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Objective: As angiogenic growth factors can stimulate the development of collateral arteries, a concept called therapeutic angiogenesis, we performed a phase I/IIa open-label clinical trial using intramuscular injection of naked plasmid DNA encoding hepatocyte growth factor (HGF). We reported long-term evaluation of 2 years after HGF gene therapy in 22 patients with severe peripheral arterial disease., Methods and Results: Twenty-two patients with peripheral arterial disease or Buerger disease staged by Fontaine IIb (n=7), III (n=4), and IV (n=11) were treated with HGF plasmid, either 2 mg or 4 mg ×2. Increase in ankle-branchial pressure index >0.1 was observed in 11 of 14 patients (79 %) at 2 years after gene therapy and in 11 of the 17 patients (65%) at 2 months. Reduction in rest pain (>2 cm in visual analog scale) was observed in 9 of 9 patients (100%) at 2 years and in 8 of 13 (62%) patients at 2 months. At 2 years, 9 of 10 (90%) ischemic ulcers reduced by >25%, accompanied by a reduction in the size of ulcer. Severe complications and adverse effects caused by gene transfer were not detected in any patient throughout the period up to 2 years., Conclusions: Overall, the present study demonstrated long-term efficacy of HGF gene therapy up to 2 years. These findings may be cautiously interpreted to indicate that intramuscular injection of naked HGF plasmid is safe, feasible, and can achieve successful improvement of ischemic limbs as sole therapy.

Objective: To evaluate the safety and feasibility of intramuscular gene transfer using naked plasmid DNA-encoding hepatocyte growth factor (HGF) and to assess its potential therapeutic benefit in patients with critical limb ischemia., Methods and Results: Gene transfer was performed in 22 patients with critical limb ischemia by intramuscular injection of HGF plasmid, either 2 or 4 mg, 2 times. Safety, ankle-brachial index, resting pain on a 10-cm visual analog scale, wound healing, and walking distance were evaluated before treatment and at 2 months after injection. No serious adverse event caused by gene transfer was detected over a follow-up of 6 months. Of particular importance, no peripheral edema, in contrast to that seen after treatment with vascular endothelial growth factor, was observed. In addition, the systemic HGF protein level did not increase during the study. At 2 months after gene transfer, the mean ± SD ankle-brachial index increased from 0.46 ± 0.08 to 0.59 ± 0.13 (P<0.001), the mean ± SD size of the largest ischemic ulcers decreased from 3.08 ± 1.54 to 2.32 ± 1.88 cm (P=0.007), and the mean ± SD visual analog scale score decreased from 5.92 ± 1.67 to 3.04 ± 2.50 cm (P=0.001). An increase in ankle-brachial index by >0.1, a reduction in ulcer size by >25%, and a reduction in visual analog scale score by >2 cm at 2 months after gene transfer were observed in 11 (64.7%) of 17 limbs, 18 (72%) of 25 ulcers, and 8 (61.5%) of 13 limbs, respectively., Conclusions: Intramuscular injection of naked HGF plasmid is safe and feasible and can achieve successful improvement of ischemic limbs as sole therapy.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra (SNi). As neurotrophic factors support the survival and enhance the function of dopaminergic neurons, gene therapy using neurotrophic factors has become the center of interest. Thus, we focused on hepatocyte growth factor (HGF) as a neurotrophic and angiogenic growth factor. At 7 days before injection of 6-hydroxydopamine into the SNi, stereotaxic transfection of human HGF or lacZ plasmid was performed into the unilateral striatum of rats. Expression of human HGF in the injected sites could be detected in rats transfected with HGF plasmid DNA, using immunohistochemical staining. Consistently, human immunoreactive HGF protein could be detected at least up to 12 days after transfection. Interestingly, PD rats transfected with lacZ demonstrated amphetamine-induced rotational asymmetry. However, transfection of HGF plasmid DNA resulted in significant inhibition of abnormal rotation up to 24 weeks in a dose-dependent manner. Over 90% of dopaminergic neurons were lost in PD rats transfected with lacZ, whereas over 70% survived in rats transfected with HGF, as assessed by immunohistochemical staining. Overall, the present study demonstrated that overexpression of HGF prevented neuronal death in a PD rat model, providing a potential novel therapy for PD.

Background: Lymphedema is a disorder of the lymphatic vascular system characterized by impaired lymphatic return and swelling of the extremities. Treatment for this disabling condition remains limited and largely ineffective. The goal of the present study was to investigate the therapeutic efficacy of hepatocyte growth factor (HGF) in animal models of lymphedema., Methods and Results: Immunofluorescent analysis demonstrated that canine primary lymphatic endothelial cells (cLECs) were positive for lymphatic-specific markers (vascular endothelial growth factor receptor-3, LYVE-1, podoplanin, and Prox1) and the HGF receptor c-Met. Treating cLECs with human recombinant HGF resulted in a dose-dependent increase in cell growth and migration and increased activity of extracellular signal-regulated kinase and Akt. In human LECs, c-Met also was expressed, and treatment with HGF increased cell growth and migration in a dose-dependent manner. Transfection of human HGF plasmid DNA in cLECs also increased the c-fos promoter activity. Furthermore, weekly HGF gene transfer in a rat tail lymphedema model by disruption of lymphatic vessels resulted in a decrease in lymphedema thickness. Although expression of the endothelial cell marker PECAM-1 was increased in both HGF- and vascular endothelial growth factor 165-injected groups, expression of LEC markers (LYVE-1 and Prox1) was increased only in the HGF-injected group., Conclusions: These data demonstrate that expression of HGF via plasmid transfer improves lymphedema via promotion of lymphangiogenesis. Further studies to determine the clinical utility of this approach would be of benefit to patients with lymphedema.

Although skin diseases are one of the target diseases for gene therapy, there has been no practical gene transfer method. First, we examined gene transfer efficiency of the spring-powered jet injector, Shima Jet, which was originally developed as a non-needle jet injector of insulin. Local gene expression was about 100 times higher when the luciferase plasmid was transferred by the Shima Jet than by a needle. Gene transfer of beta-galactosidase revealed gene expression in the epidermis. Based on these results, we then examined the potential of gene therapy using the Shima Jet for wound healing. An increase of cellular proliferation of the epidermis and the number of microvessels in the granulation tissue was observed after hepatocyte growth factor (HGF) gene transfer. An increase in blood flow around the wound was observed after prostacyclin synthase (PGIS) gene transfer. Moreover, promotion on wound healing was observed in HGF gene transferred group, and further promotion was observed in combined gene transferred group as assessed by measuring wound area. These results indicate that co-transfer of HGF and PGIS genes by the Shima Jet could be an effective strategy to wound healing.

There is no specific treatment to improve the functional recovery in the chronic stage of ischemic stroke. To provide the new therapeutic options, we examined the effect of overexpression of hepatocyte growth factor (HGF) in the chronic stage of cerebral infarction by transferring the HGF gene into the brain using hemagglutinating virus of Japan envelope vector. Sixty rats were exposed to permanent middle cerebral artery occlusion (day 1). Based on the sensorimotor deficits at day 7, the rats were divided equally into control vector or HGF-treated rats. At day 56, rats transfected with the HGF gene showed a significant recovery of learning and memory in Morris water maze tests (control vector 50+/-4 s; HGF 33+/-5 s; P<0.05) and passive avoidance task (control vector 132.4+/-37.5 s; HGF 214.8+/-26.5 s; P<0.05). Although the total volume of cerebral infarction was not related to the outcome, immunohistochemical analysis for Cdc42 and synaptophysin in the peri-infarct region revealed that HGF enhanced the neurite extension and increased synapses. Immunohistochemistry for glial fibriary acidic protein revealed that the formation of glial scar was also prevented by HGF gene treatment. Additionally, the number of the arteries was increased in the HGF group at day 56. These data demonstrated that HGF has a pivotal role for the functional recovery after cerebral infarction through neuritogenesis, improved microcirculation, and the prevention of gliosis. Our results also provide evidence for the feasibility of gene therapy in the chronic stage of cerebral infarction.

VEGF and HGF are pleiotropic factors that regulate cell growth, cell motility, and morphogenesis of various types of cells. The receptors of these growth factors are expressed in neurons and endothelial cells, and are identified as neurotrophic, neuroprotective, and angiogenic factors. Indeed, gene therapy using viral vectors encoding the VEGF or HGF gene has been reported to be effective for preventing the expansion of ischemic injury. However, the safety issue of viral vectors is a major problem in clinical application. To overcome this problem, we have developed an HVJ-based non-viral vector, which achieves high-efficiency transfection rates of viral vectors with the safety of liposomes. This review discusses the feasibility of gene therapy using an HVJ-based non-viral vector containing the VEGF or HGF gene for cerebral ischemia.

Background: Although a left ventricular assist device is often used to provide circulatory support until transplantation in severe heart failure, the mortality of long-term use of left ventricular assist devices remains high. We have shown that hepatocyte growth factor causes angiogenesis, antifibrosis, and antiapoptosis in the myocardium. Therefore, gene therapy with hepatocyte growth factor-complementary DNA plasmids may enhance the chance of "bridge to recovery." In this study, we performed gene therapy with hepatocyte growth factor in the impaired goat heart with a left ventricular assist device., Methods: Cardiac impairment was induced in 6 adult goats (56-65 kg) by ligation of the coronary artery, and ventricular assist devices were installed. The hepatocyte growth factor group (HGF; n = 3) was administered human hepatocyte growth factor-complementary DNA plasmid (2.0 mg) in the myocardium. The control group (n = 3) was similarly administered beta-galactosidase plasmid. Four weeks after gene transfection, we attempted to wean all goats from the ventricular assist device., Results: The myocardia transfected with human hepatocyte growth factor-complementary DNA contained human hepatocyte growth factor protein at levels as high as 1.0 +/- 0.3 ng/g tissue 3 days after transfection. After weaning from the ventricular assist device, the HGF group showed good hemodynamics, whereas the control group showed deterioration. The percentage of fractional shortening was significantly higher in the HGF group than the control group (HGF vs control, 37.9% +/- 1.7% vs 26.4% +/- 0.3%, respectively; P < .01). Left ventricular dilatation associated with myocyte hypertrophy and fibrotic changes was detected in the control group but not in the HGF group. Vascular density was markedly increased in the HGF group., Conclusions: These results suggest that gene therapy with human hepatocyte growth factor may enhance the chance of bridge to recovery in the impaired heart supported with a ventricular assist device.

Hepatocyte growth factor (HGF) is well known to be involved in many biological functions, such as organ regeneration and angiogenesis, and to exert neurotrophic effects on motor, sensory, and parasympathetic neurons. In this study, we gave repeated intramuscular injections of the human HGF gene, using nonviral HVJ (hemagglutinating virus of Japan) liposome method, to examine whether transfection of the rat nervous system with this gene is able to exert neurotrophic effects facilitating recovery of a crushed nerve. The expression of HGF protein and HGF mRNA indicated that gene transfer into the nervous system did occur via retrograde axonal transport. At 4 weeks after crush, electrophysiological examination of the crushed nerve showed a significantly shorter mean latency and a significantly greater mean maximum M-wave amplitude with repeated injections of HGF gene. Furthermore, histological findings showed that the mean diameter of the axons, the axon number and the axon population were significantly larger in the group with repeated injections of HGF gene. The above results show that repeated human HGF gene transfer into the rat nervous system is able to promote crushed-nerve recovery, both electrophysiologically and histologically, and suggest that HGF gene transfer has potential for the treatment of crushed nerve.

It was recently reported that gene therapy using hepatocyte growth factor (HGF) has the potential to preserve cardiac function after myocardial ischemia. We speculated that this HGF gene therapy could also prevent ventricular arrhythmia. To investigate this possibility, we examined the antiarrhythmic effect of HGF gene therapy in rat acute and old myocardial infarction models. Myocardial ischemia was induced by ligation of the left descending coronary artery. Hemagglutinating virus of Japan (HVJ)-coated liposome containing HGF genes were injected directly into the myocardium fourteen days before programmed pacing. Ventricular fibrillation (VF)was induced by programmed pacing. The VF duration was reduced and the VF threshold increased after HGF gene therapy ( p< 0.01). Histological analyses revealed that the number of vessels in the ischemic border zone was greatly increased after HGF gene injection. These findings revealed that HGF gene therapy has an anti-arrhythmic effect after myocardial ischemia.

Rationale and Objectives: Although lung volume reduction surgery (LVRS) has been widely used as a therapeutic strategy for pulmonary emphysema, the procedure carries significant disadvantages, including significant operative mortality and a limited duration of effective response. Pulmonary resection is known to elicit compensatory growth in remnant lung tissues; however, it remains unclear whether and how compensatory growth occurs and contributes to clinical outcomes after LVRS. The goal of the present study was to characterize the role of hepatocyte growth factor (HGF) in compensatory lung growth after LVRS in a rat model of elastase-induced emphysema, since HGF is a potent pulmotrophic factor responsible for the regeneration of lung parenchyma in damaged lungs, including after a pulmonary resection., Methods and Main Results: Unexpectedly, LVRS did not cause apparent increases in the endogenous HGF profiles of emphysematous lungs. Further, the lowered HGF production reflected a histologically inferior regenerative capacity in remnant lungs and was linked with impaired pulmonary functional recoveries after LVRS. When HGF was exogenously supplemented by gene transfection into emphysematous lungs simultaneously with LVRS, compensatory lung growth (as evidenced by increased lobe weight and alveolar regeneration and angiogenesis) was significantly enhanced as compared with rats that underwent LVRS alone. Consequently, pulmonary function and gas exchange were also significantly improved., Conclusions: We concluded that the induction of compensatory growth by growth factors after LVRS may be a new strategy to further improve clinical outcomes of LVRS in patients with pulmonary emphysema.

Hepatocyte growth factor is a mesenchyme-derived pleiotropic factor that regulates the growth, motility and morphogenesis of various types of cells, and is also a member of the angiogenic growth factors. Hepatocyte growth factor is secreted by vascular endothelial cells and smooth muscle cells, and the hepatocyte growth factor receptor, c-met, was also observed in these vascular cells. Treatment of human aortic endothelial cells with recombinant hepatocyte growth factor resulted in a significant increase in cell proliferation, accompanied by mitogen-activated protein kinase and Akt/protein kinase B phosphorylation. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As preclinical study of gene therapy using hepatocyte growth factor to treat peripheral arterial disease, naked hepatocyte growth factor plasmid was intramuscularly injected into the ischemic hind limb of rabbits in order to evaluate its angiogenic activity. Intramuscular injection of hepatocyte growth factor plasmid once on day 10 following surgery, produced significant augmentation of collateral vessel development in the ischemic limb on day 30. In the clinical setting, the authors further investigated the safety and efficacy of hepatocyte growth factor plasmid DNA in patients with critical limb ischemia, in a prospective open-labeled trial. Intramuscular injection of naked plasmid DNA was performed in the ischemic limbs of six patients with critical limb ischemia with arteriosclerosis obliterans (n = 3) or Buerger disease (n = 3) graded as Fontaine III or IV. In the efficacy evaluation, a reduction of pain scale of more than 1 cm on a visual analog pain scale was observed in five out of six patients. An increase in ankle pressure index of more than 0.1 was observed in five out of five patients. The long diameter of eight out of 11 ischemic ulcers in four patients was reduced by more than 25%. Intramuscular injection of naked hepatocyte growth factor plasmid is safe, feasible and can achieve successful improvement of ischemic limbs. Although the present data were obtained to demonstrate safety in a Phase I/early Phase II trial, the initial clinical outcome with hepatocyte growth factor gene transfer seems to indicate its usefulness as sole therapy for critical limb ischemia. Randomized placebo-controlled clinical trials of alternative dosing regimens of gene therapy will be required to define the efficiency of this therapy.

Hepatocyte growth factor (HGF), a multifunctional cytokine, accelerates intestinal epithelial proliferation. We studied the effects of HGF in mice with trinitrobenzene sulfonic acid-induced colitis, which shows clinical and molecular resemblance to Crohn's disease. Mice with colitis repeatedly were transfected intramuscularly with human HGF cDNA. Weight, survival, histopathology, proinflammatory cytokine mRNAs, and leukocyte infiltration were assessed. Treatment with HGF cDNA induced tyrosine phosphorylation of intestinal c-Met/HGF receptors, inhibited apoptosis, and promoted mitosis in intestinal epithelial cells, accelerating intestinal epithelial restoration and suppressing inflammation. Transfection with HGF cDNA markedly suppressed intestinal mRNA expression of T-helper 1 cytokines such as interleukin-12 and -1beta, interferon-gamma, and tumor necrosis factor-alpha. Numbers of total and CD4-positive T cells, neutrophils, and myloperoxidase activity in intestinal epithelium were diminished by HGF gene transfer, which also prevented weight loss, and improved survival. HGF might prove useful for controlling inflammatory bowel disease.

Background: Severe degree of pulmonary vascular hypoplasia remains a major limitation in congenital heart surgery. Considering the potential effect of gene transfer with hepatocyte growth factor to induce the angiogenesis in the lung, we assessed the effects of hepatocyte growth factor gene transfer in neonatal porcine lung with pulmonary vascular hypoplasia to achieve treatment for severe pulmonary vascular hypoplasia., Methods: The model of pulmonary vascular hypoplasia was introduced with left pulmonary artery banding in piglet lung. After 7 days of pulmonary artery banding, piglets were transfected selectively to the left lung via the left pulmonary artery with a hemagglutinating virus of Japan E vector bearing the cDNA encoding human hepatocyte growth factor (H group) or control vector (C group)., Results: Seven days after the transfection, selective angiography of the left pulmonary artery showed the progression of left pulmonary vascular hypoplasia of the left lung in the C group but a significant attenuation of left pulmonary vascular hypoplasia in the H group. A right pulmonary artery occlusion test showed a marked increase in right ventricular systolic pressure in the C group, but this was significantly attenuated in the H group (C: 22.0 +/- 2.9, H: 13.0 +/- 2.7 mm Hg; P < .05). Histologic examination revealed that hepatocyte growth factor gene transfection increased the pulmonary vasculature in the left lung., Conclusions: Our results demonstrated that gene transfer of hepatocyte growth factor via the pulmonary artery showed the angiogenic effects in porcine model of pulmonary vascular hypoplasia after pulmonary artery banding.

Background: Hepatocyte growth factor (HGF) is an important mitogen and morphogen that contributes to the repair process after lung injury. The goal of the present study was to characterize its role in pulmonary emphysema, which may lead to the development of new treatment strategies with HGF., Methods and Results: HGF mRNA and protein levels in lung tissue and plasma from elastase-induced emphysema rats transiently increased, then declined significantly to below the basal level in a time-dependent manner (P<0.01). Furthermore, changes in HGF were correlated with histologically progressive emphysematous changes and deterioration in pulmonary physiology. Use of the HVJ (hemagglutinating virus of Japan) envelope method resulted in successful transfection of cDNA encoding human HGF, as demonstrated by an efficient expression of HGF in alveolar endothelial and epithelial cells. Transfection of HGF resulted in a more extensive pulmonary vasculature and inhibition of alveolar wall cell apoptosis, and those effects led to improved exercise tolerance and gas exchange (P<0.05), which persisted for more than 1 month., Conclusions: Decreased HGF expression due to a failure in sustained endogenous production after injury was associated with emphysema-related histopathologic and physiological changes in the present rat model. In addition, induction of HGF expression by a gene-transfection method resulted in improved pulmonary function via inhibition of alveolar cell apoptosis, enhancement of alveolar regeneration, and promotion of angiogenesis.

Peripheral neuropathy is common and ultimately accounts for significant morbidity in diabetes. Recently, several neurotrophic factors have been used to prevent progression of diabetic neuropathy. In this study, we gave repeated intramuscular injections of the human hepatocyte growth factor (HGF) gene percutaneously, using liposomes containing the hemagglutinating virus of Japan (HVJ), to examine therapeutic efficacy of nonviral gene transfer of HGF for experimental diabetic sensorimotor neuropathy in rats. Experimental diabetes induced by intraperitoneal injection of streptozotocin resulted in a marked tactile allodynia (but not in a thermal hyperalgesia), in a reduction of both the conduction velocity and the amplitude, and in a decreased laser Doppler flux of the nerve and the muscle at 6 weeks after the induction. All these changes were significantly reversed by repeated gene transfer of HGF. Furthermore, we analyzed the density of endoneurial capillaries and morphometrical changes of the nerve. The density of endoneurial capillaries, disclosing marked reduction in diabetic rats, was also reversed significantly by repeated gene transfer of HGF; however, no considerable differences were observed morphometrically in either myelinated or unmyelinated axons. These results suggest that nonviral HVJ liposome-mediated gene transfer of human HGF has potential for the safe effective treatment of diabetic sensorimotor neuropathy.

Therapeutic angiogenesis using angiogenic growth factors is expected to be a new treatment for patients with critical limb ischemia (CLI). Because hepatocyte growth factor (HGF) has potent angiogenic activity, we investigated the safety and efficiency of HGF plasmid DNA in patients with CLI as a prospective open-labeled clinical trial. Intramuscular injection of naked HGF plasmid DNA was performed in ischemic limbs of 6 CLI patients with arteriosclerosis obliterans (n=3) or Buerger disease (n=3) graded as Fontaine III or IV. The primary end points were safety and improvement of ischemic symptoms at 12 weeks after transfection. Severe complications and adverse effects caused by gene transfer were not detected in any patients. Of particular importance, no apparent edema was observed in any patient throughout the trial. In addition, serum HGF concentration was not changed throughout the therapy period in all patients. In contrast, a reduction of pain scale of more than 1 cm in visual analog pain scale was observed in 5 of 6 patients. Increase in ankle pressure index more than 0.1 was observed in 5 of 5 patients. The long diameter of 8 of 11 ischemic ulcers in 4 patients was reduced >25%. Intramuscular injection of naked HGF plasmid is safe, feasible, and can achieve successful improvement of ischemic limbs. Although the present data are conducted to demonstrate the safety as phase I/early phase IIa, the initial clinical outcome with HGF gene transfer seems to indicate usefulness as sole therapy for CLI.

In this study, we investigated the role of hepatocyte growth factor (HGF) in blood formation during Xenopus development. First, we examined the gene expression of HGF and its receptor, c-met, by whole-mount in situ hybridization during development. Strong signals of HGF as well as c-met were detected early in the developing ventral mesoderm, which later gives rise to the ventral blood island. Furthermore, to study the role of HGF, we blocked the HGF signaling pathway in Xenopus embryos by using truncated c-met lacking the tyrosine kinase domain. Injection of truncated c-met mRNA resulted in a marked decrease in the number of circulating blood cells. Similar results were obtained using morpholino antisense HGF oligonucleotides. Moreover, we also analyzed the expression of several early primitive blood markers in the blood island of these embryos. RNA in situ analysis revealed a significant reduction (or absence) of stem cell leukemia (SCL), alpha-globin, and GATA-1 expression, but not GATA-2 expression. In contrast, no significant difference was observed in the levels of expression of early definitive blood markers, SCL, GATA-2, and GATA-3 in the dorsolateral plate, as analyzed by in situ hybridization. Overall, the present study demonstrated that HGF is necessary for primitive hematopoiesis by regulating the expression of SCL.

Recently, a novel therapeutic treatment for ischemic diseases using angiogenic growth factors to augment collateral artery development has been proposed. As intramuscular injection of naked human hepatocyte growth factor (HGF) plasmid DNA induced therapeutic angiogenesis in several animal test subjects, we have started a clinical trial to treat peripheral arterial disease. However, one might assume that over-expression of angiogenic growth factors could enhance tumor growth. To resolve this issue, we examined the over-expression of HGF in tumor bearing mice. Tumors on their backs were prepared with an intradermal inoculation of A431, human epidermoid cancer cells expressing c-Met. These mice were intramuscularly injected with human HGF plasmid or control plasmid into the femoral muscle. Human HGF concentration was increased only in the femoral muscle, but not in blood. Although recombinant HGF stimulated the growth of A431 cells in vitro, temporally and locally HGF elevation in hindlimb had no effect on tumor growth in mice.

Background: Although cerebral occlusive disease leads to cerebral ischemic events, an effective treatment has not yet been established. An ideal therapeutic approach to treat ischemia might have both aspects of enhancement of collateral formation and prevention of neuronal death. Hepatocyte growth factor (HGF) is a potent angiogenic factor that also acts as a neurotrophic factor. Thus, in this study, we examined the therapeutic effects of HGF on brain injury in a rat permanent middle cerebral artery occlusion model., Methods and Results: Gene transfer into the brain was performed by injection of human HGF gene with hemagglutinating virus of Japan-envelope vector into the cerebrospinal fluid via the cisterna magna. Overexpression of the HGF gene resulted in a significant decrease in the infarcted brain area as assessed by triphenyltetrazolium chloride staining, whereas rats transfected with control vector exhibited a wide area of brain death after 24 hours of ischemia. Consistently, the decrease in neurological deficit was significantly attenuated in rats transfected with the HGF gene at 24 hours after the ischemic event. Stimulation of angiogenesis was also detected in rats transfected with the HGF gene compared with controls. Of importance, no cerebral edema or destruction of the blood-brain barrier was observed in rats transfected with the HGF gene., Conclusions: Overall, the present study demonstrated that overexpression of the HGF gene attenuated brain ischemic injury in a rat model, without cerebral edema, through angiogenic and neuroprotective actions. In particular, the reduction of brain injury by HGF may provide a new therapeutic option to treat cerebrovascular disease.

Hearing impairment, which is the most prevalent sensory deficit of human beings, needs a breakthrough in therapeutic technologies. One technology is the usage of a vector system to reach the inner ear, and another is by a therapeutic molecule. Here we developed a novel gene therapy strategy by combining hepatocyte growth factor (HGF) with hemagglutinating virus of Japan envelope (HVJ-E) vector. When HVJ-E containing human HGF gene was injected intrathecally into the cerebrospinal fluid via cisterna magna of rats, the vector reached the inner ear region, and human HGF gene expression was detected in the spiral ganglion cells (SGCs) of the inner ear. Expression of endogenous rat HGF and its receptor, c-Met, was also induced in SGCs by human HGF. Kanamycin treatment results in hearing impairment by inducing degeneration of hair cells (HCs) and apoptosis of SGCs in rats. By HGF gene transfer before kanamycin treatment, both loss of HCs and apoptosis of SGCs were prevented. Furthermore, hearing function, evaluated by auditory brainstem response, was maintained at a normal level. When HGF gene transfer was performed 2 wk after kanamycin treatment, hearing impairment was significantly recovered. These results indicate a novel and effective therapeutic strategy against sensorineural hearing impairment.

Systemic sclerosis (SSc) is a connective tissue disorder with an unknown etiology. There are currently no effective therapies for SSc. (In this study, working with a bleomycin(BLM)-induced scleroderma model mice, we performed two transfections of human hepatocyte growth factor (HGF) cDNA into the skeletal muscle and showed that this treatment not only helped to prevent the dermal sclerosis simultaneously injected BLM but also improved the symptoms of dermal sclerosis induced by BLM 4 weeks previously.) RT-PCR, ELISA and an immunohistochemical analysis revealed that both mRNA and protein of human HGF as well as murine HGF were enhanced in the skin, lung, muscle and the serum after two transfections of human HGF cDNA. These analyses also revealed that this treatment significantly reduced both the expression of the TGF-beta1 mRNA and the production of TGF-beta1 on macrophage-like cells that infiltrated the dermis and the fibroblastic cells in BLM-induced scleroderma. Furthermore, HGF-gene transfection both prevented and ameliorated the symptoms of not only dermal sclerosis but also of lung fibrosis induced by a subcutaneous BLM injection. These results indicated that gene therapy by the transfection of the human HGF cDNA may thus be a useful therapy for SSc and lung fibrosis involved with SSc.

The current therapeutic angiogenesis strategy to treat ischemic disease by using angiogenic growth factors has been limited to use of a single gene. However, as vasodilator substances such as prostacyclin are widely used for the treatment of peripheral arterial disease, it might be useful to combine angiogenesis with vasodilation of new vessels. In a mouse hind limb ischemia model, cotransfection of the hepatocyte growth factor (HGF) gene with the prostacyclin synthase gene demonstrated a further increase in blood flow and capillary density compared with a single gene. Even in the rabbit ischemia model, cotransfection of HGF plasmid with the prostacyclin synthase gene demonstrated a further increase in angiogenic activity compared with HGF alone. Because peripheral neuropathy due to diabetes is common for significant morbidity, we examined the hypothesis that experimental diabetic neuropathy can be reversed by HGF and prostacyclin synthase genes. Severe peripheral neuropathy, characterized by significant slowing of nerve conduction velocity compared with nondiabetic control animals, was ameliorated. Overall, cotransfection of the prostacyclin synthase and HGF genes is more effective than single-gene transfection to stimulate angiogenesis, and it significantly improved neuropathy. These data provide important information relating to the clinical application of therapeutic angiogenesis to treat peripheral arterial disease.

Background: Although hepatocyte growth factor (HGF) is an angiogenic growth factor, it is still unclear how it exerts its angiogenic effects. Thus, we focused on the role of an essential transcription factor for angiogenesis, ets-1. In this study, we addressed the following specific questions: (1) what genes responsible for angiogenesis can be regulated by HGF and (2) whether upregulation of gene expression for angiogenesis is dependent on ets-1., Methods and Results: In human endothelial cells, HGF significantly stimulated the matrix-degrading pathway, such as the production of matrix metalloprotease-1 (MMP-1) through its specific receptor, c-met. In addition, HGF also significantly increased HGF itself and its specific receptor, c-met. Moreover, HGF significantly increased the transcription activity and mRNA expression of ets-1 in a time-dependent manner. Importantly, transfection of antisense ets-1 oligodeoxynucleotides (ODN) resulted in a significant reduction in MMP-1, HGF and c-met. Interestingly, HGF also stimulated ets-1 mRNA in vascular smooth muscle cells, similar to endothelial cells. Of importance, transfection of antisense ets-1 ODN resulted in a significant decrease in vascular endothelial growth factor (VEGF) and HGF expression, whereas HGF stimulated both HGF and VEGF expression. Moreover, in vivo transfection of ets-1 antisense ODN resulted in an inhibition of angiogenesis induced by the HGF gene in a rat ischemic hindlimb model., Conclusions: Here, we demonstrated that HGF stimulated the expression of MMP-1, VEGF, HGF itself, and c-met in human endothelial cells and vascular smooth muscle cells. Upregulation of angiogenesis-related genes was largely dependent on the induction of ets, especially ets-1. These data provide new information about the mechanisms of angiogenesis.

Aims/hypothesis: As vascular endothelial growth factor (VEGF) plays a pivotal role in the development of diabetic retinopathy, inhibition of angiogenesis induced by VEGF is crucial to treat diabetic retinopathy. HGF (hepatocyte growth factor)/NK4, containing the N-terminal hairpin domain and the four subsequent kringle domains of HGF, is considered as a specific antagonist for HGF. Our aim was to explore the inhibitory effects of HGF/NK4 on angiogenesis induced by VEGF., Methods: To analyze the in vivo angiogenesis, we used rabbit corneal micropocket assay. Proliferation and migration of human endothelial cells, expression of ets-1, an essential transcription factor for angiogenesis, and the phosphorylation of extracellular signal-regulated kinase (ERK) was examined with or without HGF/NK4., Results: Using corneal micropocket assay, in vivo administration of HGF/NK4 inhibited angiogenesis induced by VEGF. HGF/NK4 inhibited proliferation and migration of human endothelial cells induced by VEGF in a dose-dependent manner. Interestingly, VEGF-mediated phosphorylation of ERK was significantly attenuated by HGF/NK4. Of importance, HGF/NK4 attenuated the increase in ets-1 protein stimulated by VEGF. Nevertheless, HGF/NK4 did not affect phosphorylation of VEGF receptor-2 [kinase domain region (KDR)/foetal liver kinase (Flk)-1]. Although tyrosine phosphatase inhibitor (Na(3)VO(4)), or okadaic acid, serine-threonin kinase inhibitor, did not prevent the inhibition of ERK phosphorylation by HGF/NK4, co-incubation of HGF/NK4 with VEGF significantly diminished mitogen-activated protein (MAP) ERK kinase (MEK) phosphorylation (p<0.01)., Conclusions/interpretation: Overall, HGF/NK4 inhibited angiogenesis induced by VEGF through inhibition of phosphorylation of ERK and ets-1 expression in in vitro cultured endothelial cells and in vivo rabbit model.

Hepatocyte growth factor (HGF) regulates cell growth, cell motility, and morphogenesis in various types of cells, including epithelial and endothelial cells, indicating that it probably promotes epithelial repair and neovascularization during wound healing. To better understand the effects of HGF on wound healing, we performed human HGF-gene transfer into skin wounds in rats. The rat HGF mRNA levels, and human and rat HGF protein concentrations in the wounds in HGF gene-transfer rats were significantly elevated at 3 days, 3 to 14 days, and 3 and 14 days after gene transfer, respectively. An expression of human HGF mRNA and protein was revealed in squamous cells in the epidermis, in endothelial cells and smooth muscle cells in blood vessels, and in fibroblasts in granulation tissues at 3, 7, and 14 days after gene transfer in HGF gene-transfer rats. The wound lesion area in HGF gene-transfer rats was significantly less than that in control rats from 3 to 7 days after gene transfer. The re-epithelialization rate, microvessel counts in granulation tissues, proliferating cell nuclear antigen index of fibroblasts in granulation tissues, and the proliferating cell nuclear antigen index in the epidermis of HGF gene-transfer rats were significantly increased at 3 and 7 days after gene transfer. Semiquantitative reverse transcriptase-polymerase chain reaction revealed that the expression levels of transforming growth factor-beta1 and Colalpha2(I) mRNAs in the wounds of HGF gene-transfer rats were significantly decreased at 7 and 14 days, respectively. The hydroxyproline concentration in the wound was significantly less in HGF gene-transfer rats than in control rats at 3 days after gene transfer. These results suggest that HGF gene transfer into a skin wound may aid re-epithelialization and neovascularization in the early phase of wound healing, and that HGF may play a role in modulating cutaneous wound healing.

Background: Recent studies have demonstrated that gene transfer with hepatocyte growth factor (HGF) induces angiogenesis for coronary and peripheral artery diseases. We investigated the ability of gene transfer with human HGF to induce angiogenesis in the rat lung., Methods and Results: The left lung was selectively transfected with a cDNA encoding human HGF via the left pulmonary artery, using the HVJ-liposome method (H group); rats transfected with the same vector lacking the HGF gene served as controls (C group). HGF gene transfer significantly increased the capillary density in the left lung compared with the C group 7 days after transfection (15.0+/-1.3 versus 8.0+/-1.7 mm(2), P<0.01). The left to right average blood perfusion ratio detected by laser Doppler imaging increased significantly in the H group 14 days after transfection (1.12+/-0.09 versus 0.91+/-0.11, P<0.01). A right pulmonary artery clamp test, in which only the left lung received all the pulmonary blood flow from the right ventricle, revealed that the increase in right ventricular pressure was significantly attenuated in the H group compared with the C group 7 days after transfection (8.6+/-3.5 versus 15.3+/-2.8 mm Hg, P<0.01)., Conclusions: Trans-pulmonary arterial transfer of the human HGF gene into the left lung increased capillary density and blood perfusion, and decreased vascular resistance when blood flow increased. These results suggest therapeutic angiogenesis induced by HGF gene expression in the lung may be found suitable in treating subjects with decreased pulmonary vasculature or increased pulmonary vascular resistance.

Injury of endothelial cells has been postulated to be an initial trigger of the progression of atherosclerosis in patients with diabetes. Previously, we demonstrated high D-glucose induced endothelial apoptosis through the bax-caspase pathway and the potential contribution of hepatocyte growth factor (HGF) to the pathogenesis of endothelial dysfunction. In this study, we analyzed the molecular mechanisms of the protective actions of HGF against endothelial cell death under high D-glucose conditions. High concentrations of D-glucose resulted in a significant increase in apoptosis and necrosis. In contrast, HGF attenuated high D-glucose-induced apoptosis and necrosis (P < 0.01). High D-glucose significantly increased bax protein, but not bcl-2, and activated caspase 3-like and 9, whereas HGF significantly increased bcl-2 expression without affecting bax level and attenuated the increase in caspase 3 and 9 activity. Interestingly, high D-glucose resulted in translocation of bax protein from cytosol to the mitochondrial membrane, whereas HGF inhibited the bax translocation. Importantly, this bax translocation was also completely blocked by overexpressed bcl-2. These findings suggest that HGF can activate bcl-2 expression and inhibit translocation of bax protein upstream of the mitochondria, thereby leading to the inhibition of caspase 3 and 9 activation. HGF may be an important factor in the maintenance of endothelial function.

Impairment of cardiac function in cardiomyopathy has been postulated to be related to decreased blood blow and increased collagen synthesis. Therefore, a therapeutic approach to alter the blood flow or fibrosis directly by means of growth factors may open a new therapeutic concept in dilated cardiomyopathy. From this viewpoint, hepatocyte growth factor (HGF) is a unique growth factor with antifibrosis and angiogenesis effects. Using the hereditary cardiomyopathic Syrian hamster as a model of genetically determined cardiomyopathy and heart failure, the effects of overexpression of HGF on fibrosis and microvascular dysfunction were examined. HGF gene or control vector was injected by the Hemagglutinating Virus of Japan-liposome method into the anterior heart of cardiomyopathic hamsters (Bio 14.6) under echocardiography once a week, from 12 to 20 weeks of age (total, 8 times). Blood flow, as assessed by a laser Doppler imager score, and the capillary density in hearts, as assessed by alkaline phosphatase staining, were significantly increased in hamsters transfected with HGF gene compared with control-vector-transfected hamsters (P<0.01). In contrast, the fibrotic area was significantly decreased in hamsters transfected with HGF gene compared with control (P<0.01). Overall, in vivo experiments demonstrated that transfection of HGF gene into the myocardium of cardiomyopathic hamsters stimulated blood flow through the induction of angiogenesis and reduction of fibrosis. These results suggest that HGF gene transfer may be useful to protect against myocardial injury in cardiomyopathy through its cardioprotective effects such as antifibrosis and angiogenesis actions.

Although cerebral hypoperfusion caused by cerebral occlusive disease leads to cerebral ischemic events, an effective treatment has not yet been established. Recently, a novel therapeutic strategy for ischemic disease using angiogenic growth factors to expedite and/or augment collateral artery development has been proposed. Therapeutic angiogenesis might be useful for the treatment of cerebral occlusive disease. Hepatocyte growth factor (HGF) is a potent angiogenic factor, in addition to vascular endothelial growth factor (VEGF), whereas in the nervous system HGF also acts as neurotrophic factor. Therefore, we hypothesized that gene transfer of these angiogenic growth factors could induce angiogenesis, thus providing an effective therapy for cerebral hypoperfusion or stroke. In this study, we employed a highly efficient gene transfer method, the viral envelop (Hemagglutinating Virus of Japan [HVJ]-liposome) method, because we previously documented that beta-galactosidase gene could be transfected into the brain by the HVJ-liposome method. Indeed, we confirmed wide distribution of transgene expression using beta-galactosidase via injection into the subarachnoid space. Of importance, transfection of HGF or VEGF gene into the subarachnoid space 7 days before occlusion induced angiogenesis on the brain surface as assessed by alkaline phosphatase staining (P<0.01). In addition, significant improvement of cerebral blood flow (CBF) was observed by laser Doppler imaging (LDI) 7 days after occlusion (P<0.01). Unexpectedly, transfection of HGF or VEGF gene into the subarachnoid space immediately after occlusion of the bilateral carotid arteries also induced angiogenesis on the brain surface and had a significant protective effect on the impairment of CBF by carotid occlusion (P<0.01). Interestingly, coinjection of recombinant HGF with HGF gene transfer revealed a further increase in CBF (P<0.01). Here, we demonstrated successful therapeutic angiogenesis using HGF or VEGF gene transfer into the subarachnoid space to improve cerebral hypoperfusion, thus providing a new therapeutic strategy for cerebral ischemic disease.

Background: Although lipoprotein(a) (Lp[a]) is a risk factor for atherosclerosis, no study has documented the effects of Lp(a) on angiogenesis. In this study, we examined collateral formation in peripheral arterial disease (PAD) model in Lp(a) transgenic mice. In addition, we examined the feasibility of gene therapy by using an angiogenic growth factor, hepatocyte growth factor (HGF), to treat PAD in the presence of high Lp(a)., Methods and Results: In Lp(a) transgenic mice, the degree of natural recovery of blood flow after operation was significantly lower than that in nontransgenic mice. Of importance, there was a significant negative correlation between serum Lp(a) concentration and the degree of natural recovery of blood flow (P<0.05). In addition, Lp(a) significantly stimulated the growth of vascular smooth muscle, accompanied by the phosphorylation of ERK. These data demonstrated the association of impairment of collateral formation with serum Lp(a) concentration. Thus, we examined the feasibility of therapeutic angiogenesis by using HGF, with the goal of progression to human gene therapy. Intramuscular injection of HGF plasmid resulted in a significant increase in blood flow even in Lp(a) transgenic mice, accompanied by the detection of human HGF protein. A significant increase in capillary density also was detected in Lp(a) transgenic mice transfected with human HGF compared with control (P<0.01)., Conclusions: Overall, a high serum Lp(a) concentration impaired collateral formation. Although the delay of angiogenesis in high serum Lp(a) might diminish angiogenesis, intramuscular injection of HGF plasmid induced therapeutic angiogenesis in the Lp(a) transgenic ischemic hindlimb mouse model as potential therapy for PAD.

Although clinical trials of stimulation of angiogenesis by transfection of angiogenic growth factors using naked plasmid DNA or adenoviral vector have been successful, there are still unresolved problems for human gene therapy such as low transfection efficiency and safety. From this viewpoint, it is necessary to develop safe and efficient novel nonviral gene transfer methods. As therapeutic ultrasound induces cell membrane permeabilization, ultrasound irradiation might increase the transfection efficiency of naked plasmid DNA into skeletal muscle. Thus, we examined the transfection efficiency of naked plasmid DNA using ultrasound irradiation with echo contrast microbubble (Optison) in vitro and in vivo experiments. First, we examined the feasibility of ultrasound-mediated transfection of naked plasmid DNA into skeletal muscle cells. Luciferase plasmid mixed with or without Optison was transfected into cultured human skeletal muscle cells using ultrasound (1 MHz; 0.4 W(2)) for 30 s. Interestingly, luciferase activity was markedly increased in cells treated with Optison, while little luciferase activity could be detected without Optison (P < 0.01). Electron microscopy demonstrated the transient formation of holes (less than 5 microM) in the cell surface, which could possibly explain the rapid migration of the transgene into the cells. Next, we studied the in vivo transfection efficiency of naked plasmid DNA using ultrasound with Optison into skeletal muscle. Two days after transfection, luciferase activity in skeletal muscle transfected with Optison using ultrasound was significantly increased about 10-fold as compared with plasmid alone. Successful transfection was also confirmed by beta-galactosidase staining. Finally, we examined the feasibility of therapeutic angiogenesis using naked hepatocyte growth factor (HGF) plasmid in a rabbit ischemia model using the ultrasound-Optison method. Five weeks after transfection, the angiographic score and the number of capillary density in rabbits transfected with Optison using ultrasound was significantly increased as compared with HGF plasmid alone (P < 0.01), accompanied by a significant increase in blood flow and blood pressure ratio (P < 0.01). Overall, the ultrasound transfection method with Optison enhanced the transfection efficiency of naked plasmid DNA in vivo as well as in vitro. Transfection of HGF plasmid by the ultrasound-Optison method could be useful for safe clinical gene therapy to treat peripheral arterial disease without a viral vector system.

Background: Because no study has documented the angiogenic properties of hepatocyte growth factor (HGF) in a diabetes model, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease in diabetes., Methods and Results: Because intramuscular injection of luciferase plasmid by the hemagglutinating virus of Japan (HVJ)-liposome method had much higher efficiency than injection of naked plasmid, we used the HVJ-liposome method to transfect the human HGF gene into the rat diabetic hindlimb model. As expected, transfection of human HGF vector resulted in a significant increase in blood flow as assessed by laser Doppler imaging and capillary density, even in the diabetes model, accompanied by the detection of human HGF protein. Interestingly, the degree of natural recovery of blood flow was significantly greater in nondiabetic rats than in diabetic rats. Thus, in an in vitro culture system, we further studied the molecular mechanisms of how diabetes delayed angiogenesis. Importantly, high-D-glucose treatment of endothelial cells resulted in a significant decrease in matrix metalloproteinase (MMP)-1 protein and ets-1 expression in human aortic endothelial cells. Similarly, high D-glucose significantly decreased mRNA and protein of HGF in endothelial cells. Downregulation of MMP-1 and ets-1 by high D-glucose might be due to a significant decrease in HGF, because HGF stimulated MMP-1 production and activated ets-1., Conclusions: Overall, intramuscular injection of human HGF plasmid induced therapeutic angiogenesis in a rat diabetic ischemic hindlimb model as a potential therapy for peripheral arterial disease. The delay of angiogenesis in diabetes might be due to downregulation of MMP-1 and ets-1 through a decrease in HGF by high D-glucose.

Aims/hypothesis: Cilostazol, a well-known phosphodiesterase type 3 (PDE3) inhibitor for the treatment of peripheral arterial disease, has vasodilator properties and an anti-proliferative action on the growth of vascular smooth muscle cells. In this study, we tested whether cilostazol inhibits neointimal formation and improves endothelial dysfunction after balloon injury in non-diabetic and diabetic rats., Methods: Cilostazol or vehicle was administered to non-diabetic and streptozotocin-induced diabetic rats from 7 days before to 14 days after balloon injury of the carotid artery. We focused on the expression of hepatocyte growth factor to explore how cilostazol improved endothelial dysfunction. Also, we studied the effects of cilostazol on hepatocyte growth factor production in in vitro experiments., Results: At 14 days after injury, the ratio of neointimal to medial area was decreased in rats treated with cilostazol in non-diabetic and diabetic animals. The impaired response to acetylcholine in balloon injured vessels was improved by cilostazol in non-diabetic and diabetic rats (p < 0.05). Vascular hepatocyte growth factor concentration was decreased in injured vessels of non-diabetic rats compared to uninjured vessels. Moreover, hepatocyte growth factor was further decreased in injured vessels of diabetic rats as compared to those of non-diabetic rats (p < 0.05). Of note, administration of cilostazol attenuated the decrease in hepatocyte growth factor concentration in injured vessels of both non-diabetic and diabetic rats (p < 0.01). Increase in vascular hepatocyte growth factor by cilostazol was confirmed by in vitro experiments showing that cilostazol increased hepatocyte growth factor concentration in cultured human vascular smooth muscle cells, accompanied by cAMP accumulation., Conclusion/interpretation: Our study shows that the increase in vascular hepatocyte growth factor by cilostazol could improve abnormal growth of vascular smooth muscle cells and endothelial dysfunction through rapid regeneration of endothelial cells.

To develop a novel strategy to prevent delayed neuronal death (DND) following transient occlusion of arteries, the gene of hepatocyte growth factor (HGF), a novel neurotrophic factor, was transfected into the subarachnoid space of gerbils after transient forebrain ischemia. Importantly, transfection of HGF gene into the subarachnoid space prevented DND, accompanied by a significant increase in HGF in the cerebrospinal fluid. Prevention of DND by HGF is due to the inhibition of apoptosis through the blockade of bax translocation from the cytoplasm to the nucleus. HGF gene transfer into the subarachnoid space may provide a new therapeutic strategy for cerebrovascular disease.

Acute graft-versus-host disease (GVHD) is a major complication of bone marrow transplantation (BMT) and is characterized by hematopoietic dysfunction, immunosuppression, and tissue injury in the skin, liver, and intestinal mucosa. Hepatocyte growth factor (HGF), originally identified and cloned as a potent mitogen for hepatocytes, induces mitogenic and antiapoptotic activity in various epithelial cells and promotes hematopoiesis. Working in a murine model of acute GVHD, we performed repeated transfection of the human HGF cDNA into skeletal muscle and showed that this treatment inhibited apoptosis of intestinal epithelial cells and donor T-cell infiltration into the liver, thereby ameliorating the enteropathy and liver injury caused by acute GVHD. HGF also markedly suppressed IFN-gamma and TNF-alpha expression in the intestine and liver and decreased the serum IL-12. Furthermore, extramedullary hematopoiesis by donor cells was increased, and the survival rate was improved. These results suggest that HGF may be useful for controlling acute GVHD after allogeneic BMT.

Angiogenic growth factors play important roles in angiogenic responses, such as vasculogenesis and angiogenesis in response to hypoxia. A novel angiogenic growth factor, hepatocyte growth factor (HGF), has been reported to inhibit endothelial cell death. However, its molecular mechanisms are largely unknown. Thus, we studied (1) the effects of HGF on hypoxia-induced endothelial apoptosis and (2) the molecular mechanisms of the antiapoptotic actions of HGF in endothelial cells. Severe hypoxia increased the cell death rate in human aortic endothelial cells, whereas HGF significantly attenuated cell death. In addition, hypoxic treatment resulted in a significant increase in apoptotic cells, whereas HGF could attenuate apoptosis, accompanied by attenuation of the increase in caspase-3-like activity (P<0.01). Of importance, HGF significantly increased Bcl-2, an inhibitor of apoptosis, in a dose-dependent manner under normoxic and hypoxic conditions (P<0.01), whereas hypoxic conditions resulted in a significant decrease in Bcl-2. In contrast, HGF failed to affect Bcl-xL, which is also well known as an inhibitor of apoptosis under both normoxic and hypoxic conditions, whereas Bcl-xL was significantly decreased in endothelial cells exposed to hypoxia (P<0.01). No significant change in Bax, a promoter of apoptosis, was also observed in endothelial cells under hypoxia, whereas HGF did not affect BAX: Overall, this study demonstrated that HGF prevented endothelial cell death induced by hypoxia through its antiapoptotic action. The antiapoptotic mechanisms of HGF in hypoxia-induced endothelial cell death largely depend on Bcl-2, but not Bcl-xL and BAX:

Hepatocyte growth factor (HGF) exclusively stimulates the growth of endothelial cells without replication of vascular smooth muscle cells, and acts as a survival factor against endothelial cell death. Recently, a novel therapeutic strategy for ischemic diseases using angiogenic growth factors to expedite and/or augment collateral artery development has been proposed. We have previously reported that intra-arterial administration of recombinant HGF induced angiogenesis in a rabbit hindlimb ischemia model. In this study, we examined the feasibility of gene therapy using HGF to treat peripheral arterial disease rather than recombinant therapy, due to its disadvantages. Initially, we examined the transfection of 'naked' human HGF plasmid into a rat hindlimb ischemia model. Intramuscular injection of human HGF plasmid resulted in a significant increase in blood flow as assessed by laser Doppler imaging, accompanied by the detection of human HGF protein. A significant increase in capillary density was found in rats transfected with human HGF as compared with control vector, in a dose-dependent manner (P < 0.01). Importantly, at 5 weeks after transfection, the degree of angiogenesis induced by transfection of HGF plasmid was significantly greater than that caused by a single injection of recombinant HGF. As an approach to human gene therapy, we also employed a rabbit hindlimb ischemia model as a preclinical study. Naked HGF plasmid was intramuscularly injected in the ischemic hindlimb of rabbits, to evaluate its angiogenic activity. Intramuscular injection of HGF plasmid once on day 10 after surgery produced significant augmentation of collateral vessel development on day 30 in the ischemia model, as assessed by angiography (P < 0.01). Serial angiograms revealed progressive linear extension of collateral arteries from the origin stem artery to the distal point of the reconstituted parent vessel in HGF-transfected animals. In addition, a significant increase in blood flow was assessed by a Doppler flow wire and the ratio in blood pressure of the ischemic limb to the normal limb was observed in rabbits transfected with HGF plasmid as compared with rabbits transfected with control vector (P < 0.01). Overall, intramuscular injection of naked human HGF plasmid induced therapeutic angiogenesis in rat and rabbit ischemic hindlimb models, as potential therapy for peripheral arterial disease.

Hepatocyte growth factor (HGF), a member of the angiogenic growth factors, may play a pivotal role in the regulation of endothelial cells, inasmuch as HGF shows mitogenic and antiapoptotic actions in endothelial cells. Because the mechanism of these actions is still unclear, we examined the signal transduction system of HGF in human aortic endothelial cells. Treatment of endothelial cells with recombinant HGF (rHGF) resulted in a significant increase in DNA synthesis as assessed by thymidine incorporation. Importantly, phosphorylation of extracellular signal-related kinase (ERK) and Akt by rHGF was clearly observed. Thus, we further examined the effects of specific inhibitors of ERK or Akt on cell proliferation. Pretreatment with PD98059, a mitogen-activated protein kinase kinase inhibitor, significantly attenuated cell proliferation induced by rHGF, whereas inhibitors of phosphatidylinositol-3-OH kinase, wortmannin, and LY-294002, did not. Interestingly, treatment with rHGF significantly increased the phosphorylation of the signal transducers and activators of transcription (STAT)3 (Ser727), whereas PD98059 attenuated the phosphorylation of Ser727 induced by rHGF. In addition, treatment with rHGF significantly increased the promoter activity of c-fos, which includes the sis-inducible element and serum response element, whereas PD98059 completely attenuated the activation of the c-fos promoter induced by rHGF. In contrast, inhibition of Akt by wortmannin and LY-294002 failed to inhibit the phosphorylation of STAT3 and c-fos activation. On the other hand, treatment with rHGF attenuated the increase in LDH release and caspase-3 activity induced by tumor necrosis factor-alpha stimulation. In contrast to DNA synthesis, wortmannin and LY-294002 markedly attenuated the decrease in caspase-3 activity mediated by rHGF, whereas PD98059 did not. Overall, the present study demonstrated that HGF stimulated cell proliferation through the ERK-STAT3 (Ser727) pathway and had an antiapoptotic action through the phosphatidylinositol-3-OH kinase-Akt pathway in human aortic endothelial cells. These findings provide new perspectives in the role of HGF in cardiovascular disease.

Although most therapeutic strategies to prevent restenosis are designed to inhibit vascular smooth muscle cell (VSMC) proliferation directly, VSMC proliferation might be indirectly inhibited by re-endothelialization, as endothelial cells secrete antiproliferative and antithrombotic substances. We hypothesized that application of an endothelium-specific growth factor to balloon-injured arteries could accelerate re-endothelialization, thereby attenuating intimal hyperplasia. In this study, we investigated in vivo gene transfer of human HGF that exclusively stimulated endothelial cells without replication of VSMC growth into injured vessels. Transfection of human HGF gene into rat balloon-injured carotid artery resulted in significant inhibition of neointimal formation up to at least 8 weeks after transfection, accompanied by detection of human immunoreactive HGF. Induction of re-endothelialization induced by overexpression of human HGF gene transfer into balloon-injured vessels is supported by several lines of evidence: (1) Administration of HGF vector. but not control vector, markedly inhibited neointimal formation, accompanied by a significant increase in vascular human and rat HGF concentrations. (2) Planimetric analysis demonstrated a significant increase in re-endothelialized area in arteries transfected with human HGF vector. (3) Induction of NO content in balloon-injured vessels transfected with human HGF vector was observed in accordance with the recovery of endothelial vasodilator properties in response to acetylcholine. As endogenous HGF expression in balloon-injured vessels was significantly decreased as compared with normal vessels, the present study demonstrated the successful inhibition of neointimal formation by transfection of human HGF gene as 'cytokine supplement therapy' in a rat balloon injury model.

The feasibility of a novel therapeutic strategy using angiogenic growth factors to expedite and/or augment collateral artery development has recently entered the realm of treatment of ischemic diseases. Hepatocyte growth factor (HGF) is a novel member of endothelium-specific growth factors whose mitogenic activity on endothelial cells is very potent. Although it has been demonstrated that HGF is a potential angiogenic growth factor in in vitro culture systems, there is no direct in vivo evidence for the angiogenic activity of HGF in physiological conditions. In this study, we hypothesized that transfection of HGF gene into infarcted myocardium could induce angiogenesis, potentially resulting in a beneficial response to hypoxia. Human HGF gene or control vector driven by the SRalpha promoter was transfected into rat myocardium by the HVJ-liposome method. Four days after in vivo transfection of human HGF gene, there was a marked increase in human immunoreactive HGF as compared with control vector (P < 0.01). In myocardium transfected with HGF vector, a significant increase in PCNA-positive endothelial cells was observed, while few PCNA-positive endothelial cells were detected in both control-vector-transfected and untreated myocardium. The number of vessels around the HGF injection sites was significantly increased as compared with control vector or vehicle (P < 0.01). Angiogenic activity induced by the transfection of HGF vector was also confirmed by the activation of a transcription factor, ets, which is essential for angiogenesis. Furthermore, we studied the pathophysiological role of HGF in a myocardial infarction model. The concentration of endogenous HGF was significantly decreased in infarcted myocardium. Therefore, we hypothesized that transfection of HGF gene into infarcted myocardium could induce a beneficial response to the decreased endogenous HGF. Indeed, transfection of human HGF into infarcted myocardium also resulted in a significant increase in the number of vessels (P < 0. 01), accompanied by marked induction of ets binding activity and a significant increase in blood flow. Overall, the present results provide direct in vivo evidence for the induction of angiogenesis by transfection of the human HGF gene in rat non-infarcted and infarcted myocardium. The constant production of local HGF resulting from the transgene may be considered as an innovative therapeutic angiogenesis strategy for ischemic diseases such as myocardial infarction. Gene Therapy (2000) 7, 417-427.

Background: Hepatocyte growth factor (HGF), a ligand for the c-Met receptor tyrosine kinase, plays a role as organotrophic factor for regeneration of various organs. HGF has an angiogenic activity and exhibits a potent antiapoptotic activity in several types of cells. Although HGF and the c-Met/HGF receptor are expressed in the heart, the role of HGF in the heart has remained unknown., Methods: After we analyzed changes in expression of endogenous HGF and c-Met mRNA levels in the rat left ventricle after myocardial infarction, the human HGF gene in hemagglutinating virus of Japan (HVJ)-liposome was transfected into the normal whole rat heart. Three days after transfection, the heart was subjected to global warm ischemia and subsequent reperfusion, followed by assessment of its cardiac functions., Results: Both HGF and c-Met/HGF receptor mRNAs were expressed in adult rat heart, and c-Met/HGF receptor mRNA was upregulated in response to myocardial infarction. HGF-transfected heart showed significant increase of human HGF protein level in the heart. Cardiac functions in terms of the left ventricular developed pressure, maximum dp/dt, and pressure rate product in hearts with HGF gene transfection were significantly superior to those in control hearts. In addition, leakage of creatine phosphokinase in the coronary artery effluent in hearts with HGF gene transfection was significantly lower than that in control hearts., Conclusions: These data indicated that both HGF and c-Met/HGF receptor mRNAs were upregulated in response to myocardial ischemic injury, and that HGF is likely to have a cytoprotective effect on cardiac tissue, presumably through the c-Met/HGF receptor.

Liver cirrhosis is the irreversible end result of fibrous scarring and hepatocellular regeneration, characterized by diffuse disorganization of the normal hepatic structure of regenerative nodules and fibrotic tissue. It is associated with prominent morbidity and mortality, and is induced by many factors, including chronic hepatitis virus infections, alcohol drinking and drug abuse. Hepatocyte growth factor (HGF), originally identified and cloned as a potent mitogen for hepatocytes, shows mitogenic, motogenic and morphogenic activities for a wide variety of cells. Moreover, HGF plays an essential part in the development and regeneration of the liver, and shows anti-apoptotic activity in hepatocytes. In a rat model of lethal liver cirrhosis produced by dimethylnitrosamine administrations, repeated transfections of the human HGF gene into skeletal muscles induced a high plasma level of human as well as enodogenous rat HGF, and tyrosine phosphorylation of the c-Met/HGF receptor. Transduction with the HGF gene also suppressed the increase of transforming growth factor-beta1 (TGF-beta1), which plays an essential part in the progression of liver cirrhosis, inhibited fibrogenesis and hepatocyte apoptosis, and produced the complete resolution of fibrosis in the cirrhotic liver, thereby improving the survival rate of rats with this severe illness. Thus, HGF gene therapy may be potentially useful for the treatment of patients with liver cirrhosis, which is otherwise fatal and untreatable by conventional therapy.

Although hepatocyte growth factor (HGF) is synthesized in vascular cells, it is not known whether locally synthesized HGF acts similarly to exogenously added HGF. Therefore, we transfected cultured cells with human HGF vector and examined the effects on growth of vascular cells. Endothelial cells (EC) transfected with HGF vector synthesized and secreted high levels of HGF, and also showed significantly higher number. Addition of conditioned medium from vascular smooth muscle cells (VSMC) or EC transfected with HGF vector to nontransfected EC resulted in a significant increase in cell number, which was abolished by anti-HGF antibody. Co-culture of HGF-transfected VSMC with EC showed that HGF released from VSMC or EC stimulated EC growth. These results demonstrate that endogenously produced HGF by transfection of human HGF vector can exert autocrine and paracrine stimulatory effects on EC growth, but not VSMC growth, suggesting the role of local HGF system in cardiovascular disease.