| Co-Investigator(Kenkyū-buntansha) |
FURUTANI Akira Yamaguchi University, Hospital, Assistant Professor, 医学部附属病院, 講師 (90346552)
ITO Hiroshi Yamaguchi University, Hospital, Research Associate, 医学部附属病院, 助手 (90363100)
LI Tao-Sheng Yamaguchi University, Faculty of Medicien, Research Associate, 医学部, 助手 (50379997)
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| Budget Amount *help |
¥12,400,000 (Direct Cost: ¥12,400,000)
Fiscal Year 2005: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥8,600,000 (Direct Cost: ¥8,600,000)
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| Research Abstract |
Cardiovascular regeneration by the implantation of autologous bone marrow stem cells is expected as an effective new therapy for serious heart failure. However, there are various cases as a cause of heart failure, such as myocardial ischemia, cardiomyopathy, or others. So, it is requested to develop a tailor-made therapy for heart failure by the implantation of autologous bone marrow stem cells, according to each patient's condition.
At first, we tried to regenerate infarcted myocardium by implanting ex vivo TGF-β-preprogrammed CD117 (c-kit)-positive (CD117^+) bone marrow stem cells. CD117^+ cells were isolated from the bone marrow mononuclear cells of GFP-transgenic or normal C57/BL6 mice. The myogenic differentiation of CD117^+ cells was achieved by cultivation with TGF-β. We found that TGF-beta increased the cellular expression of myosin, troponins, connexin-43, GATA-4, and NKx-2.5, which suggested that it induced the myogenic differentiation of CD117^+ cells. Using an acute myocardi
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al infarction model, we also tried to regenerate infarcted myocardium by implanting untreated (newly isolated) or preprogrammed (24 hours of cultivation with 5 ng/mL TGF-β_1) CD117^+ cells intramyocardially. Histological analysis revealed newly regenerated myocardium in the left ventricular anterior wall after the implantation of TGF-β-preprogrammed cells but not untreated cells. Furthermore, the left ventricular percent fraction shortening was significantly higher after the implantation of TGF-β-preprogrammed cells than after the implantation of untreated CD117^+ cells. These results indicated that ex vivo TGF-β-preprogramming increased the myogenic differentiation of CD117^+ stem cells, which contributed to improved potency for the myocardial regeneration.
Secondly, we tried to enhance the angiogenic potential of bone marrow cells by ex vivo hypoxia stimulation before implantation. Bone marrow cells were collected and cultured under hypoxia (2% O_2) or normoxia conditions. Cells were also injected into the ischemic hindlimb of rats after 24 h of culture. Hypoxia culture increased the mRNA expression of VEGF, VE-cadherin, and Flk-1 from 2.5- to five-fold in bone marrow cells. The microvessel density and blood flow rate in the ischemic hindlimbs were also significantly higher 2 weeks after implantation with hypoxia-cultured cells than with normoxia-cultured cells. These results indicated that ex vivo hypoxia pre-stimulation increased the VEGF mRNA expression and endothelial differentiation of bone marrow cells, which contributed to improved potency for the induction of therapeutic angiogenesis.
Ex vivo pre-treatment of the marrow stem cell by TGF-β or hypoxia was able to improve their effect for regenerating injured myocardium or vessels, respectively. It seemed that the tailor-made therapy for heart failure could be developed by different ex vivo pre-treatments of bone marrow stem cells before implantation. Less
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