Myocardial protection from ischemia/reperfusion injury by endogenous and exogenous HGF

Growth factor signaling for cardioprotection against oxidative stress-induced apoptosis

The heart is subjected to oxidative stress during various clinical situations, such as ischemia-reperfusion injury and anthracycline chemotherapy. The loss of cardiac myocytes is the major problem in heart failure; thus, it is important to protect cardiac myocytes against cell death. Various growth factors, including insulin like growth factor, hepatocyte growth factor, endothelin-1, fibroblast growth factor, and transforming growth factor, have been shown to protect the heart against oxidative stress. The mechanism of growth factor-mediated cardioprotection may involve the attenuation of cardiac myocyte apoptosis. The present article summarizes the current knowledge on the molecular mechanisms of growth factor-mediated antiapoptotic signaling in cardiac myocytes. Insulin-like growth factor-1 activates phosphatidylinositol 3' -kinase and extracellular signal-regulated kinase pathways. Recent data showed that GATA-4 might be an important mediator of cardiac myocyte survival by endothelin-1 and hepatocyte growth factor. These growth factors, as well as mediators of growth factor-signaling, may be useful in therapeutic strategies against oxidative stress-induced cardiac injury.

Bcl-xL gene transfer protects the heart against ischemia/reperfusion injury

Ischemia and reperfusion (I/R) injury causes the progression of cardiac dysfunction. The prevention of cardiomyocyte-loss due to I/R injury is important for the treatment of heart failure. Therefore, we employed antiapoptotic Bcl-xL protein to prevent I/R injury in the heart and evaluated the cardioprotective effect of Bcl-xL transduction by adenoviral vector (Adv) after I/R injury. Adv with Bcl-xL gene was injected in the rat heart 4 days prior to I/R. The prevention of cardiac performance-loss and the reduction of cardiac apoptosis, after 30min ischemia and 30min reperfusion of global I/R, were demonstrated in the heart with adenoviral Bcl-xL transduction. Also, significant reductions of the infarct size and serum creatine kinase levels were observed in the heart transduced with Bcl-xL gene compared with control after 30min ischemia and 24h reperfusion of the left anterior coronary artery. Thus, Bcl-xL may serve as a potential therapeutic tool for cardioprotection.

Gene transfer of hepatocyte growth factor attenuates postinfarction heart failure

BACKGROUND

Despite advances in surgical and percutaneous coronary revascularization, ongoing ischemia that is not amenable to standard revascularization techniques is a major cause of morbidity and mortality. Hepatocyte Growth Factor (HGF) has potent angiogenic and anti-apoptotic activities, and this study evaluated the functional and biochemical effects of HGF gene transfer in a rat model of postinfarction heart failure.

METHODS AND RESULTS

Lewis rats underwent ligation of the left anterior descending coronary artery with direct intramyocardial injection of replication-deficient recombinant adenovirus encoding HGF (n=10) or empty null virus as control (n=9), and animals were analyzed after six weeks. Pressure-volume conductance catheter measurements demonstrated significantly preserved contractile function in the HGF group compared with Null control animals as measured by maximum developed LV pressure (79+/-5 versus 56+/-4 mm Hg, P<0.001) and maximum dP/dt (2890+/-326 versus 1622+/-159 mm Hg/sec, P<0.01). Significant preservation of LV geometry was associated with HGF treatment (LV Diameter HGF 13.1+/-0.54 versus Null 14.4+/-0.15 mm P<0.01; LV wall thickness 1.73+/-0.10 versus 1.28+/-0.07 mm P<0.01). Angiogenesis was significantly enhanced in HGF treated animals as measured by both Von Willebrand's Factor immunohistochemical staining and a microsphere assay. TUNEL analysis revealed a significant reduction in apoptosis in the HGF group (3.42+/-0.83% versus 8.36+/-1.16%, P<0.01), which correlated with increased Bcl-2 and Bcl-xL expression in the HGF animals.

CONCLUSIONS

Hepatocyte Growth Factor gene transfer following a large myocardial infarction results in significantly preserved myocardial function and geometry, and is associated with significant angiogenesis and a reduction in apoptosis. This therapy may be useful as an adjunct or alternative to standard revascularization techniques in patients with ischemic heart failure.

Myoblast-based cell transplantation

Cell transplantation is emerging as a new treatment designed tot improve the poor outcome of patients with cardiac failure. Its rationale is that implantation of contractile cells into postinfarction scars can functionally rejuvenate these areas. Primarily for practical reasons, autologous skeletal myoblasts have been the first to be tested clinically but bone marrow stromal and hematopoietic stem cells may represent an interesting alternative in select situations because of their autologous origin and their purported plasticity. However, several key issues still need to be addressed including (1) the optimal type of cells, (2) the mechanism by which cell engraftment improves cardiac function, i.e., increased contractility or limitation of remodeling, (3) the most effective strategies for optimizing cell survival, and (4) the potential benefits of cell transplantation in nonischemic heart failure. In parallel to the experimental studies designed to address these issues, initial clinical trials are underway and should hopefully allow to know whether the hopes raised by cellular therapy are met by clinically meaningful improvements in function and outcome in patients with severe left ventricular ischemic dysfunction.

Counteractive effects of HGF on PDGF-induced mesangial cell proliferation in a rat model of glomerulonephritis

Activation and proliferation of glomerular mesangial cells play an important role in the development of mesangioproliferative glomerulonephritis. We investigated the role of hepatocyte growth factor (HGF) in regulating activated mesangial cell proliferation. In glomeruli of normal rats, mesangial cells barely expressed the c-Met/HGF receptor. However, when mesangioproliferative glomerulonephritis was induced in rats by the administration of an anti-Thy 1.1 antibody, glomerular HGF expression transiently decreased along with mesangiolysis, and activation of mesangial cells was associated with upregulation of the c-Met receptor. Activated mesangial cells in culture also expressed the c-Met/HGF receptor. Although addition of HGF to cultured mesangial cells did not increase DNA synthesis, HGF did diminish PDGF-induced DNA synthesis. PDGF induced activation of ERK, which continued for at least 48 h. When PDGF and HGF were simultaneously added, HGF inhibited the prolonged activation of ERK, which suggests that early inactivation of PDGF-induced ERK may be involved in the inhibitory effect of HGF on mesangial cell proliferation. Furthermore, administration of HGF to rats with anti-Thy 1.1 nephritis resulted in a selective suppression of activated mesangial cell proliferation, and this suppressive effect was associated with attenuation of phosphorylated glomerular ERK. These results indicate that HGF counteracts PDGF-induced mesangial cell proliferation and functions as a negative regulator of activated mesangial cell proliferation.

Cell transplantation in myocardium

Cell transplantation is gaining a growing interest as a potential new means of improving the prognosis of patients with cardiac failure. The basic assumption is that left ventricular dysfunction is largely due to the loss of a critical number of cardiomyocytes and that it can be partly reversed by implantation of new contractile cells into the postinfarction scars. Primarily for practical reasons, autologous skeletal myoblasts have been the first to undergo clinical trials but other cell types are also considered, particularly bone marrow stem cells, which are attractive because of their autologous origin and their purported cardiomyocyte/endothelial transdifferentiation potential in response to cues provided by the target organ. However several key issues still need to be addressed including (1) the optimal type of donor cells, (2) the mechanism by which cell engraftment improves cardiac function, (3) the optimization of cell survival, and (4) the potential benefits of cell transplantation in non-ischemic heart failure. In parallel to the experimental studies designed to address these issues clinical trials are under way and should hopefully allow assessing to what extent cell transplantation may improve the outcome of patients with heart failure.

Postinfarction treatment with an adenoviral vector expressing hepatocyte growth factor relieves chronic left ventricular remodeling and dysfunction in mice

BACKGROUND

Hepatocyte growth factor (HGF) is implicated in tissue regeneration, angiogenesis, and antiapoptosis. However, its chronic effects are undetermined on postinfarction left ventricular (LV) remodeling and heart failure.

METHODS AND RESULTS

In mice, on day 3 after myocardial infarction (MI), adenovirus encoding human HGF (Ad.CAG-HGF) was injected into the hindlimb muscles (n=13). As a control (n=15), LacZ gene was used. A persistent increase in plasma human HGF was confirmed in the treated mice: 1.0+/-0.2 ng/mL 4 weeks later. At 4 weeks after MI, the HGF-treated mice showed improved LV remodeling and dysfunction compared with controls, as indicated by the smaller LV cavity and heart/body weight ratio, greater % fractional shortening and LV +/-dP/dt, and lower LV end-diastolic pressure. The cardiomyocytes near MI, including the papillary muscles and trabeculae, were greatly hypertrophied in the treated mice. The old infarct size was similar between the groups, but the infarct wall was thicker in the treated mice, where the density of noncardiomyocyte cells, including vessels, was greater. Fibrosis of the ventricular wall was significantly reduced in them. Examination of 10-day-old MI revealed no proliferation or apoptosis but showed augmented expression of c-Met/HGF receptor in cardiomyocytes near MI, whereas a greater proliferating activity and smaller apoptotic rate of granulation tissue cells in the HGF-treated hearts was observed compared with controls.

CONCLUSIONS

Postinfarction HGF gene therapy improved LV remodeling and dysfunction through hypertrophy of cardiomyocytes, infarct wall thickening, preservation of vessels, and antifibrosis. These findings imply a novel therapeutic approach against postinfarction heart failure.

Evidence for association of coronary sinus levels of hepatocyte growth factor and collateralization in human coronary disease

The therapeutic use of angiogenic factors to protect ischemic myocardium is limited by our incomplete understanding of their endogenous production. We determined the association between angiogenic factors and collateral formation in patients with coronary artery disease (CAD). A total of 71 patients underwent catheterization with sampling of the pulmonary artery, aorta, and coronary sinus (CS) to determine the levels of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). VEGF and HGF levels were not different in the three vascular sites, suggesting that the heart is not a major source of these cytokines in the circulation. CS VEGF and HGF levels were similar in patients with and without CAD. Elevated CS HGF levels were associated with collateral formation, whereas VEGF levels were not. Additionally, CS HGF was significantly elevated in patients with left ventricular dysfunction. These data map for the first time the concentration of endogenous angiogenic factors in the coronary circulation and support further studies to determine whether HGF may be an endogenous cardioprotective angiogenic factor.

Antiapoptotic effect of endothelin-1 in rat cardiomyocytes in vitro

Apoptosis of cardiac myocytes is thought to be a feature of many pathological disorders, including congestive heart failure (CHF) and ischemic heart disease (IHD). Because recent investigations indicate that endothelin-1 (ET-1) plays an important role in CHF and IHD, we investigated the effect of ET-1 on cardiomyocyte apoptosis. The presence of apoptosis in rat cardiomyocytes (H9c2 and neonatal) was evaluated by morphological criteria, electrophoresis of DNA fragments, 4',6'-diamidine-2'-phenylindole staining, and TUNEL analysis. ET-1, but not angiotensin II, prevented apoptosis induced by serum deprivation via ETA receptors in a dose-dependent manner (1 to 100 nmol/L). ET-1 also prevented cytochrome c release from mitochondria to the cytosol. The use of specific pharmacological inhibitors demonstrated that the antiapoptotic effect of ET-1 was mediated through a tyrosine kinase pathway (genistein and AG490) but not through protein kinase C (PKC; calphostin C), mitogen-activated protein kinases (PD98059 and SB203580), or PKA (KT5270) pathways. Adenovirus-mediated gene transfer of kinase-inactive (KI) c-Src reversed the antiapoptotic effect of ET-1. We further investigated whether Bcl-xL, an antiapoptotic molecule, would be upregulated by using a luciferase-based reporter system. ET-1 upregulated Bcl-xL, and this upregulation was inhibited by genistein or AG490 but not by calphostin C. The experiments with KI mutants for various tyrosine kinases revealed that c-Src and Pyk2 (but not JAK1, Jak2, Syk, and Tec) are involved in ET-1-induced upregulation of Bcl-xL expression. These findings suggest that ET-1 prevents apoptosis in cardiac myocytes through the ETA receptor and the subsequent c-Src/Bcl-xL-dependent pathway.

Gene transfer of hepatocyte growth factor improves angiogenesis and function of chronic ischemic myocardium in canine heart

BACKGROUND

Hepatocyte growth factor (HGF) induces angiogenesis in myocardium. In the present study, its effects in chronic ischemic myocardium were tested.

METHODS

Four weeks after left anterior descending coronary artery ligation in canine hearts, HVJ-liposome containing either human HGF gene (160 microg; HGF group, n = 7) or nothing (control group, n = 6) was directly injected into ischemic myocardium. Four weeks after gene transfection, the thickness fraction (TF), an index of regional myocardial contractility (assessed by epicardial pulse-Doppler crystals), the myocardial perfusion flow (assessed by color microspheres), and the capillary density (assessed by immunostaining of vessels) were evaluated in ischemic myocardium.

RESULTS

Thickness fraction (percent of nonischemic myocardium) was significantly improved in the HGF group (80 +/- 15 from 52 +/- 16 of pregene; p < 0.05) whereas it was not changed in the control group (52 +/- 10 from 50 +/- 8 of pregene). The perfusion flow (% of nonischemic myocardium) was significantly improved in the HGF group (98 +/- 17 from 51 +/- 14 of pregene; p < 0.05) while it was not changed in the Control group (58 +/- 13 from 62 +/- 18 of pregene). The capillary density was significantly higher in the HGF group (894 +/- 211/mm2; p < 0.05) than that in the control group (511 +/- 127/mm2).

CONCLUSIONS

Gene transfection of HGF improved angiogenesis, thereby improved regional myocardial function and perfusion in chronic ischemic myocardium. It indicates a potent therapeutic value of HGF gene transfection for chronic ischemic heart diseases such as myocardial infarction.

Hepatocyte growth factor induces GATA-4 phosphorylation and cell survival in cardiac muscle cells

Hepatocyte growth factor (HGF) is released in response to myocardial infarction and may play a role in regulating cardiac remodeling. Recently, HGF was found to inhibit the apoptosis of cardiac muscle cells. Because GATA-4 can induce cell survival, the effects of HGF on GATA-4 activity were investigated. Treatment of HL-1 cells or primary adult rat cardiac myocytes with HGF, at concentrations that can be detected in the human serum after myocardial infarction, rapidly enhances GATA-4 DNA-binding activity. The enhanced DNA-binding activity is associated with the phosphorylation of GATA-4. HGF-induced phosphorylation and activation of GATA-4 is abolished by MEK inhibitors or the mutation of the ERK phosphorylation site (S105A), suggesting that HGF activates GATA-4 via MEK-ERK pathway-dependent phosphorylation. HGF enhances the expression of anti-apoptotic Bcl-x(L), and this is blocked by dominant negative mutants of MEK or GATA-4. Forced expression of wild-type GATA-4, but not the GATA-4 mutant (S105A) increases the expression of Bcl-x(L). Furthermore, expression of the GATA-4 mutant (S105A) suppresses HGF-mediated protection of cells against daunorubicin-induced apoptosis. These results demonstrate that HGF protects cardiac muscle cells against apoptosis via a signaling pathway involving MEK/ERK-dependent phosphorylation of GATA-4.

Prognostic significance of angiogenic growth factor serum levels in patients with acute coronary syndromes

BACKGROUND

In patients with acute coronary syndromes, compensatory processes are initiated, including angiogenesis and endothelial regeneration of ruptured or eroded plaques. Angiogenic growth factors like vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and basic fibroblast growth factor (bFGF) are upregulated during ischemia. However, it is unknown whether their serum levels are related to clinical outcome.

METHODS AND RESULTS

We measured VEGF, HGF, and bFGF levels in 1090 patients with acute coronary syndromes. Angiographic evaluation was performed at baseline as well as death, and nonfatal myocardial infarctions were recorded during 6-month follow-up. HGF and VEGF, but not bFGF, were significantly and independently associated with the patients' outcome. Patients with elevated VEGF serum levels suffered from adverse outcome (adjusted hazard ratio, 2.50 [1.52 to 4.82]; P=0.002). VEGF elevation was associated with evidence of ischemia and was a significant predictor of the effect of glycoprotein IIb/IIIa inhibition. In contrast, patients with high HGF levels had a significantly lower event rate compared with patients with low HGF levels (adjusted hazard ratio, 0.33 [0.21 to 0.51]; P<0.001). HGF levels did not correlate with evidence of ischemia and did not predict the effect of abciximab. Intriguingly, however, HGF levels significantly correlated with angiographically visible collateralization of the target vessel (22.4% versus 10.5%; P<0.001).

CONCLUSIONS

The angiogenic growth factors VEGF and HGF are independent predictors of the patients' prognosis in acute coronary syndromes. Whereas VEGF elevation correlated with the evidence of myocardial ischemia and indicated an adverse outcome, HGF elevation was independent of ischemia and associated with improved collateralization as well as a favorable prognosis.

Early treatment with hepatocyte growth factor improves cardiac function in experimental heart failure induced by myocardial infarction

Plasma levels of hepatocyte growth factor (HGF) are increased within hours of cardiac ischemia/reperfusion in rats, and HGF has been shown to be cardioprotective toward acute ischemic injury. Myocardial levels of HGF mRNA and protein are increased for several days after myocardial infarction (MI), however, indicating a possible additional protective effect of HGF toward the progression of MI to heart failure. The purpose of this study was to determine whether HGF administration during the time course of endogenous cardiac HGF induction would lead to long-term improvement in cardiac function in rats with MI. MI was induced by 2-h occlusion of the left coronary artery, followed by reperfusion. HGF was given by intravenous infusion at 0.45 mg/kg/day for 6 days beginning on the day after surgery. Cardiac function and hemodynamic parameters were measured by using indwelling catheters and perivascular flow probes in conscious animals 8 weeks post-MI. Myocardial infarcts were approximately 30% of the left ventricle, and there was no difference in infarct size between the vehicle-treated and HGF-treated groups. Compared with untreated sham-operated rats, vehicle-treated MI animals had significantly lower cardiac index and stroke volume index and higher systemic vascular resistance, indicating heart failure developed. Treatment with HGF caused a significant increase in cardiac index and stroke volume index and a reduction in systemic vascular resistance in rats with MI, restoring these parameters close to those observed in sham-operated control animals. These results provide direct evidence that HGF may be of benefit to cardiovascular function in ischemic cardiomyopathy.

Neutralization of hepatocyte growth factor leads to retarded cutaneous wound healing associated with decreased neovascularization and granulation tissue formation

To elucidate biologic functions of hepatocyte growth factor and the c-Met receptor in cutaneous wound healing, we analyzed expression and localization of hepatocyte growth factor and c-Met receptor and used a strategy to neutralize endogenous hepatocyte growth factor in a cutaneous wound healing model in mice. Following excision of full-thickness skin on the dorsum of mice, expression of both hepatocyte growth factor and the c-Met receptor increased transiently in cutaneous tissues. Expressions of hepatocyte growth factor increased as early as 2 d postwounding and reached a peak on day 2, whereas the c-Met receptor expression reached a peak 2-4 d postwounding. Immunolocalization of the c-Met receptor indicated that c-Met receptor expression was upregulated in keratinocytes, vascular endothelial cells, and myofibroblasts in granulation tissue, hence these are potential target cells of hepatocyte growth factor. When normal rabbit IgG or neutralizing anti-hepatocyte growth factor IgG was locally and continuously delivered to subcutaneous lesions, the number of capillary vessels decreased with the neutralization of hepatocyte growth factor and there was an associated decreased expansion of granulation tissue. Likewise, retardation in re-epithelialization and the rate of wound closure occurred with neutralization of endogenous hepatocyte growth factor on days 4 and 7 postwounding. Therefore, hepatocyte growth factor is definitely involved in enhancing cutaneous wound healing processes, including re-epithelialization, neovascularization, and granulation tissue formation.

Hepatocyte growth factor: from diagnosis to clinical applications

Hepatocyte growth factor (HGF), initially identified and molecularly cloned as a potent mitogen of primary cultured hepatocytes, has multiple activities in a variety of tissues during the course of development and also in various disease states. HGF plays key roles in the attenuation of disease progression as an intrinsic repair factor. It is also evident that HGF levels are regulated under different conditions, for example, during the course of pregnancy, aging, and disease. This review focuses on the levels of HGF in normal and pathophysiological situations and examines the relationships between HGF levels and disease, disease stage, and disease prognosis. The clinical potential of HGF as a treatment for subjects with various diseases is also given attention.

Therapeutic angiogenesis in the ischemic canine heart induced by myocardial injection of naked complementary DNA plasmid encoding hepatocyte growth factor

OBJECTIVE

We investigated the efficacy of directly injecting a plasmid with complementary DNA encoding human hepatocyte growth factor into ischemic canine myocardium to induce angiogenesis.

METHODS

Four weeks after ligation of the left anterior descending coronary artery, 125 microg of a complementary DNA plasmid encoding the gene for either hepatocyte growth factor (n = 8) or LacZ (transfection control group, n = 8) was injected directly into the myocardium at the border between the normal tissue and the infarction. Eight other dogs were used as a sham control group. Regional thickening fraction, which indicated contractile function, and blood flow in the normal (circumflex branch territory) and ischemic areas were evaluated under dobutamine administration just before and 4 weeks after transfection. The animals were killed, and capillary numbers in both areas were assessed. These data in the ischemic area were evaluated as the percentage of those in the normal.

RESULTS

The number of myocardial capillaries in the ischemic area was successfully increased to approximately 140% of usual in the hepatocyte growth factor group, whereas no change was observed in the other groups (P =.0017 by analysis of variance). Furthermore, regional thickening fraction and blood flow in the ischemic area, which had deteriorated after coronary ligation, showed significant improvement in the hepatocyte growth factor group relative to the other groups (thickening fraction P <.0001 by analysis of variance, blood flow P =.0005 by analysis of variance).

CONCLUSIONS

These results support the efficacy of the direct injection of plasmid complementary DNA encoding human hepatocyte growth factor to induce therapeutic angiogenesis in the ischemic myocardium.

Gene transfection of hepatocyte growth factor attenuates cardiac remodeling in the canine heart: A novel gene therapy for cardiomyopathy

OBJECTIVE

Hepatocyte growth factor, a potent angiogenic agent, is unique in having the effects of antiapoptosis and antifibrosis. In the present study we used the rapid pacing-induced heart failure canine model to investigate the effect of gene transfection of hepatocyte growth factor on the failing heart.

METHODS

Four weeks after onset of rapid pacing, either the human hepatocyte growth factor gene (160 microg; hepatocyte growth factor group, n = 7) or empty vector (control group, n = 7) was directly injected into the left ventricular myocardium by means of the hemagglutinating virus of Japan liposome method.

RESULTS

At 4 weeks after gene transfection, the left ventricular global function, assessed by means of pressure-volume loop analysis, was improved in the hepatocyte growth factor group as preload-recruitable stroke work (percentage of baseline: 80% +/- 20% from 38% +/- 15% before gene transfection, P =.005), whereas it was not changed in the control group (50% +/- 18% from 50% +/- 18%). Weekly echocardiography showed that this improvement began in the week after gene transfer. The hearts in the hepatocyte growth factor group had a large wall thickness, large myocyte diameter, high capillary density, low fibrotic area fraction, and low density of apoptotic nuclei revealed by means of histologic analysis compared with that in the control group. Myocardial perfusion flow, assessed with color microspheres, was increased in the hepatocyte growth factor group (percentage of baseline: 79% +/- 16% from 48% +/- 14%, P =.010), whereas it was reduced in the control group (30% +/- 12% from 45% +/- 17%).

CONCLUSIONS

Gene transfection of hepatocyte growth factor promoted angiogenesis, improved perfusion, decreased fibrosis and apoptosis, promoted recovery from myocyte atrophy, and thereby attenuated cardiac remodeling and improved myocardial function in the failing heart. It is a novel gene therapy for human heart failure.

Overexpression of HGF retards disease progression and prolongs life span in a transgenic mouse model of ALS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by a progressive loss of motoneurons and degeneration of motor axons. We show that overexpression of hepatocyte growth factor (HGF) in the nervous system attenuates motoneuron death and axonal degeneration and prolongs the life span of transgenic mice overexpressing mutated Cu2+/Zn2+ superoxide dismutase 1. HGF prevented induction of caspase-1 and inducible nitric oxide synthase (iNOS) in motoneurons and retained the levels of the glial-specific glutamate transporter (excitatory amino acid transporter 2/glutamate transporter 1) in reactive astrocytes. We propose that HGF may be the first example of an endogenous growth factor that can alleviate the symptoms of ALS by direct neurotrophic activities on motoneurons and indirect activities on glial cells, presumably favoring a reduction in glutamatergic neurotoxicity.

Hepatocyte growth factor is a survival factor for endothelial cells and is expressed in human atherosclerotic plaques

Hepatocyte growth factor (HGF) has multiple effects on target cells upon activation of its receptor, c-Met. In endothelial cells, HGF induces migration, proliferation, and angiogenesis. HGF can also act as an anti-apoptotic factor for several cell types. The signal transduction pathways involved in mediating its anti-apoptotic effects have not been fully clarified. We demonstrated that HGF is anti-apoptotic for human endothelial cells, and identified the signaling pathways by which it mediates its effects. Human umbilical vein endothelial cells (HUVEC) exhibited significant levels of apoptosis after serum deprivation. HGF inhibited apoptosis in a dose dependent manner in serum-deprived cultures. HGF induced the phosphorylation of Akt and Erk1/2, cell survival factors, in a time dependent manner in serum deprived HUVEC. Inhibition of Akt and Erk1/2 activation abolished the anti-apoptotic effects of HGF. The transcription factor, NF-kappaB, can also play a role in promoting cell survival. However, NF-kappaB does not appear to contribute to the anti-apoptotic properties of HGF, as nuclear translocation of NF-kappaB was not detected in HGF-treated cultures. Endothelial cell migration, proliferation, and apoptosis contribute to the pathogenesis of atherosclerosis, and HGF may play a role in the development and progression of vascular lesions. Immunohistochemical analysis of human carotid artery sections demonstrated HGF protein localization within atherosclerotic lesions but not in normal vessels, suggesting that HGF may participate in atherogenesis.

Highly multiplexed genotyping of coronary artery disease-associated SNPs using MALDI-TOF mass spectrometry

Highly multiplexed genotyping methods are needed to support a comprehensive analysis of single nucleotide polymorphisms (SNPs) in coronary artery disease (CAD)-related genes. In this study we evaluated chip-based MALDI-TOF mass spectrometry for multiplexed genotyping of SNPs associated with CAD. Our analysis included 14 healthy Japanese individuals and 19 Japanese patients with myocardial infarction whose first attack occurred before age 50. We selected 29 candidate genes involved in 1) the renin-angiotensin system, 2) lipid metabolism, 3) cytokines and adhesion molecules, 4) growth factors, and 5) the coagulation-fibrinolysis system. Genotyping of candidate SNPs was performed by MALDI-TOF MS using a MassARRAY system, and 4-plex analysis was achieved at a maximum. All 39 SNPs determined by the fluorescent dye-terminator cycle sequencing method from four randomly selected patients were found to be in complete agreement with the results obtained from MassARRAY system. Significant differences were observed in the -1965delG of PAI1 (SERPINE1) with respect to allelic frequency, the G>A in the promoter region SNP in SM22 (TAGLN) for dominant genotype, and in two other SNPs (C>T in intron 1 of HGF, and -1965delG of PAI1) for recessive genotype. Three SNPs (803T>C of AGT, 677CT of MTHFR, 190T>C of ADRB3) showed weak differences in allelic frequency. MALDI-TOF-MS provided high performance with a multiplex assay design for analysis of CAD-related SNPs by increasing the throughput while maintaining a high level of accuracy.

Localization and functional role of hepatocyte growth factor (HGF) and its receptor c-met in the rat developing cerebral cortex

Development of the cerebral cortex is a series of precisely timed proliferative, migratory, and maturational processes. Hepatocyte growth factor (HGF) is a pleiotrophic cytokine, which plays important roles in the organogenesis and regeneration of various tissues, both during development and in the adult, due to its mitogenic, motogenic and morphogenic activities. In the present study, we examined expression and functional roles of HGF and c-Met during development of the rat cerebral cortex. Quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR) revealed that expression levels of c-met and HGF mRNAs were increased in the cerebral cortex during late embryonic development and peaked at E18. Immunohistochemical analyses revealed that c-Met-immunoreactivity (IR) was localized to the preplate (PP), with weaker-IR in neuroepithelial layer (NE) at embryonic day 14 (E14). At E16, c-Met-IR was present in the cortical plate (CP) and the intermediate zone (IZ), with a weak presence in the ventricular zone (VZ). On the other hand, HGF-IR was present in NE and VZ at E14 and E16, respectively. HGF-IR appeared in cortical plate tissue from E16 onward. Double labeling immunofluorescent cytochemical studies revealed that c-Met-IR was localized both in TuJ-1-IR- and non-TuJ-1-IR-cells, purified from E18 cerebral cortex in vitro, suggesting the presence of c-Met-IR in postmitotic neurons as well as in neuroepithelial cells. c-Met-IR was strong in cell bodies and neurites shortly after in vitro culture, while at 7DIV c-Met-IR decreased in neurites and was evident in growth cones. HGF dose dependently supported neuronal survival in vitro under serum-deprived conditions. In a transwell culture chamber, HGF increased neuronal migration, and co-incubation with functional blocking antibody against HGF abrogated this motogenic effect of HGF. These lines of evidence suggest that HGF is involved in the development and maintenance of cortical neurons during differentiation, motogenesis, neuritogenesis and neuronal survival.

Hepatocyte growth factor as cardiovascular hormone: role of HGF in the pathogenesis of cardiovascular disease

Hepatocyte growth factor (HGF) is a mesenchyme-derived pleiotropic factor which regulates cell growth, cell motility, and morphogenesis of various types of cells, and is thus considered a humoral mediator of epithelial-mesenchymal interactions responsible for morphogenic tissue interactions during embryonic development and organogenesis. Although HGF was originally identified as a potent mitogen for hepatocytes, HGF has also been identified as a member of angiogenic growth factors. Interestingly, the presence of its specific receptor, c-met, is observed in vascular cells, endothelial cells and cardiac myocytes. In addition, the mitogenic action of HGF on human endothelial cells was most potent among growth factors. Recent studies have demonstrated the potential application of HGF to treat cardiovascular disease such as peripheral vascular disease, myocardial infarction and restenosis after angioplasty. On the other hand, serum HGF concentration was significantly correlated with blood pressure. These results suggest that HGF secretion might be elevated in response to high blood pressure as a counter-system against endothelial dysfunction, and may be considered as an index of severity of hypertension. In this review, we discussed the potential role of HGF in cardiovascular disease.

Protection of myocytes from hypoxia-reoxygenation injury by nitric oxide is mediated by modulation of transforming growth factor-beta1

BACKGROUND

Reoxygenation injury is a result of several complex events, including release of reactive oxygen species, protein kinase C (PKC) activation, and altered expression of transforming growth factor-beta1 (TGF-beta(1)). Nitric oxide (NO) generally protects tissues from reperfusion injury.

METHODS AND RESULTS

We examined the modulation of TGF-beta1 expression and activity and PKC activation in cultured rat heart myocytes exposed to a brief period of hypoxia-reoxygenation (H-R) by NO donor 3-morpholino-sydnonimine (SIN-1). H-R resulted in an increased expression of total TGF-beta1 (mRNA and protein) but a decrease in the release of active TGF-beta1. Myocyte PKC-alpha protein level was not altered by H-R, but its phosphorylation was augmented. Pretreatment of myocytes with SIN-1 diminished myocyte injury quantified as lactate dehydrogenase release. Simultaneously, release of active TGF-beta1 increased and total TGF-beta1 expression decreased (all P<0.05 versus H-R alone). PKC-alpha phosphorylation increased further in cells treated with SIN-1. The effects of SIN-1 were blocked by the NO scavenger phenyl-tetramethyl-imidazoline-oxyl-oxide as well as by the PKC inhibitor staurosporine. To examine if another NO donor would have a similar effect, cardiomyocytes were treated with nitroglycerin before H-R. With nitroglycerin treatment, similar to SIN-1 treatment, myocyte injury was diminished, TGF-beta1 release increased, and total TGF-beta1 expression decreased.

CONCLUSIONS

These observations suggest modulation of TGF-beta1 expression as a novel mechanism of salutary effect of NO donors. PKC-alpha activation may play an important role in the protective effect of NO against H-R injury.

Hepatocyte growth factor stimulates proliferation of respiratory epithelial cells during postpneumonectomy compensatory lung growth in mice

Although it is known that the lung undergoes compensatory growth after pulmonary resection, mechanisms by which lung cells exhibit compensatory proliferation are not well defined. We investigated the involvement of hepatocyte growth factor (HGF) in postpneumonectomy compensatory lung regeneration in mice, because HGF has mitogenic and morphogenic actions on lung epithelial cells. Following left pneumonectomy, alveolar and airway epithelial cells underwent compensatory DNA synthesis, reaching maximal levels 5 d after the surgery. Before changes in DNA synthesis in lung epithelial cells, expression of HGF mRNA and protein levels in the remaining lung, liver, and kidney were changed in response to left pneumonectomy, and these changes were associated with postoperative increases in plasma HGF levels. c-Met/HGF receptor expression was localized predominantly in alveolar type II and airway epithelial cells, whereas c-Met/HGF receptor mRNA expressions were transiently upregulated before the peak in lung DNA synthesis. Neutralization of endogenous HGF by an antibody in pneumonectomized mice suppressed the compensatory DNA synthesis in lung epithelial cells, whereas administration of recombinant HGF to pneumonectomized mice stimulated DNA synthesis in lung epithelial cells. These results strongly suggest that HGF has a role as a pulmotrophic factor in postpneumonectomy compensatory lung regeneration.

TCV-116, an angiotensin II type 1 receptor antagonist, reduces hepatic ischemia-reperfusion injury in rats

BACKGROUND

In Pringle's maneuver during liver surgery and liver transplantation, ischemia-reperfusion (I/R) is an unavoidable process, and protection against hepatic I/R injury is a major unresolved problem. Therefore, various pharmacologic approaches to prevent hepatic I/R injury are currently under trial. In this study, we investigated whether TCV-116, an angiotensin II type 1 receptor antagonist, can reduce this injury.

METHODS

The rats were pretreated either with TCV-116 (group 1) or with the vehicle alone (group 2). The rats in group 3 were not pretreated. Thereafter, they were subjected to partial hepatic I/R.

RESULTS

After reperfusion, the mean peak plasma concentrations of aspartate aminotransferase, alanine aminotransferase, lactic dehydrogenase, and creatine kinase were lower in group 1 than in groups 2 and 3. The magnitude of hepatic injury was reduced in group 1 compared with that in groups 2 and 3. The mean peak plasma concentrations of tumor necrosis factor-alpha, cytokine-induced neutrophil chemoattractants-1, and interleukin-6 were lower in group 1 than in groups 2 and 3. The number of neutrophils infiltrating the liver was also lower in group 1 than in groups 2 and 3. The mean peak plasma concentration of hepatocyte growth factor (HGF) was higher in group 1 than in groups 2 and 3.

CONCLUSIONS

TCV-116 reduced the hepatic I/R injury by inhibiting inflammatory cytokine production and by enhancing HGF production.

A differentiation switch for genetically modified hepatocytes

The hepatocyte growth factor (HGF) receptor mediates a two-sided response-cell proliferation and differentiation. This process, defined as "branching morphogenesis," involves cell scatter and redistribution to form ramified hollow tubules within the extracellular matrix, and protection from apoptosis. We have fused the intracellular domain of the HGF receptor (HGFR) with three FK506-binding protein (FKBP) domains and a membrane-targeting signal. This molecule (FKBP-HGFR) dimerizes after administration of a bifunctional ligand specific for FKBP domains. We show that, in mouse hepatocyte progenitors, FKBP-HGFR dimerization elicits the differentiative side of the HGF response, including cell scatter, morphogenesis, and protection from apoptosis. Surprisingly, FKBP-HGFR does not induce cell proliferation. We could correlate the segregation of the differentiative response with a distinctive signaling kinetic of FKBP-HGFR: a) reduced and prolonged tyrosine kinase activation; and b) low early peak of MAP kinase activation (a log lower than the peak induced by the wild-type receptor), followed by a sustained activation over 6 h. These data show that the biological response triggered by the HGFR can be dissected on the basis of the quantitative signaling profile, and that FKBP-HGFR may be used to control selectively the differentiation of hepatocytes, without promoting cell expansion.

The biology of apoptosis

Apoptosis is a complex process that removes aging or injured cells from the body and occurs in a wide variety of organisms. Cell death has always been an integral aspect of the study of pathology, but only over the last 30 years or so has the interest in apoptosis gained appreciation in this field. This review analyzes pertinent aspects of apoptosis, from Virchow's initial descriptions of necrobiosis to more modern research, and reviews some of the key events and molecules involved in the process. Finally, the role of apoptosis in certain diseases and its importance in the clinical setting is addressed.

Gene therapy for therapeutic angiogenesis in critically ischaemic lower limb - on the way to the clinic

Currently, no effective pharmacological treatment is available for vascularisation defects in lower limbs. Many patients presenting with persistent pain and ischaemic ulcers are not suitable candidates for surgical or endovascular approaches. Further refinement of the available methods will undoubtedly lead to a more active approach towards treatment of peripheral arterial occlusive disease (PAOD). Recently, therapeutic angiogenesis, in the form of recombinant growth factor administration or gene therapy, has emerged as a novel tool to treat these patients. However, improved gene transfer methods and better understanding of blood vessel formation are required to bring therapeutic angiogenesis to clinical practice. Here we review the clinical problem (PAOD), mechanisms of blood vessel formation (angiogenesis, vasculogenesis and arteriogenesis), experimental evidence and clinical trials for therapeutic angiogenesis in critically ischaemic lower limbs. Also, angiogenic growth factors, including vascular endothelial growth factors (VEGFs) and fibroblast growth factors (FGFs), delivery methods, and vectors for gene transfer in skeletal muscle, are discussed. In addition to vascular growth, gene transfer of growth factors may enhance regeneration, survival, and innervation of ischaemic skeletal muscle. Nitric oxide (NO) appears to be a key mediator in vascular homeostasis and growth, and a reduction in its production by age, hypercholesterolemia or diabetes leads to the impairment of ischaemic disorders.