Ki Hyun Byun
Kwandong University
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Featured researches published by Ki Hyun Byun.
Biomaterials | 2013
Sung-Hwan Moon; Sun-Woong Kang; Soon-Jung Park; Daekyeong Bae; Sung Joon Kim; Hyang-Ae Lee; Kyung Soo Kim; Ki-Sung Hong; Jong Soo Kim; Jeong Tae Do; Ki Hyun Byun; Hyung-Min Chung
Embryonic stem cells (ESCs) have the capacity to undergo directed differentiation into contracting cardiomyocytes. Therefore, functional cardiomyocytes derived from human embryonic stem cells (hESC-CMs) are potential candidates for cellular cardiomyoplasty to regenerate the myocardium after infarction. However, the directed differentiation of hESCs induces not only contracting cardiomyocytes but also other cell types. Thus, a risk of teratoma formation and oncologic transformation exists following the transplantation of hESC-CMs containing other cell lineages. In addition, the transplantation of hESC-CMs into the infarcted myocardium limits therapeutic efficacy due to low viability and poor engraftment. In this study, we established an efficient preparation method to obtain pure contracting cardiomyocytes from hESCs. We also developed a delivery system to achieve enhanced viability and a functional connection with the host myocardium after transplantation in a myocardial infarction model. A serum-free medium was used to obtain pure contracting cardiomyocytes from other cell lineages after the cardiac differentiation of hESCs. Aggregates of purified hESC-CMs were formed, and then the expression of cardiomyocyte-specific markers and the viability of the aggregated CMs were examined in hypoxic conditions. In addition, we determined whether the viability of the hESC-CMs and their ability to engraft with the host myocardium could be enhanced by transplanting them as aggregates in a myocardial infarction model. The therapeutic efficacy of the cardiomyocytes was examined by immunohistochemical analyses as well as physiological analyses of left-ventricular function. We found that the transplantation of contracting hESC-CM aggregates improved their survival and function in infarcted rat hearts in comparison to the transplantation of dissociated cells. Our method using hESC-CMs can be considered an effective strategy for clinical applications without critical barriers.
Biochemical and Biophysical Research Communications | 2010
Lucy Youngmin Eun; Byeong-Wook Song; Min-Ji Cha; Heesang Song; Il-Kwon Kim; Eunmi Choi; Woochul Chang; Soyeon Lim; Eun Ju Choi; Onju Ham; Se-Yeon Lee; Ki Hyun Byun; Yangsoo Jang; Ki-Chul Hwang
The efficacy of mesenchymal stem cell (MSC) therapy for myocardial regeneration is limited by the poor survival of stem cells after transplantation into the infarcted heart. To improve the cell survival of MSCs in the infarcted heart, MSCs were genetically engineered to overexpress phosphoinositide-3-kinase class II alpha (PI3K-C2α). PI3K-C2α overexpression increased PI3K expression and the cell viability of MSCs. Furthermore, levels of survival-related phosphorylation were elevated in PI3K-C2α-MSCs. But, the level of apoptotic proteins downregulated and the number of PI-positive cells decreased in PI3K-C2α-MSCs compared to hypoxic MSCs. Nine rats per group had 1×10(6) cells (20 μl PBS) transplanted after myocardial infarction. One week after transplantation, infarct size and area of fibrosis were reduced in the PI3K-C2α-MSC-transplanted group. The number of TUNEL positive cells declined, while the mean microvessel count per field was higher in the PI3K-C2α-MSC group than the MSC-injected group. Heart function was improved in the PI3K-C2α-MSCs group as assessed using a Millar catheter at 3weeks after transplantation. These findings suggest that overexpression of PI3K-C2α in MSCs can assist cell survival and enhance myocardial regeneration.
Yonsei Medical Journal | 2005
Eui-Young Choi; Hyuck Moon Kwon; Chul Woo Ahn; Geun Taek Lee; Boyoung Joung; Bum Kee Hong; Young Won Yoon; Dong Soo Kim; Ki Hyun Byun; Tae Soo Kang; Se Jung Yoon; Sung Woo Kwon; Sung Ju Lee; Jong Kwan Park; Hyun Seung Kim
The formation of advanced glycation end products (AGEs), in various tissues has been known to enhance immunoinflammatory reactions and local oxidant stresses in long standing diabetes. Recently, AGEs have been reported to play a role in neointimal formation in animal models of arterial injury. We attempted to determine whether the serum levels of AGEs are associated with coronary restenosis in diabetic patients. Blood samples were collected from diabetic patients with coronary artery disease undergoing stent implantation and the serum levels of AGEs were analyzed by the fluorescent intensity method. The development of in-stent restenosis (ISR) was evaluated by a 6-month follow-up coronary angiography. A total of 263 target lesions were evaluated, in 203 patients. The ISR rate in the high-AGE (>170 U/ml) group (40.1%) was significantly higher than in the low-AGE group (≤170 U/ml) (19.6%) (p<0.001). Furthermore, multivariate analysis revealed that a high level of serum AGEs is an independent risk factor for the development of ISR (odds ratio, 2.659; 95% CI, 1.431-4.940; p=0.002). The serum levels of AGEs constitute an excellent predictive factor for ISR, and should be one of the guidelines for medical therapy and interventional strategy to prevent ISR in diabetic patients.
Coronary Artery Disease | 2009
Jae-Hun Jung; Pil-Ki Min; Sang-Hak Lee; Chong Won Sung; Seonghoon Choi; Jung Rae Cho; Namho Lee; Ki Hyun Byun
BackgroundAggressive platelet inhibition is crucial to reduce myocardial injury and early cardiac events after coronary intervention. As compared with the conventional 300-mg dose, pretreatment with a 600-mg loading dose of clopidogrel significantly reduced periprocedural myocardial infarction (MI) in patients undergoing percutaneous coronary intervention (PCI). We investigated that the advantage of the 600-mg dose in inhibiting platelet aggregation more rapidly than the 300-mg dose may actually have special value for acute ST-segment elevation MI patients. MethodsA total of 171 patients with ST-segment elevation MI underwent primary PCI. A 600-mg (n=73) or 300-mg (n=98) loading regimen of clopidogrel was given before the procedure. We did a follow-up of all patients clinically for 30 days after coronary intervention. The primary endpoint was the 30-day occurrence of death, MI, urgent revascularization, or stroke. ResultsThe primary endpoint occurred in 1.4% (1 of 73) of patients in the high dose versus 11.2% (11 of 98) of those in the conventional loading dose group (P=0.013). Death, recurrent MI, urgent revascularization, and stroke were lower in patients treated with the high dose of clopidogrel compared with conventional dose. Safety endpoints were similar in the two groups. ConclusionPretreatment with a 600-mg loading dose of clopidogrel before the procedure is safe and, as compared with the conventional 300-mg dose, significantly reduces recurrent MI and urgent revascularization in patients with primary PCI.
Korean Circulation Journal | 2011
Yun Ju Jo; Eun Jeong Lee; Jin Won Oh; Chang Min Moon; Deok Kyu Cho; Yun Hyeong Cho; Ki Hyun Byun; Lucy Youngmin Eun
After developing sudden severe chest pain, an 11-year-old boy presented to the emergency room with chest pain and palpitations and was unable to stand up. The sudden onset of chest pain was first reported while swimming at school about 30 minutes prior to presentation. Arterial blood pressure (BP) was 150/90 mmHg, heart rate was 120/minute, and the chest pain was combined with shortness of breath and diaphoresis. During the evaluation in the emergency room, the chest pain worsened and abdominal pain developed. An aortic dissection was suspected and a chest and abdomen CT was obtained. The diagnosis of aortic dissection type B was established by CT imaging. The patient went to surgery immediately with BP control. He died prior to surgery due to aortic rupture. Here we present this rare case of aortic dissection type B with rupture, reported in an 11-year-old Korean child.
Experimental and Molecular Medicine | 2002
Eui-Young Choi; Dong Soo Kim; Bum Kee Hong; Hyuck Moon Kwon; Young Goo Song; Ki Hyun Byun; Hyun-Young Park; Ki Chul Whang; Hyun Seung Kim
Yonsei Medical Journal | 1999
In Jai Kim; Bum Kee Hong; Byoung Kwon Lee; Hyuck Moon Kwon; Dong Soo Kim; Eui-Young Choi; Ki Hyun Byun; Jeongho Kim; Kyung Soon Song; Hyun Seung Kim
Korean Circulation Journal | 2009
Beodeul Kang; Deok-Kyu Cho; Ki Hyun Byun; Lucy Youngmin Eun; Yun-Hyeong Cho
Korean Circulation Journal | 2007
Ji Hoon Cho; Deok-Kyu Cho; Jin Yi Choi; Lucy Youngmin Eun; Yun-Hyeong Cho; Jong Hoon Koh; Ki Hyun Byun
Korean Circulation Journal | 2004
Ki Hyun Byun; Jae Kwang Shim; Sang Jo Min; Su Jin Jeon; Jong Hyun Kim