Therapeutic angiogenesis induced by human hepatocyte growth factor gene in rat and rabbit hindlimb ischemia models: preclinical study for treatment of peripheral arterial disease

Combined strategy using myoblasts and hepatocyte growth factor in dilated cardiomyopathic hamsters

BACKGROUND

There are few reports on treating dilated cardiomyopathy (DCM) with myoblast transplantation, and these show limited efficacy. Hepatocyte growth factor has cardioprotective effects on failed myocardium. Here, we combined these two treatments and analyzed cardiac function in DCM hamsters.

METHODS

Twenty-seven-week-old BIO TO-2 hamsters, which show moderate cardiac remodeling, were divided into four treatment groups: myoblast transplantation (T group, n = 24), human hepatocyte growth factor gene transfection (H group, n = 29), combined treatment (T+H group, n = 21), and medium alone (C group, n = 26).

RESULTS

Significantly better fractional shortening was observed in the T+H group compared with the others (14.9% +/- 1.0%, 11.7% +/- 1.5%, 11.3% +/- 1.3%, and 8.6% +/- 1.1 %, in the T+H, H, T, and C groups, respectively). Immunohistochemical analysis showed alpha- and beta-sarcoglycan expression in the hearts of the H and T+H groups but not in the other groups. There was less myocardial fibrosis in the H and T+H groups than in the other two, and neovascularization in the T+H group was significantly greater than in the other groups (266 +/- 24, 209 +/- 27, 199 +/- 36, and 96 +/- 17 vessels/mm2, in the T+H, H, T, and C groups, respectively). Survival was significantly prolonged in the H and T+H groups compared with the other groups.

CONCLUSIONS

Hepatocyte growth factor gene transfection and myoblast transplantation preserved the cardiac function of DCM hamsters, probably through different mechanisms, and the combined treatments preserved cardiac performance better than either treatment alone. The combined therapy is a promising strategy for treating DCM.

A fusion protein of hepatocyte growth factor for immobilization to collagen

We describe here a fusion protein consisting of hepatocyte growth factor (HGF; an angiogenic factor) and a collagen-binding domain (CBD) polypeptide of fibronectin (FN). This fusion protein (CBD-HGF), produced by a baculovirus expression system, exhibited much stronger collagen binding activity than native HGF in the range of 0.4-6.4microg/ml. Its binding at the lowest concentration exceeded that of HGF at the highest concentration. In addition, the collagen-bound CBD-HGF promoted growth of endothelial cells (ECs) to a greater degree at least 4 days longer than HGF added to the culture medium; about 5-fold greater increase in cell number after 10 days. These findings suggest that the fused CBD moiety not only helped immobilize HGF on collagen but also helped stabilize the fusion molecule, resulting in prolonged activity. The angiogenic activity of CBD-HGF in animal tissues was examined by subcutaneously implanting collagen sponges containing bound CBD-HGF. Blood vessel formation in the sponges after 7 days was 4-6-fold extensive as compared to the control sponges without sample. Implanted sponges with native HGF did not show significant difference from control. These results indicate that CBD-HGF is suitable for in vitro culture of ECs, and that this fusion protein can be used to confer HGF activity on biomaterials for use in tissue engineering.

Improvement of survival of skin flaps by combined gene transfer of hepatocyte growth factor and prostacyclin synthase

BACKGROUND

Increasing the local blood flow is a critical factor for long-term survival of skin flaps. Thus, a molecular therapy to increase the blood flow by means of an angiogenic factor is considered to be a useful strategy to improve skin flap survival. We focused on a combined strategy to stimulate not only angiogenesis, but also vasodilation of local microvessels, using co-transfection of the hepatocyte growth factor (HGF) and prostacyclin synthase (PGIS) genes to enhance the survival of random-pattern skin flaps.

METHODS AND RESULTS

A 2 x 8 cm full thickness cranial pedicled random-pattern flap was made on the back of each 12-week-old male rat. At 3 days before operation, 400 microg of human HGF and PGIS naked plasmid DNA or control plasmid was transfected into the flaps by needle-less injection using a Shima Jet, resulting in successful expression of human HGF and PGIS in the skin flaps. Transfection of both genes into the distal half of skin flaps at 3 days prior to operation significantly increased the survival rate of skin flaps, while transfection all over the flaps did not. In addition, transfection prior to operation was more effective than simultaneous treatment. Moreover, co-transfection of these genes improved the survival area of skin flaps, accompanied by an increase in blood flow of skin flaps, even in a diabetic model.

CONCLUSIONS

Overall, these results indicate that combination treatment with HGF and PGIS genes by Shima Jet could be an effective strategy to improve skin flap survival.

In vivo hepatocyte growth factor gene transfer to bladder smooth muscle after bladder outlet obstruction in the rat: a morphometric analysis

PURPOSE

We determined whether hepatocyte growth factor gene transfer after partial bladder outlet obstruction would prove effective for decreasing transforming growth factor-beta expression and consequently decreasing collagen deposition in partially obstructed rat bladders.

MATERIALS AND METHODS

Ten-week-old male Sprague-Dawley rats were divided into 3 groups of 10 each, including group 1--sham operation, group 2--bladder outlet obstruction for 4 weeks and group 3--hepatocyte growth factor gene transfer after bladder outlet obstruction. Two weeks after the onset of bladder outlet obstruction in group 3 hepatocyte growth factor-liposome complex (50 microg human hepatocyte growth factor cDNA) was injected into the smooth muscle of the rats.

RESULTS

We noted no difference between groups 2 and 3 with regard to the ratio of bladder weight to body weight. The ratio in groups 2 and 3 was significantly higher than in group 1 (p = 0.043). The mean percent of collagen area +/- SE was 36.32% +/- 1.83%, 27.90% +/- 2.66% and 8.97% +/- 3.35% in groups 1 to 3, respectively (p <0.05). Relative hepatocyte growth factor and c-met mRNA and protein expression were higher in group 3 than in groups 1 and 2. However, the expression of transforming growth factor-beta1 mRNA and protein was higher in group 2 than in groups 1 and 3.

CONCLUSIONS

These findings may imply a possible novel therapeutic strategy against bladder dysfunction arising in patients with bladder outlet obstruction.

Enhanced suppression of tumor growth using a combination of NK4 plasmid DNA-PEG engrafted cationized dextran complex and ultrasound irradiation

This investigation aims to determine experimentally whether or not ultrasound (US) irradiation is effective in enhancing the in vivo gene expression of NK4 plasmid DNA and suppressing tumor growth. NK4, composed of the NH2-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. Dextran was cationized by introducing spermine to the hydroxyl groups to allow for polyionic complexation with NK4 plasmid DNA. The cationized dextran was additionally modified with poly(ethylene glycol) (PEG) molecules giving PEG engrafted cationized dextran. Significant suppression of tumor growth was observed when PEG engrafted cationized dextran-NK4 plasmid DNA complexes were intravenously injected into mice carrying a subcutaneous Lewis lung carcinoma tumor mass with subsequent US irradiation when compared with the cationized dextran-NK4 plasmid DNA complex and naked NK4 plasmid DNA with or without US irradiation. We conclude that complexation with PEG-engrafted cationized dextran in combination with US irradiation is a promising way to target the NK4 plasmid DNA to the tumor for gene expression.

Mature Hepatocyte Growth Factor/Scatter Factor on the Surface of Human Granulocytes Is Released by a Mechanism Involving Activated Factor Xa

Serum hepatocyte growth factor (HGF) is rapidly increased in patients suffering from various tissue injuries including arterial occlusive diseases. However, the cellular sources of the HGF increase remain largely unknown. In the present study, we showed that bioactive mature HGF is constitutively present on the surface of granulocytes in human peripheral blood. Exogenously added 125I-labeled iodo-HGF efficiently bound to granulocyte surface, whereas only a scarce amount of HGF mRNA was detected in granulocytes, indicating that the mature HGF on granulocytes is likely to be derived from other cell types. Interestingly, treatment of granulocytes with human serum rapidly induced the release of the cell surface-associated HGF. In vivo, thromboplastin injection into mice increased HGF release from transplanted human granulocytes, which was inhibited by the pretreatment with DX9065a, a specific inhibitor of factor Xa. Furthermore, DX9065a also inhibited the serum-induced HGF release from human granulocytes in vitro, suggesting that the HGF-releasing factor(s) in serum is associated with factor Xa activation. Thus, human granulocytes may function as a transporter of HGF in the peripheral blood, releasing HGF at the injured sites caused by blood coagulation, where HGF may promote tissue repair.

Prostaglandin E2 EP4 receptor-selective agonist facilitates sternal healing after harvesting bilateral internal thoracic arteries in diabetic rats

OBJECTIVE

Sternal wound complications are devastating events occurring in coronary artery bypass surgery, particularly in patients with diabetes. Prostaglandin E2 receptors have 4 subtypes, and the activation of the EP4 receptor induces bone regeneration. The present study investigated the utility of a prostaglandin E2 EP4 receptor-selective agonist in sternal healing after median sternotomy with the removal of the bilateral internal thoracic arteries in diabetic rats.

METHODS

Diabetic Wistar rats with blood glucose levels of greater than 400 mg/dL were established by means of a single intraperitoneal injection of streptozotocin. After median sternotomy and bilateral internal thoracic artery removal in 16 diabetic rats, 8 rats were administered the EP4 agonist (300 microg) on the posterior table of the sternum (EP4 group), whereas 8 did not receive any treatment (control group). Sternal healing and incidence of sternal wound complications were evaluated 4 weeks after the operation.

RESULTS

Sternal wound complications developed in 5 rats in the control group but in only 1 rat in the EP4 group (P < .01). Histologic examination revealed an almost completely healed sternum filled with regenerated bone tissue only in the EP4 group. Both bone mineral content and bone mineral density, as assessed with dual-energy x-ray absorptiometry, were higher in the EP4 group than in the control group (71.7 +/- 12.1 vs 48.9 +/- 11.7 mg for bone mineral content [P < .01] and 66.8 +/- 14.6 vs 47.9 +/- 6.3 mg/mm2 for bone mineral density [P < .05]).

CONCLUSIONS

The prostaglandin E2 EP4 agonist accelerated the sternal healing and decreased the incidence of sternal wound complications in the diabetic ischemic sternum. This method might help in decreasing sternal necrosis in high-risk patients or permit wider application of bilateral internal thoracic arteries in coronary artery bypass surgery, even in patients with diabetes.

Angiogenic and antifibrotic actions of hepatocyte growth factor improve cardiac dysfunction in porcine ischemic cardiomyopathy

Impairment of cardiac function in ischemic cardiomyopathy has been postulated to be due to the decrease in blood flow and increase in collagen synthesis. Therefore, an approach to alter them directly by means of a growth factor may open up a new therapeutic concept in ischemic cardiomyopathy. From this viewpoint, hepatocyte growth factor (HGF) is a unique growth factor with angiogenic and antifibrotic effects. Thus, we examined the feasibility of gene therapy using HGF plasmid DNA for ischemic cardiomyopathy. Human HGF plasmid DNA at a dose of 0.4 or 4 mg was injected into ischemic myocardium of pigs induced by ameroid constrictor with the NOGA system. At 1 month after injection, the ischemic area was significantly reduced in the HGF group, accompanied by a significant increase in capillary density and regional myocardial perfusion in the ischemic area (P<0.01). In contrast, a significant decrease in fibrotic area was observed in the HGF group, associated with a significant decrease in collagen I, III and TGF-beta synthesis as compared to the control group (P<0.01). Consistently, cardiac function was significantly improved in the 4 mg HGF group as compared to the control group (P<0.05). Overall, the present in vivo experiments demonstrated that intramyocardial injection of human HGF plasmid DNA in ischemic cardiomyopathy resulted in a significant improvement in cardiac function through an increase in blood flow and decrease in fibrosis. These favorable outcomes suggest potential utility to treat patients with ischemic heart disease using HGF gene transfer. Currently, a phase I study using human HGF plasmid DNA is ongoing to test the validity of this concept.

Optimization of adenovirus-mediated endothelial nitric oxide synthase delivery in rat hindlimb ischemia

Adenovirus-mediated overexpression of endothelial nitric oxide synthase (eNOS) induces collateral artery development and substantially increases blood flow after induction of experimental acute hindlimb ischemia. However, the optimal technique of gene delivery for this or any other form of gene therapy in limb ischemia is still unknown. The purpose of this study was to determine the effect of the two most commonly used techniques, intra-arterial and intramuscular injection, on blood flow recovery, collateral artery development, and preservation of muscle mass. We compared intra-arterial injection under vascular isolation, intra-arterial injection under transient vascular occlusion, and intramuscular injection of phosphate buffered saline (PBS) or adenovirus encoding either the eNOS (AdeNOS) or LacZ (AdlacZ) gene after induction of acute hindlimb ischemia. Delivery of AdeNOS by both intra-arterial injection techniques increased eNOS activity (22.30 versus 10.56, P<0.01), blood flow (0.90+/-0.02 versus 0.69+/-0.07, P<0.001) and collateral artery development (17.56484 versus 13.74259, P<0.05) more than by intramuscular delivery. Intra-arterial injection under transient vascular occlusion led to better preservation of muscle mass, muscle architecture, and clinical ischemic index, but led to greater transgene expression in distant organs and contralateral limb muscles. Intra-arterial injection of AdeNOS under transient vascular occlusion is the optimal technique to reverse severe hindlimb ischemia in the rat. This is the first systematic comparison of different delivery techniques used in gene therapy of experimental hindlimb ischemia.

Novel autologous cell therapy in ischemic limb disease through growth factor secretion by cultured adipose tissue-derived stromal cells

OBJECTIVE

The delivery of autologous progenitor cells into ischemic tissue of patients is emerging as a novel therapeutic option. Here, we report the potential impact of cultured adipose tissue-derived cells (ADSC) on angiogenic cell therapy.

METHOD AND RESULTS

ADSC were isolated from C57Bl/6 mouse inguinal adipose tissue and showed high expression of ScaI and CD44, but not c-kit, Lin, CD34, CD45, CD11b, and CD31, compatible with that of mesenchymal stem cells from bone marrow. In coculture conditions with ADSC and human aortic endothelial cells (ECs) under treatment with growth factors, ADSC significantly increased EC viability, migration and tube formation mainly through secretion of vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). At 4 weeks after transplantation of ADSC into the ischemic mouse hindlimb, the angiogenic scores were improved in the ADSC-treated group, which were evaluated with blood flow by laser Doppler imaging (LDI) and capillary density by immunostaining with anti-CD31 antibody. However, injected ADSC did not correspond to CD31, von Willebrand factor, and alpha-smooth muscle actin-positive cells in ischemic tissue.

CONCLUSIONS

These adipose tissue-derived cells demonstrated potential as angiogenic cell therapy for ischemic disease, which appears to be mainly achieved by their ability to secrete angiogenic growth factors.

Hepatocyte growth factor contributes to fracture repair by upregulating the expression of BMP receptors

Hepatocyte growth factor (HGF) is activated and the expression of BMP receptors (BMPRs) is induced around the fracture site during the early phase of fracture repair. HGF facilitates the expression of BMPRs in mesenchymal cells. This study suggests that HGF contributes to fracture repair by inducing the expression of BMPRs.

INTRODUCTION

The precise mechanisms that control the upregulation of BMP, BMPRs, and other molecules involved in bone repair are not completely understood. In this study, we hypothesized that HGF, activated through the action of thrombin on the HGF activator, may enhance BMP action through the local induction of BMP or BMPRs.

MATERIALS AND METHODS

Callus samples from tibial fractures in mice were harvested for immunohistochemical analysis of HGF and phosphorylated c-Met, for in situ hybridization of BMPRs, and for real-time RT-PCR analysis for the expression of HGF, c-Met, and BMPRs. To study the changes in gene expression of BMPRs in response to HGF, C3H10T1/2 cells were cultured with or without HGF and harvested for real-time RT-PCR and for Western blot analysis. To evaluate the contribution of HGF to the biological action of BMP2, C3H10T1/2 cells and primary muscle-derived mesenchymal cells were precultured with HGF and cultured with BMP2. In addition, the expression of the luciferase gene linked to the Id1 promoter containing the BMP responsive element and alkaline phosphatase (ALP) activity were assayed.

RESULTS

Positive immunostaining of HGF and phosphorylated c-Met was detected around the fracture site at 1 day after the fracture was made. mRNA expression of BMPRs was increased 1 day after fracture and localized in mesenchymal cells at the fracture site. From an in vitro study, the expression of mRNA for BMPRs was elevated by treatment with HGF, but the expression of BMP4 did not change. Western blot analysis also showed the upregulation of BMPR2 by HGF treatment. The results from the luciferase and ALP assays indicated increased responsiveness to BMPs by treating with HGF.

CONCLUSIONS

This study indicates that HGF is activated and expressed at the fracture site and that HGF induces the upregulation of BMPRs in mesenchymal cells. Furthermore, HGF may facilitate BMP signaling without altering the expression of BMP molecules.

Gene transfection with human hepatocyte growth factor complementary DNA plasmids attenuates cardiac remodeling after acute myocardial infarction in goat hearts implanted with ventricular assist devices

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.

Reorganization of cytoskeletal proteins and prolonged life expectancy caused by hepatocyte growth factor in a hamster model of late-phase dilated cardiomyopathy

OBJECTIVE

It has been postulated recently that changes in cytoskeletal and sarcolemmal proteins initiate a final common pathway for contractile dysfunction in dilated cardiomyopathy. In ischemic cardiomyopathy, hepatocyte growth factor plays an important role in reorganizing the impaired cytoskeletal proteins in several cell types. We have tested the hypothesis that hepatocyte growth factor might improve life expectancy through modification of the molecular process that contributes to impairment in dilated cardiomyopathy.

METHODS

Adult male 27-week-old BIO TO-2 hamsters, which show moderate cardiac remodeling, were divided into treatment groups that received (1) hemagglutinating virus of Japan liposomes containing human hepatocyte growth factor cDNA (H group), (2) culture medium (C group), or (3) sham operation (S group).

RESULTS

After the operation, echocardiography demonstrated that the enlarged left ventricular end-systolic dimension and decreased fractional shortening were significantly attenuated in the H group compared with the C group. There was significantly less myocardial fibrosis in the H group compared with the C group. Immunohistochemical analysis showed alpha-dystroglycan and alpha- and beta-sarcoglycan expression in the basement membrane beneath the cardiomyocytes in the H group, whereas no expression of these proteins was seen in the C group. The 40-week survival was significantly better in the H group than in the C and S groups.

CONCLUSION

An improved survival associated with transient reorganization of the cytoskeletal proteins and reduction in myocardial fibrosis was achieved by hepatocyte growth factor treatment in an adult hamster model of dilated cardiomyopathy. The results suggest a therapeutic potential of hepatocyte growth factor in the treatment of dilated cardiomyopathy.

Tissue-Specific Characteristics of in Vivo Electric Gene: Transfer by Tissue and Intravenous Injection of Plasmid DNA

PURPOSE

To evaluate the tissue-specific characteristics of electric gene transfer after tissue and intravenous injection of naked plasmid DNA (pDNA).

METHODS

pDNA encoding firefly luciferase was injected directly into the liver, kidney, spleen, skin and muscle, or into the tail vein of mice, and electric pulses were then applied to one of these organs. The distribution of transgene expressing cells was evaluated using pDNA encoding beta-galactosidase.

RESULTS

Tissue injection of pDNA produced a significant degree of transgene expression in any tissue with the greatest amount in the liver, followed by kidney and spleen. The expression in these organs decreased quickly with time, and muscle showed the greatest expression at 7 days. Electroporation significantly increased the expression, and the expression level was comparable among the organs. Intravenous injection of pDNA followed by electroporation resulted in a significant expression in the liver, spleen, and kidney but not in the skin or muscle.

CONCLUSIONS

Electric gene transfer to the liver, kidney, and spleen can be an effective approach to obtain significant amounts of transgene expression by either tissue or intravenous injection of pDNA, whereas it is only effective after tissue injection as far as skin- or muscle-targeted gene transfer is concerned.

Gene transfer of bFGF to recipient bed improves survival of ischemic skin flap

BACKGROUND

The recipient bed is a promising target of angiogenic therapy to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) gene to the recipient bed by a plasmid-based method with electroporation, and assessed the effects on flap viability in a rat dorsal skin flap model.

METHODS

A 25 x 90 mm(2) axial skin flap was elevated on the back of male Sprague-Dawley rats. Two days before flap elevation, an expression plasmid vector containing the bFGF gene with the signal sequence was injected into the dorsal muscles beneath the skin flap, and then electroporation was delivered (FGF-E(+) group). As control, rats were injected with a plasmid vector containing LacZ gene (LacZ-E(+) group), instead of bFGF gene. Other groups of animals received plasmid vector containing bFGF (FGF-E(-) group) or LacZ (LacZ-E(-) group) gene without electroporation. Seven days later, the area of necrosis and neovascularisation of the skin flap were evaluated.

RESULTS

The bFGF gene was successfully transferred to the dorsal muscles, and bFGF was expressed in muscle tissue. The area of flap necrosis (%) in the FGF-E(+) group (21.7+/-5.3%) was significantly smaller than that in the LacZ-E(+) (28.3+/-4.1%), FGF-E(-) (29.7+/-3.3%), and LacZ-E(-) (28.1+/-2.5%) groups. Postmortem angiograms and histological analyses showed that vascularisation in the distal part of the skin flap was significantly increased in the FGF-E(+) group compared with the other groups.

CONCLUSION

These findings suggested that gene delivery of bFGF to the recipient bed muscles enhanced vascularity and viability of an ischemic skin flap, and that plasmid-based gene delivery with electroporation was a suitable delivery method.

The effect of gradual or acute arterial occlusion on skeletal muscle blood flow, arteriogenesis, and inflammation in rat hindlimb ischemia

BACKGROUND

Current experimental models of critical limb ischemia are based on acute ischemia rather than on chronic ischemia. Human peripheral vascular disease is largely a result of chromic ischemia. We hypothesized that a model of chronic hindlimb ischemia would develop more collateral arteries, more blood flow, and less necrosis and inflammation than would acute hindlimb ischemia. We therefore developed a rat model of chronic hindlimb ischemia and compared the effects of chronic ischemia with those of acute ischemia on hindlimb skeletal muscle.

METHODS

Acute or chronic ischemia was induced in 36 male Sprague-Dawley rats. Chronic ischemia caused blood flow, as measured by laser Doppler scanning and confirmed by muscle oxygen tension measurements, to gradually decrease over 1 to 2 weeks after operation.

RESULTS

Histologic analysis showed chronic hindlimb ischemia better preserved muscle mass and architecture and stimulated capillary angiogenesis, while lacking the muscle necrosis and inflammatory cell infiltrate seen after acute ischemia. Surprisingly, the chronic ischemia group recovered dermal blood flow more slowly and less completely than did the acute ischemia group, as measured by laser Doppler (0.66 +/- 0.02 vs 0.76 +/- 0.04, P < .05) and tissue oxygen tension (0.61 +/- 0.06 vs 0.81 +/- 0.05, P < .05) at 40 days postoperatively. Consistent with poorer blood flow recovery, chronic ischemia resulted in smaller diameter collateral arteries (average diameter of the five largest collaterals on angiogram was 0.01 +/- 0.0003 mm vs 0.013 +/- 0.0007 mm for acute, P < .005 at 40 days postoperatively). Acute ischemia resulted in decreased tissue concentrations of vascular endothelial growth factor (VEGF) (0.96 +/- 0.23 pg/mg of muscle for acute vs 4.4 +/- 0.75 and 4.8 +/- 0.75 pg/mg of muscle for unoperated and chronic, respectively, P < .05 acute vs unoperated), and in increased tissue concentrations of interleukin (IL)-1beta (7.3 +/- 4.0 pg/mg of muscle for acute vs undetectable and 1.7 +/- 1.6 pg/mg of muscle for unoperated and chronic, respectively, P < 0.05 acute vs unoperated).

CONCLUSIONS

We describe here the first model of chronic hindlimb ischemia in the rat. Restoration of blood flow after induction of hindlimb ischemia is dependent on the rate of arterial occlusion. This difference in blood flow recovery correlates with distinct patterns of muscle necrosis, inflammatory cell infiltration, and cytokine induction in the ischemic muscle. Differences between models of acute and chronic hindlimb ischemia may have important consequences for future studies of mechanisms regulating arteriogenesis and for therapeutic approaches aimed at promoting arteriogenesis in humans suffering from critical limb ischemia.

CLINICAL RELEVANCE

Despite the substantial clinical differences between acute and chronic ischemia, researchers attempting to develop molecular therapies to treat critical limb ischemia have only tested those therapies in experimental models of acute hindlimb ischemia. We present here a novel model of chronic hindlimb ischemia in the rat. We further demonstrate that when hindlimb ischemia is developed chronically, collateral artery development is poorer than when hindlimb ischemia is developed acutely. These findings suggest that further tests of molecular therapies for critical limb ischemia should be performed in chronic hindlimb ischemia models rather than in acute hindlimb ischemia models.

The effect of gene transfer with hepatocyte growth factor for pulmonary vascular hypoplasia in neonatal porcine model

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.

Does gene therapy become pharmacotherapy?

Recent progress in molecular and cellular biology has led to the development of numerous effective cardiovascular drugs. However, there are still a number of diseases for which no known effective therapy exists, such as peripheral arterial disease, ischaemic heart disease, restenosis after angioplasty, and vascular bypass graft occlusion. Currently, gene therapy is emerging as a potential strategy for the treatment of cardiovascular disease despite its limitations. The first human trial in gene therapy for cardiovascular disease was started at 1994 to treat peripheral vascular disease using vascular endothelial growth factor (VEGF). Then, many different potent angiogenic growth factors were tested in clinical trials to treat peripheral arterial disease and ischaemic heart disease. Improvement of clinical symptoms in peripheral arterial disease and ischaemic heart disease has been reported. This review focuses on the future potential of gene therapy for the treatment of cardiovascular disease. In the future, gene therapy might become a real pharmacotherapy to treat cardiovascular disease.

Development of pro-angiogenic engineered transcription factors for the treatment of cardiovascular disease

Gene therapies that use engineered transcription factors to regulate a patient's own endogenous genetic loci offer several advantages over cDNA-based approaches, including the capacity to upregulate all splice variants of a therapeutic gene. Currently, two engineered transcription factors are being developed for use in gene-mediated revascularisation therapies of cardiovascular disease. Both proteins target a powerful, constitutive transcriptional activation module to a defined sequence in the promoter region of vascular endothelial growth factor-A via linkage to an appropriately specific DNA-binding domain, either the basic helix-loop-helix motif of hypoxia-inducible factor-1alpha (HIF-1alpha) or a designed zinc finger protein. Both factors activate the expression of vascular endothelial growth factor-A in cellular studies and induce angiogenesis in animal models of cardiovascular disease. Phase I studies are underway for the HIF-1alpha-based factor and are expected to commence for the zinc finger protein-based factor by the second half of 2004.

Hepatocyte growth factor suppresses vascular endothelial growth factor-induced expression of endothelial ICAM-1 and VCAM-1 by inhibiting the nuclear factor-kappaB pathway

Vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF) are potent angiogenic factors that have been used clinically to induce angiogenesis. However, concerns have been raised about VEGF because of its proinflammatory actions, which include enhancing the adhesion of leukocytes to endothelial cells. We have examined the possible antiinflammatory effects of HGF on the vasculature. HGF, unlike VEGF, did not alter leukocyte adhesion to endothelial cells. Instead it inhibited VEGF-induced leukocyte-endothelial cell interactions and the endothelial expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). In a skin inflammation model, VEGF-treated mice showed a significant increase of leukocytes infiltrated or adherent to the luminal surface of blood vessels, as compared with vehicle- or HGF-treated mice. The VEGF effect was markedly suppressed by coadministration of HGF. RT-PCR and promoter analysis revealed that HGF downregulated VEGF-mediated expression of ICAM-1 and VCAM-1 at the transcriptional level. Furthermore, these inhibitory effects coincided with suppression of IkappaB kinase activity, and this in turn prevented the activation of the inflammatory transcription factor NF-kappaB. Taken together, our results demonstrate that HGF suppresses VEGF-induced inflammation presumably by inhibiting the endothelial NF-kappaB pathway. This suggests that combined treatment with HGF and VEGF could be superior to treatment with either factor alone for enhancing therapeutic angiogenesis while avoiding inflammation.

A New Technique With Calcium Phosphate Precipitate Enhances Efficiency of In Vivo Plasmid DNA Gene Transfer

In vivo gene transfer with plasmid vector has been applied experimentally and clinically; however, the low level of gene transfer efficiency with plasmid vector is a problem. We speculated that the combination of calcium phosphate precipitate (CaP) and plasmid vector could solve this problem because CaP stabilizes plasmid DNA. In the present study, we used a plasmid exression vector encoding enhanced green fluorescent protein and combined the vector with CaP. Then, this combination was mixed with bovine type I atelocollagen. After incubating this mixture in phosphate-buffered saline, the amount of the plasmid DNA in the supernatant was low when the plasmid DNA was combined with CaP. Furthermore, the plasmid DNA, which was combined with CaP, was stable in DNase digestion in vitro. The plasmid vector with or without CaP, together with the atelocollagen, was transplanted subcutaneously or injected in the bone marrow of the femurs of rats. Then, the fluorescence was observed under a confocal laser scanning microscope and the fluorescence intensity in the tissue homogenates was measured. In these animal experiments, the fluorescence was extensive when the plasmid DNA was combined with CaP. These results indicate that our formula, collagen/CaP/DNA, appeared efficient for in vivo gene transfer.

Hepatocyte growth factor induces angiogenesis in injured lungs through mobilizing endothelial progenitor cells

Circulating endothelial progenitor cells (EPCs) play a pivotal role in angiogenesis. Hepatocyte growth factor (HGF) is known to induce proliferation and motility in endothelial cells, and to play a role in mitogenic and morphogenic actions. However, the role of HGF in EPC mobilization has not been clearly described yet. We investigated the effect of HGF on mobilizing EPCs and on angiogenesis in elastase-induced lung injury. HGF significantly increased the triple-positive (Sca-1(+), Flk-1(+), and c-kit(+)) fraction in peripheral mononuclear cells in mice. The bone marrow-derived cells were recruited into the injured lungs, where they differentiated to capillary endothelial cells. HGF induced proliferation of both bone marrow-derived and resident endothelial cells in the alveolar wall. In conclusion, the present study suggests that HGF induces EPC mobilization from the bone marrow and enhances the proliferation of endothelial cells in vivo. These complex effects induced by HGF orchestrate pulmonary regeneration in emphysematous lung parenchyma.

Treatment of acute myocardial infarction by hepatocyte growth factor gene transfer: the first demonstration of myocardial transfer of a "functional" gene using ultrasonic microbubble destruction

OBJECTIVES

We examined whether ultrasonic microbubble destruction (US/MB) enables therapeutic myocardial gene transfer of hepatocyte growth factor (HGF) for acute myocardial infarction (MI).

BACKGROUND

Hepatocyte growth factor gene transfer provides cardioprotective effects in MI, which requires direct intramyocardial injection or special vectors. Although US/MB was used in myocardial gene transfer, its feasibility in transfer of a therapeutic gene with non-viral vector remains unknown.

METHODS

In a rat model of acute MI, naked plasmid (pVaxl) encoding human HGF (1,500 microg) was infused into the left ventricular (LV) chamber during US/MB (HGF-US/MB) or insonation only (HGF-US) or alone (HGF-alone), while control MI rats received empty pVaxl during US/MB (pVaxl-US/MB). For US/MB, transthoracic intermittent insonation with a diagnostic transducer (1.3 MHz) was performed for 2 min at a peak negative pressure of -2,160 kPa during intravenous 20% Optison.

RESULTS

Baseline risk area was comparable among the groups. Immunohistology seven days after treatment revealed significant myocardial expression of HGF protein only in HGF-US/MB. At three weeks, LV weight in HGF-US/MB (0.89 +/- 0.03 g) was significantly lower than those in HGF-alone (1.09 +/- 0.08 g), HGF-US (1.04 +/- 0.07 g), and pVaxl-US/MB (1.04 +/- 0.05 g). Moreover, scar size was significantly smaller (16 +/- 6% vs. 39 +/- 5%, 41 +/- 6%, and 40 +/- 4% of total myocardial circumferential length, respectively), while capillary density (49 +/- 8 vs. 34 +/- 5, 37 +/- 6, and 36 +/- 4 capillaries/high-power field, respectively) and arterial density (37 +/- 7 vs. 15 +/- 9, 18 +/- 4, and 14 +/- 11 arterioles/high-power field, respectively) in the risk area were higher in HGF-US/MB than the other groups.

CONCLUSIONS

Ultrasound-mediated microbubble destruction may enable myocardial HGF gene transfer with systemic administration of naked plasmid, which enhances angiogenesis, limits infarction size, and prevents LV remodeling after MI.

Hepatocyte growth factor protects small airway epithelial cells from apoptosis induced by tumor necrosis factor-alpha or oxidative stress

Involvement of hepatocyte growth factor (HGF) in lung morphogenesis and regeneration has been established by in vitro and in vivo experiments in animals. In the present study, the protective activity of HGF against tumor necrosis factor (TNF)-alpha or hydrogen peroxide (H2O2)-induced damage of pulmonary epithelial cells was examined using the human small airway epithelial cell line (SAEC). Western blot analysis revealed that the receptor for HGF (c-Met) was highly expressed on the surface of SAEC and its downstream signal transduction pathway was functional. The SAEC was induced into apoptosis by the treatment with TNF-alpha or H2O2 in a dose-dependant manner, but was significantly rescued from apoptosis in the presence of HGF. The HGF effect was evident when added not only at the same time but also within several hours after treatment. This protective activity of HGF against the TNF-alpha- or H2O2-induced apoptosis was mediated, at least in part, by up-regulating the nuclear factor kappaB activity and an increase in the ratio of apoptosis-suppressing to apoptosis-inducing proteins. These results suggest that administration of HGF might exhibit a potent function in vivo for protection and improvement of acute and chronic lung injuries induced by inflammation and/or oxidative stress.

Suppression of tumor metastasis by NK4 plasmid DNA released from cationized gelatin

NK4, composed of the NH(2)-terminal hairpin and subsequent four-kringle domains of hepatocyte growth factor (HGF), acts as an HGF-antagonist and angiogenesis inhibitor. This study is an investigation to evaluate the feasibility of controlled release formulation of NK4 plasmid DNA in suppressing the tumor growth, and lung metastasis. Biodegradable cationized gelatin microspheres were prepared for the controlled release of an NK4 plasmid DNA. The cationized gelatin microspheres incorporating NK4 plasmid DNA could continuously release plasmid DNA over 28 days as a result of microspheres degradation following the subcutaneous injection. The injection of cationized gelatin microspheres incorporating NK4 plasmid DNA into the subcutaneous tissue significantly prolonged the survival time period of the mice bearing Lewis lung carcinoma tumor. Increases in the tumor volume and the number of lung metastatic nodules of NK4 plasmid DNA release group were suppressed to a significantly greater extent than that of solution-injected group (77.4 and 64.0%, respectively). The number of blood vessels and the apoptosis cells in the tumor tissue were significantly suppressed (80.4%) and increased (127.3%) against free NK4 plasmid DNA-injected group. Thus, the controlled release of NK4 plasmid DNA augmented angiogenesis suppression and apoptosis of tumor cells, which resulted in suppressed tumor growth. We conclude that this controlled release technology is promising to enhance the tumor suppression achieved by gene expression of NK4.

Safety Evaluation of Clinical Gene Therapy Using Hepatocyte Growth Factor to Treat Peripheral Arterial Disease

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.

Local administration of hepatocyte growth factor gene enhances the regeneration of dermis in acute incisional wounds

Hepatocyte growth factor (HGF) has a number of biological activities, e.g., mitogenic, motogenic, antiapoptotic, antifibrous, and morphogenic. It also has angiogenic and angioprotective activities for endothelial cells. The aim of this study was to characterize the role of HGF in wound healing by administering the HGF gene locally to acute incisional skin wounds created on the backs of rats. To create wounds, the backs of Wistar rats were clipped and three 2-cm-long incisional wounds were made deep to the fascia. The wounds contained pannicrus carnosum and were created at intervals of 2 cm. After suturing, the HGF gene was then administered intradermally. Apoptotic cells in wound lesions were identified by TUNEL method as well as by immunological detection of active caspase-3. In the HGF-treated animals, we found almost complete suppression of apoptosis and well-organized wound healing. Histopathological examination revealed that the proliferation of fibroblasts was suppressed and that scar formation was less apparent in the HGF-treated animals compared to the controls. It is thought that administration of the HGF gene immediately after surgery may enhance the healing process through suppressing apoptosis, which occurred in the controls 1 week after suturing the incisional wound. In addition, locally increased HGF expression due to the introduction of the HGF gene to cells around wounds enhances dermal regeneration, possibly by promoting regeneration of dermal tissue, which results in less scarring due to its antifibrotic effect. Thus, HGF supplementation through gene therapy may be an effective strategy for treating wounds, as it increases the regeneration of the dermis to allow for "scarless wound healing."

In vivo electroporation enhances plasmid-based gene transfer of basic fibroblast growth factor for the treatment of ischemic limb

BACKGROUND

Angiogenic therapy for ischemic tissues using angiogenic growth factors has been reported on an experimental and a clinical level. Electroporation enhances the efficiency of plasmid-based gene transfer in a variety of tissues. The purpose of this study was to evaluate the angiogenic effects of plasmid-based gene transfer using basic fibroblast growth factor (bFGF) in combination with electroporation.

MATERIALS AND METHODS

The transfection efficiency of in vivo electroporation in rabbit skeletal muscles was evaluated using pCAccluc+ encoding luciferase. To evaluate the angiogenic effects of bFGF gene in ischemic limb, we constructed a plasmid, pCAcchbFGFcs23, containing human bFGF cDNA fused with the secretory signal sequence of interleukin (IL)-2. Then, 500 microg of pCAcchbFGFcs23 or pCAZ3 (control plasmid) was injected into the ischemic thigh muscles in a rabbit model of hind limb ischemia with in vivo electroporation (bFGF-E(+) group and LacZ-E(+) group). Other sets of animals were injected with pCAcchbFGFcs23 (bFGF-E(-) group) or pCAZ3 (LacZ-E(-) group) without electroporation. Then 28 days later, calf blood pressure ratio, angiographic score, in vivo blood flow, and capillary density in the ischemic limb were measured.

RESULTS

Gene transfer efficiency increased markedly with the increase in voltage up to 100 V. Regarding angiogenic responses, calf blood pressure ratio, in vivo blood flow, and capillary density only in the bFGF-E(+) group were significantly higher than those in LacZ-E(-) group. Angiographic scores in the bFGF-E(+) and bFGF-E(-) groups were significantly higher than that in the LacZ-E(-) group.

CONCLUSION

These data suggest that in vivo electroporation enhances bFGF gene transfer for the treatment of ischemic limb muscles.

In vivo evidence of angiogenesis induced by transcription factor Ets-1: Ets-1 is located upstream of angiogenesis cascade

BACKGROUND

A transcription factor, ets-1, regulates the transcription of metalloproteinase genes, the activity of which is necessary for matrix degradation and the migration of endothelial cells. However, no study has demonstrated that ets-1 itself has an angiogenic action in vivo. Thus, we examined (1) the effects of overexpression of the ets-1 gene on angiogenesis in a rat hindlimb ischemia model, and (2) how ets-1 induced angiogenesis.

METHODS AND RESULTS

In this study, we used the HVJ-liposome method, which is highly effective for transfection, to transfect the human ets-1 gene. At 4 weeks after transfection, the capillary density and blood flow were significantly increased in a hindlimb transfected with the human ets-1 gene compared with control. These data clearly demonstrated that ets-1 has the ability to stimulate angiogenesis in vivo. To elucidate the molecular mechanisms by which ets-1 induced angiogenesis, we focused especially on the expression of hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF), potent angiogenic growth factors, because the promoter regions of both genes contain ets binding sites. Interestingly, overexpression of ets-1 upregulated both tissue HGF and VEGF concentrations in rat hindlimb. More importantly, administration of neutralizing antibody against HGF and VEGF attenuated the increase in blood flow and BrdU-positive cells induced by ets-1. Upregulation of HGF and VEGF by ets-1 was also confirmed by in vitro experiments using human vascular smooth muscle cells.

CONCLUSIONS

The present study demonstrated that ets-1 regulated angiogenesis through the induction of angiogenic growth factors (VEGF and HGF). Overexpression of ets may provide a new therapeutic strategy to treat peripheral arterial disease.

Increase in peripheral blood flow by intravenous administration of prostaglandin E1 in patients with peripheral arterial disease, accompanied by up-regulation of hepatocyte growth factor

Since endothelial damage is a trigger for the progression of atherosclerosis, we evaluated the clinical utility of prostaglandin E1 (PGE1) in relation to peripheral blood flow and regulation of hepatocyte growth factor (HGF), an angiogenic growth factor, in patients with peripheral arterial disease (PAD). Fourteen male patients with PAD who showed the characteristic symptoms of arteriosclerosis obliterans (Fontaine I: n=2; Fontaine II: n=4; Fontaine III: n=2; Fontaine IV: n=6), confirmed by angiography, were enrolled in this study. Patients were administrated synthetic PGE1 at a dose of 120 microg per day for 14 consecutive days. Measurement of peripheral blood flow and serum HGF concentration was performed before PGE1 treatment and after 14 days of administration. Interestingly, intravenous administration of PGE1 for 2 weeks significantly increased the blood flow as assessed by a laser Doppler imager (p<0.01). In patients with Fontaine III and IV, serum HGF concentration was significantly higher than that in patients with Fontaine I or II and normal subjects. Of importance, administration of PGE1 further increased serum HGF concentration as compared to that before treatment (p<0.01). The increase in circulating HGF might work as a compensatory mechanism to decrease local HGF expression in patients with PAD, since HGF acts as an angiogenic growth factor with anti-apoptotic actions on endothelial cells. Moreover, to confirm the stimulatory effect of PGE1 on HGF in vessels, we employed an in vitro culture system. PGE1 increased HGF production and the growth of human cultured vascular endothelial cells. The stimulatory effect of PGE1 on HGF production might be due to an increase in cAMP, since forskolin and 8-bromo-cAMP induced HGF production. In conclusion, we demonstrated that administration of PGE1 stimulated peripheral blood flow, accompanied by an increase in systemic HGF concentration. Also, our in vitro data suggested that PGE1 augmented not only the systemic HGF level, but also local HGF production, probably through cAMP accumulation, resulting in improvement of endothelial function and blood flow.

Epidermal cells accelerate the restoration of the blood flow in diabetic ischemic limbs

Epidermal progenitor cells (EpPCs) were long thought to be unipotent, giving rise only to other keratinocytes but recent studies question this assumption. Here, we investigated whether mouse EpPCs can adopt other antigenic and functional phenotypes. To test this, we injected freshly isolated and cultured EpPCs and transient amplifying cells into diabetic and non-diabetic mouse ischemic hindlimb and followed the cells' fate and the recovery of the ischemic limb blood flow over time. Both freshly isolated and cultured EpPCs and transient amplifying cells were incorporated into the vasculature of the ischemic limb 2 and 5 weeks post-injection, and some expressed endothelial cell but not keratinocyte antigens. Additionally, in the non-diabetic animals, first transient amplifying cells and then EpPCs accelerated the restoration of the blood flow. By contrast, in diabetic animals, only injected EpPCs or unsorted epidermal cells accelerated the restoration of the blood flow. These data indicate that epidermal cells can adopt non-skin phenotypes and functions, and that this apparent pluripotency is not lost by differentiation of EpPCs into transient amplifying cells. They also suggest that epidermal cell therapy might be of therapeutic value in the treatment of diabetic ischemia. Finally, because epidermal cells are readily accessible and expandable, they appear to be ideally suited for use as a non-viral gene delivery therapy.

Relative rates of blood flow reduction during transcatheter arterial embolization with tris-acryl gelatin microspheres or polyvinyl alcohol: quantitative comparison in a swine model

PURPOSE

To determine whether two commonly used embolic agents have differing rates of blood flow reduction during transcatheter embolization of the renal arteries in an animal model.

MATERIALS AND METHODS

The renal arteries of 10 pigs were embolized with either polyvinyl alcohol (300-500 or 500-700- micro m) or tris-acryl gelatin microspheres (300-500 or 700-900- micro m). Equivalent unit doses of each agent were suspended in 40 mL of fluid and injected in 1-mL aliquots for 20 mL and then in 5-mL aliquots for 20 mL. Blood flow was measured after each aliquot with an intraarterial Doppler flow wire placed through the embolization catheter.

RESULTS

Renal arterial blood flow was most rapidly and reliably decreased by 300-500- and 700-900- micro m microspheres, both of which had achieved >90% reduction from baseline flow after the injection of 6 mL of suspension. An equivalent reduction in flow required 25 mL of 300-500- micro m PVA suspension and 30 mL of 500-700- micro m PVA suspension. The reduction in blood flow with microspheres was significantly greater (P <.05) than that with PVA between 5 and 19 mL of suspension delivered. Differences between larger and smaller particle sizes of the same agent were not statistically significant.

CONCLUSIONS

Tris-acryl gelatin microspheres reduced renal blood flow more quickly and reliably than did PVA. The type of agent used in embolization had a greater impact on the rate of flow reduction than did particle size in the range of sizes tested.

No influence of tumor growth by intramuscular injection of hepatocyte growth factor plasmid DNA: safety evaluation of therapeutic angiogenesis gene therapy in mice

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.

Perspective in Progress of Cardiovascular Gene Therapy

Recent progress in molecular and cellular biology has developed numerous effective cardiovascular drugs. However, there are still a number of diseases for which no known effective therapy exists, such as peripheral arterial disease, ischemic heart disease, restenosis after angioplasty, vascular bypass graft occlusion, and transplant coronary vasculopathy. Currently, gene therapy is emerging as a potential strategy for the treatment of cardiovascular disease to treat such diseases despite of its limitations. The first human trial in cardiovascular disease was started in 1994 to treat peripheral vascular disease using vascular endothelial growth factor (VEGF). Since then, many different potent angiogenic growth factors have been tested in clinical trials to treat peripheral arterial disease. The results from these clinical trials seem to exceed expectations. Improvement of clinical symptoms in peripheral arterial disease and ischemic heart disease has been reported. In addition, another strategy for combating disease processes, the targeting of transcriptional processes, has been tested in a human trial. Genetically modified vein grafts transfected with decoy against E2F, an essential transcription factor in cell cycle progression, revealed apparent long-term potency in human patients. This review focuses on the future potential of gene therapy for the treatment of cardiovascular disease.

Miniaturization: an overview of biotechnologies for monitoring the physiology and pathophysiology of rodent animal models

Recent advances in bioengineering technologies have made it possible to collect high-quality reproducible data quantitatively in a wide range of laboratory animal species, including rodents. Several of these technologies are incorporated into a plan called Miniaturization, which aims to design, develop, and maintain rodent animal models to study the pathophysiology and therapy of human diseases. Laser Doppler flowmetry, digital sonomicrometry, bioelectrical impedance, and microdialysis are some of the most widely used methods under the plan because they cause minimal pain and distress, reduce the number of animals used in biomedical research, and allow chronic, nonterminal assessment of physiological parameters in rodents. An overview of each of these technologies and their major applications in rodents used for biomedical research is provided.

Angiogenesis induced by endothelial nitric oxide synthase gene through vascular endothelial growth factor expression in a rat hindlimb ischemia model

BACKGROUND

Because the mechanism of the angiogenic property of nitric oxide (NO) was not fully understood in vivo, we focused on the role of vascular endothelial growth factor (VEGF) in angiogenesis induced by endothelial NO synthase (eNOS) gene transfer.

METHODS AND RESULTS

After intramuscular injection of eNOS DNA into a rat ischemic hindlimb, transfection of eNOS vector resulted in a significant increase in eNOS protein 1 week after transfection. In addition, tissue concentrations of nitrite and nitrate were significantly increased in rats transfected with the eNOS gene up to 2 weeks after transfection. The increase in tissue nitrite and nitrate concentrations was completely inhibited by NG-nitro-L-arginine methyl ester (L-NAME). In contrast, serum concentrations of nitrite and nitrate and blood pressure were not changed by eNOS gene transfer. Importantly, overexpression of the eNOS gene resulted in a significant increase in peripheral blood flow, whereas L-NAME inhibited the increase in blood flow. Interestingly, basal blood flow was significantly lower in rats treated with L-NAME than in control rats. A significant increase in capillary number was consistently detected in rats transfected with the eNOS gene at 4 weeks after transfection, accompanied by a significant increase in VEGF. Moreover, administration of neutralizing anti-VEGF antibody abolished the increase in blood flow and capillary density induced by eNOS plasmid injection.

CONCLUSIONS

Overall, intramuscular injection of bovine eNOS plasmid induced therapeutic angiogenesis in a rat ischemic hindlimb model, a potential therapy for peripheral arterial disease. The stimulation of angiogenesis by NO might be due to upregulation of local VEGF expression.

The N-terminal domain of hepatocyte growth factor inhibits the angiogenic behavior of endothelial cells independently from binding to the c-met receptor

Hepatocyte growth factor (HGF) is a pleiotropic factor that plays an important role in complex biological processes such as embryogenesis, tissue regeneration, cancerogenesis, and angiogenesis. HGF promotes cell proliferation, survival, motility, and morphogenesis through binding to its receptor, a transmembrane tyrosine kinase encoded by the MET proto-oncogene (c-met). Structurally speaking, HGF is a polypeptide related to the enzymes of the blood coagulation cascade. Thus, it comprises kringle domains that in some other proteins have been shown to be responsible for the anti-angiogenic activity. To check whether the isolated kringles of HGF were able to inhibit angiogenesis, we produced them as recombinant proteins and compared their biological activity with that of the recombinant HGF N-terminal domain (N). We showed that (i) none of the isolated HGF kringle exhibits an anti-angiogenic activity; (ii) N is a new anti-angiogenic polypeptide; (iii) the inhibitory action of N is not specific toward HGF, because it antagonized the angiogenic activity of other growth factors, such as fibroblast growth factor-2 and vascular endothelial growth factor; and (iv) in contrast with full-length HGF, N does not bind to the c-met receptor in vitro, but fully retains its heparin-binding capacity. Our results suggest that N inhibits angiogenesis not by disrupting the HGF/c-met interaction but rather by interfering with the endothelial glycosaminoglycans, which are the secondary binding sites of HGF.

Intramuscular gene transfer of FGF-2 attenuates endothelial dysfunction and inhibits intimal hyperplasia of vein grafts in poor-runoff limbs of rabbit

We previously demonstrated that sustained disturbance of endothelium-dependent vasorelaxation and poor distal runoff in ischemic limbs were critical factors affecting the neointimal development of autologous vein grafts (VGs). Also, we recently showed the superior therapeutic potential of basic fibroblast growth factor (bFGF/FGF-2) boosted by the recombinant Sendai virus (SeV) for severe limb ischemia compared with that of vascular endothelial growth factor. Here, the effect of FGF-2 on neointimal hyperplasia of VGs was examined in a rabbit model of poor-runoff limbs. Two weeks after initial surgery for the induction of poor-runoff, SeV-expressing human FGF-2 (SeV-hFGF2) or that encoding firefly luciferase (109 plaque-forming units/head) was injected into the thigh and calf muscle. At that time, the femoral vein was implanted in the femoral artery in an end-to-end manner in some groups. FGF-2 gene-transferred limbs demonstrated significantly increased blood flow assessed not only by laser Doppler flow image but also by ultrasonic transit-time flowmeter (USTF). USTF also showed a significant increase in the blood flow ratio of the deep femoral artery to external iliac artery, indicating that collateral flow was significantly restored in the thigh muscles (P < 0.01). Reduction of neointimal hyperplasia was also observed in the VGs treated by SeV-hFGF2; these grafts demonstrated significant restoration of endothelium-dependent vasorelaxation. These findings thus extend the indications of therapeutic angiogenesis using SeV-hFGF2 to include not only limb salvage but also prevention of late graft failure.

Enhanced angiogenesis and improvement of neuropathy by cotransfection of human hepatocyte growth factor and prostacyclin synthase gene

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.

Angiogenic property of hepatocyte growth factor is dependent on upregulation of essential transcription factor for angiogenesis, ets-1

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.

Delivery of a growth factor fusion protein having collagen-binding activity to wound tissues

Recently, we established a collagen-binding growth factor consisting of epidermal growth factor and the fibronectin collagen-binding domain (FNCBD-EGF). FNCBD-EGF is a biologically active fusion protein that could stably bind to collagen materials, and exert its growth factor activity even after collagen binding. In this study, we investigated the concept that FNCBD moiety with high collagen affinity may enhance the effective local concentration of EGF at the site of administration in the following tissues: skin wounds, catheter-injured arteries, and hind limb muscles. In an animal model of impaired wound healing, application of FNCBD-EGF in combination with collagen gel induced granulation tissue formation in the wounds due to its sustained retention. In the injured artery, infused FNCBD-EGF remained bound to collagen exposed on the injured tissues even after blood circulation was restored. Injection of the fusion protein into the hind limbs revealed that our delivery system was effective for direct administration to muscular tissue.

Gene therapy progress and prospects: therapeutic angiogenesis for limb and myocardial ischemia

After extensive investigation in preclinical studies and recent clinical trials, gene therapy has been established as a potential method to induce therapeutic angiogenesis in ischemic myocardial and limb disease. Advancements in viral and nonviral vector technology including cell-based gene transfer will continue to improve transgene transmission and expression efficiency. An alternative strategy to the use of transgenes encoding angiogenic growth factors is therapy based on transcription factors such as hypoxia-inducible factor-1alpha (HIF-1alpha) that regulate the expression of multiple angiogenic genes. Further understanding of the underlying biology of neovascularization is needed to determine the ability of growth factors to induce functionally significant angiogenesis in patients with atherosclerotic disease and associated comorbid conditions including endothelial dysfunction, which may inhibit blood vessel growth. The safety and tolerability of therapeutic angiogenesis by gene transfer has been demonstrated in phase I clinical trials. However, limited evidence of efficacy resulted from early phase II studies of angiogenic gene therapy for ischemic myocardial and limb disease. The utility of therapeutic angiogenesis by gene transfer as a treatment option for ischemic cardiovascular disease will be determined by adequately powered, randomized, placebo-controlled phase II and III clinical trials.

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.

Recent progress in gene therapy for cardiovascular disease

Gene therapy is emerging as a potential strategy for the treatment of cardiovascular diseases, such as peripheral arterial disease, ischemic heart disease, restenosis after angioplasty, vascular bypass graft occlusion and transplant coronary vasculopathy, for which no known effective therapy exists. The first human trial in cardiovascular disease started in 1994 treating peripheral vascular disease with vascular endothelial growth factor (VEGF) and since then, many different potent angiogenic growth factors have been tested in clinical trials for the treatment of peripheral arterial disease. In addition, therapeutic angiogenesis using the VEGF gene has been used to treat ischemic heart disease since 1997. The results from these clinical trials have exceeded expectations; improvement in the clinical symptoms of peripheral arterial disease and ischemic heart disease has been reported. Another strategy for combating the disease processes, targeting the transcriptional process, has been tested in a human trial. IN particular, transfection of cis-element double-stranded (ds) oligodeoxynucleotides (ODN) (= decoy) is a powerful tool in a new class of anti-gene strategies. Transfection of ds-ODN corresponding to the cis sequence will attenuate the authentic cis-trans interaction, leading to removal of trans-factors from the endogenous cis-elements and subsequent modulation of gene expression. Genetically modified vein grafts transfected with a decoy against E2F, an essential transcription factor in cell cycle progression, appear to have long-term potency in human patients. There is great potential in gene therapy for cardiovascular disease.

[Gene therapy in cardiovascular medicine as new pharmacological therapy]

Gene therapy is emerging as a potential strategy for the treatment of cardiovascular disease, for which no known effective therapy exists. The first human trial in cardiovascular disease was started in 1994 to treat peripheral vascular disease using VEGF. Since then, at least 5 different potent angiogenic growth factors has been tested in clinical trials to treat peripheral arterial disease. In addition, therapeutic angiogenesis using VEGF gene was applied to treat ischemic heart disease. Results from these clinical trials seems to be more than expected. Improvement of clinical symptoms in peripheral arterial disease or ischemic heart disease has been reported. In this review, we have focused on the future potential of gene therapy for the treatment of cardiovascular disease as a new pharmacological therapy.

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.

Myocardial regeneration therapy for heart failure: hepatocyte growth factor enhances the effect of cellular cardiomyoplasty

BACKGROUND

We hypothesized that transfection of the gene for human hepatocyte growth factor (hHGF) combined with cellular cardiomyoplasty might regenerate the impaired myocardium.

METHODS AND RESULTS

We used a ligation model of proximal left anterior descending coronary artery (LAD) of Lewis rats. Two weeks after LAD ligation, 3 different treatments were conducted: (1) neonatal rat cardiomyocytes group (10(6) cells, T group, n=11), (2) HVJ-liposomes bearing the hHGF gene group (H group, n=10), and (3) combined (T-H group, n=10). The injection site was the scar area of myocardial infarction. For control, culture medium was injected (C group, n=13). Echocardiography demonstrated that cardiac performance was significantly ameliorated in the T-H group 4 and 8 weeks after injection. Contrast echocardiography also showed a marked increase in myocardial perfusion in the T-H group but not in the other groups. In the T-H group, neovascularization and a marked reduction of fibrosis were observed histologically. In an immunohistochemical study, strong staining for beta(1)-integrin, alpha-, and beta-dystroglycan were found principally in the basement membrane of myocytes in the T-H group 8 weeks after transplantation, although there was weak immunoreactivity in the T group.

CONCLUSIONS

hHGF gene transfection enhanced the cellular cardiomyoplasty possibly by stimulating angiogenesis, restoring the impaired ECM, and promoting the integration of the dissociated grafted myocytes. The combined effects might have lead to the improved cardiac performance. Thus, combined therapy may be a promising strategy for the treatment of heart failure caused by myocardial infarction.

Alterations in endothelial cell proliferation and apoptosis contribute to vascular remodeling following hind-limb ischemia in rabbits

Hind-limb ischemia is a potent stimulus for angiogenesis. However, capillary density does not change in tibialis anterior muscle (TA) following hind-limb ischemia, despite increases in angiogenic growth factors. The objective of this study was to determine whether changes in proliferation and apoptosis occurred in the same muscle. In total, 19 New Zealand white rabbits underwent femoral artery ligation and excision and the ischemic and contra-lateral (control) TA muscles were harvested after 1 (n = 7), 5 (n = 7) and 21 (n= 5). Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) was used to detect apoptosis and double staining was used to identify the apoptotic cell types. Proliferation was assessed by immunohistochemistry for proliferating cell nuclear antigen (PCNA) and [3H]thymidine incorporation, in vitro. TUNEL positive nuclei were greater in ischemic than control muscle at 1 day (1.83 +/- 0.70% vs 1.03 +/- 0.20%), 5 days (2.13 +/- 0.50% vs 1.21 +/- 0.42%) and at 21 days the difference was statistically significant (3.42 +/- 0.80% vs 0.96 +/- 0.40%, p < 0.01). The majority of TUNEL positive nuclei were endothelial (Tie2 positive) cells. The number of PCNA positive cells in ischemic versus control muscle was similar at 1 day (0.71 +/- 0.20% vs 0.53 +/- 0.20%) and 5 days (1.28 +/- 0.30% vs 0.77 +/- 0.30%), but was significantly (p < 0.05) reduced in ischemic muscle at 21 days (0.18 +/- 0.20% vs 1.35 +/- 0.30%) with no difference in [3H]thymidine incorporation. Directionally opposite changes in endothelial cell proliferation and apoptosis occur in TA muscle following hind-limb ischemia. Modulating apoptosis in ischemic skeletal muscle may present a novel therapeutic target in peripheral arterial disease.