Antagomir-92a impregnated gelatin hydrogel microsphere sheet enhances cardiac regeneration after myocardial infarction in rats.

INTRODUCTION: We investigated whether attachment of gelatin hydrogel microsphere (GHM) sheet impregnated with antagomir-92a on the infarcted heart promotes angiogenesis and cardiomyogenesis, and improves cardiac function after myocardial infarction (MI) in rats. METHODS: GHM sheet impregnated with antagomir-92a, its scramble sequence antagomir-control sheet or the sheet alone was attached on the area at risk of MI after the left anterior descending coronary artery ligation. Bromodeoxyuridine (BrdU) was included in the sheet to trace proliferating cells. RESULTS: The antagomir-92a sheet significantly increased capillary density in the infarct border zone 14 days after MI compared to the antagomir-control sheet or the sheet alone, associated with an increase in endothelial cells incorporated with BrdU. The antagomir-92a sheet significantly increased cardiac stem cells incorporated with BrdU 3 days after MI in the infarct border zone. This was associated with an increase in cardiomyocytes incorporated with BrdU 14 days after MI. Scar area was significantly reduced by the antagomir-92a sheet compared to the antagomir-control sheet or the sheet alone (12.8 ± 1.3 vs 25.2 ± 2.2, 24.0 ± 1.7% LV area, respectively) 14 days after MI. LV dilatation was inhibited, and LV wall motion was improved 14 days after MI in rats with the antagomir-92a sheet compared to the antagomir-control sheet or the sheet alone. CONCLUSIONS: These results suggest that attachment of the GHM sheet impregnated with antagomir-92a on the area at risk of MI enhances angiogenesis, promotes cardiomyogenesis, and ameliorates LV function.

Sepiapterin prevents left ventricular hypertrophy and dilatory remodeling induced by pressure overload in rats.

Uncoupling of nitric oxide (NO) synthase (NOS) has been implicated in left ventricular (LV) hypertrophy (LVH) and dilatory remodeling induced by pressure overload. We investigated whether administration of sepiapterin, a substrate of the salvage pathway of tetrahydrobiopterin synthesis, prevents LVH and dilatory LV remodeling by inhibiting NOS uncoupling and increasing bioavailable NO. Pressure overload was induced in rats by transverse aortic constriction (TAC). Concentric LVH developed during 8 wk after TAC, and dilatory LV remodeling and dysfunction developed between 8 and 16 wk after TAC associated with a decrease in capillary density. Oral administration of sepiapterin or the superoxide/peroxynitrite scavenger N-(2-mercaptopropionyl)-glycine for 8 wk after TAC inhibited oxidative stress, but only sepiapterin increased bioavailable NO and inhibited cardiomyocyte hypertrophy associated with a further increase in capillary density. When sepiapterin was administered between 8 and 16 wk after TAC, cardiomyocyte hypertrophy was regressed and capillary density was restored. This was associated with the inhibition of interstitial fibrosis and dilatory LV remodeling. N-nitro-l-arginine methyl ester abrogated all the beneficial effects of sepiapterin in rats with TAC. These results suggest that sepiapterin prevents concentric LVH and dilatory remodeling after TAC primarily by increasing the bioavailability of NO.

Granulocyte colony-stimulating factor does not enhance recruitment of bone marrow-derived cells in rats with acute myocardial infarction.

Despite the potential benefit of granulocyte colony-stimulating factor (G-CSF) therapy in patients with acute myocardial infarction (MI), the efficacy of G-CSF in regenerating the heart after MI remains controversial. The authors hypothesize that the limited efficacy of G-CSF is related to its inhibitory effect on recruitment of bone marrow-derived cells (BMCs) to the infarcted tissue. MI was induced in rats with intrabone marrow-bone marrow transplantation from syngenic rats expressing green fluorescence protein to track BMCs. G-CSF was administered for five days after the onset of MI. G-CSF increased the number of CD45(+) cells in the peripheral circulation but did not increase their recruitment to the heart. G-CSF had no effect on myocardial stromal-derived factor-1 alpha and chemokine (C-X-C motif) receptor 4 (CXCR4) expression in mononuclear cells in the peripheral blood and CXCR4(+) cells in the heart. G-CSF had no effect on angiogenesis, myocardial fibrosis or left ventricular function four weeks after MI. These results suggest that G-CSF mobilizes BMCs to the peripheral circulation but does not increase recruitment to the infarcted myocardium despite preservation of the stromal-derived factor-1 alpha/CXCR4 axis.

Sepiapterin enhances angiogenesis and functional recovery in mice after myocardial infarction.

Uncoupling of nitric oxide synthase (NOS) has been implicated in left ventricular (LV) remodeling and dysfunction after myocardial infarction (MI). We hypothesized that inducible NOS (iNOS) plays a crucial role in LV remodeling after MI, depending on its coupling status. MI was created in wild-type, iNOS-knockout (iNOS(-/-)), endothelial NOS-knockout (eNOS(-/-)), and neuronal NOS-knockout (nNOS(-/-)) mice. iNOS and nNOS expressions were increased after MI associated with an increase in nitrotyrosine formation. The area of myocardial fibrosis and LV end-diastolic volume and ejection fraction were more deteriorated in eNOS(-/-) mice compared with other genotypes of mice 4 wk after MI. The expression of GTP cyclohydrolase was reduced, and tetrahydrobiopterin (BH(4)) was depleted in the heart after MI. Oral administration of sepiapterin after MI increased dihydrobiopterin (BH(2)), BH(4), and BH(4)-to-BH(2) ratio in the infarcted but not sham-operated heart. The increase in BH(4)-to-BH(2) ratio was associated with inhibition of nitrotyrosine formation and an increase in nitrite plus nitrate. However, this inhibition of NOS uncoupling was blunted in iNOS(-/-) mice. Sepiapterin increased capillary density and prevented LV remodeling and dysfunction after MI in wild-type, eNOS(-/-), and nNOS(-/-) but not iNOS(-/-) mice. N(ω)-nitro-L-arginine methyl ester abrogated sepiapterin-induced increase in nitrite plus nitrate and angiogenesis and blocked the beneficial effects of sepiapterin on LV remodeling and function. These results suggest that sepiapterin enhances angiogenesis and functional recovery after MI by activating the salvage pathway for BH(4) synthesis and increasing bioavailable nitric oxide predominantly derived from iNOS.

Ascorbic acid and N-acetyl cysteine prevent uncoupling of nitric oxide synthase and increase tolerance to ischemia/reperfusion injury in diabetic rat heart.

Oxidative stress may cause a loss of tetrahydrobiopterin (BH4), a co-factor of nitric oxide synthase (NOS), decrease the bioavailability of NO and aggravate ischemia/reperfusion (I/R) injury in diabetic heart. We hypothesized that ascorbic acid (AA) and N-acetyl cysteine (NAC) protect the diabetic heart from I/R injury by increasing BH4/dihydrobiopterin (BH2) ratio and inhibiting uncoupling of NOS. Diabetes mellitus was induced in rats by streptozotocin treatment, and the hearts were isolated and perfused. BH4 and BH4/BH2 ratio decreased in the diabetic heart associated with increased production of superoxide and nitrotyrosine (NT). Treatment with AA or NAC significantly increased BH4/BH2 ratio in the diabetic heart associated with decreased production of superoxide and NT and increased generation of nitrate plus nitrite (NOx). Pre-treatment with AA or NAC before 30 min ischemia followed by 120 min reperfusion improved left ventricular (LV) function and reduced infarct size in the diabetic but not non-diabetic hearts. The NOS inhibitor, L-NAME, inhibited the increase in the generation of superoxide, NT and NOx, but aggravated LV function and increased infarct size in the diabetic heart. L-NAME also abrogated the increase in NOx and improvement of LV function and the infarct size-limiting effect induced by AA or NAC in the diabetic heart. These results suggest that AA and NAC increase BH4/BH2 ratio and prevent NOS uncoupling in the diabetic heart. Resultant increase in the bioavailability of NO renders the diabetic heart toleratant to I/R injury.

Inhibition of nitric oxide synthase uncoupling by sepiapterin improves left ventricular function in streptozotocin-induced diabetic mice.

1. Uncoupling of nitric oxide synthase (NOS) has been implicated in the pathogenesis of left ventricular (LV) dysfunction in diabetes mellitus. In the present study, we investigated the role of NOS uncoupling in oxidative/nitrosative stress and LV dysfunction in the diabetic mouse heart. 2. Diabetes was induced in wild-type (WT), endothelial (e) NOS knockout (eNOS(-/-)), inducible (i) NOS knockout (iNOS(-/-)) and neuronal (n) NOS knockout (nNOS(-/-)) mice by streptozotocin (STZ) treatment. 3. In the diabetic heart, iNOS, but not eNOS or nNOS, expression was increased. Levels of malondialdehyde (MDA), 4-hydroxy-noneal (HNE) and nitrotyrosine (NT), as markers of oxidative/nitrosative stress, were increased in the diabetic mouse heart, but the increase in oxidative/nitrosative stress was significantly repressed in the iNOS(-/-) diabetic mouse heart. Levels of nitrite and nitrate (NO(x)), as an index of nitric oxide, bioavailability were significantly decreased in the iNOS(-/-) diabetic mouse heart. 4. Oral administration of sepiapterin (10 mg/kg per day), a precursor of tetrahydrobiopterin (BH(4)), significantly increased BH(4) and the BH(4)/BH(2) ratio in diabetic mouse heart. Similarly, sepiapterin inhibited the formation of HNE, MDA and NT in diabetic hearts from all three genotypes, but the increase in NO(x) following sepiapterin treatment was significantly attenuated in the iNOS(-/-) diabetic mouse heart. Percentage fractional shortening (FS), evaluated by echocardiography, decreased significantly in all genotypes of diabetic mice. Sepiapterin significantly increased percentage FS in diabetic mice, except in iNOS(-/-) mice. 5. These results suggest that sepiapterin inhibits uncoupling of NOS and improves LV function presumably by increasing iNOS-derived nitric oxide in the diabetic heart.

Reversal of inducible nitric oxide synthase uncoupling unmasks tolerance to ischemia/reperfusion injury in the diabetic rat heart.

The diabetic heart is known to be susceptible to ischemia/reperfusion (I/R) injury by increased oxidative stress. Although oxidative stress upregulates inducible nitric oxide (iNOS), the role of iNOS in I/R injury in the diabetic heart has been poorly understood. Because iNOS-derived nitric oxide (NO) plays a crucial role in cardioprotection against I/R injury, we hypothesized that inhibition of iNOS uncoupling would restore tolerance to I/R injury in the diabetic heart. The present study demonstrated that iNOS-derived superoxide generation was reduced, and that the NO bioavailability was increased, by treatment with the NOS-cofactor, tetrahydrobiopterin (BH4), before I/R in the hearts isolated from diabetic rats. This was associated with a reduction of infarct size and improvement of left ventricular (LV) function after I/R. The cardioprotective effect of BH4 was abrogated by treatment with a thiol reducing agent dithiothreitol (DTT), but not a NO-sensitive guanylyl cyclase inhibitor ODQ, suggesting that iNOS-derived NO-mediated cardioprotection occurs through protein S-nitrosylation but not cGMP-dependent signaling in the diabetic heart. Indeed, protein S-nitrosylation was increased by treatment with BH4 in the diabetic heart and was inhibited by DTT. These results suggest that the inhibition of iNOS uncoupling unmasks tolerance to I/R injury through enhanced protein S-nitrosylation in the diabetic rat heart.

Inhibition of contractile activity during postconditioning enhances cardioprotection by restoring sarcolemmal dystrophin through phosphatidylinositol 3-kinase.

BACKGROUND: Although ischemic postconditioning (IPost) confers cardioprotection by protecting the mitochondria though the activation of phosphatidylinositol 3-kinase (PI3K), a potential drawback of IPost is impairment of aerobic ATP generation during reperfusion by repeated ischemia. This decrease in ATP might inhibit the restoration of sarcolemmal dystrophin, which is translocated during ischemia, and render cardiomyocytes susceptible to contraction-induced oncosis. METHODS AND RESULTS: Isolated rat hearts were subjected to 30 min ischemia and 120 min reperfusion. IPost induced by 20 cycles of 10-s reperfusion and 10-s ischemia enhanced the activation of PI3K as evidenced by the increased phosphorylation of Akt, but had no effect on myocardial ATP, restoration of sarcolemmal dystrophin, or cardiomyocyte oncosis during IPost. Administration of the contractile blocker, 2,3-butanedione monoxim (BDM), during IPost increased myocardial ATP and facilitated the redistribution of dystrophin to the sarcolemma. This led to reduced cardiomyocyte oncosis and infarct size, and improved the left ventricular function. The anti-oncotic effect of BDM occurred without changing the anti-apoptotic effect of IPost. The PI3K inhibitor, LY294002, prevented the phosphorylation of Akt, decreased the recovery of ATP and restoration of sarcolemmal dystrophin, and blocked the anti-oncotic and anti-apoptotic effects of IPost. CONCLUSIONS: These results suggest that the inhibition of contractile activity during IPost prevents cardiomyocyte oncosis and enhances cardioprotection through PI3K-dependent restoration of sarcolemmal dystrophin.

Soluble TRAIL prevents RANTES-dependent restenosis after percutaneous coronary intervention in patients with coronary artery disease.

Some factors play pathogenic roles in the development of restenosis after percutaneous coronary intervention (PCI). We measured and compared the ratio of elevated levels of regulated on activation normally T-cell expressed and secreted (RANTES), soluble (s) P-selectin, sE-selectin, s vascular cell adhesion molecule (VCAM)-1, s interleukin-2 receptor (IL-2R) and s tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) after PCI. Plasma levels of chemokines and soluble markers were measured before and 30 days after PCI in 85 patients (61 males and 24 females, aged 61 +/- 7 years) who underwent PCI and who had repeated angiograms at a 6-month follow-up. Restenosis occurred in 29 (34.1%) patients. The significant and time-dependent increases in RANTES, sIL-2R and sVCAM-1 were observed in the restenosis group. However, there were no significant differences in sP-selectin and sE-selectin levels with or without restenosis. sTRAIL levels in patients with coronary artery disease were significantly higher than levels in normal controls. Furthermore, unlike the restenosis group, sTRAIL levels after PCI were significantly increased in the non-restenosis group, and sTRAIL levels correlated significantly with sVCAM-1 and sE-selectin. These findings suggest that restenosis development after PCI in patients with coronary artery disease involve the participation of RANTES and activated T-lymphocyte expressing CD25 after PCI, and sTRAIL may prevent this RANTES-dependent restenosis.

Effects of pitavastatin on monocyte chemoattractant protein-1 in hyperlipidemic patients.

The effects of statins on platelet activation markers, chemokines and adiponectin, were investigated in 135 patients with hyperlipidemia. Of the 135 hyperlipidemic patients, 63 were allocated to the simvastatin group, treated with simvastatin at the dose of 10 mg daily, and the remaining 72 were allocated to the pitavastatin group, treated with pitavastatin at the dose of 2 mg daily. Plasma levels of platelet-derived microparticles (PDMP), cell adhesion molecules (sCD40L and sP-selectin), chemokines [monocyte chemoattractant protein-1 (MCP-1) and regulated on activation normally T-cell expressed and secreted] and adiponectin were measured at the baseline and after 6 months of treatment in both the groups. In addition, we carried out a basic study to investigate the MCP-1-dependent induction of tissue factor expression on a histiocytic cell line (U937 cells). The plasma levels of PDMP, sCD40L, sP-selectin, regulated on activation normally T-cell expressed and secreted and MCP-1 were higher, whereas those of adiponectin were lower, in the hyperlipidemic patients than in the normolipidemic controls. Plasma PDMP and sCD40L were positively correlated, whereas plasma adiponectin was negatively correlated, with the plasma levels of MCP-1. No significant differences in the plasma levels of PDMP, sCD40L, sP-selectin, regulated on activation normally T-cell expressed and secreted and MCP-1 measured before and after treatment were observed in either the simvastatin or pitavastatin group. A significant increase of the plasma adiponectin levels was observed after 6 months of treatment with pitavastatin but not after an equal duration of treatment with simvastatin. When pitavastatin-treated patients were divided into two groups according to the adiponectin response to pitavastatin treatment, significant decreases of the plasma MCP-1, PDMP and sCD40L levels were observed after pitavastatin treatment in the responder group. In the aforementioned basic study, MCP-1 by itself did not induce the expression of tissue factor on the U937 cells. However, the recombinant sCD40L-induced expression of tissue factor on U937 was enhanced by the addition of MCP-1. These findings suggest that PDMP, sCD40L and MCP-1 may participate in the development of atherothrombosis in patients with hyperlipidemia and that pitavastatin may exert an adiponectin-dependent antiatherothrombotic effect in hyperlipidemic patients.

Effect of acarbose on platelet-derived microparticles, soluble selectins, and adiponectin in diabetic patients.

Platelet-derived microparticles (PDMP), selectins, and adiponectin play an important role in the development of atherosclerosis in diabetes. Acarbose has been shown to have a beneficial effect on postprandial hyperglycemia in diabetic patients. However, its influence on PDMP, selectins, and adiponectin in these patients is poorly understood. We investigated the effect of acarbose on circulating levels of PDMP, selectins, and adiponectin in patients with type 2 diabetes. Acarbose (300 mg/day) was administered for 3 months. Levels of PDMP, sP-selectin, sL-selectin, and adiponectin were measured by ELISA at baseline and after 1 and 3 months of treatment. The levels of PDMP, sP-selectin, and sL-selectin were higher in diabetic patients than in hypertensive patients (PDMP; 35.1 +/- 34.2 vs. 53.3 +/- 56.7 U/ml, P < 0.05: sP-selectin; 134 +/- 52 vs. 235 +/- 70 ng/dl, P < 0.01: sL-selectin; 569 +/- 183 vs. 805 +/- 146 ng/ml, P < 0.05), while there were no significant differences between hypertensive and hyperlipidemic patients. Before acarbose treatment, the adiponectin level of diabetic patients was lower than that of hypertensive patients. Acarbose therapy significantly decreased the plasma PDMP level relative to baseline. Acarbose also caused a significant decrease of sP-selectin and sL-selectin. On the other hand, acarbose therapy led to a significant increase of adiponectin after 3 months of administration compared with baseline (adiponectin: diabetes versus hypertension, 3.61 +/- 1.23 vs. 5.87 +/- 1.92 microg/ml, P < 0.05; diabetes versus controls, 2.81 +/- 0.95 vs. 6.13 +/- 1.24 microg/ml, P < 0.01). Twelve of the 30 diabetic patients had a history of thrombotic complications. Furthermore, the reduction of PDMP and selectins during acarbose therapy was significantly greater in the thrombotic group (12 of 30) than in the nonthrombotic group (18 of 30) of diabetic patients. Acarbose may be beneficial for primary prevention of atherothrombosis in patients with type 2 diabetes. However, it requires a large clinical trial to test this hypothesis.

Adiponectin incompletely prevent MCP-1-dependent restenosis after percutaneous coronary intervention [corrected] in patients with coronary artery disease.

BACKGROUND: Some factors play pathogenic roles in the development of restenosis after percutaneous coronary intervention (PCI). We measured and compared the ratio of elevated levels of monocytic chemotactic peptide-1 (MCP-1), regulated on activation normally T-cell expressed and secreted (RANTES), soluble (s) P-selectin, sE-selectin and adiponectin after PCI. METHODS: Plasma levels of chemokines and soluble markers were measured before and 30 days after PCI in 96 patients (69 males and 27 females, aged 63 +/- 9 years) who underwent PCI and who had repeated angiograms at a 6-month follow-up. In addition, we carried out the basic study of the tissue factor expression on monocytic cell line (THP-1) by MCP-1. RESULTS: Restenosis occurred in 33 (34.4%) patients. A significant and time-dependent increase in MCP-1 was observed in the restenosis group. However, there were no significant differences in RANTES, sP-selectin, and sE-selectin levels with or without restenosis. Adiponectin levels in patients with coronary artery disease were significantly lower than levels in normal controls. However, adiponectin levels were no different at baseline between patients with or without restenosis. MCP-1 did not induce the expression of tissue factor on THP-1. However, the recombinant sCD40 ligand-induced expression of tissue factor on THP-1 was enhanced by the addition of MCP-1. CONCLUSION: These findings suggest that restenosis development after PCI in patients with coronary artery disease may involve the participation of MCP-1 after PCI, and adiponectin incompletely prevent this MCP-1-dependent restenosis.