and 8 showed a significant reduction in the number of writhes by 56%, 62%, and 63%, respectively. The compounds were also tested for their cytotoxic potential against human HeLa cell line via trypan blue dye exclusion test followed by cell counting kit-8 (CCK-8) assay. Compound 6 demonstrated significant cytotoxic activity with an IC50 value of 54 µg/mL. Molecular docking simulations revealed that compounds 2, 7, and 8 had a comparable binding affinity to cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) enzymes. Additionally, the bridged nucleoside analogs 7 and 8 potently inhibited adenosine kinase enzyme as well, which indicates an alternate mechanistic pathway behind their anti-nociceptive action. Cytotoxic compound 6 demonstrated strong docking with cancer drug targets human cytidine deaminase, proto-oncogene tyrosine-protein kinase Src, human thymidine kinase 1, human thymidylate synthase, and human adenosine deaminase 2. This is the first ever reporting of the synthesis and analgesic property of compound 8 and the cytotoxic potential of compound 6.

Impact of Autophagy on Prognosis of Patients With Dilated Cardiomyopathy.

BACKGROUND: Autophagy is a cellular process that degrades a cell's own cytoplasmic components for energy provision and to maintain a proper intracellular environment. Left ventricular reverse remodeling (LVRR) promises a better prognosis for patients with dilated cardiomyopathy (DCM). OBJECTIVES: The authors tested the hypothesis that autophagy is involved in LVRR and has prognostic value in the human failing heart. METHODS: Using left ventricular endomyocardial biopsy specimens from 42 patients with DCM (21 LVRR-positive and 21 LVRR-negative) and 7 patients with normal cardiac function (control), the authors performed immunohistochemistry and immunofluorescent labeling of LC3 and cathepsin D and electron microscopic observation in addition to general morphometry under light microscopy. RESULTS: The clinical characteristics of LVRR-positive patients were similar to those of the LVRR-negative patients, except for pulmonary artery pressure and left atrial dimension. Morphometry under light microscopy did not differ among specimens from DCM patients, regardless of their LVRR status. Electron microscopy revealed that autophagic vacuoles (autophagosomes and autolysosomes) and lysosomes were abundant within cardiomyocytes from DCM patients. Moreover, cardiomyocytes from LVRR-positive patients contained significantly more autophagic vacuoles with higher autolysosome ratios and cathepsin D expression levels than cardiomyocytes from LVRR-negative patients. Logistic regression analysis adjusted for age showed that increases in autophagic vacuole number and cathepsin D expression were predictive of LVRR. DCM patients who achieved LVRR experienced fewer cardiovascular events during the follow-up period. CONCLUSIONS: The authors show that autophagy is a useful marker predictive of LVRR in DCM patients. This provides novel pathologic insight into a strategy for treating the failing DCM heart.

Stem cell therapy for acute myocardial infarction - focusing on the comparison between Muse cells and mesenchymal stem cells.

Rapid percutaneous coronary intervention for acute myocardial infarction (AMI) reduces acute mortality, but there is an urgent need for treatment of left ventricular dysfunction and remodeling after AMI to improve the prognosis. The myocardium itself does not have a high regenerative capacity, and it is important to minimize the loss of cardiomyocytes and maintain the cardiac function after AMI. To overcome these problems, attention has been focused on myocardial regeneration therapy using cells derived from bone marrow. The clinical use of bone marrow stem cells is considered to have low safety concerns based on the experience of using bone marrow transplantation for blood diseases in clinical practice. It has been reported that bone marrow mononuclear cells (BM-MNC) and mesenchymal stem cells (BM-MSC) differentiate into cardiomyocytes both in vitro and in vivo, and they have been considered a promising source for stem cell therapy. To prevent heart failure after human AMI, studies have been conducted to regenerate myocardial tissue by transplanting bone marrow stem cells, such as BM-MSCs and BM-MNCs. Therapies using those cells have been administered to animal models of AMI, and were effective to some extent, but the effect in clinical trials was limited. Recently, it was reported that multilineage-differentiating stress enduring cells (Muse cells), which are endogenous pluripotent stem cells obtainable from various tissues including the bone marrow, more markedly reduced the myocardial infarct size and improved the cardiac function via regeneration of cardiomyocytes and vessels and paracrine effects compared with BM-MSCs. Here, we describe stem cell therapies using conventional BM-MNCs and BM-MSCs, and Muse cells which have potential for clinical use for the treatment of AMI.

Morphological characteristics in diabetic cardiomyopathy associated with autophagy.

Diabetic cardiomyopathy, clinically diagnosed as ventricular dysfunction in the absence of coronary atherosclerosis or hypertension in diabetic patients, is a cardiac muscle-specific disease that increases the risk of heart failure and mortality. Its clinical course is characterized initially by diastolic dysfunction, later by systolic dysfunction, and eventually by clinical heart failure from an uncertain mechanism. Light microscopic features such as interstitial fibrosis, inflammation, and cardiomyocyte hypertrophy are observed in diabetic cardiomyopathy, but are common to failing hearts generally and are not specific to diabetic cardiomyopathy. Electron microscopic studies of biopsy samples from diabetic patients with heart failure have revealed that the essential mechanism underlying diabetic cardiomyopathy involves thickening of the capillary basement membrane, accumulation of lipid droplets, and glycogen as well as increased numbers of autophagic vacuoles within cardiomyocytes. Autophagy is a conserved mechanism that contributes to maintaining intracellular homeostasis by degrading long-lived proteins and damaged organelles and is observed more often in cardiomyocytes within failing hearts. Diabetes mellitus (DM) impairs cardiac metabolism and leads to dysregulation of energy substrates that contribute to cardiac autophagy. However, a "snapshot" showing greater numbers of autophagic vacuoles within cardiomyocytes may indicate that autophagy is activated into phagophore formation or is suppressed due to impairment of the lysosomal degradation step. Recent in vivo studies have shed light on the underlying molecular mechanism governing autophagy and its essential meaning in the diabetic heart. Autophagic responses to diabetic cardiomyopathy differ between diabetic types: they are enhanced in type 1 DM, but are suppressed in type 2 DM. This difference provides important insight into the pathophysiology of diabetic cardiomyopathy. Here, we review recent advances in our understanding of the pathophysiology of diabetic cardiomyopathy, paying particular attention to autophagy in the heart, and discuss the therapeutic potential of interventions modulating autophagy in diabetic cardiomyopathy.

Synthesis, chirality-dependent conformational and biological properties of siRNAs containing 5'-(R)- and 5'-(S)-C-methyl-guanosine.

Various chemical modifications have been identified that enhance potency of small interfering RNAs (siRNAs) and that reduce off-target effects, immune stimulation, and toxicities of metabolites of these therapeutic agents. We previously described 5'-C-methyl pyrimidine nucleotides also modified at the 2' position of the sugar. Here, we describe the synthesis of 2'-position unmodified 5'-(R)- and 5'-(S)-C-methyl guanosine and evaluation of these nucleotides in the context of siRNA. The (R) isomer provided protection from 5' exonuclease and the (S) isomer provided protection from 3' exonuclease in the context of a terminally modified oligonucleotide. siRNA potency was maintained when these modifications were incorporated at the tested positions of sense and antisense strands. Moreover, the corresponding 5' triphosphates were not substrates for mitochondrial DNA polymerase. Models generated based on crystal structures of 5' and 3' exonuclease oligonucleotide complexes with 5'-(R)- and 5'-(S)-C-methyl substituents attached to the 5'- and 3'-terminal nucleotides, respectively, provided insight into the origins of the observed protections. Structural properties of 5'-(R)-C-methyl guanosine incorporated into an RNA octamer were analysed by X-ray crystallography, and the structure explains the loss in duplex thermal stability for the (R) isomer compared with the (S) isomer. Finally, the effect of 5'-C-methylation on endoribonuclease activity has been explained.

Metformin Enhances Autophagy and Provides Cardioprotection in δ-Sarcoglycan Deficiency-Induced Dilated Cardiomyopathy.

BACKGROUND: Metformin is a popular antidiabetic agent that is also used to treat heart failure patients with type 2 diabetes mellitus. Several reports suggest that metformin may also have cardioprotective effects in patients without diabetes mellitus. In the present study, we investigated the possible therapeutic effect of metformin in heart failure and its underlying molecular mechanisms using a δ-sarcoglycan-deficient mouse model of dilated cardiomyopathy. METHODS AND RESULTS: Thirty-two-week-old δ-sarcoglycan-deficient mice exhibiting established cardiomyopathy with extensive left ventricular dilatation and dysfunction were administered saline or metformin (200 mg/kg per day) for 4 weeks using osmotic mini-pumps. Metformin partially reversed the left ventricular dilatation (reverse remodeling) and significantly improved cardiac function. The hearts of metformin-treated mice showed less fibrosis, less cardiomyocyte hypertrophy, and fewer degenerative subcellular changes than saline-treated mice. These effects were accompanied by restored expression of the sarcomeric proteins myosin heavy chain and troponin I, and their transcription factor, GATA-4. Autophagy was enhanced in the hearts from metformin-treated mice, as indicated by increase of myocardial microtubule-associated protein-1 LC-3 (light chain 3)-II levels and LC3-II/-I ratios as well as levels of cathepsin D and ATP. In addition, increased numbers of autophagic vacuoles and lysosomes were accompanied increased AMP-activated protein kinase activity and suppression of mammalian target of rapamycin phosphorylation. Finally, autophagic flux assays using short-term chloroquine treatment revealed that autophagy was activated in δ-sarcoglycan-deficient hearts and was further augmented by metformin treatment. CONCLUSIONS: Metformin is a beneficial pharmacological tool that mitigates heart failure caused by δ-sarcoglycan deficiency in association with enhanced autophagy.

(Pro)renin Receptor Blockade Ameliorates Heart Failure Caused by Chronic Kidney Disease.

BACKGROUND: The (pro)renin receptor [(P)RR)] is involved in the activation of local renin-angiotensin system and subsequent development of cardiovascular disease. We investigated the therapeutic effect of a (P)RR blocker, handle-region peptide (HRP), on chronic kidney disease (CKD)-associated heart failure. METHODS AND RESULTS: CKD was induced in C57BL/6J mice by means of five-sixths nephrectomy. Eight weeks later, cardiac dysfunction and cardiac dilatation with hypertension developed. Mice were then assigned to 1 of the 3 following groups: vehicle, low-dose (0.01 mg·kg-1·d-1) HRP, or high-dose (0.3 mg·kg-1·d-1) HRP for 4 weeks. High-dose HRP treatment reversed left ventricular dilation and significantly improved cardiac dysfunction with ameliorated hypertension compared with the vehicle. The hearts with high-dose HRP treatment showed significant attenuation of cardiac fibrosis, cardiomyocyte hypertrophy, macrophage infiltration, and oxidative DNA damage. This treatment decreased the myocardial expressions of angiotensin (Ang) II, Ang II type 1 receptor, transforming growth factor ß1, extracellular matrix-related proteins, and lipid peroxidation. Autophagy was activated in the cardiomyocyte from nephrectomized mice, but HRP treatment had no effect on cardiomyocyte autophagy. CONCLUSIONS: This study indicates that (P)PR blockade is a beneficial strategy by suppressing cardiac fibrosis and hypertrophy to ameliorate heart failure caused by CKD.

The intestine responds to heart failure by enhanced mitochondrial fusion through glucagon-like peptide-1 signalling.

AIMS: Glucagon-like peptide-1 (GLP-1) is a neuroendocrine hormone secreted by the intestine. Its receptor (GLP-1R) is expressed in various organs, including the heart. However, the dynamics and function of the GLP-1 signal in heart failure remains unclear. We investigated the impact of the cardio-intestinal association on hypertensive heart failure using miglitol, an α-glucosidase inhibitor known to stimulate intestinal GLP-1 production. METHODS AND RESULTS: Dahl salt-sensitive (DS) rats fed a high-salt diet were assigned to miglitol, exendin (9-39) (GLP-1R blocker) and untreated control groups and treated for 11 weeks. Control DS rats showed marked hypertension and cardiac dysfunction with left ventricular dilatation accompanied by elevated plasma GLP-1 levels and increased cardiac GLP-1R expression as compared with age-matched Dahl salt-resistant (DR) rats. Miglitol further increased plasma GLP-1 levels, suppressed adverse cardiac remodelling, and mitigated cardiac dysfunction. In cardiomyocytes from miglitol-treated DS hearts, mitochondrial size was significantly larger with denser cristae than in cardiomyocytes from control DS hearts. The change in mitochondrial morphology reflected enhanced mitochondrial fusion mediated by protein kinase A activation leading to phosphorylation of dynamin-related protein 1, expression of mitofusin-1 and OPA-1, and increased myocardial adenosine triphosphate (ATP) content. GLP-1R blockade with exendin (9-39) exacerbated cardiac dysfunction and led to fragmented mitochondria with disarrayed cristae in cardiomyocytes and reduction of myocardial ATP content. In cultured cardiomyocytes, GLP-1 increased expression of mitochondrial fusion-related proteins and ATP content. When GLP-1 and exendin (9-39) were administered together, their effects cancelled out. CONCLUSIONS: Increased intestinal GLP-1 secretion is an adaptive response to heart failure that is enhanced by miglitol. This could be an effective strategy for treating heart failure through regulation of mitochondrial dynamics.

Post-MI treatment with G-CSF and EPO-liposome with SLX repairs infarcted myocardium through EPCs mobilization and activation of prosurvival signals in rabbits.

We investigated whether combination therapy of G-CSF and erythropoietin (EPO)-liposome with Siaryl Lewis X (SLX) is more cardioprotective than G-CSF or EPO-liposome with SLX alone. For the purpose of generating myocardial infarction (MI), rabbits underwent 30 minutes of coronary occlusion and 14 days of reperfusion. We administered saline (control group, i.v.,), G-CSF (G group, 10 µg/kg/day × 5 days, i.c., starting at 24 hours after reperfusion), EPO-liposome with SLX (LE group, i.v., 2500 IU/kg EPO containing liposome with SLX, immediately after reperfusion), and G-CSF + EPO-liposome with SLX (LE + G group) to the rabbits. The MI size was the smallest in the LE+G group (14.7 ± 0.8%), and smaller in the G group (22.4 ± 1.5%) and LE group (18.5 ± 1.1%) than in the control group (27.8 ± 1.5%). Compared with the control group, the cardiac function and remodeling of the G, LE, and LE + G groups were improved, and LE + G group tended to show the best improvement. The number of CD31-positive microvessels was the greatest in the LE + G group, greater in the G and LE groups than in the control group. Higher expressions of phosphorylated (p)-Akt and p-ERK were observed in the ischemic area of the LE and LE + G groups. The number of CD34+/CXCR4+ cells was significantly higher in the G and LE + G groups. The cardiac SDF-1 was more expressed in the G and LE + G groups. In conclusion, Post-MI combination therapy with G-CSF and EPO-liposome with SLX is more cardioprotective than G-CSF or EPO-liposome with SLX alone through EPCs mobilization, neovascularization, and activation of prosurvival signals.

Acute Myocardial Infarction, Cardioprotection, and Muse Cells.

Acute myocardial infarction (AMI) is a common cause of morbidity and mortality worldwide. Severe MI leads to heart failure due to a marked loss of functional cardiomyocytes. First-line treatment for AMI is to reperfuse the occluded coronary artery by PCI as soon as possible. Besides PCI, there are several therapies to reduce the infarct size and improve the cardiac function and remodeling. These are drug therapies such as pharmacological pre- and postconditioning, cytokine therapies, and stem cell therapies. None of these therapies have been clinically developed as a standard treatment for AMI. Among many cell sources for stem cell therapies, the Muse cell is an endogenous non-tumorigenic pluripotent stem cell, which is able to differentiate into cells of all three germ layers from a single cell, suggesting that the Muse cell is a potential cell source for regenerative medicine. Endogenous Muse cell dynamics in the acute phase plays an important role in the prognosis of AMI patients; AMI patients with a higher number of Muse cells in the peripheral blood in the acute phase show more favorable improvement of the cardiac function and remodeling in the chronic phase, suggesting their innate reparative function for the heart. Intravenously administered exogenous Muse cells engrafted preferentially and efficiently to infarct border areas via the S1P-S1PR2 axis and differentiated spontaneously into working cardiomyocytes and vessels, showed paracrine effects, markedly reduced the myocardial infarct size, and delivered long-lasting improvement of the cardiac function and remodeling for 6 months. These findings suggest that Muse cells are reparative stem cells, and thus their clinical application is warranted.

S1P-S1PR2 Axis Mediates Homing of Muse Cells Into Damaged Heart for Long-Lasting Tissue Repair and Functional Recovery After Acute Myocardial Infarction.

RATIONALE: Multilineage-differentiating stress enduring (Muse) cells, pluripotent marker stage-specific embryonic antigen-3+ cells, are nontumorigenic endogenous pluripotent-like stem cells obtainable from various tissues including the bone marrow. Their therapeutic efficiency has not been validated in acute myocardial infarction. OBJECTIVE: The main objective of this study is to clarify the efficiency of intravenously infused rabbit autograft, allograft, and xenograft (human) bone marrow-Muse cells in a rabbit acute myocardial infarction model and their mechanisms of tissue repair. METHODS AND RESULTS: In vivo dynamics of Nano-lantern-labeled Muse cells showed preferential homing of the cells to the postinfarct heart at 3 days and 2 weeks, with ≈14.5% of injected GFP (green fluorescent protein)-Muse cells estimated to be engrafted into the heart at 3 days. The migration and homing of the Muse cells was confirmed pharmacologically (S1PR2 [sphingosine monophosphate receptor 2]-specific antagonist JTE-013 coinjection) and genetically (S1PR2-siRNA [small interfering ribonucleic acid]-introduced Muse cells) to be mediated through the S1P (sphingosine monophosphate)-S1PR2 axis. They spontaneously differentiated into cells positive for cardiac markers, such as cardiac troponin-I, sarcomeric α-actinin, and connexin-43, and vascular markers. GCaMP3 (GFP-based Ca calmodulin probe)-labeled Muse cells that engrafted into the ischemic region exhibited increased GCaMP3 fluorescence during systole and decreased fluorescence during diastole. Infarct size was reduced by ≈52%, and the ejection fraction was increased by ≈38% compared with vehicle injection at 2 months, ≈2.5 and ≈2.1 times higher, respectively, than that induced by mesenchymal stem cells. These effects were partially attenuated by the administration of GATA4-gene-silenced Muse cells. Muse cell allografts and xenografts efficiently engrafted and recovered functions, and allografts remained in the tissue and sustained functional recovery for up to 6 months without immunosuppression. CONCLUSIONS: Muse cells may provide reparative effects and robust functional recovery and may, thus, provide a novel strategy for the treatment of acute myocardial infarction.

Mobilized Muse Cells After Acute Myocardial Infarction Predict Cardiac Function and Remodeling in the Chronic Phase.

BACKGROUND: Multilineage differentiating stress-enduring (Muse) cells are SSEA3+and CD105+double-positive pluripotent-like stem cells. We aimed to examine the mobilization of Muse cells into peripheral blood after acute myocardial infarction (AMI) and their effects on left ventricular (LV) function and remodeling.Methods and Results:In 79 patients with AMI, 44 patients with coronary artery disease (CAD), and 64 normal subjects (Control), we measured the number of Muse cells in the peripheral blood by fluorescence-activated cell sorting. Muse cells were measured on days 0, 1, 7, 14, and 21 after AMI. Plasma sphingosine-1-phosphate (S1P) levels were measured. Cardiac echocardiography was performed in the acute (within 7 days) and chronic (6 months) phases of AMI. Muse cell number on day 1 was significantly higher in the AMI (276±137 cells/100 µL) than in the CAD (167±89 cells/100 µL) and Control (164±125 cells/100 µL) groups. Muse cell number peaked on day 1, and had gradually decreased on day 21. Muse cell number positively correlated with plasma S1P levels. Patients with a higher increase in the number of Muse cells in the peripheral blood but not those with a lower increase in number of Muse cells in the acute phase showed improved LV function and remodeling in the chronic phase. CONCLUSIONS: Endogenous Muse cells were mobilized into the peripheral blood after AMI. The number of Muse cells could be a predictor of prognosis in patients with AMI.

Excessively low salt diet damages the heart through activation of cardiac (pro) renin receptor, renin-angiotensin-aldosterone, and sympatho-adrenal systems in spontaneously hypertensive rats.

OBJECTIVE: A high salt intake causes hypertension and leads to cardiovascular disease. Therefore, a low salt diet is now recommended to prevent hypertension and cardiovascular disease. However, it is still unknown whether an excessively low salt diet is beneficial or harmful for the heart. METHODS: Wistar Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) received normal salt chow (0.9% salt diet) and excessively low salt chow (0.01% salt diet referred to as saltless diet) for 8 weeks from 8 to 16 weeks of age. The effects of the excessively low salt diet on the cardiac (pro) renin receptor, renin-angiotensin-aldosterone, and sympatho-adrenal systems were investigated. RESULTS: The excessively low salt diet did not affect the systolic blood pressure but significantly increased the heart rate both in WKYs and SHRs. The excessively low salt diet significantly elevated plasma renin activity, plasma angiotensin I, II and aldosterone concentrations, and plasma noradrenaline and adrenaline concentrations both in WKYs and SHRs. Cardiac expressions of renin, prorenin, (P)RR, angiotensinogen, and angiotensin II AT1 receptor and phosphorylated (p)-ERK1/2, p-HSP27, p-38MAPK, and TGF-ß1 were significantly enhanced by the excessively low salt diet in both WKYs and SHRs. The excessively low salt diet accelerated cardiac interstitial and perivascular fibrosis and increased the cardiomyocyte size and interventricular septum thickness in WKYs and SHRs but the extent was greater in SHRs. CONCLUSION: An excessively low salt diet damages the heart through activation of plasma renin-angiotensin-aldosterone and sympatho-adrenal systems and activation of cardiac (P)RR and angiotensin II AT1 receptor and their downstream signals both in WKYs and SHRs.

[Relationship between Coronary Plaque Stability Evaluated by Intravascular Ultrasound and Laboratory Parameters].

Tissue characteristics of coronary plaque have been reported to be associated with cardiovascular events. The stabilization of vulnerable tissue components such as the lipid pool rather than regression of the plaque volume is considered to be of major benefit in the reduction of cardiovascular events. Conventional echocardiography, especially intravascular ultrasound imaging (IVUS), is widely used to determine calcification and the three layers of the arterial wall. However, differentiation of the lipid pool from fibrous tissue using the echo intensity is difficult. Recently, an integrated backscatter (IB) ultrasound technique was developed. The ultrasound IB power ratio is a function of the difference in acoustic characteristic impedance between the medium and target tissue, and the acoustic characteristic impedance is determined by the density of tissue multiplied by the speed of sound. For more comprehensive plaque analysis using IB-IVUS, three-dimensional IB-IVUS offers the potential for the quantitative volumetric tissue characterization of coronary atherosclerosis. Several large clinical trials demonstrated that lipid-lowering therapy with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) reduces cardiovascular events. The IB techniques provide useful clinical information on the effects of statins and other medications. The presence of lipid-rich plaque is associated with the incidence of atherosclerotic diseases; therefore, ultrasound IB techniques are useful to detect coronary atherosclerotic lesions.

Intravenous Administration of Endothelial Colony-Forming Cells Overexpressing Integrin ß1 Augments Angiogenesis in Ischemic Legs.

When injected directly into ischemic tissue in patients with peripheral artery disease, the reparative capacity of endothelial progenitor cells (EPCs) appears to be limited by their poor survival. We, therefore, attempted to improve the survival of transplanted EPCs through intravenous injection and gene modification. We anticipated that overexpression of integrin ß1 will enable injected EPCs to home to ischemic tissue, which abundantly express extracellular matrix proteins, the ligands for integrins. In addition, integrin ß1 has an independent angiogenesis-stimulating function. Human endothelial colony-forming cells (ECFCs; late-outgrowth EPCs) were transduced using a lentiviral vector encoding integrin ß1 (ITGB1) or enhanced green fluorescent protein (GFP). We then locally or systemically injected phosphate-buffered saline or the genetically modified ECFCs (GFP-ECFCs or ITGB1-ECFCs; 1 × 10(5) cells each) into NOD/Shi-scid, IL-2Rγnull mice whose right femoral arteries had been occluded 24 hours earlier. Upregulation of extracellular matrix proteins, including fibronectin, was apparent in the ischemic legs. Four weeks later, blood perfusion of the ischemic limb was significantly augmented only in the ITGB1-ECFC group. Scanning electron microscopy of vascular casts revealed increases in the perfused blood vessels in the ischemic legs of mice in the ITGB1-ECFC group and significant increases in the density of both capillaries and arterioles. Transplanted ECFC-derived vessels accounted for 28% ± 4.2% of the vessels in the ITGB1-ECFC group, with no cell fusion. Intravenous administration of ECFCs engineered to home to ischemic tissue appears to efficiently mediate therapeutic angiogenesis in a mouse model of peripheral artery disease. Significance: The intravenous administration of endothelial colony-forming cells (ECFCs) genetically modified to overexpress integrin ß1 effectively stimulated angiogenesis in ischemic mouse hindlimbs. Transplanted ECFCs were observed in the ischemic leg tissue, even at the chronic stage. Moreover, the cells appeared functional, as evidenced by the improved blood flow. The cell type used (ECFCs), the route of administration (intravenous, not directly injected into the affected area), and the use of ligand-receptor interactions (extracellular matrix and integrins) for homing represent substantial advantages over previously reported cell therapies for the treatment of peripheral artery disease.