Bio

Professional Education


  • Doctor of Philosophy, Virginia Polytech Inst & State Univ (2010)
  • Master of Science, Virginia Polytech Inst & State Univ (Virginia Tech), Biomedical Engineering (2007)

Stanford Advisors


Research & Scholarship

Lab Affiliations


Publications

Journal Articles


  • Microfluidic Single-Cell Analysis Shows That Porcine Induced Pluripotent Stem Cell-Derived Endothelial Cells Improve Myocardial Function by Paracrine Activation CIRCULATION RESEARCH Gu, M., Nguyen, P. K., Lee, A. S., Xu, D., Hu, S., Plews, J. R., Han, L., Huber, B. C., Lee, W. H., Gong, Y., de Almeida, P. E., Lyons, J., Ikeno, F., Pacharinsak, C., Connolly, A. J., Gambhir, S. S., Robbins, R. C., Longaker, M. T., Wu, J. C. 2012; 111 (7): 882-893

    Abstract

    Induced pluripotent stem cells (iPSCs) hold great promise for the development of patient-specific therapies for cardiovascular disease. However, clinical translation will require preclinical optimization and validation of large-animal iPSC models.To successfully derive endothelial cells from porcine iPSCs and demonstrate their potential utility for the treatment of myocardial ischemia.Porcine adipose stromal cells were reprogrammed to generate porcine iPSCs (piPSCs). Immunohistochemistry, quantitative PCR, microarray hybridization, and angiogenic assays confirmed that piPSC-derived endothelial cells (piPSC-ECs) shared similar morphological and functional properties as endothelial cells isolated from the autologous pig aorta. To demonstrate their therapeutic potential, piPSC-ECs were transplanted into mice with myocardial infarction. Compared with control, animals transplanted with piPSC-ECs showed significant functional improvement measured by echocardiography (fractional shortening at week 4: 27.2±1.3% versus 22.3±1.1%; P<0.001) and MRI (ejection fraction at week 4: 45.8±1.3% versus 42.3±0.9%; P<0.05). Quantitative protein assays and microfluidic single-cell PCR profiling showed that piPSC-ECs released proangiogenic and antiapoptotic factors in the ischemic microenvironment, which promoted neovascularization and cardiomyocyte survival, respectively. Release of paracrine factors varied significantly among subpopulations of transplanted cells, suggesting that transplantation of specific cell populations may result in greater functional recovery.In summary, this is the first study to successfully differentiate piPSCs-ECs from piPSCs and demonstrate that transplantation of piPSC-ECs improved cardiac function after myocardial infarction via paracrine activation. Further development of these large animal iPSC models will yield significant insights into their therapeutic potential and accelerate the clinical translation of autologous iPSC-based therapy.

    View details for DOI 10.1161/CIRCRESAHA.112.269001

    View details for Web of Science ID 000308868800015

    View details for PubMedID 22821929

  • Whole Brain Radiation-Induced Cognitive Impairment: Pathophysiological Mechanisms and Therapeutic Targets BIOMOLECULES & THERAPEUTICS Lee, Y. W., Cho, H. J., Lee, W. H., Sonntag, W. E. 2012; 20 (4): 357-370
  • Irradiation Alters MMP-2/TIMP-2 System and Collagen Type IV Degradation in Brain INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Lee, W. H., Warrington, J. P., Sonntag, W. E., Lee, Y. W. 2012; 82 (5): 1559-1566

    Abstract

    Blood-brain barrier (BBB) disruption is one of the major consequences of radiation-induced normal tissue injury in the central nervous system. We examined the effects of whole-brain irradiation on matrix metalloproteinases (MMPs)/tissue inhibitors of metalloproteinases (TIMPs) and extracellular matrix (ECM) degradation in the brain.Animals received either whole-brain irradiation (a single dose of 10 Gy ?-rays or a fractionated dose of 40 Gy ?-rays, total) or sham-irradiation and were maintained for 4, 8, and 24 h following irradiation. mRNA expression levels of MMPs and TIMPs in the brain were analyzed by real-time reverse transcriptase-polymerase chain reaction (PCR). The functional activity of MMPs was measured by in situ zymography, and degradation of ECM was visualized by collagen type IV immunofluorescent staining.A significant increase in mRNA expression levels of MMP-2, MMP-9, and TIMP-1 was observed in irradiated brains compared to that in sham-irradiated controls. In situ zymography revealed a strong gelatinolytic activity in the brain 24 h postirradiation, and the enhanced gelatinolytic activity mediated by irradiation was significantly attenuated in the presence of anti-MMP-2 antibody. A significant reduction in collagen type IV immunoreactivity was also detected in the brain at 24 h after irradiation. In contrast, the levels of collagen type IV were not significantly changed at 4 and 8 h after irradiation compared with the sham-irradiated controls.The present study demonstrates for the first time that radiation induces an imbalance between MMP-2 and TIMP-2 levels and suggests that degradation of collagen type IV, a major ECM component of BBB basement membrane, may have a role in the pathogenesis of brain injury.

    View details for DOI 10.1016/j.ijrobp.2010.12.032

    View details for Web of Science ID 000301891300019

    View details for PubMedID 22429332

  • Radiation Attenuates Physiological Angiogenesis by Differential Expression of VEGF, Ang-1, Tie-2 and Ang-2 in Rat Brain RADIATION RESEARCH Lee, W. H., Cho, H. J., Sonntag, W. E., Lee, Y. W. 2011; 176 (6): 753-760

    Abstract

    The etiology of radiation-induced cerebrovascular rarefaction remains unknown. In the present study, we examined the effect of whole-brain irradiation on endothelial cell (EC) proliferation/apoptosis and expression of various angiogenic factors in rat brain. F344 × BN rats received either whole-brain irradiation (a single dose of 10 Gy ? rays) or sham irradiation and were maintained for 4, 8 and 24 h after irradiation. Double immunofluorescence staining was employed to visualize EC proliferation/apoptosis in brain. The mRNA and protein expression levels of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), endothelial-specific receptor tyrosine kinase (Tie-2), and Ang-2 in brain were determined by real-time RT-PCR and immunofluorescence staining. A significant reduction in CD31-immunoreactive cells was detected in irradiated rat brains compared with sham-irradiated controls. Whole-brain irradiation significantly suppressed EC proliferation and increased EC apoptosis. In addition, a significant decrease in mRNA and protein expression of VEGF, Ang-1 and Tie-2 was observed in irradiated rat brains. In contrast, whole-brain irradiation significantly upregulated Ang-2 expression in rat brains. The present study provides novel evidence that whole-brain irradiation differentially affects mRNA and protein expression of VEGF, Ang-1, Tie-2 and Ang-2. These changes are closely associated with decreased EC proliferation and increased EC apoptosis in brain.

    View details for DOI 10.1667/RR2647.1

    View details for Web of Science ID 000297904000007

    View details for PubMedID 21962003

  • AT1 Receptor Antagonism Does Not Influence Early Radiation-Induced Changes in Microglial Activation or Neurogenesis in the Normal Rat Brain RADIATION RESEARCH Conner, K. R., Forbes, M. E., Lee, W. H., Lee, Y. W., Riddle, D. R. 2011; 176 (1): 71-83

    Abstract

    Blockers of the renin-angiotensin-aldosterone system (RAAS) ameliorate cognitive deficits and some aspects of brain injury after whole-brain irradiation. We investigated whether treatment with the angiotensin II type 1 receptor antagonist L-158,809 at a dose that protects cognitive function after fractionated whole-brain irradiation reduced radiation-induced neuroinflammation and changes in hippocampal neurogenesis, well-characterized effects that are associated with radiation-induced brain injury. Male F344 rats received L-158,809 before, during and after a single 10-Gy dose of radiation. Expression of cytokines, angiotensin II receptors and angiotensin-converting enzyme 2 was evaluated by real-time PCR 24 h, 1 week and 12 weeks after irradiation. At the latter times, microglial density and proliferating and activated microglia were analyzed in the dentate gyrus of the hippocampus. Cell proliferation and neurogenesis were also quantified in the dentate subgranular zone. L-158,809 treatment modestly increased mRNA expression for Ang II receptors and TNF-? but had no effect on radiation-induced effects on hippocampal microglia or neurogenesis. Thus, although L-158,809 ameliorates cognitive deficits after whole-brain irradiation, the drug did not mitigate the neuroinflammatory microglial response or rescue neurogenesis. Additional studies are required to elucidate other mechanisms of normal tissue injury that may be modulated by RAAS blockers.

    View details for DOI 10.1667/RR2560.1

    View details for Web of Science ID 000292441900008

    View details for PubMedID 21545290

  • Role of NADPH oxidase in interleukin-4-induced monocyte chemoattractant protein-1 expression in vascular endothelium INFLAMMATION RESEARCH Lee, Y. W., Lee, W. H., Kim, P. H. 2010; 59 (9): 755-765

    Abstract

    The pro-oxidative and pro-inflammatory pathways in vascular endothelium have been implicated in the development of atherosclerosis. In the present study, we investigated effect of interleukin-4 (IL-4) on monocyte chemoattractant protein-1 (MCP-1) expression in vascular endothelium and examined the role of distinct sources of reactive oxygen species (ROS) in this process.Real-time reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay showed that IL-4 significantly up-regulated mRNA and protein expression of MCP-1 in human aortic endothelial cells (HAEC) and C57BL/6 mice. A significant and dose-dependent inhibition of IL-4-induced MCP-1 expression was observed in HAEC pre-treated with antioxidants, such as pyrrolidine dithiocarbamate and epigallocatechin gallate, indicating that IL-4-induced MCP-1 expression is mediated via a ROS-dependent mechanism. Additionally, pharmacological inhibitors of NADPH oxidase (NOX) significantly attenuated IL-4-induced MCP-1 expression in HAEC. Furthermore, the disruption of the NOX gene dramatically reduced IL-4-induced MCP-1 expression in NOX knockout mice (B6.129S6-Cybb(tm1Din)/J). In contrast, overexpression of MCP-1 in IL-4-stimulated HAEC was not affected by inhibiting other ROS generating pathways, such as xanthine oxidase and the mitochondrial electron transport chain.These results demonstrate that IL-4 up-regulates MCP-1 expression in vascular endothelium through NOX-mediated ROS generation.

    View details for DOI 10.1007/s00011-010-0187-3

    View details for Web of Science ID 000280728100008

    View details for PubMedID 20349326

  • Aging attenuates radiation-induced expression of pro-inflammatory mediators in rat brain NEUROSCIENCE LETTERS Lee, W. H., Sonntag, W. E., Lee, Y. W. 2010; 476 (2): 89-93

    Abstract

    The present study was designed to examine the effect of aging on radiation-induced expression of pro-inflammatory mediators in rat brain. Male F344xBN rats (4, 16, and 24 months of age) received either whole brain irradiation with a single dose of 10Gy gamma-rays or sham-irradiation, and were maintained for 4, 8, and 24h post-irradiation. The mRNA expression levels of various pro-inflammatory mediators such as cytokines, adhesion molecules, chemokine, and matrix metalloproteinase were analyzed by quantitative real-time reverse transcription-polymerase chain reaction (RT-PCR). The acute inflammatory responses to irradiation, including overexpression of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), E-selectin, monocyte chemoattractant protein-1 (MCP-1), and matrix metalloproteinase-9 (MMP-9) were markedly attenuated in the hippocampus of middle-aged and old rats compared with young groups. Specifically, a significant age-dependent decrease in TNF-alpha expression was detected 8 and 24h after irradiation and a similar age-related attenuation was observed in IL-1beta, ICAM-1, and VCAM-1 expression 4 and 8h post-irradiation. MCP-1 expression was reduced 4h post-irradiation and MMP-9 expression at 8h post-irradiation. These results provide evidence for the first time that radiation-induced pro-inflammatory responses in the brain are suppressed in aged animals.

    View details for DOI 10.1016/j.neulet.2010.04.009

    View details for Web of Science ID 000278605100009

    View details for PubMedID 20385203

  • Interleukin-4, Oxidative Stress, Vascular Inflammation and Atherosclerosis BIOMOLECULES & THERAPEUTICS Lee, Y. W., Kim, P. H., Lee, W. H., Hirani, A. A. 2010; 18 (2): 135-144

    Abstract

    The pro-oxidative and pro-inflammatory pathways in vascular endothelium have been implicated in the initiation and progression of atherosclerosis. In fact, inflammatory responses in vascular endothelium are primarily regulated through oxidative stress-mediated signaling pathways leading to overexpression of pro-inflammatory mediators. Enhanced expression of cytokines, chemokines and adhesion molecules in endothelial cells and their close interactions facilitate recruiting and adhering blood leukocytes to vessel wall, and subsequently stimulate transendothelial migration, which are thought to be critical early pathologic events in atherogenesis. Although interleukin-4 (IL-4) was traditionally considered as an anti-inflammatory cytokine, recent in vitro and in vivo studies have provided robust evidence that IL-4 exerts pro-inflammatory effects on vascular endothelium and may play a critical role in the development of atherosclerosis. The cellular and molecular mechanisms responsible for IL-4-induced atherosclerosis, however, remain largely unknown. The present review focuses on the distinct sources of IL-4-mediated reactive oxygen species (ROS) generation as well as the pivotal role of ROS in IL-4-induced vascular inflammation. These studies will provide novel insights into a clear delineation of the oxidative mechanisms of IL-4-mediated stimulation of vascular inflammation and subsequent development of atherosclerosis. It will also contribute to novel therapeutic approaches for atherosclerosis specifically targeted against pro-oxidative and pro-inflammatory pathways in vascular endothelium.

    View details for DOI 10.4062/biomolther.2010.18.2.135

    View details for Web of Science ID 000277582000002

  • Irradiation induces regionally specific alterations in pro-inflammatory environments in rat brain INTERNATIONAL JOURNAL OF RADIATION BIOLOGY Lee, W. H., Sonntag, W. E., Mitschelen, M., Yan, H., Lee, Y. W. 2010; 86 (2): 132-144

    Abstract

    Pro-inflammatory environments in the brain have been implicated in the onset and progression of neurological disorders. In the present study, we investigate the hypothesis that brain irradiation induces regionally specific alterations in cytokine gene and protein expression.Four month old F344 x BN rats received either whole brain irradiation with a single dose of 10 Gy gamma-rays or sham-irradiation, and were maintained for 4, 8, and 24 h following irradiation. The mRNA and protein expression levels of pro-inflammatory mediators were analysed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and immunofluorescence staining. To elucidate the molecular mechanisms of irradiation-induced brain inflammation, effects of irradiation on the DNA-binding activity of pro-inflammatory transcription factors were also examined.A significant and marked up-regulation of mRNA and protein expression of pro-inflammatory mediators, including tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and monocyte chemoattractant protein-1 (MCP-1), was observed in hippocampal and cortical regions isolated from irradiated brain. Cytokine expression was regionally specific since TNF-alpha levels were significantly elevated in cortex compared to hippocampus (57% greater) and IL-1beta levels were elevated in hippocampus compared to cortical samples (126% greater). Increases in cytokine levels also were observed after irradiation of mouse BV-2 microglial cells. A series of electrophoretic mobility shift assays (EMSA) demonstrated that irradiation significantly increased activation of activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), and cAMP response element-binding protein (CREB).The present study demonstrated that whole brain irradiation induces regionally specific pro-inflammatory environments through activation of AP-1, NF-kappaB, and CREB and overexpression of TNF-alpha, IL-1beta, and MCP-1 in rat brain and may contribute to unique pathways for the radiation-induced impairments in tissue function.

    View details for DOI 10.3109/09553000903419346

    View details for Web of Science ID 000274629400006

    View details for PubMedID 20148699

  • Oxidative mechanisms of IL-4-induced IL-6 expression in vascular endothelium CYTOKINE Lee, Y. W., Lee, W. H., Kim, P. H. 2010; 49 (1): 73-79

    Abstract

    The present study is designed to investigate the effects of interleukin-4 (IL-4) on expression of interleukin-6 (IL-6), as well as to examine the role of distinct sources of reactive oxygen species (ROS) in this process. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) showed that IL-4 significantly up-regulated the mRNA and protein expression of IL-6 in human aortic endothelial cells (HAEC) and C57BL/6 mice. Dihydroethidium (DHE) and dichlorofluorescein (DCF) fluorescence staining demonstrated that IL-4 significantly increased ROS generation in HAEC. A significant and dose-dependent inhibition of IL-4-induced IL-6 expression was observed in HAEC pre-treated with antioxidants, such as pyrrolidine dithiocarbamate (PDTC) and epigallocatechin gallate (EGCG), indicating that IL-4-induced IL-6 expression is mediated via an ROS-dependent mechanism. Additionally, pharmacological inhibitor of NADPH oxidase (NOX) significantly attenuated IL-4-induced ROS generation and IL-6 expression in HAEC. Furthermore, the disruption of NOX gene dramatically and significantly reduced IL-4-induced IL-6 expression in NOX knockout mice (B6.129S6-Cybb(tm1Din)/J). In contrast, overexpression of IL-6 in IL-4-activated HAEC was not affected by inhibiting other ROS generating pathways, such as xanthine oxidase, arachidonic acid metabolism, and the mitochondrial electron transport chain. These results demonstrate that IL-4 up-regulates IL-6 expression in vascular endothelium through NOX-mediated ROS generation.

    View details for DOI 10.1016/j.cyto.2009.08.009

    View details for Web of Science ID 000273864000011

    View details for PubMedID 19822443

  • A novel in vitro ischemia/reperfusion injury model ARCHIVES OF PHARMACAL RESEARCH Lee, W. H., Kang, S., Vlachos, P. P., Lee, Y. W. 2009; 32 (3): 421-429

    Abstract

    The reperfusion of blood flow occurred in a number of conditions such as stroke and organ transplantation immensely augments tissue injury and causes more severe damage than prolonged ischemia. In the present study, we designed a novel double-layer parallel-plate flow chamber (PPFC) to develop an in vitro ischemia/reperfusion (I/R) injury model and examined the effects of I/R on inflammatory responses in human microvascular endothelial cells (HMEC-1). The expression of pro-inflammatory mediators, such as interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), E-selectin, and vascular cell adhesion molecule-1 (VCAM-1) in HMEC-1 was measured by quantitative real-time RT-PCR. The cells were also pre-treated with antioxidant pyrrolidine dithiocarbamate (PDTC) to verify involvement of an oxidative mechanism in I/R injury in vitro. The morphological changes and attenuated expression of pro-inflammatory mediators were observed in HMCE-1 exposed to the physiological flow. In contrast, I/R markedly and significantly up-regulated expression of pro-inflammatory mediators in HMEC-1. Additionally, pretreatment with PDTC significantly reduced I/R-mediated overexpression of pro-inflammatory mediators. The data from the present study provide evidence demonstrating that our newly designed PPFC can be utilized as an effective in vitro cell culture model system to develop new drugs specifically targeting against ischemia/reperfusion (I/R) injury.

    View details for DOI 10.1007/s12272-009-1316-9

    View details for Web of Science ID 000265440100018

    View details for PubMedID 19387587

  • Protective effects of genistein on proinflammatory pathways in human brain microvascular endothelial cells JOURNAL OF NUTRITIONAL BIOCHEMISTRY Lee, Y. W., Lee, W. H. 2008; 19 (12): 819-825

    Abstract

    Proinflammatory cerebromicrovascular environment has been implicated in the critical early pathologic events in a variety of neurodegenerative diseases. Recent studies also have demonstrated the potential beneficial effects of soy isoflavones. However, cellular and molecular mechanisms underlying these processes are not fully understood. The present study was designed to examine the hypothesis that soy isoflavone genistein may attenuate cytokine-induced proinflammatory pathways in human brain microvascular endothelial cells. The quantitative real-time reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbent assay showed that pretreatment of HBMEC with increasing concentrations of genistein significantly and dose-dependently inhibited cytokine-induced up-regulation of mRNA and protein expression of proinflammatory mediators such as tumor necrosis factor-alpha, interleukin-1beta, monocyte chemoattractant protein-1, interleukin-8, and intercellular adhesion molecule-1. In addition, genistein pretreatment significantly reduced cytokine-mediated up-regulation of transmigration of blood leukocytes in a dose-dependent manner. Our results suggest that genistein may attenuate proinflammatory pathways through inhibition of cytokine-induced overexpression of proinflammatory mediators and inflammatory reactions in human brain microvascular endothelial cells.

    View details for DOI 10.1016/j.jnutbio.2007.10.006

    View details for Web of Science ID 000261253700004

    View details for PubMedID 18479900

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