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Biomedical subjects

Masataka Sata

Publications and source records attributed to Masataka Sata.

At least 37 records · Page 2Linked to original sources
PubMed2005

The angiotensin II type 1 receptor blocker candesartan attenuates graft vasculopathy.

OBJECTIVE: Transplant arteriosclerosis remains the major cause of graft failure after cardiac transplantation, although recent progress in immunosuppressive therapy has dramatically improved short-term survival of recipient. We investigated the effects of the angiotensin II type 1 receptor (AT(1)R) blocker candesartan on the development of transplant arteriosclerosis in a murine model of cardiac transplantation. MATERIALS AND METHODS: Hearts from DBA/2 (H-2(d)) mice were heterotopically transplanted into B10.D2 (H-2(d)) mice. Recipients were treated with oral administration of candesartan (1 mg/kg per day) or vehicle. Allografts were analyzed at 14 or 30 days after transplantation. RESULTS: Candesartan significantly reduced the development of coronary arteriosclerosis (intima/media ratio: 0.86 +/- 0.09 versus 0.57 +/- 0.10, P < 0.05), without affecting the degree of parenchymal rejection at 30 days. There was no significant difference in the expression of adhesion molecules and cytokines at 14 days. Candesartan significantly reduced the number of peripheral mononuclear cells that differentiated into smooth muscle-like cells in the presence of basic fibroblast growth factor and platelet-derived growth factor BB (27.1 +/- 3.1 versus 17.3 +/- 1.8 cells/HPF, P < 0.05). CONCLUSIONS: Angiotensin II may play a role in the pathogenesis of transplant arteriosclerosis. Blockade of AT(1)R might be effective as a prophylactic therapy for transplant arteriosclerosis along with conventional immunosuppressive drugs.

Angiotensin II Type 1 Receptor Blockers↗
PubMed2005

Hepatic gene induction in murine bone marrow after hepatectomy.

BACKGROUND/AIMS: Bone marrow cells are highly plastic and differentiate into various cell types, including hepatocytes. To explore the mechanisms underlying these processes, we focused on the initial responses of bone marrow to hepatectomy, using a mouse model. METHODS: To evaluate hepatic differentiation in bone marrow cells we measured hepatocyte-related gene expression in mice undergoing partial hepatectomy with or without pretreatment for 1 week with 2-acetyl aminofluorene (AAF). RESULTS: Hepatectomy induced several genes related to early hepatic differentiation in bone marrow. Expression of these genes was enhanced by the administration of AAF, whereas genes specific for mature hepatocytes were not detected. We characterised the bone marrow cell population expressing hepatocyte differentiation genes. alpha-fetoprotein mRNA was induced in Lin- and either CD34+, c-kit+, Sca-1+, CD49f+ or CD45+ cells. The genes upregulated in the liver after AAF treatment and hepatectomy were identified using oligonucleotide microarrays. These included genes associated with the acute phase response. Dexamethasone inhibited the expression of early hepatic differentiation genes in the bone marrow of AAF/PHx mice. CONCLUSIONS: Early hepatic differentiation genes were induced in bone marrow in response to hepatectomy, especially when regeneration of the remnant liver was suppressed. Circulating signals generated in the AAF/PHx liver might activate this differentiation.

2-Acetylaminofluorene↗
PubMed2005

Age-associated aortic stenosis in apolipoprotein E-deficient mice.

OBJECTIVES: The present study was designed to assess aortic valve morphology and function in mice of advanced age. We also evaluated the potential contribution of bone-marrow-derived cells to the pathogenesis of aortic stenosis. BACKGROUND: Age-associated valvular degeneration is characterized by lipid accumulation, collagen deposition, and calcification containing smooth muscle-like cells and osteoblast-like cells. Cellular and molecular factors that mediate these changes remain unknown. METHODS: We extensively examined the aortic valves of senile wild-type and apolipoprotein E (ApoE)-/- mice with echocardiography. The aortic valves were analyzed by immunohistochemistry and electron microscopy. The bone marrow of wild-type and ApoE-/- mice was reconstituted with that of green fluorescent protein (GFP) or beta-galactosidase (LacZ) mice, which expressed GFP or LacZ ubiquitously. RESULTS: Transaortic flow velocity was correlated with age in wild-type and ApoE-/- mice. The aortic valves of old ApoE-/- mice showed sclerosis that resembled the pathology of human aortic stenosis. A significant number of GFP-positive cells (10.7 +/- 4.1%) in the sclerotic valves of ApoE-/- mice expressed alpha-smooth muscle actin, whereas most of the GFP-positive cells were identified as endothelial cells or macrophages in wild-type mice. There were bone-marrow-derived cells that were positive for osteoblast-related proteins near the sites of ectopic calcification. The sclerotic valves displayed frequent apoptotic cell death and chemokine expression. CONCLUSIONS: Senile ApoE-deficient mice display aortic valve sclerosis that is similar to that observed in humans. The sclerotic valves displayed frequent apoptotic cell death and chemokine expression. Smooth muscle-like cells observed in degenerative valves might derive, at least in part, from bone marrow.

Age Factors↗
PubMed2005

Blockade of the stromal cell-derived factor-1/CXCR4 axis attenuates in vivo tumor growth by inhibiting angiogenesis in a vascular endothelial growth factor-independent manner.

The interaction between the chemokine receptor CXCR4 and its specific ligand, stromal cell-derived factor-1 (SDF-1/CXCL12), mediates several cellular functions. In cancer, SDF-1-positive or CXCR4-positive cells of various lineages are detected within tumor tissues. Recent intensive research has indicated the possibility that blocking CXCR4 could reduce the metastatic potential of cancer cells. Here, we show that the inhibition of the SDF-1/CXCR4 axis decreases the growth of s.c. gastrointestinal tumors through the suppression of tumor neoangiogenesis. The neutralization of CXCR4 suppressed the growth in vivo of tumors derived from mouse Colon38 and PancO2 cells, whereas it did not affect the growth of Colon38 and PancO2 cells in vitro. This attenuation of tumor growth was found to be independent of the expression of CXCR4 by the cancer cells themselves, because CXCR4 knocked-down Colon38 cells grew similarly to control cells. Furthermore, CD31-positive tumor capillaries were reduced to 45% (P < 0.001) and intratumor blood flows were decreased to 65% (P < 0.01) by blockade of CXCR4. The vascular endothelial growth factor (VEGF) concentration in the tumors was not affected by the neutralization of CXCR4. Taken together with the detection of CXCR4-positive endothelial cells in the tumor tissues, the findings suggest that the antiangiogenic effects of the blockade of CXCR4 are related to a reduction of the establishment of tumor endothelium independently of VEGF inhibition. Our data indicate that the SDF-1/CXCR4 pathway might be a general target for anticancer strategies and that blocking this system could be cooperatively effective in combination with other antiangiogenic therapies, such as blockade of VEGF.

Animals↗
PubMed2005

Comparison of various bone marrow fractions in the ability to participate in vascular remodeling after mechanical injury.

In contrast to conventional assumption, recent reports propose the possibility that hematopoietic stem cells (HSCs) may have broader potential to differentiate into various cell types. Here, we tested the pluripotency of HSCs by comparing vascular lesions induced by mechanical injury after bone marrow reconstitution with total bone marrow (TBM) cells, c-Kit+ Sca-1+ Lin- (KSL) cells, or a single HSC cell (Tip-SP CD34-KSL cell, CD34- c-Kit+ Sca-1+ Lin- cell with the strongest dye-efflux activity) harboring green fluorescent protein (GFP). The lesions contained a significant number of GFP-positive cells in the TBM and KSL groups, whereas GFP-positive cells were rarely detected in the HSC group. These results suggest that transdifferentiation of a highly purified HSC seems to be a rare event, if it occurs at all, whereas bone marrow cells including the KSL fraction can give rise to vascular cells that substantially contribute to repair or lesion formation after mechanical injury.

Animals↗
PubMed2005

Uni-axial stretching regulates intracellular localization of Hic-5 expressed in smooth-muscle cells in vivo.

Hic-5 is a focal adhesion protein belonging to the paxillin LIM family that shuttles in and out of the nucleus. In the present study, we examined the expression of Hic-5 among mouse tissues by immunohistochemistry and found its expression only in smooth-muscle cells in several tissues. This result is consistent with a previous report on adult human tissues and contradicts the relatively ubiquitous expression of paxillin, the protein most homologous to Hic-5. One factor characterizing smooth-muscle cells in vivo is a continuous exposure to mechanical stretching in the organs. To study the involvement of Hic-5 in cellular responses to mechanical stress, we exposed mouse embryo fibroblasts to a uni-axial cyclic stretching and found that Hic-5 was relocalized from focal adhesions to stress fibers through its C-terminal LIM domains during the stress. In sharp contrast to this, paxillin did not change its focal-adhesion-based localization. Of the factors tested, which included interacting partners of Hic-5, only CRP2 (an only-LIM protein expressed in vascular smooth-muscle cells) and GIT1 were, like Hic-5, localized to stress fibers during the cyclic stretching. Interestingly, Hic-5 showed a suppressive effect on the contractile capability of cells embedded in three-dimensional collagen gels, and the effect was further augmented when CRP2 co-localized with Hic-5 to fiber structures of those cells. These results suggested that Hic-5 was a mediator of tensional force, translocating directly from focal adhesions to actin stress fibers upon mechanical stress and regulating the contractile capability of cells in the stress fibers.

Actinin↗
PubMed2005

Potent inhibitory effect of sirolimus on circulating vascular progenitor cells.

BACKGROUND: Neointimal hyperplasia is the major cause of in-stent restenosis (ISR). The sirolimus-eluting stent (SES) has emerged as a promising therapy to prevent ISR; however, the exact mechanism by which locally delivered sirolimus, an immunosuppressive agent, prevents ISR remains unknown. Recent evidence suggests that circulating progenitor cells may contribute to neointimal formation. METHODS AND RESULTS: Mononuclear cells (MNCs) were isolated from peripheral blood of healthy human volunteers. Smooth muscle (SM)-like cells outgrew from the culture of MNCs (1x10(6)) in the presence of platelet-derived growth factor-BB and basic fibroblast growth factor, whereas endothelial cell-like cells were obtained in the presence of vascular endothelial growth factor. Sirolimus potently inhibited SM-like cell outgrowth. The number of SM-like cells was significantly reduced at a concentration as low as 0.1 ng/mL (15.9+/-5.8% of control, P<0.001). Sirolimus also exerted an inhibitory effect on endothelial cell-like cells that originated from MNCs. Wire-mediated vascular injury was induced in femoral arteries of bone marrow chimeric mice. Either vehicle or sirolimus was administered locally to the perivascular area of the injured arteries. Sirolimus significantly reduced neointima hyperplasia at 4 weeks (intima/media ratio 2.0+/-0.3 versus 1.0+/-0.2, P<0.05) with a decreased number of bone marrow-derived SM-like cells and hematopoietic cells in the lesion. Reendothelialization was retarded in the arteries treated with sirolimus. CONCLUSIONS: The potent inhibitory effects of sirolimus on circulating smooth muscle progenitor cells may mediate the clinical efficacy of SES, at least in part. Sirolimus potentially may affect reendothelialization after stent implantation.

Animals↗
PubMed2005

Human umbilical cord blood cells improve cardiac function after myocardial infarction.

Human umbilical cord blood (UCB) contains an abundance of immature stem/progenitor cells and has been clinically used as an alternative to bone marrow transplantation. In addition, cord blood can be obtained non-invasively, in contrast to invasive bone marrow aspiration. We investigated the potential of human UCB CD34(+) cells to improve cardiac function following myocardial infarction. Myocardial infarction was induced in Wistar rats by ligation of the left coronary artery. Either 2x10(5) human UCB CD34(+) cells or equivalent cell-free medium was injected into the injured myocardium of the rats following induction of myocardial infarction. CD34(+) cell transplantation significantly improved ventricular function as compared to the control group. Immunofluorescence staining for human CD34, CD45, and PECAM-1 revealed surviving cells in the myocardium. Our findings suggest that transplanted human cells survived and improved cardiac function following myocardial infarction. These results may show the usefulness of UCB CD34(+) cells for myocardial infarction.

Animals↗
PubMed2005

Cimetidine inhibits angiogenesis and suppresses tumor growth.

Cimetidine, a histamine type-2 receptor antagonist, has been reported to improve survival of patients with cancers. However, the exact mechanisms by which cimetidine suppresses development of cancers remain to be elucidated. Solid tumors require neovascularization for their growth. Here, we investigated the effects of cimetidine on tumor growth and angiogenesis. Syngeneic colon cancer cells, CMT93 cells, were inoculated into the subcutaneous space of C57BL/6 mice. Mice were treated with either saline or cimetidine. Tumor size was measured everyday and angiogenesis was evaluated histologically. Cimetidine markedly suppressed tumor growth with reduced neovascularization in the tumor. Cimetidine had no effect on proliferation of CMT93 cells in vitro. Vascular endothelial growth factor production by cancer cells was not affected by cimetidine, while vascular-like tube formation by endothelial cells in vitro was significantly impaired in the presence of cimetidine. Our findings suggest that cimetidine suppresses tumor growth, at least in part, by inhibiting tumor-associated angiogenesis.

Angiogenesis Inhibitors↗
PubMed2005

Reduced p38 mitogen-activated protein kinase in donor grafts accelerates acute intestinal graft-versus-host disease in mice.

The gastrointestinal tract is a major target of graft-versus-host disease (GVHD), which constitutes a life-threatening complication of bone marrow transplantation. GVHD is mainly caused by the activation of donor-derived lymphocytes, in which cytokine cascades play essential roles. Since p38 MAPK (p38) has been identified as a regulator of cytokine reactions and proposed as a molecular target for anti-inflammatory therapy, we investigated the contribution of p38 to the severity of murine intestinal GVHD. Unexpectedly, p38alpha(+/-) donor graft induced more acute GVHD-related mortality and more severe gut injury. The survival of p38alpha(+/-) donor-derived intestinal intraepithelial lymphocytes (IEL) was prolonged in vitro and in vivo, and TNF-alpha expression in the p38alpha(+/-) donor-derived IEL was also increased compared with wild-type cells. In contrast, the p38alpha(+/-) grafted mice resulted in decreased expansion of donor lymphocytes in mesenteric lymph nodes, and the up-regulation of IL-12p40 and IL-18 was diminished. These findings suggest that p38 has dichotomous effects for inflammatory response in vivo; not only regulates inflammatory cytokine expression and lymphocyte expansion, but also has distinct regulatory functions for IEL in intestinal GVHD. In conclusion, the inhibition of p38 may not be a suitable anti-inflammatory strategy for GVHD due to the associated intestinal injury.

Acute Disease↗
PubMed2005

Seeding of recipient bone marrow cells reduces neointimal hyperplasia of de-endothelialized rat aortic allograft.

Transplant vasculopathy is a leading cause of graft failure and a major contributor to the lack of success with small caliber vascular allografts. In this study we evaluate techniques of bone marrow cell seeding on small caliber vessels and assess the impact of this tactic on neointimal hyperplasia in de-endothelialized rat aortic allografts. In a preliminary study, bone marrow cells from Lewis rats were seeded onto the chemically de-endothelialized luminal surface of the abdominal aorta of WKY rats - with or without fibrin glue. In the allograft transplantation model, de-endothelialized fresh aortic allografts of WKY rats were orthotopically transplanted into Lewis recipients either directly (n = 6) or after recipient bone marrow cell seeding (n = 6). Histological evaluation was performed at 28 days. Bone marrow cells were able to adhere to the de-endothelialized aortic wall owing to the use of fibrin glue, but were unable to do so without fibrin glue. In the de-endothelialized allograft transplantation model, recipient bone marrow seeding led to a significant reduction of the ratio of intimal to medial area (0.40 +/- 0.08 versus 0.79 +/- 0.08, P = 0.0077). Some of the seeded cells remained in the intima for 4 weeks and some infiltrated the media, expressing CD31 or alpha-SMA. The results suggest that recipient bone marrow cell seeding on de-endothelialized aortic allograft is feasible with the use of fibrin glue and that this technique reduces neointimal hyperplasia of the graft.

Actins↗
PubMed2005

Reversible left ventricular hypertrophy after tako-tsubo-like cardiomyopathy.

Tako-tsubo-like cardiomyopathy is a newly-recognized enigmatic disease characterized by transient left ventricular dysfunction of a broad area of the apex with a hyperkinetic area around the cardiac base. There is ST-segment elevation with no coronary stenosis. The exact mechanism for this entity remains unknown. Here, we report a case of tako-tsubo-like cardiomyopathy that showed a marked left ventricular hypertrophy (LVH) when the wall motion returned to normal. LVH was normalized at 10 months. The cause of LVH remains unknown.

Aged↗
PubMed2005

[Circulating progenitors contribute to angiogenesis, vascular repair, and lesion formation].

Atherosclerosis is responsible for more than half of all deaths in western countries. Numerous studies have reported that exuberant accumulation of smooth muscle cells plays a principal role in the pathogenesis of vascular diseases. It has been assumed that smooth muscle cells derived from the adjacent medial layer migrate, proliferate and synthesize extracellular matrix. Although much effort has been devoted, targeting migration and proliferation of medial smooth muscle cells, no effective therapy to prevent occlusive vascular remodeling has been established. Recently, we reported that bone marrow cells substantially contribute to the pathogenesis of vascular diseases, in models of post-angioplasty restenosis, graft vasculopathy and hyperlipidemia-induced atherosclerosis. It was suggested that bone marrow cells may have the potential to give rise to vascular progenitor cells that home in the damaged vessels and differentiate into smooth muscle cells or endothelial cells, thereby contributing to vascular repair, remodeling, and lesion formation. This article overviews recent findings on circulating vascular precursors and describes potential therapeutic strategies for vascular diseases, targeting mobilization, homing, differentiation and proliferation of circulating progenitor cells.

Animals↗
PubMed2004

Administration of ANG II induces iron deposition and upregulation of TGF-beta1 mRNA in the rat liver.

We previously found that ANG II infusion into rats causes iron deposition in the kidney and heart, which may have a role in the regulation of profibrotic gene expression and tissue fibrosis. In the present study, we have investigated whether ANG II can also induce iron accumulation in the liver. Prussian blue staining detected frequent iron deposition in the interstitium of the liver of rats treated with pressor dose ANG II for 7 days, whereas iron deposition was absent in the livers of control rats. Immunohistochemical and histological analyses showed that some iron-positive nonparenchymal cells were positive for ferritin and heme oxygenase-1 (HO-1) protein and TGF-beta1 mRNA and were judged to be monocytes/macrophages. It was shown that ANG II infusion caused about a fourfold increase in ferritin and HO-1 protein expression by Western blot analysis and about a twofold increase in TGF-beta1 mRNA expression by Northern blot analysis, which were both suppressed by treating ANG II-infused rats with losartan and deferoxamine. In addition, mild interstitial fibrosis was observed in the liver of rats that had been treated with pressor dose ANG II for 7 days or with nonpressor dose ANG II for 30 days, the latter of which also caused loss of hepatocytes and intrahepatic hemorrhage in the liver. Taken together, our data suggest that ANG II infusion induces aberrant iron homeostasis in the liver, which may have a role in the ANG II-induced upregulation of profibrotic gene expression in the liver.

Angiotensin II↗
PubMed2004

Iron chelation and a free radical scavenger suppress angiotensin II-induced upregulation of TGF-beta1 in the heart.

Long-term administration of angiotensin II causes myocardial loss and cardiac fibrosis. We previously found iron deposition in the heart of the angiotensin II-infused rat, which may promote angiotensin II-induced cardiac damage. In the present study, we have investigated whether an iron chelator (deferoxamine) and a free radical scavenger (T-0970) affect the angiotensin II-induced upregulation of transforming growth factor-beta1 (TGF-beta1). Angiotensin II infusion for 7 days caused a robust increase in TGF-beta1 mRNA expression in vascular smooth muscle cells, myofibroblast-like cells, and migrated monocytes/macrophages. T-0970 and deferoxamine suppressed the upregulation of TGF-beta1 mRNA and reduced the extent of cardiac fibrosis in the heart of rats treated with angiotensin II. These agents blocked the angiotensin II-induced upregulation of heme oxygenase-1, a potent oxidative and cellular stress-responsive gene, but they did not significantly affect systolic blood pressure or plasma levels of aldosterone. In addition, T-0970 and deferoxamine suppressed the angiotensin II-induced upregulation of monocyte chemoattractant protein-1 in the heart. These results collectively suggest that iron and the iron-mediated generation of reactive oxygen species may contribute to angiotensin II-induced upregulation of profibrotic and proinflammatory genes, such as TGF-beta1 and monocyte chemoattractant protein-1.

Aldosterone↗
PubMed2004

The angiotensin II type 1 receptor blocker valsartan attenuates graft vasculopathy.

OBJECTIVE: Transplant arteriosclerosis remains the major cause of graft failure after cardiac transplantation. Here, we investigated the effects of the angiotensin II type 1 receptor blocker valsartan on the development of transplant arteriosclerosis in a murine model of cardiac transplantation. METHODS: Hearts from DBA/2 (H-2(d)) mice were heterotopically transplanted into B10.D2 (H-2(d)) mice. Recipients were treated with oral administration of valsartan (10 mg/kg/day) or vehicle. RESULTS: Morphometrical analysis of the cardiac allografts harvested at 30 days revealed that valsartan significantly reduced the development of coronary atherosclerosis (intima/media ratio: 0.39 +/- 0.05 vs. 0.66 +/- 0.08, P < 0.01). At two weeks after transplantation, there was no significant difference between the two groups in expression of adhesion molecules and cytokines. Valsartan significantly reduced the number of peripheral mononuclear cells that differentiated into smooth muscle-like cells in the presence of basic fibroblast growth factor and platelet-derived growth factor BB (18.0 +/- 1.5 vs. 30.3 +/- 4.4 cells/HPF, P = 0.01). CONCLUSIONS: These results suggest that angiotensin II plays a role in the pathogenesis of transplant arteriosclerosis and that blockade of angiotensin II type 1 receptor might be effective as a prophylactic therapy for transplant arteriosclerosis along with conventional immunosuppressive drugs.

Angiotensin II Type 1 Receptor Blockers↗