Keisuke Kawachi

Coronary vein infusion of multipotent stromal cells from bone marrow preserves cardiac function in swine ischemic cardiomyopathy via enhanced neovascularization

Few reports have examined the effects of adult bone marrow multipotent stromal cells (MSCs) on large animals, and no useful method has been established for MSC implantation. In this study, we investigate the effects of MSC infusion from the coronary vein in a swine model of chronic myocardial infarction (MI). MI was induced in domestic swine by placing beads in the left coronary artery. Bone marrow cells were aspirated and then cultured to isolate the MSCs. At 4 weeks after MI, MSCs labeled with dye (n=8) or vehicle (n=5) were infused retrogradely from the anterior interventricular vein without any complications. Left ventriculography (LVG) was performed just before and at 4 weeks after cell infusion. The ejection fraction (EF) assessed by LVG significantly decreased from baseline up to a follow-up at 4 weeks in the control group (P<0.05), whereas the cardiac function was preserved in the MSC group. The difference in the EF between baseline and follow-up was significantly greater in the MSC group than in the control group (P<0.05). The MSC administration significantly promoted neovascularization in the border areas compared with the controls (P<0.0005), though it had no affect on cardiac fibrosis. A few MSCs expressed von Willebrand factor in a differentiation assay, but none of them expressed troponin T. In quantitative gene expression analysis, basic fibroblast growth factor and vascular endothelial growth factor (VEGF) levels were significantly higher in the MSC-treated hearts than in the controls (P<0.05, respectively). Immunohistochemical staining revealed VEGF production in the engrafted MSCs. In vitro experiment demonstrated that MSCs significantly stimulated endothelial capillary network formation compared with the VEGF protein (P<0.0001). MSC infusion via the coronary vein prevented the progression of cardiac dysfunction in chronic MI. This favorable effect appeared to derive not from cell differentiation, but from enhanced neovascularization by angiogenic factors secreted from the MSCs.

Effects of erythropoietin on angiogenesis after myocardial infarction in porcine

Erythropoietin (EPO) has recently been shown to confer cardioprotective effects via angiogenesis and antiapoptosis. The administration of EPO after myocardial infarction (MI) reduces infarct size and improves cardiac function in small animals. The purpose of this study is to investigate the protective effects of EPO in porcine MI. Each animal in the EPO group received four injections of recombinant human EPO (rhEPO; 6000 U per injection) at 2-day intervals, starting after coronary occlusion. Animals in the control group received saline. Left ventriculography was performed just after coronary occlusion and at 28 days. Time-course changes in serum levels of vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and fibroblast growth factor (FGF) were measured. The number of vessels was calculated, and the mRNA expressions of VEGF and insulin-like growth factor (IGF) were examined. Left ventricular function was similar between the groups. The numbers of cells positive for anti-α-smooth muscle actin, von Willebrand factor, and c-kit were significantly higher in the EPO group than in the controls (P < 0.05). The EPO group exhibited significantly higher HGF and FGF concentrations (P < 0.05) and higher expression of VEGF and IGF mRNA (P < 0.05) compared with the controls. In conclusion, EPO accelerates angiogenesis via the upregulation of systemic levels such as HGF and FGF, and the local expression of VEGF and IGF, in porcine MI.

Pulmonary vein isolation under direct visual identification of the left atrium—pulmonary vein junction using intra-cardiac echography

Introduction: Intra-cardiac echocardiography (ICE) which has some benefits, can be used to obtain detailed anatomy of the heart chambers or large vessels, and the catheter positions, and it has been considered useful for improving the outcome of the ablation. In the present study, we performed pulmonary vein isolation (PVI) under real time monitoring of ICE imaging utilizing an ICE catheter placed at the junction of the left atrium (LA) and PVs (LA-PV junction).Methods: PVI for atrial fibrillation (AF) was performed in 30 cases with drug-resistant AF (mean age: 66-years-old; including 22 males). An ICE catheter utilizing a 9 MHz frequency was inserted into the LA via the atrial septum, and placed at the LA-PV junction. Circumferential ablation was performed in the LA outside of the PV ostium, encircling both the superior and inferior ostia together under ICE imaging.Results: The anatomy of the LA to the PVs and catheter sites were clearly identified by the ICE during the procedure, which enabled a precise and safe catheter manipulation with minimal fluoroscopy. Further, the wall thickness of the PV and LA, and position of the esophagus could be obtained by ICE, facilitating care in adjusting the power and/or duration of the current delivery.Conclusion: ICE imaging of the LA-PV junction permitted real time monitoring of the target sites for PVI during the ablation procedure, and was considered a useful technique for performing PVI.

A Case of Transient Rise of Pacing Threshold during the Chronic Phase of Pacemaker Implantation

We experienced a case of pacing failure with transient rise of the pacing threshold more than one year after implantation. Neither the generator nor lead system was found to be defective. During the antibiotics therapy to treat cholecystitis, which was found on admission, pacing failure was improved. The clinical course suggested that the infection was related to the improvement, although accurate mechanisms were unknown.

Cardioprotective effect of G-CSF administration after coronary reperfusion in swine AMI model

[Purpose] Recent studies have suggested that granulocyte colony-stimulating factor (G-CSF) may accelerate angiogenesis or cardio-myogenesis. No previous studies, however, have used large animal models to investigete how clinical doses of G-CSF affect cardiac function after acute myocardial infarction (AMI). [Methods] Diagonal branch of the left anterior descending coronary artery of domestic swine was balloon-occluded for 1-hour and then reperfused. The G-CSF group received a subcutaneous injection of G-CSF at a dose of 5.0/µg/kg/day for 6 days after MI. Left ventriculography was performed 4 weeks after Ml. The number of vessels in the infarcted area were calculated using sections stained by anti-α-smooth muscle actin (SMA) and anti-von Willebrand factor (vWF). Reverse transcription polymerase chain reactions for collagen I, collagen III, and transforming growth factor (TGF)-β were also examined. [Results] The G-CSF group showed a significantly higher ejection fraction and lower end-diastolic volume in left ventriculography. The numbers of α-SMA- and vWF-positive vessels in the G-CSF group were significantly larger. The expression of collagen III mRNA was significantly lower in the G-CSF group in the infarct and border areas. The expression of TGF-β mRNA was significantly lower in the G-CSF group in the border area. [Conclusions] The administration of clinical doses of G-CSF improved cardiac function after reperfusion in AMI. G-CSF confers its effects by accelerating angio-genesis and modifying the wound-healing process.