Gene targeting MRI: Nucleic acid-based imaging and applications

Department of Radiology, AA Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA.
Methods in molecular biology (Clifton, N.J.) (Impact Factor: 1.29). 01/2011; 711:363-77. DOI: 10.1007/978-1-61737-992-5_18
Source: PubMed


Gene action plays a role in neural cell migration, learning processes, stress response, drug addiction, cancer, mental health, psychiatric and neurological disorders, as well as neurodegenerative diseases. Studies also show that upregulation of certain gene activities in neurons may contribute to the development of Alzheimer's disease and other progressive cognitive disorders many decades after the alteration itself occurs. Endogenous, environmental stress-related, or drug-induced chemical imbalances in the brain affect the homeostasis of gene activities in neurons in specific brain regions and contribute to the comorbidity of mental illness and substance dependence. On the other hand, altered gene activities are also a necessary part of repair processes after brain injury. Our general well-being is governed by the highly regulated gene activities in our brains. A better understanding of gene activities and their relationship to the progression of neurological disease can help the research and medical communities develop necessary measures for early intervention, as well as plan more appropriate interventions or new therapeutic approaches that can benefit a broad spectrum of patients who will be or have been affected by brain diseases. We developed a non-invasive imaging technique that allows real-time assessment of gene transcription profiles in live brains. This imaging method has the potential to provide first-hand information about the progression of neurological disorders by gene targeting and cell typing, and it could elucidate a surrogate marker for therapeutic efficacy for future planning of treatments for human diseases. We have established a workable and reproducible MRI technique in live rodent brains.

Download full-text


Available from: Philip K. Liu
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: How amphetamine affects the neuroglia in living brains is not well understood. In an effort to elucidate this effect, we investigated neuroglia in response to amphetamine exposure using antisense (AS) or sense (S) phosphorothioate-modified oligodeoxynucleotide (sODN) sequences that correspond to glial fibrillary acidic protein (GFAP) mRNA (AS-gfap or S-gfap, respectively) expression. The control is a random-sequence sODN (Ran). Using cyanine 5.5-superparamagnetic iron oxide nanoparticle (Cy5.5-SPION) labeling and fluorescent microscopy, we demonstrated that living neural progenitor cells (PC-12.1), as well as the cells in fresh brain slices and intact brains of male C57BL6 mice, exhibited universal uptake of all of the sODNs but rapidly excluded all sODN-Ran and most S-gfap. Moreover, transmission electron microscopy revealed electron-dense nanoparticles only in the neuroglia of normal or transgenic mice [B6;DBA-Tg(Fos-tTA, Fos-EGFP*)1MmayTg(tetO-lacZ,tTA*)1Mmay/J] that had been administered AS-gfap or Cy5.5-SPION-gfap. Subtraction R2* maps from mice with acute and chronic amphetamine exposure demonstrated, validated by postmortem immunohistochemistry, a reduction in striatal neuroglia, with gliogenesis in the subventricular zone and the somatosensory cortex in vivo. The sensitivity of our unique gene transcript targeted MRI was illustrated by a positive linear correlation (r(2)=1.0) between in vivo MRI signal changes and GFAP mRNA copy numbers determined by ex vivo quantitative RT-PCR. The study provides direct evidence for targeting neuroglia by antisense DNA-based SPION-gfap that enables in vivo MRI of inaccessible tissue with PCR sensitivity. The results enable us to conclude that amphetamine induces toxicity to neuroglia in vivo, which may cause remodeling or reconnectivity of neuroglia.-Liu, C. H., Yang, J., Ren, J. Q., Liu, C.-M., You, Z., Liu, P. K. MRI reveals differential effects of amphetamine exposure on neuroglia in vivo.
    Full-text · Article · Nov 2012 · The FASEB Journal
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Delivery of antibodies to monitor key biomarkers of retinopathy in vivo represents a significant challenge because living cells do not take up immunoglobulins to cellular antigens. We met this challenge by developing novel contrast agents for retinopathy, which we used with magnetic resonance imaging (MRI). Biotinylated rabbit polyclonal to chick IgY (rIgPxcIgY) and phosphorylthioate-modified oligoDNA (sODN) with random sequence (bio-sODN-Ran) were conjugated with NeutrAvidin-activated superparamagnetic iron oxide nanoparticles (SPION). The resulting Ran-SPION-rIgPxcIgY carries chick polyclonal to microtubule-associated protein 2 (MAP2) as Ran-SPION-rIgP/cIgY-MAP2, or to rhodopsin (Rho) as anti-Rho-SPION-Ran. We examined the uptake of Ran-SPION-rIgP/cIgY-MAP2 or SPION-rIgP/cIgY-MAP2 in normal C57black6 mice (n = 3 each, 40 μg/kg, i.c.v.); we found retention of Ran-SPION-rIgP/cIgY-MAP2 using molecular contrast-enhanced MRI in vivo and validated neuronal uptake using Cy5-goat IgPxcIgY ex vivo. Applying this novel method to monitor retinopathy in a bilateral carotid artery occlusion-induced ocular ischemia, we observed pericytes (at d 2, using Gd-nestin, by eyedrop solution), significant photoreceptor degeneration (at d 20, using anti-Rho-SPION-Ran, eyedrops, P = 0.03, Student's t test), and gliosis in Müller cells (at 6 mo, using SPION-glial fibrillary acidic protein administered by intraperitoneal injection) in surviving mice (n ≥ 5). Molecular contrast-enhanced MRI results were confirmed by optical and electron microscopy. We conclude that chimera and molecular contrast-enhanced MRI provide sufficient sensitivity for monitoring retinopathy and for theranostic applications.-Ren, J., Chen, Y. I., Mackey, A. M., Liu, P. K. Imaging rhodopsin degeneration in vivo in a new model of ocular ischemia in living mice.
    Full-text · Article · Nov 2015 · The FASEB Journal
  • Source

    Full-text · Dataset · Nov 2015