Biomedical subjects

Keiji Oi

Publications and source records attributed to Keiji Oi.

17 recordsLinked to original sources

PubMed2006

Increased immunosuppression, not anticoagulation, extends cardiac xenograft survival.

BACKGROUND: Cardiac xenograft function is lost due to delayed xenograft rejection (DXR) characterized by microvascular thrombosis and myocardial necrosis. The cause of DXR is unknown but may result from thrombosis induced by antibody-mediated activation of endothelial cells and/or by incompatibilities in thromboregulatory interactions. METHODS: To examine these issues, a series (Groups 1-6) of previous transgenic CD46 pig-to-baboon heterotopic cardiac transplants were reanalyzed for baseline immunosuppressive levels, graft survival and infectious complications with and without systemic anticoagulation. Groups 1-4 received low dose tacrolimus and sirolimus maintenance therapy, with splenectomy, anti-CD20 and daily alpha-Gal polymer. Group 1 recipients received no anticoagulation. Groups 2-4 were anticoagulated with aspirin and Plavix, Lovenox, or Coumadin, respectively. Group 5 was treated with Lovenox and high dose tacrolimus and sirolimus maintenance therapy. Group 6 recipients received no postoperative anticoagulation but the same immunosuppression as group 5. RESULTS: Median survival (15-22 days) within groups 1-4 was not significantly different. At rejection all tissues exhibited microvascular thrombosis, coagulative necrosis and similar levels of platelet and fibrin deposition. Groups 5 and 6 median survival (76 days) was significantly increased compared to groups 1-4. There was no significant difference in median survival between Lovenox treated recipients (68 days) and anticoagulant free recipients (96 days). Rejected tissues showed vascular antibody deposition, microvascular thrombosis, and myocyte necrosis. CONCLUSION: Significant prolongation in xenograft survival is achieved by improved immunosuppression. These results suggest that ongoing immune responses remain the major stimulus for DXR.

Animals↗

PubMed2006

Ex vivo hypothermic recirculatory adenoviral gene transfer to the transplanted pig heart.

BACKGROUND: To facilitate the application of adenoviral gene therapy in clinical heart transplantation, we developed an ex vivo hypothermic recirculatory adenoviral gene transfer method to the transplanted pig heart. METHODS: Experimental animals were assigned into three groups; controls, 1x10(8) plaque-forming units (pfu)/ml group and 1x10(9) pfu/ml group. During the 30 min gene transfer perfusion, 200 ml of University of Wisconsin solution containing the adenoviral vector was recirculated through the coronary vessels. The myocardial temperature was maintained below 4 degrees C and the perfusion pressure was adjusted at 50 mmHg. RESULTS: Cardiac myocyte transduction efficiencies in the 1x10(8) pfu/ml group were 0.04% and 0.07%, whereas transduction efficiencies in the 1x10(9) pfu/ml group were widely distributed from 0.45% to 22.62%. The gene transduction efficiency increased with the virus titer. Additionally, no difference in the transduction efficiency was observed between different segments of the left ventricle. The current gene transfer method at 1x10(9) pfu/ml of adenovirus titer enabled homogeneous gene transduction into the transplanted pig heart up to a maximum of 22.62%. CONCLUSIONS: This model can be applied to a large isolated heart and will greatly facilitate the investigation of gene therapy in large animal models of heart transplantation.

Adenoviridae↗

PubMed2006

Long-term inhibition of Rho-kinase ameliorates hypoxia-induced pulmonary hypertension in mice.

Pulmonary hypertension (PH) is a fatal disease characterized by endothelial dysfunction, hypercontraction and proliferation of vascular smooth muscle cells, and migration of inflammatory cells for which no satisfactory treatment has yet been developed. It has been recently demonstrated that Rho-kinase, an effector of the small GTPase Rho, is involved in the pathogenesis of arteriosclerosis and that long-term inhibition of Rho-kinase markedly ameliorates monocrotaline-induced PH in rats. However, it remains to be examined whether direct inhibition of Rho-kinase also ameliorates PH with a different etiology and whether endothelial nitric oxide synthase (eNOS) is involved in the beneficial effects of Rho-kinase inhibition. This study was designed to address those 2 important issues in a hypoxia-induced PH model using wild-type (WT) and eNOS-deficient (eNOS) mice. Long-term blockade of Rho-kinase with fasudil (100 mg/kg/d) for 3 weeks markedly improved PH and right ventricular hypertrophy in WT mice with a lesser but significant inhibition noted in eNOS mice. Fasudil upregulated eNOS with increased Akt phosphorylation in WT but not in eNOS mice. These results suggest that long-term inhibition of Rho-kinase also ameliorates hypoxia-induced PH in mice, for which eNOS activation may partially be involved.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2006

T-cell responses during pig-to-primate xenotransplantation.

UNLABELLED: Xenotransplantation using porcine organs may resolve a chronic shortage of donor organs for clinical transplantation if significant immunological barriers can be overcome. To determine the potential role of T lymphocytes in Xenograft (Xg) rejection, we transplanted transgenic hCD46 porcine hearts heterotopically into baboon recipients. METHODS: Recipients were treated to deplete anti-Gal antibody with a non-antigenic alpha-Gal polyethylene glycol polymer (TPC) (n = 2), TPC plus rituximab (anti-CD20) (n = 1) or were untreated (n = 1). None of the recipients received T-cell immunosuppression. RESULTS: All Xgs failed within 7 days and showed evidence of a mixed humoral and cellular rejection process. Cellular infiltration consisting primarily of CD4+ T cells and few CD8+ T cells. Proliferation and cytotoxicity assays showed sensitization of CD4+ and CD8+ T cells that reacted with porcine IFN-gamma (pIFN-gamma)-stimulated porcine aortic endothelial cells (PAEC). The CD4+ lymphocytes displayed greater cytotoxicity than CD8+ cells. An increased frequency of PAEC-specific interleukin (IL) 2 and IFN-gamma-secreting T cells was observed, suggesting a Th1 cytokine bias. An increase in the percentage of circulating CD4+CD28- cells was observed at the time of rejection and over 50% of the CD4+ cells recovered from residual pig tissue at necropsy lacked CD28 expression. CONCLUSIONS: These findings show that lymphocytes are efficiently stimulated by PAEC antigens and can mediate direct tissue destruction. These studies (1) provide an insight into the potential of cellular-mediated cardiac Xg rejection, (2) show for the first time the induction of cytotoxic pig-specific CD4+CD28- lymphocytes and (3) provide a rational basis for determining different modes of immunosuppression to treat Xg rejection.

Animals↗

PubMed2005

Cyclosporine decreases vascular progenitor cell numbers after cardiac transplantation and attenuates progenitor cell growth in vitro.

OBJECTIVE: Recent experimental evidence suggests that the neointimal proliferation seen in cardiac allograft vasculopathy may in part derive from recipient progenitor cells. The effect of cyclosporine on these circulating progenitors in the setting of cardiac transplantation is currently unknown. METHODS: Three surgical series were performed: sham operation alone, sham operation with immunosuppression, and heterotopic porcine cardiac transplantation with immunosuppression. The sham operation involved laparotomy and consecutive clamping of the abdominal aorta and inferior vena cava. Post-operative immunosuppression consisted of cyclosporine at therapeutic levels (100-300 ng/ml) and 0.5 mg/kg methylprednisolone. Endothelial outgrowth colony numbers (EOC(CFU)) and smooth muscle outgrowth colony numbers (SOC(CFU)) were quantified weekly for 4 weeks post-operatively. A series of in vitro experiments were performed to determine the effect of cyclosporine on the differentiation, migration, and proliferation of EOCs and SOCs. RESULTS: In the sham alone series there were no changes to either EOC(CFU) or SOC(CFU). In the sham with immunosuppression and the transplant series, both EOC(CFU) and SOC(CFU) fell in the first 2 weeks (p < 0.05) compared with baseline (EOC(CFU), 3.4 +/- 0.6; SOC(CFU), 11.1 +/- 2.8). EOC(CFU) recovered at 4 weeks to above baseline levels in the sham immunosuppression group only (15.2 +/- 3.9; p = 0.01). SOC(CFU) showed no recovery in the immunosuppression groups. Cyclosporine, even at a low dose, prevented differentiation, inhibited proliferation, and attenuated migration of both EOCs and SOCs. CONCLUSION: Immunosuppression in the setting of cardiac transplantation causes a profound reduction in circulating progenitor cells capable of differentiating into endothelial and smooth muscle cells. This effect can in part be explained by the inhibitory effects of cyclosporine on progenitor growth and differentiation seen in this study.

Animals↗

PubMed2005

Safe coronary artery occlusion with a new tourniquet in off-pump bypass grafting.

Coronary artery occlusion during off-pump coronary artery bypass grafting may lead to mechanical trauma of the arterial wall. My colleagues and I describe a safe coronary artery occlusion technique in off-pump bypass grafting that uses a new spring-equipped tourniquet, which enables precise adjustment of the least force necessary to occlude the coronary flow. This prevents snare-induced vessel wall damage.

Coronary Artery Bypass, Off-Pump↗

PubMed2005

Cardiac xenotransplantation: recent preclinical progress with 3-month median survival.

OBJECTIVES: Transplantation is limited by a lack of human organ donors. Organs derived from animals, most likely the pig, represent a potential solution to this problem. For the heart, 90-day median graft survival of life-supporting pig hearts transplanted to nonhuman primates has been considered a reasonable standard for entry into the clinical arena. Overcoming the immune barrier to successful cardiac xenotransplantation is most appropriately first explored with the non-life-supporting heterotopic model. METHODS: We performed a series of 7 heterotopic heart transplantations from CD46 transgenic pigs to baboons using a combination of therapeutic agents largely targeted at controlling the synthesis of anti-pig antibodies. Rituximab (anti-CD20) and Thymoglobulin (rabbit antithymocyte globulin [ATG]; SangStat Medical Corp, Fremont, Calif) were used as induction therapy. Baseline immunosuppression consisted of splenectomy, tacrolimus, sirolimus, steroids, and TPC (an anti-Gal antibody therapeutic). Rejection events were not treated. RESULTS: By using Kaplan-Meier analysis, median graft survival was 96 days (range, 15-137 days; 95% confidence interval, 38-99 days). Only 2 grafts were lost as a result of rejection, as defined by cessation of graft palpation. There was no evidence of a consumptive coagulopathy, infectious complications were treatable, and no posttransplantation lymphoproliferative disorders occurred. No cellular infiltration was observed. CONCLUSIONS: This study reports the longest median survival to date (96 days) of pig hearts transplanted heterotopically into baboons. Duplication of these results in the orthotopic life-supporting position could bring cardiac xenotransplantation to the threshold of clinical application.

Animals↗

PubMed2005

Prostacyclin does not inhibit rho-kinase: an implication for the treatment of pulmonary hypertension.

Primary pulmonary hypertension continues to be a fatal disease. We have recently demonstrated that long-term inhibition of Rho-kinase, an effector of the small GTPase Rho, is effective for the treatment of pulmonary hypertension (PH) in rats and humans. Prostacyclin has been clinically used for the treatment of PH with moderate success. However, it remains to be examined whether Rho-kinase inhibition is involved in its beneficial effects on PH. In an ELISA assay, neither prostacyclin nor its oral analogue, beraprost sodium, inhibited Rho-kinase even at higher concentrations (10(-7) to 10(-5) M, 100 to 10,000 times higher than their clinical concentrations), whereas specific Rho-kinase inhibitors, fasudil and hydroxyfasudil, markedly (approximately 95%) inhibited the Rho-kinase activity at 10(-5) M (near their clinical concentrations). Beraprost sodium did not significantly suppress serotonin-induced vascular smooth muscle cell (VSMC) contractions or Rho-kinase activity of the rat aorta without endothelium, as evaluated by the extent of phosphorylation of the ERM family, a substrate of Rho-kinase, whereas hydroxyfasudil markedly suppressed the VSMC contractions and Rho-kinase activity. These results indicate that prostacyclin lacks direct inhibitory effect on Rho-kinase and suggest that combination therapy with prostacyclin and a Rho-kinase inhibitor could exert further beneficial effects on PH.

Animals↗

PubMed2004

Extracorporeal cardiac shock wave therapy markedly ameliorates ischemia-induced myocardial dysfunction in pigs in vivo.

BACKGROUND: Prognosis of ischemic cardiomyopathy still remains poor because of the lack of effective treatments. To develop a noninvasive therapy for the disorder, we examined the in vitro and vivo effects of extracorporeal shock wave (SW) that could enhance angiogenesis. METHODS AND RESULTS: SW treatment applied to cultured human umbilical vein endothelial cells significantly upregulated mRNA expression of vascular endothelial growth factor and its receptor Flt-1 in vitro. A porcine model of chronic myocardial ischemia was made by placing an ameroid constrictor at the proximal segment of the left circumflex coronary artery, which gradually induced a total occlusion of the artery with sustained myocardial dysfunction but without myocardial infarction in 4 weeks. Thereafter, extracorporeal SW therapy to the ischemic myocardial region (200 shots/spot for 9 spots at 0.09 mJ/mm2) was performed (n=8), which induced a complete recovery of left ventricular ejection fraction (51+/-2% to 62+/-2%), wall thickening fraction (13+/-3% to 30+/-3%), and regional myocardial blood flow (1.0+/-0.2 to 1.4+/-0.3 mL x min(-1) x g(-1)) of the ischemic region in 4 weeks (all P<0.01). By contrast, animals that did not receive the therapy (n=8) had sustained myocardial dysfunction (left ventricular ejection fraction, 48+/-3% to 48+/-1%; wall thickening fraction, 13+/-2% to 9+/-2%) and regional myocardial blood flow (1.0+/-0.3 to 0.6+/-0.1 mL x min(-1) x g(-1)). Neither arrhythmias nor other complications were observed during or after the treatment. SW treatment of the ischemic myocardium significantly upregulated vascular endothelial growth factor expression in vivo. CONCLUSIONS: These results suggest that extracorporeal cardiac SW therapy is an effective and noninvasive therapeutic strategy for ischemic heart disease.

Animals↗

PubMed2004

In vivo MR detection of vascular endothelial injury using a new class of MRI contrast agent.

A new class of dye-based MRI contrast agents, EB-DTPA-Gd, was designed and synthesized. The contrast agent was found to accumulate at the site of endothelial injury when the reagent was applied to isolated porcine blood vessels or in an ex vivo experiment using rat. In vivo MR detection of vascular endothelial injury was also successful in rat with its common carotid artery injured by balloon treatment. These results indicate that EB-DTPA-Gd is potentially useful for the diagnosis of vascular diseases.

Animals↗

PubMed2004

Remnant lipoproteins from patients with sudden cardiac death enhance coronary vasospastic activity through upregulation of Rho-kinase.

OBJECTIVE: Sudden cardiac death (SCD) still remains a serious problem. We have previously shown that remnant-like particles (RLP) are the major risk factor for SCD and that Rho-kinase plays a central role in the molecular mechanism of coronary vasospasm. In this study, we examined whether RLP from patients with SCD upregulate Rho-kinase associated with an enhanced coronary vasospastic activity. METHODS AND RESULTS: We isolated RLP and non-RLP in very-low-density lipoprotein (VLDL) fraction from SCD patients without coronary stenosis. We performed in vivo study in which we treated the coronary artery with RLP or non-RLP fraction at the adventitia in pigs. After 1 week, intracoronary serotonin caused marked coronary hyperconstriction at the segment treated with RLP fraction but not with non-RLP fraction (P<0.001, n=6), and hydroxyfasudil, a selective Rho-kinase inhibitor, dose-dependently inhibited the spasm in vivo. In organ chamber experiments, serotonin caused hypercontraction of vascular smooth muscle cells (VSMC) from RLP-treated segment, which was significantly inhibited by hydroxyfasudil (P<0.001, n=6). In cultured human coronary VSMC, the treatment with RLP significantly enhanced the expression and activity of Rho-kinase (P<0.05, n=6). CONCLUSIONS: These results indicate that RLP from SCD patients upregulate Rho-kinase in coronary VSMC and markedly enhance coronary vasospastic activity.

Adult↗

PubMed2004

Postprandial increase in plasma concentrations of remnant-like particles: an independent risk factor for restenosis after percutaneous coronary intervention.

Postprandial increase in remnant lipoprotein concentrations has been suggested as an important atherogenic factor. However, the influence of these remnants on the development of restenosis after percutaneous coronary intervention (PCI) remains to be examined. The present study was designed to address this point. In 60 consecutive patients with successful PCI, the influences of possible risk factors on the development of restenosis, including remnant-like particles (RLP) cholesterol (RLP-C) and triglyceride (RLP-TG), were examined. While mean concentrations of RLP-C and RLP-TG were normal in fasting state, postprandial change in RLP-C concentrations was a significant and independent risk factor for restenosis after PCI. The calculated cut-off index (COI) for the change was +64%. When the patients were divided into 2 groups according to this COI, minimal lumen diameter (MLD) and reference coronary diameter were comparable before and immediately after PCI between the high- (COI < 64%) and the low- (COI < 64%) responders. However, follow-up coronary angiography 3 to 6 months after PCI demonstrated that MLD, late loss, and loss index were all worse in the high responders compared with the low responders. These results indicate that post-prandial increase in RLP-C concentrations is an independent risk factor for restenosis after successful PCI, even in patients with normal fasting RLP-C levels.

Aged↗

PubMed2004

First functionalized MRI contrast agent recognizing vascular lesions.

A new MRI-contrast agent, EB-DTPA-Gd, that has an Evans Blue analogue as a sensing unit for endothelium lesions, was designed and synthesized. The agent also has diethylenetriamine-N,N,N',N",N"-pentaacetic acid-Gd complex (Gadolinium-DTPA) units, which have been used as detection units for T1-weighted MRI. The EB-DTPA-Gd was able to recognize and adsorb to the vascular endothelium-denuded region of porcine aorta, and to decrease the relaxation time of circumferential water's protons, making possible MR imaging of the endothelium-denuded region. The compound can be employed as a contrast agent for the imaging of vascular lesions using MRI.

Contrast Media↗

PubMed2003

Long-term treatment with a Rho-kinase inhibitor improves monocrotaline-induced fatal pulmonary hypertension in rats.

Primary pulmonary hypertension is a fatal disease characterized by endothelial dysfunction, hypercontraction and proliferation of vascular smooth muscle cells (VSMCs), and migration of inflammatory cells, for which no satisfactory treatment has yet been developed. We have recently demonstrated that intracellular signaling pathway mediated by Rho-kinase, an effector of the small GTPase Rho, is involved in the pathogenesis of arteriosclerosis. In the present study, we examined whether the Rho-kinase-mediated pathway is also involved in the pathogenesis of fatal pulmonary hypertension in rats. Animals received a subcutaneous injection of monocrotaline, which resulted in the development of severe pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular lesions in 3 weeks associated with subsequent high mortality rate. The long-term blockade of Rho-kinase with fasudil, which is metabolized to a specific Rho-kinase inhibitor hydroxyfasudil after oral administration, markedly improved survival when started concomitantly with monocrotaline and even when started after development of pulmonary hypertension. The fasudil treatment improved pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular lesions with suppression of VSMC proliferation and macrophage infiltration, enhanced VSMC apoptosis, and amelioration of endothelial dysfunction and VSMC hypercontraction. These results indicate that Rho-kinase-mediated pathway is substantially involved in the pathogenesis of pulmonary hypertension, suggesting that the molecule could be a novel therapeutic target for the fatal disorder.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2003

Long-term inhibition of Rho-kinase suppresses neointimal formation after stent implantation in porcine coronary arteries: involvement of multiple mechanisms.

OBJECTIVE: We recently demonstrated that Rho-kinase, an effector of the small GTPase Rho, is substantially involved in the pathogenesis of arteriosclerosis. In this study, we examined whether Rho-kinase is also involved in in-stent restenosis and if so, what mechanism is involved. METHODS AND RESULTS: Pigs underwent stent implantation in the left coronary artery with or without administration of fasudil (30 mg/kg per day orally), a specific Rho-kinase inhibitor, starting 2 days before the procedure for a duration of 4 weeks. On day 28, reductions in coronary diameter and neointimal formation associated with macrophage accumulation, collagen deposition, and transforming growth factor (TGF)-beta1 expression were noted at the stent site, and all were significantly suppressed by fasudil. On day 7, fasudil significantly increased the frequency of TUNEL-positive apoptotic cells, while it tended to reduce that of bromodeoxyuridine-positive proliferating cells in the neointima. Western blot analysis on day 7 demonstrated that phosphorylations of the ezrin/radixin/moesin family (a marker of Rho-kinase activity in vivo) and protein expression of monocyte chemoattractant protein-1and bcl-2 were upregulated at the stent site and were significantly suppressed by fasudil. CONCLUSIONS: These results indicate that long-term inhibition of Rho-kinase suppresses in-stent neointimal formation by multiple mechanisms, including reduced vascular inflammation, enhanced apoptosis, and decreased collagen deposition.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed2003

Application of nanoparticle technology for the prevention of restenosis after balloon injury in rats.

Restenosis after percutaneous coronary intervention continues to be a serious problem in clinical cardiology. Recent advances in nanoparticle technology have enabled us to deliver an antiproliferative drug selectively to the balloon-injured artery for a longer time. NK911, which is a core-shell nanoparticle of polyethyleneglycol-based block copolymer encapsulating doxorubicin, accumulates in vascular lesions with increased permeability. We first confirmed that balloon injury caused a marked and sustained increase in vascular permeability (as evaluated by Evans blue staining) for a week in the rat carotid artery. We then observed that intravenous administration of just 3 times of NK911, but not doxorubicin alone, significantly inhibited the neointimal formation of the rat carotid artery at 4 weeks after the injury in both a single- and double-injury model. Immunostaining demonstrated that the effect of NK911 was due to inhibition of vascular smooth muscle proliferation but not to enhancement of apoptosis or inhibition of inflammatory cell recruitment. Measurement of vascular concentrations of doxorubicin confirmed the effective delivery of the agent to the balloon-injured artery by NK911 in both a single- and double-injury model. RNA protection assay demonstrated that NK911 inhibited expression of several cytokines but not that of apoptosis-related molecules. NK911 was well tolerated without any adverse systemic effects. These results suggest that nanoparticle technology to target vascular lesions with increased permeability is a promising and safe approach for the prevention of restenosis after balloon injury. The full text of this article is available at http://www.circresaha.org.

Animals↗

PubMed2002

[A lesion diagnosed by MRI in a case of transient global amnesia].

Transient global amnesia(TGA) had been recognized as a disease without abnormal findings on neuroimaging before magnetic resonance(MRI) imaging was practicable. Recently, abnormal findings on MRI reported in cases of TGA. We here reported a case of TGA showing a transient abnormal intensity in left hippocampus on MRI diffusion-weighted image. A 52-year-old man suddenly became to unable to keep his recent memory without histories of trauma or epilepsy. He showed no abnormal neurologic findings excepting for the recent memory. MRI performed within an hour after onset demonstrated no abnormality on T1- and T2-weighted images. Diffusion-weighted image (b = 1,000) showed hyperintensity in the left medial temporal lobe, and the apparent diffusion coefficient(ADC) in this region was lower(72.8 cm2/s) than that in the contralateral region(94.4 cm2/s). TGA was completely resolved 17 hours after onset.

Amnesia↗