Biomedical subjects

Yoshinori Ohtsu

Publications and source records attributed to Yoshinori Ohtsu.

7 recordsLinked to original sources

PubMed2005

Stimulation of P19CL6 with multiple reagents induces pulsating particles in vivo.

OBJECTIVE: Injection of stem cells into ischaemic areas of the heart is expected to be an effective method for myocardial regeneration. The embryogenic carcinoma (EC) cell line P19CL6 is known to differentiate into cardiomyocytes when cultured with dimethyl sulfoxide (DMSO) and is expected to be a promising source for regenerative therapy in cardiac disease. To establish a high-yield method of cardiomyocyte differentiation, P19CL6 cells were double-stimulated with 5-azacytidine. Double stimulation-induced cardiomyocytes were also transplanted into ectopic sites in mice and their function evaluated. METHODS AND RESULTS: To induce differentiation under adherent conditions, P19CL6 cells were incubated in growth medium with 10 microM 5-azacytidine for 24 h. After 5-azacytidine treatment, P19CL6 cells were incubated with 1% DMSO for nine days until they began to pulsate. Prior to transplantation, cells were treated again with 5-azacytidine. Differentiated cells were injected into the greater omentum, para-aorta region of the retroperitoneum and peri-femoral artery of adult BALB/c nude mice. Nine days after transplantation, irregularly pulsating tissues at a rate slower than the host heart were observed in the transplanted sites. Light microscopy showed formation of cardiac muscle tissues originating from P19CL6 cells. Differentiated cardiomyocytes were positive for cardiac troponin I, cadherin and alpha-smooth muscle actin, and the expressions of Csx/Nkx2.5 and GATA4 mRNAs were up-regulated. Electron microscopy demonstrated components specific to cardiomyocytes, such as Z-bands, desmosomes, fasciae adherens, myofibrils and mitochondria, which confirmed successful heterotopic cardiac muscle differentiation from P19CL6 cells. CONCLUSION: This study demonstrated high-yield cardiac muscle differentiation of P19CL6 by 5-azacytidine and DMSO double stimulation and successful formation of cardiac muscle-like tissue by ectopic transplantation of cardiomyocytes derived from P19CL6 into the retroperitoneal area as well as into the peripheral vessel area.

Adaptor Proteins, Signal Transducing↗

PubMed2005

Bone marrow cell-seeded biodegradable polymeric scaffold enhances angiogenesis and improves function of the infarcted heart.

BACKGROUND: The present study examined whether a bioengineered polyglycolic acid cloth (PGAC) impregnated with bone marrow cells (BMC) improved the function and angiogenesis of the infarcted heart. METHODS AND RESULTS: The coronary artery was ligated in Lewis rats and the infarcted area was covered with a PGAC in group 1 (n=8), with a PGAC containing basic-fibroblast growth factor (b-FGF) in group 2 (n=11) and a PGAC containing b-FGF and freshly isolated BMC in group 3 (n=10). In addition, BMC derived from transgenic mice expressing green fluorescent protein (GFP)-BMC were seeded into a PGAC, which was sutured over the infarcted area of C57BL/6 mice (n=5). In the rat study, developed and systolic pressures, dp/dt max and dp/dt min) were the highest in group 3, as were the capillary density in the PGAC and infarcted area. In the mouse study, there were few GFP-BMC in the PGAC, but none in the infarcted area. CONCLUSIONS: A PGAC with BMC improved cardiac function by inducing angiogenesis without migration of BMC. Freshly isolated BMC work as angiogenic inducers and a PGAC is useful as a "drug delivery system".

Absorbable Implants↗

PubMed2004

A novel application of myocardial contrast echocardiography to evaluate angiogenesis by autologous bone marrow cell transplantation in chronic ischemic pig model.

OBJECTIVES: We investigated the feasibility of myocardial contrast echocardiography (MCE) to evaluate regional perfusion after bone marrow cell transplantation. BACKGROUND: The myocardial microvessels improved by cell transplantation are too small to visualize with conventional angiography. METHODS: Fourteen mini-pigs from the Nippon Institute for Biological Science were used. The proximal left anterior descending coronary artery was ligated. One month later, nine pigs survived. Six pigs received autologous cell transplantation into the left ventricular anterior wall: bone marrow mononuclear cells (BMMNCs) (n = 3) and bone marrow stromal cells (BMSCs) (n = 3). The other three pigs received saline (control group, n = 3). The pigs were sacrificed one month later. Myocardial contrast intensity (MCI) with a contrast agent was measured using the SONOS 5500 system (Philips). Capillary density (CD) and MCI were measured at four areas: anteroseptum (nontransplanted infarct area), anterior wall (transplanted infarct area), septum (border zone), and lateral wall (normal). We compared the anteroseptum with the anterior wall by MCI and CD. RESULTS: In the BMMNC and BMSC subsets, the CD of the anterior wall was higher than that of the anteroseptum (p < 0.001). There was a linear relation between MCI and CD (acoustic unit [AU2] = 0.234 CD + 0.010, r = 0.92, p < 0.001). At one month after cell transplantation, MCI of the anterior wall increased in the BMMNC and BMSC subsets (p < 0.05), although it did not change in the control group. The ratio of wall thickness (systole/diastole) in the transplanted infarct area was larger than that in the nontransplanted infarct area (p < 0.01). CONCLUSIONS: Myocardial contrast echocardiography is useful to evaluate regional perfusion, which was enhanced by bone marrow cell transplantation.

Animals↗

PubMed2004

Bone marrow is a source of regenerated cardiomyocytes in doxorubicin-induced cardiomyopathy and granulocyte colony-stimulating factor enhances migration of bone marrow cells and attenuates cardiotoxicity of doxorubicin under electron microscopy.

BACKGROUND: It has been reported previously that granulocyte colony-stimulating factor (GCSF) injection improves infarcted heart function, but the mechanism remains unclear. In this study we sought to determine whether GCSF-mobilized bone marrow cells could regenerate neo-myocardium and repair doxorubicin-induced cardiomyopathy. METHODS: C57BL/6 mice were irradiated and bone marrow cells (BMC; 1 x 10(6)) from green fluorescent protein (GFP) mice (GFP-BMC) were transplanted intravenously, followed by splenectomy. Doxorubicin (2.5 mg/kg, 6 times for 2 weeks) was administered intraperitoneally 2 weeks later. GCSF (50 microg/kg/day for 8 days) was administered sub-cutaneously after doxorubicin injection (Group I, n = 11) and 3 weeks later (Group II, n = 8), and saline was injected in Group III animals (n = 8). Eight weeks after doxorubicin injection, the excised hearts were studied immunologically and electron microscopically. RESULTS: Survival rates were 81.8% in Group I, 50.0% in Group II and 62.5% in Group III. The number of GFP-BMC in Group I (15.4 +/- 7.4 per high-power field) was highest (p < 0.05). In all groups, cardiac troponin I-positive cells derived from GFP-BMC were observed in the hearts. GFP-BMC in hearts stained positively against cardiac troponin I (4.3 +/- 2.5%), myosin heavy chain (5.0 +/- 4.3%), atrial natriuretic peptide (ANP; 3.9 +/- 2.4%) and connexin 43 (11.9 +/- 7.3%) in Group I. Myofibrils, mitochondria and fundamental architecture were almost all preserved in Group I, whereas hearts were severely damaged in Groups II and III. CONCLUSIONS: Bone marrow was shown to be one of the sources of regenerated cardiomyocytes in the doxorubicin-induced cardiomyopathic heart. Early administration of GCSF enhanced the migration of bone marrow cells into the heart, and attenuated the cardiotoxicity of doxorubicin.

Animals↗

PubMed2004

Acute effects of direct cell implantation into the heart: a pressure-volume study to analyze cardiac function.

BACKGROUND: To safely implant cells into the myocardium, we must establish a volume that prevents compromising cardiac performance. We studied pressure-volume (PV) to investigate the adverse effects of direct cell implantation in the acute phase. METHODS: We used 21 minipigs. In the normal heart model, we studied PV by measuring various parameters (including end-systolic pressure, end-systolic elastance, dp/dtmax, end-diastolic volume, and time constant of isovolumetric left ventricular pressure fall [Tau]). We injected solutions into the left ventricular free wall (15 cm(2)). Sampling points were at baseline and after injection of saline (Group I, n = 4) or of blood (Group II, n = 4) at volumes of 1 ml and 10 ml up to 30 minutes after injection. In Group II, we injected additional blood (10 ml) 4 times. In the ischemic heart model, 1 month after ligating the left anterior descending artery, we injected 1 ml saline (Group III, n = 4), bone marrow mononuclear cells (10(8) cells/1 ml; Group IV, n = 4), or bone marrow stromal cells (10(8) cells/1 ml; Group V, n = 3). We studied PV before and after injection. RESULTS: In Group I, we found no significant changes in parameters. In Group II, end-diastolic volume after 10-ml injection (24.4 +/- 3.6 ml) was smaller than end-diastolic volume at baseline (29.5 +/- 5.8 ml, p < 0.01). Tau after 10-ml injection (39.4 +/- 5.3 msec) was greater than at baseline (35.6 +/- 4.0 msec, p < 0.01). One pig died of ventricular fibrillation after a 20-ml injection of blood. We observed no detrimental effects in Groups III, IV, and V. CONCLUSIONS: More than 10 ml cell suspension compromised diastolic function. We safely performed direct injection of bone marrow cells (1 x 10(8)/1 ml).

Animals↗

PubMed2004

Bone marrow mononuclear cell transplantation had beneficial effects on doxorubicin-induced cardiomyopathy.

BACKGROUND: Cell transplantation is a promising therapy for treating end-stage heart failure. Bone marrow mononuclear cells (BMMNC) have been used to enhance angiogenesis in ischemic heart disease. However, the effect of BMMNC transplantation in non-ischemic dilated cardiomyopathy is unknown. In this study, we evaluated the efficacy of BMMNC transplantation in doxorubicin-induced cardiomyopathy in a rat model. METHODS: Doxorubicin (15 mg/kg, IP) was introduced into 52 Lewis rats. They were divided into 3 groups at 4 weeks after injection: transplant group (TX, BMMNC [1 x 10(6)] implantation, n = 18), control group (CN, saline injection, n = 18), and sham group (SH, thoracotomy, n = 16). At 4 weeks after surgery, we used echocardiography to measure systolic left ventricular diameter (LVDs), diastolic left ventricular diameter (LVDd), fractional shortening (FS), and left ventricular wall thickness/LVDs. We used a Langendorff apparatus to measure systolic, diastolic, and developed pressures. We used radioimmunoassay to measure circulating atrial natriuretic peptide concentration, and we performed histologic study, including electron-microscopic study. RESULTS: Left ventricular wall thickness/LVDs in the TX group was the largest of all groups (p < 0.05). Systolic and developed pressures in the TX group were the greatest (p < 0.005). Systolic left ventricular diameter, FS, and end-diastolic pressure in the TX group were smaller than in the SH group (p < 0.05). These cardiac parameters did not differ significantly between TX and CN groups, but secondary changes (decreased heart weight, developed ascites, and increased atrial natriuretic peptide concentration) caused by doxorubicin-induced heart failure were most attenuated in the TX group. In the TX group, vascular density was greatest (p < 0.05) in the left ventricular free wall and in the septum. In addition, electron microscopy showed that myocardium in the TX group was most maintained. CONCLUSION: Bone marrow mononuclear cell transplantation had beneficial effects in doxorubicin-induced cardiomyopathy.

Animals↗

PubMed2004

G-CSF promotes bone marrow cells to migrate into infarcted mice heart, and differentiate into cardiomyocytes.

A recent study showed that granulocyte-colony stimulating factor (G-CSF) treatment improved the infarcted cardiac function. Although mobilized stem cells may affect it, the mechanism is unclear. In this study, we investigated the origins of stem cells and phenotypic changes of the migrated cells, and evaluated the efficacy of G-CSF. Eighteen C57BL/6 mice were irradiated (900 cGy) and GFP mouse-derived bone marrow cells (GFP-BMC: 10(6) cells) were injected via a tail vein followed by splenectomy 4 weeks later. Ligation of the left descending coronary artery was performed 2 weeks later. Recombinant human G-CSF (200 microg/kg/day) was injected for 3 days before and 5 days after ligation (group 1, n = 10). Saline was injected in group 2 (n = 8). Four weeks after infarction, hearts and other organs were fixed for histology. The survival rate after postoperative day 3 in group 1 was 100%, while that in group 2 was 50% (p = 0.03). Bone marrow-derived GFP cells (BMD-GFP) in group 1 (103.3+/-71.9/mm2) were located at the infarcted border area significantly more than those in group 2 (43.6+/-23.7/mm2) (p < 0.0001). BMD-GFP cells were positive for troponin I (16.6%), myosin heavy chain-slow (16.7%), and nestin (8.8%) in group 1. Ki-67-positive BMD-GFP in group 1 (10.0+/-7.0/mm2) were significantly more than those in group 2 (4.8+/-6.1/mm2) (p = 0.01). G-CSF increased the survival rate after infarction. G-CSF promoted BMC to migrate into the infarcted border area. Bone marrow was one of the origins of regenerated cardiomyocytes.

Animals↗