Zhen Zhao

Weill Cornell Medical College, New York, New York, United States

Are you Zhen Zhao?

Claim your profile

Publications (11)58.42 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: By tracking reporter molecules such as green fluorescent protein and luciferase, researchers can determine physiological status and follow processes both in vitro and in vivo. Here, we describe a dual-reporter imaging method, in which a fusion of eGFP and Luc2 is introduced into hosts using lentiviral particles based on HIV-1. The fusion molecule is both fluorescent and bioluminescent, and is therefore ideal as an optical marker in clinical and research applications. We characterized multiple technical indices of the molecule, including sensibility, biocompatibility, lifetime, and others. Lentiviral particles carrying the reporter were strongly infective in endothelial progenitor (EPC) and GL261 glioma cells, as well as in live mice. By transforming Luc2-eGFP into hosts, morphological and quantitative data can be collected not only from tissue specimens but also from live animal models.
    No preview · Article · Oct 2015 · Journal of Fluorescence
  • [Show abstract] [Hide abstract]
    ABSTRACT: Aims: We tested the hypothesis that endothelial progenitor cell (EPC)-mediated functional recovery after stroke may be associated with the endothelial nitric oxide synthase (eNOS)/brain-derived neurotrophic factor (BDNF) signaling pathway. Methods: Mice were infused with either EPCs or saline after being subjected to middle cerebral artery occlusion. The EPC-treated mice also received intravenous injections of either Nω-nitro-l-arginine methyl ester (L-NAME, the NOS inhibitor) or saline. Results: The activation of eNOS and the expression of BDNF were significantly increased in ischemic brain of the EPC-treated mice, along with increased angiogenesis and neurogenesis. On diffusion tensor imaging (DTI), significant increases in fractional anisotropy and fiber count were observed in white matter, indicating axonal growth stimulated by EPCs. However, the EPC-treated mice that were received an L-NAME injection failed to exhibit the observed increases in angiogenesis, neurogenesis, and axonal growth. In addition, the neurons cocultured with EPCs in vitro exhibited the increased expression of BDNF and decreased apoptosis after oxygen-glucose deprivation compared with the control group. This EPC-induced protective effect was virtually absent in the L-NAME treatment group. Conclusion: The eNOS/BDNF pathway may be involved in the EPC-mediated functional recovery of stroke mice. DTI is feasible for dynamically tracking the orientation of axonal projections after EPC treatment.
    No preview · Article · Sep 2015 · CNS Neuroscience & Therapeutics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Interactions among tumor cells, stromal cells, and extracellular matrix compositions are mediated through cytokines during tumor progression. Our analysis of 132 known cytokines and growth factors in published clinical breast cohorts and our 84 patient-derived xenograft models revealed that the elevated connective tissue growth factor (CTGF) in tumor epithelial cells significantly correlated with poor clinical prognosis and outcomes. CTGF was able to induce tumor cell epithelial-mesenchymal transition (EMT), and promote stroma deposition of collagen I fibers to stimulate tumor growth and metastasis. This process was mediated through CTGF-tumor necrosis factor receptor I (TNFR1)-IκB autocrine signaling. Drug treatments targeting CTGF, TNFR1, and IκB signaling each prohibited the EMT and tumor progression.
    Preview · Article · Jul 2015 · Oncotarget
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: An immature vascular phenotype in diabetes mellitus may cause more severe vascular damage and poorer functional outcomes after stroke, and it would be feasible to repair damaged functional vessels using endothelial progenitor cell (EPC) transplantation. However, high glucose induces p38 mitogen-activated protein kinase activation, which can accelerate the senescence and apoptosis of EPCs. The aim of this study was to investigate the combined effects of EPC transplantation and p38 mitogen-activated protein kinase inhibitor administration on diabetic stroke outcomes. Bone marrow-derived EPCs were injected intra-arterially into db/db mice after ischemic stroke induction. RWJ 67657 (RWJ), a p38 mitogen-activated protein kinase inhibitor, was administered orally for 7 consecutive days, with the first dose given 30 minutes before stroke induction. Functional outcome was determined at days 0, 1, 7, 14, and 21. Angiogenesis, neurogenesis, infarct volume, and Western blotting assays were performed on day 7, and white matter remodeling was determined on day 14. Neither EPC transplantation nor RWJ administration alone significantly improved diabetic stroke outcome although RWJ displayed a potent anti-inflammatory effect. By both improving the functioning of EPCs and reducing inflammation, EPC transplantation plus RWJ administration in vivo synergistically promoted angiogenesis and neurogenesis after diabetic stroke. In addition, the white matter remodeling, behavioral scores, and expressions of vascular endothelial growth factor and brain-derived neurotrophic factor were significantly increased in diabetic mice treated with both EPCs and RWJ. The combination of EPC transplantation and RWJ administration accelerated recovery from diabetic stroke, which might have been caused by increased levels of proangiogenic and neurotrophic factors. © 2015 American Heart Association, Inc.
    Full-text · Article · Jun 2015 · Stroke
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Breast cancer bone micrometastases can remain asymptomatic for years before progressing into overt lesions. The biology of this process, including the microenvironment niche and supporting pathways, is unclear. We find that bone micrometastases predominantly reside in a niche that exhibits features of osteogenesis. Niche interactions are mediated by heterotypic adherens junctions (hAJs) involving cancer-derived E-cadherin and osteogenic N-cadherin, the disruption of which abolishes niche-conferred advantages. We elucidate that hAJ activates the mTOR pathway in cancer cells, which drives the progression from single cells to micrometastases. Human data set analyses support the roles of AJ and the mTOR pathway in bone colonization. Our study illuminates the initiation of bone colonization, and provides potential therapeutic targets to block progression toward osteolytic metastases. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Jan 2015 · Cancer Cell
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Convincing epidemiological data suggest an inverse association between cancer and neurodegeneration, including Alzheimer's disease (AD). Since both AD and cancer are characterized by abnormal, but opposing cellular behavior, i.e., increased cell death in AD while excessive cell growth occurs in cancer, this motivates us to initiate the study into unraveling the shared genes and cell signaling pathways linking AD and glioblastoma multiform (GBM). In this study, a comprehensive bioinformatics analysis on clinical microarray datasets of 1,091 GBM and 524 AD cohorts was performed. Significant genes and pathways were identified from the bioinformatics analyses - in particular ERK/MAPK signaling, up-regulated in GBM and Angiopoietin Signaling pathway, reciprocally up-regulated in AD - connecting GBM and AD (P < 0.001), were investigated in details for their roles in GBM growth in an AD environment. Our results showed that suppression of GBM growth in an AD background was mediated by the ERK-AKT-p21-cell cycle pathway and anti-angiogenesis pathway.
    Full-text · Article · Dec 2013 · Scientific Reports
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Decreased cerebral blood flow causes brain ischemia and plays an important role in the pathophysiology of many neurodegenerative diseases, including Alzheimer's disease and vascular dementia. In this study, we photomodulated astrocytes in the live animal by a combination of two-photon calcium uncaging in the astrocyte endfoot and in vivo imaging of neurovasculature and astrocytes by intravital two-photon microscopy after labeling with cell type specific fluorescent dyes. Our study demonstrates that photomodulation at the endfoot of a single astrocyte led to a 25% increase in the diameter of a neighboring arteriole, which is a crucial factor regulating cerebral microcirculation in downstream capillaries. Two-photon uncaging in the astrocyte soma or endfoot near veins does not show the same effect on microcirculation. These experimental results suggest that infrared photomodulation on astrocyte endfeet may be a strategy to increase cerebral local microcirculation and thus prevent brain ischemia.
    Full-text · Article · Dec 2013 · Journal of Biomedical Optics
  • [Show abstract] [Hide abstract]
    ABSTRACT: Neurovascular dysfunction in many neurodegenerative diseases, such as Alzheimer’s disease (AD), reduces blood flow to affected brain areas and causes neuronal dysfunction and loss. A new optical imaging technique is developed to activate astrocytes in live animal models in order to investigate the increase of local cerebral blood flow as a potential therapeutic strategy for AD. The technique uses fluorescent labeling of vasculature and astrocytes coupled with intravital 2-photon microscopy to visualize the astrocyte-vasculature interactions in live animals. Using femtosecond laser stimulation, calcium uncaging is applied to specifically target and activate astrocytes in vivo with high spatial and temporal resolutions. Intravital 2-photon microscopy imaging was employed to demonstrate that single endfoot optical activation around an arteriole induced a 25% increase in arteriole diameter, which in turn increased cerebral local blood flow in down-stream capillaries. This quantitative result indicates the potential of using optical activation of astrocytes in afflicted brain areas of neurodegeneration to restore normal neurovascular functions.
    No preview · Conference Paper · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: Deep brain stimulation (DBS) of the cholinergic nuclei has emerged as a powerful potential treatment for neurodegenerative disease and is currently in a clinical trial for Alzheimer’s therapy. While effective in treatment for a number of conditions from depression to epilepsy, DBS remains somewhat unpredictable due to the heterogeneity of the projection neurons that are activated, including glutamatergic, GABAergic, and cholinergic neurons, leading to unacceptable side effects ranging from apathy to depression or even suicidal behavior. It would be highly advantageous to confine stimulation to specific populations of neurons, particularly in brain diseases involving complex network interactions such as Alzheimer’s. Optogenetics, now firmly established as an effective approach to render genetically-defined populations of cells sensitive to light activation including mice expressing Channelrhodopsin-2 specifically in cholinergic neurons, provides just this opportunity. Here we characterize the light activation properties and cell density of cholinergic neurons in healthy mice and mouse models of Alzheimer’s disease in order to evaluate the feasibility of using optogenetic modulation of cholinergic synaptic activity to slow or reverse neurodegeneration. This paper is one of the very first reports to suggest that, despite the anatomical depth of their cell bodies, cholinergic projection neurons provide a better target for systems level optogenetic modulation than cholinergic interneurons found in various brain regions including striatum and the cerebral cortex. Additionally, basal forebrain channelrhodopsin-expressing cholinergic neurons are shown to exhibit normal distribution at 60 days and normal light activation at 40 days, the latest timepoints observed. The data collected form the basis of ongoing computational modeling of light stimulation of entire populations of cholinergic neurons.
    No preview · Conference Paper · Mar 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Brain-metastatic breast cancer (BMBC) is increasing and poses a severe clinical problem because of the lack of effective treatments and because the underlying molecular mechanisms are largely unknown. Recent work has demonstrated that deregulation of epidermal growth factor receptor (EGFR) may correlate with BMBC progression. However, the exact contribution that EGFR makes to BMBC remains unclear. The role of EGFR in BMBC was explored by serial analyses in a brain-trophic clone of human MDA-MB-231 breast carcinoma cells (231-BR cells). EGFR expression was inhibited by stable short-hairpin RNA transfection or by the kinase inhibitor erlotinib, and it was activated by heparin-binding epidermal growth factor-like growth factor (HB-EGF). Cell growth and invasion activities also were analyzed in vitro and in vivo. EGFR inhibition or activation strongly affected 231-BR cell migration/invasion activities as assessed by an adhesion assay, a wound-healing assay, a Boyden chamber invasion assay, and cytoskeleton staining. Also, EGFR inhibition significantly decreased brain metastases of 231-BR cells in vivo. Surprisingly, changes to EGFR expression affected cell proliferation activities less significantly as determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, an anchorage-independent growth assay, and cell cycle analysis. Immunoblot analysis suggested that EGFR drives cells' invasiveness capability mainly through phosphoinositide 3-kinase/protein kinase B and phospholipase C γ downstream pathways. In addition, EGFR was involved less in proliferation because of the insensitivity of the downstream mitogen-activated protein kinase pathway. The current results indicated that EGFR plays more important roles in cell migration and invasion to the brain than in cell proliferation progression on 231-BR cells, providing new evidence of the potential value of EGFR inhibition in treating BMBC. Cancer 2012. © 2012 American Cancer Society.
    Full-text · Article · Nov 2012 · Cancer
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Thrombus and secondary thrombosis plays a key role in stroke. Recent molecular imaging provides in vivo imaging of activated factor XIII (FXIIIa), an important mediator of thrombosis or fibrinolytic resistance. The present study was to investigate the fibrin deposition in a thromboembolic stroke mice model by FXIIIa-targeted near-infrared fluorescence (NIRF) imaging. The experimental protocol was approved by our institutional animal use committee. Seventy-six C57B/6J mice were subjected to thromboembolic middle cerebral artery occlusion or sham operation. Mice were either intravenously injected with the FXIIIa-targeted probe or control probe. In vivo and ex vivo NIRF imaging were performed thereafter. Probe distribution was assessed with fluorescence microscopy by spectral imaging and quantification system. MR scans were performed to measure lesion volumes in vivo, which were correlated with histology after animal euthanasia. In vivo significant higher fluorescence intensity over the ischemia-affected hemisphere, compared to the contralateral side, was detected in mice that received FXIIIa-targeted probe, but not in the controlled mice. Significantly NIRF signals showed time-dependent processes from 8 to 96 hours after injection of FXIIIa-targeted probes. Ex vivo NIRF image showed an intense fluorescence within the ischemic territory only in mice injected with FXIIIa-targeted probe. The fluorescence microscopy demonstrated distribution of FXIIIa-targeted probe in the ischemic region and nearby micro-vessels, and FXIIIa-targeted probe signals showed good overlap with immune-fluorescent fibrin staining images. There was a significant correlation between total targeted signal from in vivo or ex vivo NIRF images and lesion volume. Non-invasive detection of fibrin deposition in ischemic mouse brain using NIRF imaging is feasible and this technique may provide an in vivo experimental tool in studying the role of fibrin in stroke.
    Full-text · Article · Jan 2012 · PLoS ONE