Tomokazu Nagano

Therapeutic Angiogenesis Induced by Human Recombinant Hepatocyte Growth Factor in Rabbit Hind Limb Ischemia Model as Cytokine Supplement Therapy

Hepatocyte growth factor (HGF) exclusively stimulates the growth of endothelial cells without replication of vascular smooth muscle cells and acts as a survival factor against endothelial cell death. Therefore we hypothesized that a decrease in local vascular HGF might be related to the pathogenesis of peripheral arterial disease. We initially evaluated vascular HGF concentration in the vessels of patients with arteriosclerosis obliterans. Consistent with in vitro findings that hypoxia downregulated vascular HGF production, vascular HGF concentration in the diseased segments of vessels from patients with arteriosclerosis obliterans was significantly decreased as compared with disease-free segments from the same patients (P<0.05), accompanied by a marked reduction in HGF mRNA. On the other hand, a novel therapeutic strategy for ischemic diseases that uses angiogenic growth factors to expedite and/or augment collateral artery development has recently been proposed. Thus in view of the decreased endogenous vascular HGF, rhHGF (500 micrograms/animal) was intra-arterially administered through the internal iliac artery of rabbits in which the femoral artery was excised to induce unilateral hind limb ischemia, to evaluate the angiogenic activity of HGF, which could potentially have a beneficial effect in hypoxia. Administration of rhHGF twice on days 10 and 12 after surgery produced significant augmentation of collateral vessel development on day 30 in the ischemic model as assessed by angiography (P<0.01). Serial angiograms revealed progressive linear extension of collateral arteries from the origin stem artery to the distal point of the reconstituted parent vessel in HGF-treated animals. In addition, we examined the feasibility of intravenous administration of rhHGF in a moderate ischemia model. Importantly, intravenous administration of rhHGF also resulted in a significant increase in angiographic score as compared with vehicle (P<0.01). Overall, a decrease in vascular HGF might be related to the pathogenesis of peripheral arterial disease. In the presence of decreased endogenous HGF, administration of rhHGF induced therapeutic angiogenesis in the rabbit ischemic hind limb model, as potential cytokine supplement therapy for peripheral arterial disease.

Pre‐ or Post‐treatment with Hepatocyte Growth Factor Prevents Glycerol‐Induced Acute Renal Failure

Hepatocyte growth factor (HGF) is known to have beneficial effects against damage in various organs, including liver, kidney and lung, in disease models. Previously, we reported that repeated administration of HGF ameliorates renal dysfunction and histological alteration of glycerol‐injected rats, an animal model for severe acute renal failure (ARF). In the present study, we investigated in more detail the efficacy of pre‐ and post‐treatment of HGF in this model. ARF was induced by intramuscular injection of glycerol into the hind limbs of male Wistar rats. The efficacy of pre‐treatment was studied by intravenous injection of HGF (1 mg/kg) or vehicle 1 and 18 hours prior to glycerol injection. Pre‐treatment of HGF dramatically protected glycerol‐induced ARF rats against death, and prevented deterioration of biochemical parameters for renal function. We also analyzed expression of heme oxygenase‐1 (HO‐1), a cytoprotective protein, in kidney of HGF‐injected rats. Intravenous administration of HGF enhanced renal expression of HO‐1 mRNA from 1 to 3 hours after injection. Next, as a post‐treatment study, HGF (1 mg/kg/3 hours) with dopamine was infused into glycerol‐induced ARF rats 7 hours after glycerol injection. Intravenous infusion of HGF after ARF onset also ameliorated renal biochemical parameters. These results indicate that pre‐treatment of HGF can improve ARF, and induction of HO‐1 expression in kidney may be a cause of the protective effect. In addition, post‐treatment of HGF with dopamine was also effective against the establishment of ARF.

Ameliorative Effect of Hepatocyte Growth Factor on Glycerol-Induced Acute Renal Failure with Acute Tubular Necrosis

Background/Aims: Hepatocyte growth factor (HGF), a multi-potent growth factor, is known to promote regeneration of damaged renal epithelial cells. Glycerol injection into rats induces severe acute renal failure (ARF) with ischemia and tubular necrosis, a model which shares many features with human ARF or rhabdomyolysis. We investigated the efficacy of HGF in this glycerol-induced ARF rat model. Methods: ARF was induced by intramuscular injection of glycerol into the hind limbs of male Wistar rats. HGF (0.25 mg/kg/shot) or vehicle was administered intravenously 1 h before and 1, 3, 5, 8, 24 and 36 h after glycerol injection. Biochemical parameters for serum and urine were measured and histological analyses of the kidneys were performed. We also analyzed endogenous HGF expression and phosphorylation of c-Met/HGF receptor in the kidneys of glycerol-induced ARF rats. Results: Glycerol treatment caused severe ARF which invariably led to death of the rats. Repeated administration of HGF protected rats from death caused by severe ARF. Histological analyses revealed that HGF treatment reduced necrosis of tubular cells in the renal cortex. Serum/urine biochemical parameters also showed that renal dysfunction was improved by HGF administration. Intravenous administration of HGF enhanced phosphorylation of the c-Met/HGF receptor and mitogen-activated protein kinase in the kidney. In the vehicle-treated group the renal endogenous HGF concentration decreased and there was no change in c-Met/HGF receptor phosphorylation. Conclusion: These results indicate that HGF effectively accelerated the recovery of renal function and improved survival in glycerol-induced ARF rats.

Hepatocyte Growth Factor Protects Functional and Histological Disorders of HgCl2-Induced Acute Renal Failure Mice

Hepatocyte growth factor (HGF) enhances proliferation of renal epithelial cells as well as hepatocytes. HGF accelerates recovery from acute renal failure (ARF) in animal models. However, pharmacological profiles of HGF including its action mechanism has not been studied in detail. An HgCl2-induced ARF mouse was used in this study to evaluate the efficacy of HGF. Single administrations of recombinant human HGF or vehicle were given to ARF mice 30 min after HgCl2 injection. Renal function was monitored by measuring serum creatinine, blood urea nitrogen and creatinine clearance. In the ARF mice, there was a deterioration of renal function biochemical parameters and histological evidence of renal damage including acute tubular necrosis of proximal tubules. These were both significantly ameliorated by a single HGF administration. The effect of HGF was noticeable in the early phase of ARF (1 day after onset) when there was no histological evidence of increased labeling indexes in renal tubular epithelial cells. Western blot analysis of the c-Met/HGF receptor showed that tyrosine phosphorylation was enhanced immediately after HGF administration indicating direct activation of renal epithelial cells. HGF prevented increase of apoptotic nuclei with DNA fragmentation in renal epithelial cells which suggests cytoprotective activity of HGF on renal epithelial cells in the ARF mice.

Can nonpenetrating vascular closure staples and hepatocyte growth factor prevent intimal hyperplasia following ePTFE grafting of the carotid artery in rabbits

Abstract.Abstract.Purpose: To evaluate whether nonpenetrating vascular closure staples (VCS) and hepatocyte growth factor (HGF) can effectively prevent anastomotic intimal hyperplasia.Methods: An expanded polytetrafluoroethylene graft, 2 mm in diameter, was implanted in the common carotid artery of rabbits divided into three experimental groups. In the control group, distal anastomosis was performed with interrupted suturing; in the VCS group, clips were applied along the lateral suture line after the placement of stay sutures; and in the VCS + HGF group, the same anastomotic technique was performed as in the VCS group, followed by the administration of the HGF for 4 days.Results: The time taken to complete the anastomosis was significantly less in both the VCS groups than in the control group (P < 0.0001). On postoperative day (POD) 28, the patency rate was significantly lower (P < 0.05) in the VCS group (42.9%) than in the control group (100%), but the rate in the VCS + HGF group (100%) was the same as that in the control group. Intimal thickness was significantly less in the control group than in either the VCS or VCS + HGF groups (P < 0.05). The percentage of area stenosis was significantly less (P < 0.01) in the control group than in the VCS group.Conclusion: The VCS clip failed to suppress intimal thickness or reduce the percentage of stenosis at the anastomotic site.

Synthesis and pharmacological evaluation of novel benzoylazole-based PPAR α/γ activators

In our search for new PPARα/γ agonists, we designed and synthesized a series of benzoylazole-based carboxylic acids. Compound 9 showed potent PPARγ partial agonistic activity with modest PPARα agonistic activity. The sodium salt of 9 (9Na) demonstrated potent efficacy in lowering both blood glucose and lipids in an animal model without causing significant body weight gain, a well-known side effect associated with PPARγ full agonists.