Keita Yamasaki

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.

Impact of Cilostazol on Restenosis After Percutaneous Coronary Balloon Angioplasty

BACKGROUND Restenosis after percutaneous transluminal coronary (balloon) angioplasty (PTCA) remains a major drawback of the procedure. We previously reported that cilostazol, a platelet aggregation inhibitor, inhibited intimal proliferation after directional coronary atherectomy and reduced the restenosis rate in humans. The present study aimed to determine the effect of cilostazol on restenosis after PTCA. METHODS AND RESULTS Two hundred eleven patients with 273 lesions who underwent successful PTCA were randomly assigned to the cilostazol (200 mg/d) group or the aspirin (250 mg/d) control group. Administration of cilostazol was initiated immediately after PTCA and continued for 3 months of follow-up. Quantitative coronary angiography was performed before PTCA and after PTCA and at follow-up. Reference diameter, minimal lumen diameter, and percent diameter stenosis (DS) were measured by quantitative coronary angiography. Angiographic restenosis was defined as DS at follow-up >50%. Eligible follow-up angiography was performed in 94 patients with 123 lesions in the cilostazol group and in 99 patients with 129 lesions in the control group. The baseline characteristics and results of PTCA showed no significant difference between the 2 groups. However, minimal lumen diameter at follow-up was significantly larger (1.65+/-0.55 vs 1.37+/-0.58 mm; P<0.0001) and DS was significantly lower (34.1+/-17.8% vs 45.6+/-19. 3%; P<0.0001) in the cilostazol group. Restenosis and target lesion revascularization rates were also significantly lower in the cilostazol group (17.9% vs 39.5%; P<0.001 and 11.4% vs 28.7%; P<0. 001). CONCLUSIONS Cilostazol significantly reduces restenosis and target lesion revascularization rates after successful PTCA.

Angiogenesis and Antifibrotic Action by Hepatocyte Growth Factor in Cardiomyopathy

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.

An efficient gene transfer method mediated by ultrasound and microbubbles into the kidney.

Safety issues are of paramount importance in clinical human gene therapy. From this point of view, it would be better to develop a novel non‐viral efficient gene transfer method. Recently, it was reported that ultrasound exposure could induce cell membrane permeabilization and enhance gene expression.

Therapeutic angiogenesis using hepatocyte growth factor (HGF).

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, it 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 and cardiac myocytes. In addition, among growth factors, the mitogenic action of HGF on human endothelial cells was most potent. Recent studies have demonstrated the potential application of HGF to treat cardiovascular diseases such as peripheral vascular disease, myocardial infarction and cerebrovascular disease. In this review, we will discuss a potential therapeutic strategy using HGF in cardiovascular disease.

Phase I/IIa clinical trial of therapeutic angiogenesis using hepatocyte growth factor gene transfer to treat critical limb ischemia.

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. Conclusion—Intramuscular injection of naked HGF plasmid is safe and feasible and can achieve successful improvement of ischemic limbs as sole therapy.

Inhibition of NFκB activation using cis-element ‘decoy’ of NFκB binding site reduces neointimal formation in porcine balloon-injured coronary artery model

Application of DNA technology to regulate the transcription of disease-related genes has important therapeutic potential. The transcription factor NFκB plays a pivotal role in the transactivation of inflammatory and adhesion molecule genes, leading to vascular lesion formation. Double-stranded DNA with high affinity for NFκB may be introduced as ‘decoy’ cis elements to bind NFκB and block the activation of genes mediating inflammation, resulting in effective drugs for treating intimal hyperplasia. In this study, we tested the feasibility of NFκB decoy therapy to treat neointimal formation in a porcine coronary artery balloon injury model as a pre-clinical study.An angioplasty catheter was introduced into the left anterior descending coronary artery of the pig to cause vascular injury. First, we tested the feasibility of transfection of FITC-labeled NFκB decoy ODN using a hydrogel balloon catheter. Fluorescence due to NFκB decoy ODN could be detected throughout the medial layer. Therefore, we transfected NFκB decoy ODN into the balloon-injured LAD using a hydrogel catheter. Histological evaluation demonstrated that the neointimal area in the balloon-injured artery was significantly reduced by NFκB decoy ODN as compared to scrambled decoy ODN at 1 week after single transfection, accompanied by a significant reduction in PCNA-positive stained cells (P<0.01). Interestingly, the reduction of ICAM-positive staining was observed, accompanied by the inhibition of migration of macrophages. Of importance, intravascular ultrasound (IVUS) confirmed that neointimal area in the balloon-injured artery was significantly reduced by NFκB decoy ODN at 4 weeks after transfection (P<0.01). Interestingly, the inhibition of neointimal area was only limited to the lesion transfected with NFκB decoy ODN, while other lesions without NFκB decoy ODN demonstrated a marked increase in neointimal formation.Here, we report the successful in vivo transfer of NFκB decoy ODN using a hydrogel catheter to inhibit vascular lesion formation in balloon-injured porcine coronary artery.

Impairment of Collateral Formation in Lipoprotein(a) Transgenic Mice Therapeutic Angiogenesis Induced by Human Hepatocyte Growth Factor Gene

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.

Long-Term Follow-Up Evaluation of Results From Clinical Trial Using Hepatocyte Growth Factor Gene to Treat Severe Peripheral Arterial Disease

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. Conclusion—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.

Maximum carotid intima-media thickness improves the prediction ability of coronary artery stenosis in type 2 diabetic patients without history of coronary artery disease

OBJECTIVE Carotid intima-media thickness (CIMT), a marker of early atherosclerosis and vascular remodelling, is one of the independent predictors of coronary artery disease (CAD). However, it is unknown whether ultrasonic assessment of carotid atherosclerosis, including CIMT, improves the prediction ability for CAD over and above conventional coronary risk factors in the diabetic patients. METHODS Ultrasonic scanning of the common carotid artery (CCA), the carotid bulb (Bul), and the internal carotid artery (ICA) was performed. The site with the greatest IMT, including plaque lesions, was sought along the arterial walls and max-IMT (the greatest IMT in the observation-possible areas of the CCA, Bul and ICA) was measured. The association of max-IMT with coronary artery stenosis assessed by coronary computed tomography angiography and the incremental effect of adding max-IMT to the conventional risk factors for predicting coronary artery stenosis were evaluated in 241 asymptomatic type 2 diabetic patients. RESULTS Multiple logistic regression analyses showed that max-IMT was significantly associated with coronary artery stenosis even after adjustment for conventional risk factors. ROC curve analysis revealed that the AUC significantly increased after addition of max-IMT to conventional coronary risk factors [from 0.64 (95% CI; 0.57-0.71) to 0.74 (95% CI; 0.67-0.80), p = 0.020]. The addition of max-IMT to conventional coronary risk factors increased the AUC in obese patients (from 0.58 to 0.76, p = 0.012) but not in non-obese patients (from 0.68 to 0.72, NS). CONCLUSIONS In type 2 diabetic patients without apparent cardiovascular disease, the addition of max-IMT to conventional risk factors substantially improves the risk stratification for CAD.