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

[Genic and cellular therapy for peripheral arterial diseases]

Late evolution of peripheral arterial disease consists in the apparition of critical limb ischemia. Surgical treatments allow to treat these patients during long time; however, in most patients, especially the diabetic ones, there a very few options and the clinical evolution is rapidly dramatic. For these reasons, the critical limb ischemia is one of the first diseases treated by genic or cellular therapies aiming to improve blood flow perfusion in the lower-limbs. In this short review, we describe the main clinical trials of genic therapy; most of them have been abandoned because serious side effects, modest effects and major risks. Different types of stem cells are now used for cell therapy: endothelial progenitor cells, early or late, activated or not, mesenchymal stem cells, embryonic stem cells and human induced pluripotent stem cells. Problems of characterization are described and the results of the most important clinical trials are reported.

Pro-angiogenic potential of human chorion-derived stem cells: in vitro and in vivo evaluation

Human chorion-derived stem cells (hCDSC) were previously shown to demonstrate multipotent properties with promising angiogenic characteristics in monolayer-cell culture system. In our study, we investigated the angiogenic capability of hCDSC in 3-dimensional (3D) in vitro and in vivo angiogenic models for the purpose of future application in the treatment of ischaemic diseases. Human CDSC were evaluated for angiogenic and endogenic genes expressions by quantitative PCR. Growth factors secretions were quantified using ELISA. In vitro and in vivo vascular formations were evaluated by histological analysis and confocal microscopic imaging. PECAM-1⁺ and vWF⁺ vascular-like structures were observed in both in vitro and in vivo angiogenesis models. High secretions of VEGF and bFGF by hCDSC with increased expressions of angiogenic and endogenic genes suggested the possible angiogenic promoting mechanisms by hCDSC. The cooperation of hCDSC with HUVECS to generate vessel-like structures in our systems is an indication that there will be positive interactions of hCDSC with existing endothelial cells when injected into ischaemic tissues. Hence, hCDSC is suggested as the novel approach in the future treatment of ischaemic diseases.

Hepatocyte growth factor and lung fibrosis

Idiopathic pulmonary fibrosis is currently believed to be driven by alveolar epithelial cells, with abnormally activated alveolar epithelial cells accumulating in an attempt to repair injured alveolar epithelium (1). Thus, targeting the alveolar epithelium to prevent or inhibit the development of pulmonary fibrosis might be an interesting therapeutic option in this disease. Hepatocyte growth factor (HGF) is a growth factor for epithelial and endothelial cells, which is secreted by different cell types, especially fibroblasts and neutrophils. HGF has mitogenic, motogenic, and morphogenic properties and exerts an antiapoptotic action on epithelial and endothelial cells. HGF has also proangiogenic effect. In vitro, HGF inhibits epithelial-to-mesenchymal cell transition and promotes myofibroblast apoptosis. In vivo, HGF has antifibrotic properties demonstrated in experimental models of lung, kidney, heart, skin, and liver fibrosis. Hence, the modulation of HGF may be an attractive target for the treatment of lung fibrosis.

Intramyocardial transfer of hepatocyte growth factor as an adjunct to CABG: phase I clinical study

The purpose of this phase I clinical trial was to evaluate the safety, tolerability and potential efficacy of VM202, naked DNA expressing two isoforms of hepatocyte growth factor, as an adjunct therapy to coronary artery bypass grafting (CABG) in patients with ischemic heart disease (IHD). Nine patients were assigned to receive increasing doses (0.5 to 2.0 mg) of VM202 injected into the right coronary artery (RCA) territory following completion of CABG for the left coronary artery territory. Patients were evaluated for safety and tolerability, and changes in myocardial functions were monitored via echocardiography, cardiac magnetic resonance imaging and myocardial single photon emission computed tomography throughout 6-month follow-up period. No serious complication related to VM202 was observed throughout the 6-month follow-up period. Global myocardial functions (wall motion score index, P=0.0084; stress perfusion, P=0.0002) improved during the follow-up period. In the RCA region, there was an increase in the stress perfusion (baseline vs 3-month, P=0.024; baseline vs 6-month, P=0.024) and also in the wall thickness of the diastolic and systolic phases. Intramyocardial injection of VM202 can be safely used in IHD patients with the tolerable dose of 2.0 mg. In addition, VM202 might appear to have improved regional myocardial perfusion and wall thickness in the injected region.

Hepatocyte growth factor stimulated angiogenesis without inflammation: differential actions between hepatocyte growth factor, vascular endothelial growth factor and basic fibroblast growth factor

Based on the potent angiogenic effects of hepatocyte growth factor (HGF), therapeutic angiogenesis using human HGF plasmid DNA increased tissue perfusion and reduced symptoms in patients with critical limb ischemia (CLI) in randomized placebo-controlled clinical trials. To explore further the potent angiogenic activity of HGF, the present study compared the effects of HGF, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) on angiogenesis and vascular inflammation. All of HGF, VEGF and bFGF significantly induced the formation of capillary blood vessel and granulation tissue in the rat paper disc model as an in vivo animal model of angiogenesis. However, although HGF, bFGF and VEGF significantly increased the growth of vascular endothelial cells, bFGF alone, but not HGF or VEGF, significantly increased the growth of vascular smooth muscle cells (VSMCs) in the in vitro proliferation assay. In addition, bFGF, but not HGF or VEGF, significantly activated an essential transcription factor for inflammation, NFκB, and gene expression of its downstream inflammation-related cytokines (IL-8 and MCP-1) in VSMCs, accompanied by an increase in the vascular permeability in the rat paper disc model. Thus, the present results indicated that HGF induced angiogenesis without vascular inflammation, different from bFGF and VEGF. These different properties between HGF, VEGF and bFGF might affect the efficiency of therapeutic angiogenesis.

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.

CONCLUSIONS

Overall, the present study demonstrated long-term efficacy of HGF gene therapy up to 2 years. These findings may be cautiously interpreted to indicate that intramuscular injection of naked HGF plasmid is safe, feasible, and can achieve successful improvement of ischemic limbs as sole therapy.

Autologous cell therapy for cisplatin-induced acute kidney injury by using non-expanded adipose tissue-derived cells

BACKGROUND AIMS

Recent studies have demonstrated that cultured mesenchymal stromal cells derived from adipose tissue are useful for regenerative cell therapy. The stromal vascular fraction (SVF) can be obtained readily without culturing and may be clinically applicable. We investigated the therapeutic effects of SVF and used it in the treatment of acute kidney injury (AKI).

METHODS

Liposuction aspirates were obtained from healthy donors who had provided written informed consent. We harvested the SVF and determined the growth factor secretion and anti-apoptotic ability with conditioned medium. To investigate the effect of SVF on AKI, cisplatin was injected into rats and SVF was administrated into the subcupsula of the kidney.

RESULTS

Both human and rat SVF cells secreted vascular endothelial growth factor-A (VEGF) and hepatocyte growth factor (HGF). Human SVF-conditioned media had an anti-apoptotic effect, which was inhibited by anti-HGF antibody (Ab) but not by anti-VEGF Ab. In vivo, SVF significantly ameliorated renal function, attenuated tubular damage and increased the cortical blood flow speed. In the SVF-treated group, VEGF levels in the cortex and HGF levels in both the cortex and medulla, especially tubules in the medulla, were significantly higher. Immunostaining revealed that SVF cells expressing VEGF and HGF and remained in the subcapsule on day 14.

CONCLUSIONS

The present study demonstrates that a subcapsular injection of non-expanded SVF cells ameliorates rat AKI, and that the mechanism probably involves secretion of renoprotective molecules. Administration of human SVF may be clinically applicable and useful as a novel autologous cell therapy against kidney diseases.

Pretreatment with epidermal growth factor enhances naked plasmid DNA transfer onto gastric serosal surface in mice

We have developed a simple administration method, which is gastric serosal surface instillation of naked plasmid DNA (pDNA) in experimental animals. The purpose of this study was to improve gastric gene transfer efficiency by pre-treatment with a macropinocytosis enhancer, such as fetuin or epidermal growth factor (EGF), in mice. A series of concentrations of fetuin were instilled onto gastric serosal surface prior to instillation of naked pDNA in mice; however, fetuin did not improve transgene expression in the stomach 6 h after administration of pDNA. EGF also did not affect transgene expression in the stomach when pDNA was instilled immediately after EGF instillation. On the other hand, when pDNA was instilled onto gastric serosal surface 24 h after EGF treatment, transgene expression in the stomach was significantly improved by 2.6-fold. In addition, transgene-positive cells were increased 5.3-fold by EGF pre-treatment. High transgene expression in the stomach lasted for 48 h in the EGF pre-treatment group in comparison with that in the no pre-treatment group. These findings are valuable to develop an effective method of in vivo gene transfer to the stomach.

Targets and delivery methods for therapeutic angiogenesis in peripheral artery disease

Therapeutic angiogenesis utilizing genetic and cellular modalities in the treatment of arterial obstructive diseases continues to evolve. This is, in part, because the mechanism of vasculogenesis, angiogenesis, and arteriogenesis (the three processes by which the body responds to obstruction of large conduit arteries) is a complex process that is still under investigation. To date, the majority of human trials utilizing molecular, genetic, and cellular modalities for therapeutic angiogenesis in the treatment of peripheral artery disease (PAD) have not shown efficacy. Consequently, the current available knowledge is yet to be translated into novel therapeutic approaches for the treatment of PAD. The aim of this review is to discuss relevant scientific and clinical advances in therapeutic angiogenesis and their potential application in the treatment of ischemic diseases of the peripheral arteries. Additionally, this review article discusses past and recent developments, such as some unconventional approaches that have the potential to be applied as therapeutic targets. The article also includes advances in the delivery of genetic, cellular, and bioactive endothelial growth factors.

A phase I clinical study of naked DNA expressing two isoforms of hepatocyte growth factor to treat patients with critical limb ischemia

BACKGROUND

The purpose of the present phase I clinical trial was to evaluate the safety, tolerability, and preliminary efficacy of naked DNA therapy expressing two isoforms of hepatocyte growth factor (pCK-HGF-X7) in critical limb ischemia (CLI) patients.

MATERIALS AND METHODS

Twenty-one patients with CLI were consecutively assigned to receive increasing doses (cohort I: 4  mg; cohort II: 8  mg; cohort III: 12  mg; and cohort IV: 16  mg) of pCK-HGF-X7, which was administered into the ischemic calf and/or thigh muscle at days 1 and 15. A safety and tolerability evaluation and measurement of pain severity score using a visual analog scale (VAS), ulcer status, transcutaneous oxygen (TcPO(2) ) and ankle-brachial index (ABI) were performed throughout a 3-month follow-up period.

RESULTS

No serious adverse events were observed in any of the 21 patients for the 3-month follow-up period. A significant reduction in pain was observed in the treated patients, with the mean VAS decreasing from 5.95-1.64 (p  <  0.001). The mean ABI value increased from 0.49-0.63 (p  =  0.026) at 3-month follow-up. The mean TcPO(2) value on the dorsum of the foot, the anterior calf and posterior calf significantly increased from 28.25-39.28  mmHg (p  =  0.012), from 22.00-30.63  mmHg (p  =  0.046) and 32.05-47.19  mmHg (p  =  0.001) at 3-month follow-up, respectively. Wound healing improvement was observed in the six of nine patients that had an ulcer at baseline.

CONCLUSIONS

These results support the performance of a phase II randomized controlled trial with pCK-HGF-X7.

Nonviral delivery of genetic medicine for therapeutic angiogenesis

Genetic medicines that induce angiogenesis represent a promising strategy for the treatment of ischemic diseases. Many types of nonviral delivery systems have been tested as therapeutic angiogenesis agents. However, their delivery efficiency, and consequently therapeutic efficacy, remains to be further improved, as few of these technologies are being used in clinical applications. This article reviews the diverse nonviral gene delivery approaches that have been applied to the field of therapeutic angiogenesis, including plasmids, cationic polymers/lipids, scaffolds, and stem cells. This article also reviews clinical trials employing nonviral gene therapy and discusses the limitations of current technologies. Finally, this article proposes a future strategy to efficiently develop delivery vehicles that might be feasible for clinically relevant nonviral gene therapy, such as high-throughput screening of combinatorial libraries of biomaterials.

Gene therapy in the treatment of peripheral arterial disease

BACKGROUND

Peripheral arterial disease remains a significant global health burden despite revolutionary improvements in endovascular techniques over the past decade. The durability of intervention for critical limb ischaemia is poor, and the condition is associated with high morbidity and mortality rates. To address this deficiency, alternative therapeutic options are being explored. Advances in the fields of gene therapy and therapeutic angiogenesis have led to these being advocated as potential future treatments.

METHODS

Relevant medical literature from PubMed, Embase, the Cochrane Library and Google Scholar from the inception of these databases to June 2011 was reviewed.

RESULTS

Encouraging outcomes in preclinical trials using a variety of proangiogenic growth factors have led to numerous efficacy and safety studies. However, no clinical study has shown significant benefit for gene therapy over placebo.

CONCLUSION

Identifying the optimal site for gene delivery, choice of vector and duration of treatment is needed if gene therapy is to become a credible therapeutic option for peripheral arterial disease.

Optimal culture conditions for constructing durable biografts for repairing the impaired heart--dynamic cell culture with pre-seeding

BACKGROUND

Tissue engineering with cell seeded biodegradable material has attracted attention as a novel means of treating the severely impaired heart. Here, we consider optimal preparation of a durable biograft using dynamic and static cultures.

METHODS

Vascular smooth muscle cells (VSMCs) derived from the rat aorta were seeded onto biodegradable material P (LA/CL) (poly-L-lactide-ε-caprolactone copolymer) and cultured as follows: a) Static culture (n = 11), b) dynamic culture (n = 12), c) 0 h pre-seeding (n = 12), d) 24 h pre-seeding (n = 5) and e) 1 week pre-seeding (n = 12). Dynamic culture: Cells were cultured in spinner flasks. Pre-seeding: Static cell seeding and culture before dynamic culture.

EVALUATION

The conditions of the P (LA/CL) in the five groups were evaluated as cell proliferation and by histological studies.

RESULTS

VSMCs proliferated both in and on the biodegradable materials. The quality of the dynamic culture cell with pre-seeding increased. Although the duration of pre-seeding exerted no significantly different effects, cell attachment and proliferation were widely scattered in the 0 h pre-seeding group, whereas cells proliferating on the front of the scaffold obstructed proliferation inside the biodegradable material in the 1 week pre-seeding group .

CONCLUSIONS

Dynamic cell culture with 24 h pre-seeding is effective for constructing ideal biografts.

Plasmid-mediated gene therapy for cardiovascular disease

Gene transfer within the cardiovascular system was first demonstrated in 1989 yet, despite extensive basic-science and clinical research, unequivocal benefit in the clinical setting remains to be demonstrated. Potential reasons for this include the fact that recombinant viral vectors, used in the majority of clinical studies, have inherent problems with immunogenicity that are difficult to circumvent. Attention has turned therefore to plasmid vectors, which possess many advantages over viruses in terms of safety and ease of use, and many clinical studies have now been performed using non-viral technology. This review will provide an overview of clinical trials for cardiovascular disease using plasmid vectors, recent developments in plasmid delivery and design, and potential directions for this modality of gene therapy.

Stem cells and growth factor delivery systems for cardiovascular disease

Coronary (CAD) and peripheral (PAD) artery diseases are major causes of morbidity and mortality, and millions of CAD and PAD patients are treated by various medications, bypass surgery or angioplasty around the world. Such patients might benefit from novel stem cells and tissue engineering strategies aimed at accelerating natural processes of postnatal collateral vessel formation and repairing damaged tissues. By combining three fundamental "tools", namely stem cells, biomaterials and growth factors (GFs), such strategies may enhance the efficacy of cell therapy in several ways: (a) by supplying exogenous stem cells or GFs that stimulate resident cardiac stem cell (CSC) migration, engraftment and commitment to cardiomyocytes, and that induce and modulate arterial response to ischemia; (b) by supporting the maintenance of GFs and transplanted stem cells in the damaged tissues through the use of biocompatible and biodegradable polymers for a period of time sufficient to allow histological and anatomical restoration of the damaged tissue. This review will discuss the potential of combining stem cells and new delivery systems for growth factors, such as vehicle-based delivery strategies or cell-based gene therapy, to facilitate regeneration of ischemic tissues. These approaches would promote the ability of resident CSCs or of exogenous multipotent stem cells such as adipose tissue-derived mesenchymal stem cells (AT-MSCs) to induce the healing of damaged tissue, by recruiting and directing these cells into the damage area and by improving angiogenesis and reperfusion of ischemic tissues.

Oral and nasal DNA vaccines delivered by attenuated Salmonella enterica serovar Typhimurium induce a protective immune response against infectious bronchitis in chickens

Several studies have reported that intramuscular injection of DNA vaccines against infectious bronchitis virus (IBV) induces protective immune responses. In the present study, we developed oral and nasal DNA vaccines that carried the S1 gene and N gene of IBV delivered by attenuated Salmonella enterica serovar Typhimurium strains SL/pV-S1 and SL/pV-N, respectively. The safety and stability of recombinant Salmonella vaccine were evaluated. Following oral and nasal administration to chickens, the serum and mucosal samples were collected and antibodies against IBV were measured. Chickens were then challenged with IBV strain M41 by the nasal-ocular route 3 weeks after boosting. The results showed that oral and nasal immunization with coadministered SL/pV-S1 and SL/pV-N elicited significant IBV-specific humoral and mucosal immune responses and conferred protective efficacy against IBV challenge higher than that in chickens immunized only with SL/pV-S1. The current study shows that novel DNA vaccines delivered by attenuated S. Typhimurium may be promising candidates for the prevention of infectious bronchitis (IB).These vaccines are efficacious, easily produced economically, and able to be delivered orally and nasally rather than injected. Coadministration of SL/pV-S1 and SL/pV-N may represent an effective mucosal vaccination regimen.

Safety and pharmacokinetics of recombinant human hepatocyte growth factor (rh-HGF) in patients with fulminant hepatitis: a phase I/II clinical trial, following preclinical studies to ensure safety

BACKGROUND

Hepatocyte growth factor (HGF) stimulates hepatocyte proliferation, and also acts as an anti-apoptotic factor. Therefore, HGF is a potential therapeutic agent for treatment of fatal liver diseases. We performed a translational medicine protocol with recombinant human HGF (rh-HGF), including a phase I/II study of patients with fulminant hepatitis (FH) or late-onset hepatic failure (LOHF), in order to examine the safety, pharmacokinetics, and clinical efficacy of this molecule.

METHODS

Potential adverse effects identified through preclinical safety tests with rh-HGF include a decrease in blood pressure (BP) and an increase in urinary excretion of albumin. Therefore, we further investigated the effect of rh-HGF on circulatory status and renal toxicity in preclinical animal studies. In a clinical trial, 20 patients with FH or LOHF were evaluated for participation in this clinical trial, and four patients were enrolled. Subjects received rh-HGF (0.6 mg/m2/day) intravenously for 12 to 14 days.

RESULTS

We established an infusion method to avoid rapid BP reduction in miniature swine, and confirmed reversibility of renal toxicity in rats. Although administration of rh-HGF moderately decreased BP in the participating subjects, this BP reduction did not require cessation of rh-HGF or any vasopressor therapy; BP returned to resting levels after the completion of rh-HGF infusion. Repeated doses of rh-HGF did not induce renal toxicity, and severe adverse events were not observed. Two patients survived, however, there was no evidence that rh-HGF was effective for the treatment of FH or LOHF.

CONCLUSIONS

Intravenous rh-HGF at a dose of 0.6 mg/m2 was well tolerated in patients with FH or LOHF; therefore, it is desirable to conduct further investigations to determine the efficacy of rh-HGF at an increased dose.

Targeted gene therapy for the treatment of heart failure

Chronic heart failure is one of the leading causes of morbidity and mortality in Western countries and is a major financial burden to the health care system. Pharmacologic treatment and implanting devices are the predominant therapeutic approaches. They improve survival and have offered significant improvement in patient quality of life, but they fall short of producing an authentic remedy. Cardiac gene therapy, the introduction of genetic material to the heart, offers great promise in filling this void. In-depth knowledge of the underlying mechanisms of heart failure is, obviously, a prerequisite to achieve this aim. Extensive research in the past decades, supported by numerous methodological breakthroughs, such as transgenic animal model development, has led to a better understanding of the cardiovascular diseases and, inadvertently, to the identification of several candidate genes. Of the genes that can be targeted for gene transfer, calcium cycling proteins are prominent, as abnormalities in calcium handling are key determinants of heart failure. A major impediment, however, has been the development of a safe, yet efficient, delivery system. Nonviral vectors have been used extensively in clinical trials, but they fail to produce significant gene expression. Viral vectors, especially adenoviral, on the other hand, can produce high levels of expression, at the expense of safety. Adeno-associated viral vectors have emerged in recent years as promising myocardial gene delivery vehicles. They can sustain gene expression at a therapeutic level and maintain it over extended periods of time, even for years, and, most important, without a safety risk.

Novel therapy for myocardial infarction: can HGF/Met be beneficial?

Myocardial infarction (MI) is a leading cause of hospitalization worldwide. A recently developed strategy to improve the management of MI is based on the use of growth factors which are able to enhance the intrinsic capacity of the heart to repair itself or regenerate after damage. Among others, hepatocyte growth factor (HGF) has been proposed as a modulator of cardiac repair of damage due to the pleiotropic effects elicited by Met receptor stimulation. In this review we describe the mechanistic basis for autocrine and paracrine protection of HGF in the injured heart. We also analyse the role of HGF/Met in stem cell maintenance and in stem cell therapies for MI. Finally, we summarize the most significant results on the use of HGF in experimental models of heart injury and discuss the potential of the molecule for treating ischaemic heart disease in humans.

Safety of a non-viral plasmid-encoding dual isoforms of hepatocyte growth factor in critical limb ischemia patients: a phase I study

We aimed to evaluate in a phase I dose-escalation study, the safety of intramuscular injections of a novel non-viral plasmid DNA expressing two isoforms of human hepatocyte growth factor (HGF) (VM202) in patients with critical limb ischemia (CLI). In total, 12 patients with CLI and unsuitable for revascularization were consecutively assigned to increasing doses (2 to 16 mg) of VM202 administered into the ischemic calf muscle at days 1 and 15. Patients were evaluated for safety and tolerability, changes in ankle- and toe brachial index (ABI and TBI), and pain severity score using a visual analog scale (VAS) throughout a 12-month follow-up period. Median age was 72 years and 53% of the patients were male. VM202 was safe and well tolerated with no death during the 12-month follow-up. Median ABI and TBI significantly increased from 0.35 to 0.52 (P=0.005) and from 0.15 to 0.24 (P=0.01) at 12 months follow-up. Median VAS decreased from 57.5 to 16.0 mm at 6 months follow-up (P=0.03). In this first human clinical trial, VM202, which expresses two isoforms of human HGF, appear to be safe and well tolerated with encouraging clinical results and thus supports the performance of a phase II randomized controlled trial.

Hypocellularity and insufficient expression of angiogenic factors in implanted autologous bone marrow in patients with chronic critical limb ischemia

The aim of this study was to identify the clinical parameters of absolutely poor-prognosis patients with chronic critical limb ischemia (AP-CLI). Sixteen no-option CLI patients with arteriosclerosis obliterans: ASO (nine) and non-ASO patients (seven) treated with bone marrow-mononuclear cell implantation (BMI) were analyzed. There were three AP-CLI patients (all ASO). The mRNA expression of several angiogenic factors in the implanted cells was analyzed in comparison with normal donor bone marrow. To observe the response of bone marrow components to hypoxia, normal bone marrow cells were cultured for 24 h in 2.5% O(2), and mRNA expression of angiogenic factors were measured. AP-CLI patients exhibited extraordinary low bone marrow cellularity as well as the percentage of CD34-positive cells. Among angiogenic factors, only VEGF expression was maintained in response to HIF-1, while other factors such as HGF, Ang-1, PLGF, and SDF-1 decreased in the implanted bone marrow cells of the patients with CLI compared to normal bone marrow cells. HIF-1 and all of the five angiogenic factors increased in vitro in response to hypoxia. Thus it is highly likely that angiogenic factors except VEGF do not respond to chronic ischemia in bone marrow in vivo. An organ-protection system against tissue ischemia may be applied for acute hypoxia, but it may be insufficient for chronic ischemia.

shRNA-mediated decreases in c-Met levels affect the differentiation potential of human mesenchymal stem cells and reduce their capacity for tissue repair

Mesenchymal stem cells/marrow stromal cells (MSC) are adult multipotent cells that can augment tissue repair. We previously demonstrated that culturing MSC in hypoxic conditions causes upregulation of the hepatocyte growth factor (HGF) receptor c-Met, allowing them to respond more robustly to HGF. MSC preconditioned in hypoxic environments contributed to restoration of blood flow after an ischemic injury more rapidly than MSC cultured in normoxic conditions. We now investigated the specific role of HGF/c-Met signaling in MSC function. An shRNA-mediated knockdown (KD) of c-Met in MSC did not alter their phenotypic profile, proliferation, or viability in vitro. However, we determined that while HGF/c-Met signaling does not play a role in the adipogenic differentiation of the cells, the disruption of this signaling pathway inhibited the ability of MSC to differentiate into the osteogenic and chondrogenic lineages. We next assessed the impact of c-Met KD on human MSC function in a xenogeneic hindlimb ischemia injury model. A 70% KD of c-Met in MSC resulted in a significant decrease in their capacity to regenerate blood flow to the ischemic limb, as compared to the MSC transduced with control shRNA. MSC with only a 60% KD of c-Met exhibited an intermediate capacity to restore blood flow, suggesting that MSC function is sensitive to the dosage of c-Met signaling. The current study highlights the significance of HGF/c-Met signaling in the capacity of MSC to restore blood flow after an ischemic injury and in their ability to differentiate into the osteogenic and chondrogenic lineages.

Hepatocyte growth factor twenty years on: Much more than a growth factor

Liver regeneration depends on the proliferation of mature hepatocytes. In the 1980s, the method for the cultivation of mature hepatocytes provided an opportunity for the discovery of hepatocyte growth factor (HGF) as a protein that is structurally and functionally different from other growth factors. In 1991, the scatter factor, tumor cytotoxic factor, and 3-D epithelial morphogen were identified as HGF, and Met tyrosine kinase was identified as the receptor for HGF. Thus, the connection of apparently unrelated research projects rapidly enriched the research on HGF in different fields. The HGF-Met pathway plays important roles in the embryonic development of the liver and the placenta, in the migration of myogenic precursor cells, and in epithelial morphogenesis. The use of tissue-specific knockout mice demonstrated that in mature tissues the HGF-Met pathway plays a critical role in tissue protection and regeneration, and in providing less susceptibility to chronic inflammation and fibrosis. In various injury and disease models, HGF promotes cell survival, regeneration of tissues, and suppresses and improves chronic inflammation and fibrosis. Drug development using HGF has been challenging, but extensive preclinical studies to address its therapeutic effects have provided significant results sufficient for the development of HGF as a biological drug in the regeneration-based therapy of diseases. Clinical trials using recombinant human HGF protein, or HGF genes, are in progress for the treatment of diseases.

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.

CONCLUSIONS

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

A tandem repeat of a fragment of Listeria monocytogenes internalin B protein induces cell survival and proliferation

Hepatocyte growth factor (HGF) is critical for tissue homeostasis and repair in many organs including the lung, heart, kidney, liver, nervous system, and skin. HGF is a heterodimeric protein containing 20 disulfide bonds distributed among an amino-terminal hairpin, four kringle domains, and a serine protease-like domain. Due to its complex structure, recombinant production of HGF in prokaryotes requires denaturation and refolding, processes that are impractical for large-scale manufacture. Thus, pharmaceutical quantities of HGF are not available despite its potential applications. A fragment of the Listeria monocytogenes internalin B protein from amino acids 36-321 (InlB₃₆₋₃₂₁) was demonstrated to bind to and partially activate the HGF receptor Met. InlB₃₆₋₃₂₁ has a stable β-sheet structure and is easily produced in its native conformation by Escherichia coli. We cloned InlB₃₆₋₃₂₁ (1×InlB₃₆₋₃₂₁) and engineered a head-to-tail repeat of InlB₃₆₋₃₂₁ with a linker peptide (2×InlB₃₆₋₃₂₁); 1×InlB₃₆₋₃₂₁ and 2×InlB₃₆₋₃₂₁ were purified from E. coli. Both 1× and 2×InlB₃₆₋₃₂₁ activated the Met tyrosine kinase. We subsequently compared signal transduction of the two proteins in primary lung endothelial cells. 2×InlB₃₆₋₃₂₁ activated ERK1/2, STAT3, and phosphatidylinositol 3-kinase/Akt pathways, whereas 1×InlB₃₆₋₃₂₁ activated only STAT3 and ERK1/2. The 2×InlB₃₆₋₃₂₁ promoted improved motility compared with 1×InlB₃₆₋₃₂₁ and additionally stimulated proliferation equivalent to full-length HGF. Both the 1× and 2×InlB₃₆₋₃₂₁ prevented apoptosis by the profibrotic peptide angiotensin II in cell culture and ex vivo lung slice cultures. The ease of large-scale production and capacity of 2×InlB₃₆₋₃₂₁ to mimic HGF make it a potential candidate as a pharmaceutical agent for tissue repair.

Naked DNA expressing two isoforms of hepatocyte growth factor induces collateral artery augmentation in a rabbit model of limb ischemia

Hepatocyte growth factor (HGF) has been shown to induce angiogenesis in vivo and has potential as a candidate gene for 'therapeutic angiogenesis'. In vivo, two isoforms of HGF, HGF₇₂₃ and HGF₇₂₈, consisting of 723 and 728 amino acids, are generated through alternative splicing between exons 4 and 5, but the biological effects of their coexpression have not yet been elucidated. In this study, we generated a series of genomic-complementary DNA (cDNA) hybrids of the HGF gene by inserting various truncated intron 4 into the junction of exons 4 and 5 of HGF cDNA and analyzed the biological activities of these hybrid constructs. We showed that: (1) the hybrid called HGF-X7, which contained 1502 base pairs of intron 4, could drive a higher level of HGF expression than other hybrid constructs and cDNAs of each isoform alone; (2) the pCK vector was most efficient for the gene expression of HGF-X7; (3) coexpression of both isoforms of HGF could more efficiently induce the migration of human umbilical vein endothelial cell (HUVEC) and of the mouse myoblast cell line C₂C₁₂ myoblasts than a single isoform of HGF and human vascular endothelial growth factor (VEGF)₁₆₅ at a given concentration; (4) intramuscular administration of pCK-HGF-X7 resulted in transient and localized HGF expression in the injected muscle without an increase in the HGF protein levels in other tissues including serum; and (5) intramuscular injection of pCK-HGF-X7 could more efficiently increase the number of angiographically recognizable collateral vessels, as well as improve an intra-arterial Doppler wire-measured blood flow in the rabbit model of hindlimb ischemia when compared with the identical vector encoding VEGF₁₆₅ gene. These results showed that transfer of the genomic-cDNA hybrid of the HGF gene could be used as a potential therapeutic approach to human vascular diseases.

Regenerative therapy in peripheral artery disease

Patients with peripheral artery disease (PAD) and critical limb ischemia are the main candidates for limb amputations and have a poor life expectancy. Frequently, these patients are not eligible for either surgical or percutaneous interventions aimed at mechanical revascularization. Therefore, new strategies need to be identified to offer these patients a viable therapeutic option. Gene and cell therapy hold great promise for the treatment of peripheral vascular diseases because, in animal models, local delivery of growth factors and endothelial progenitor cells result in new blood vessel formation and regeneration of ischemic tissues. In this article, are reviewed phase I and phase II gene, and cell therapy clinical trials in patients with PAD.

The discovery of hepatocyte growth factor (HGF) and its significance for cell biology, life sciences and clinical medicine

It has been more than 25 years since HGF was discovered as a mitogen of hepatocytes. HGF is produced by stromal cells, and stimulates epithelial cell proliferation, motility, morphogenesis and angiogenesis in various organs via tyrosine phosphorylation of its receptor, c-Met. In fetal stages, HGF-neutralization, or c-Met gene destruction, leads to hypoplasia of many organs, indicating that HGF signals are essential for organ development. Endogenous HGF is required for self-repair of injured livers, kidneys, lungs and so on. In addition, HGF exerts protective effects on epithelial and non-epithelial organs (including the heart and brain) via anti-apoptotic and anti-inflammatory signals. During organ diseases, plasma HGF levels significantly increased, while anti-HGF antibody infusion accelerated tissue destruction in rodents. Thus, endogenous HGF is required for minimization of diseases, while insufficient production of HGF leads to organ failure. This is the reason why HGF supplementation produces therapeutic outcomes under pathological conditions. Moreover, emerging studies delineated key roles of HGF during tumor metastasis, while HGF-antagonism leads to anti-tumor outcomes. Taken together, HGF-based molecules, including HGF-variants, HGF-fragments and c-Met-binders are available as regenerative or anti-tumor drugs. Molecular analysis of the HGF-c-Met system could provide bridges between basic biology and clinical medicine.

Accelerated adhesion of grafted skin by laser-induced stress wave-based gene transfer of hepatocyte growth factor

Gene therapy using wound healing-associated growth factor gene has received much attention as a new strategy for improving the outcome of tissue transplantation. We delivered plasmid DNA coding for human hepatocyte growth factor (hHGF) to rat free skin grafts by the use of laser-induced stress waves (LISWs); autografting was performed with the grafts. Systematic analysis was conducted to evaluate the adhesion properties of the grafted tissue; angiogenesis, cell proliferation, and reepithelialization were assessed by immunohistochemistry, and reperfusion was measured by laser Doppler imaging as a function of time after grafting. Both the level of angiogenesis on day 3 after grafting and the increased ratio of blood flow on day 4 to that on day 3 were significantly higher than those in five control groups: grafting with hHGF gene injection alone, grafting with control plasmid vector injection alone, grafting with LISW application alone, grafting with LISW application after control plasmid vector injection, and normal grafting. Reepithelialization was almost completed on day 7 even at the center of the graft with LISW application after hHGF gene injection, while it was not for the grafts of the five control groups. These findings demonstrate the validity of our LISW-based HGF gene transfection to accelerate the adhesion of grafted skins.

Human studies of angiogenic gene therapy

Despite significant advances in medical, interventional, and surgical therapy for coronary and peripheral arterial disease, the burden of these illnesses remains high. To address this unmet need, the science of therapeutic angiogenesis has been evolving for almost two decades. Early preclinical studies and phase I clinical trials achieved promising results with growth factors administered as recombinant proteins or as single-agent gene therapies, and data accumulated through 10 years of clinical trials indicate that gene therapy has an acceptable safety profile. However, more rigorous phase II and phase III clinical trials have failed to unequivocally demonstrate that angiogenic agents are beneficial under the conditions and in the patients studied to date. Investigators have worked to understand the biology of the vascular system and to incorporate their findings into new treatments for patients with ischemic disease. Recent gene- and cell-therapy trials have demonstrated the bioactivity of several new agents and treatment strategies. Collectively, these observations have renewed interest in the mechanisms of angiogenesis and deepened our understanding of the complexity of vascular regeneration. Gene therapy that incorporates multiple growth factors, approaches that combine cell and gene therapy, and the administration of "master switch" agents that activate numerous downstream pathways are among the credible and plausible steps forward. In this review, we examine the clinical development of angiogenic gene therapy, summarize several of the lessons learned during the conduct of these trials, and suggest how this prior experience may guide the conduct of future preclinical investigations and clinical trials.

Synergistic effects of autologous cell and hepatocyte growth factor gene therapy for neovascularization in a murine model of hindlimb ischemia

Autologous cell implantation and angiogenic gene therapy have been evaluated in critical limb ischemic patients. Here, we compared the features of these strategies individually and in combination. C57BL/6J mice with ischemic hindlimbs were injected with adherent mononuclear cells (aMNCs) from bone marrow or adenovirus encoding the hepatocyte growth factor (HGF) gene (Ad-HGF). Under comparable angiogenic conditions, 10 × 105 aMNCs produced significantly higher amounts of VEGF and FGF-2 and stimulated the number of arterioles in ischemic muscle compared with 1 × 108 plaque-forming units (pfu) of Ad-HGF. Ad-HGF produced 10 times more HGF in ischemic muscle compared with aMNCs. Injection of 0.3 × 105 aMNCs previously transfected with Ad-HGF (aMNC/Ad-HGF) increased blood flow and elevated the numbers of capillaries and arterioles to levels comparable with that seen with 10 × 105 aMNCs or 1 × 108 pfu of Ad-HGF. Hypoxic conditions induced the apoptotic death of aMNCs. However, coincubation with HGF or aMNC/Ad-HGF protected cells against apoptosis. HGF stimulated the migration of aMNCs, and the migration capacity of the aMNC/Ad-HGF group was significantly higher than that in the aMNC/Ad-LacZ group. In conclusion, cell-based HGF gene therapy decreased the number of cells required for neovascularization. This strategy can be an effective angiogenic therapy.

Highly stomach-selective gene transfer following gastric serosal surface instillation of naked plasmid DNA in rats

BACKGROUND

The purpose of this study was to achieve stomach-selective gene transfer in rats by our simple and novel administration method, which is gastric serosal surface instillation of naked plasmid DNA (pDNA).

METHODS

Naked pDNA encoding firefly luciferase as a reporter gene was instilled onto the gastric serosal surface in male Wistar rats. As controls, we performed intraperitoneal, intragastric and intravenous administration of naked pDNA. At appropriate time intervals, we measured luciferase activities in the stomach and other tissues.

RESULTS

Gene expression in the stomach 6 h after gastric serosal surface instillation of naked pDNA (5 microg) was significantly higher than that after using other administration methods. The present study is the first report on stomach-selective gene transfer following instillation of naked pDNA onto the gastric serosal surface in rats. Also, the gene expression level in the stomach 6 h after gastric serosal surface instillation of naked pDNA was markedly higher than that in other tissues. In a dose-dependent study, the gene expression level was saturated over 5 microg. Gene expression in the stomach was detected 3 h after gastric serosal surface instillation of naked pDNA. The gene expression level peaked 12-24 h after instillation of naked pDNA, then decreased to a level similar to 3 h at 48 h.

CONCLUSIONS

Gastric serosal surface in stillation of naked pDNA can be a highly stomach-selective gene transfer method in rats.

Tc-99m-MIBI scintigraphy in evaluating the effect of hepatocyte growth factor gene therapy for peripheral arteriosclerosis obliterans

We report an 81-year-old man with arteriosclerosis obliterans with sharp rest pain of the left lower leg below the knee that was resistant to conventional drug therapy. Gene therapy using hepatocyte growth factor (HGF) was performed, following which the symptoms remarkably improved. Magnetic resonance (MR) angiography did not detect any development of collateral vessels following gene therapy; however, technetium-99m-methoxyisobutylisonitrile (Tc-99m)-MIBI scintigraphy revealed the development of micro-circulation in the lower leg following HGF gene therapy. This is the first report on the usefulness of Tc-99m-MIBI scintigraphy to evaluate the effectiveness of HGF gene therapy for peripheral arteriosclerosis obliterans.

Novel jet-injection technology for nonviral intratumoral gene transfer in patients with melanoma and breast cancer

PURPOSE

This phase I clinical trial evaluated safety, feasibility, and efficiency of nonviral intratumoral jet-injection gene transfer in patients with skin metastases from melanoma and breast cancer.

EXPERIMENTAL DESIGN

Seventeen patients were enrolled. The patients received five jet injections with a total dose of 0.05 mg beta-galactosidase (LacZ)-expressing plasmid DNA (pCMVbeta) into a single cutaneous lesion. Clinical and laboratory safety monitoring were done. Systemic plasmid clearance was monitored by quantitative real-time PCR of blood samples throughout the study. All lesions were resected after 2 to 6 days. Intratumoral plasmid DNA load, DNA distribution, and LacZ expression was analyzed by quantitative real-time PCR, quantitative reverse transcription-PCR, Western blot, immunohistochemistry, and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside staining.

RESULTS

Jet injection of plasmid DNA was safely done in all patients. No serious side effects were observed. Thirty minutes after jet injection, peak plasmid DNA levels were detected in the blood followed by rapid decline and clearance. Plasmid DNA and LacZ mRNA and protein expression were detected in all treated lesions. Quantitative analysis revealed a correlation of plasmid DNA load and LacZ-mRNA expression confirmed by Western blot. Immunohistochemistry and 5-bromo-4-chloro-3-indolyl-beta-D-galactoside staining showed LacZ-protein throughout the tumor. Transfected tumor areas were found close and distant to the jet-injection site with varying levels of DNA load and transgene expression.

CONCLUSION

Intratumoral jet injection of plasmid DNA led to efficient LacZ reporter gene expression in all patients. No side effects were experienced, supporting safety and applicability of this novel nonviral approach. A next step with a therapeutic gene product should determine antitumor efficacy of jet-injection gene transfer.

Role of the Wilms' tumour transcription factor, Wt1, in blood vessel formation

Blood vessel formation is important for normal organ development and tumour growth. A highly specialised developmental program of vessel formation exists in the heart and is essential for normal cardiogenesis. From mouse models, it became clear that the Wilms' tumour protein Wt1 is required for normal heart development. Originally identified as a tumour suppressor gene based on its mutational inactivation in Wilms' tumour or nephroblastoma, Wt1 is nowadays recognised to have much broader functions in organogenesis and pathophysiology. The multiple tasks of Wt1 are not only limited to the kidney but involve the heart and vascular system as well. In this review, we focus on recent findings about the importance of Wt1 in heart and coronary vessel development and the identified molecular mechanisms. In addition, we discuss the implication of Wt1 in the vascular response to myocardial ischaemia and its oncogenic potential as a promoter of tumour angiogenesis.

Percutaneous nonviral delivery of hepatocyte growth factor in an osteotomy gap promotes bone repair in rabbits: a preliminary study

Hepatocyte growth factor (HGF) was initially identified in cultured hepatocytes and subsequently reported to induce angiogenic, morphogenic, and antiapoptotic activity in various tissues. These properties suggest a potential influence of HGF on bone healing. We asked if gene transfer of human HGF (hHGF) into an osteotomy gap with a hemagglutinating virus of Japan-envelope (HVJ-E) vector promotes bone healing in rabbits. HVJ-E that contained either hHGF or control plasmid was percutaneously injected into the osteotomy gap of rabbit tibias on Day 14. The osteotomy gap was evaluated by radiography, pQCT, mechanical tests, and histology at Week 8. The expression of hHGF was evaluated by reverse transcriptase-polymerase chain reaction and immunohistochemistry at Week 3. Radiography, pQCT, and histology suggested the hHGF group had faster fracture healing. Mechanical tests demonstrated the hHGF group had greater mechanical strength. The injected tissues at 3 weeks expressed hHGF mRNA by reverse transcriptase-polymerase chain reaction. hHGF-positive immunohistochemical staining was observed in various cells at the osteotomy gap at Week 3. The data suggest delivery of hHGF plasmid into the osteotomy gap promotes fracture repair, and HGF could become a novel agent for fracture treatment.