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Iordanova B.,Carnegie Mellon University | Iordanova B.,Pittsburgh Center for Biomedical Research | Goins W.F.,University of Pittsburgh | Clawson D.S.,University of Pittsburgh | And 3 more authors.
Gene Therapy | Year: 2013

The development of effective strategies for gene therapy has been hampered by difficulties verifying transgene delivery in vivo and quantifying gene expression non-invasively. Magnetic resonance imaging (MRI) offers high spatial resolution and three-dimensional views, without tissue depth limitations. The iron-storage protein ferritin is a prototype MRI gene reporter. Ferritin forms a paramagnetic ferrihydrite core that can be detected by MRI via its effect on the local magnetic field experienced by water protons. In an effort to better characterize the ferritin reporter for central nervous system applications, we expressed ferritin in the mouse brain in vivo using a neurotropic herpes simplex virus type 1 (HSV-1). We computed three-dimensional maps of MRI transverse relaxation rates in the mouse brain with ascending doses of ferritin-expressing HSV-1. We established that the transverse relaxation rates correlate significantly to the number of inoculated infectious particles. Our results are potentially useful for quantitatively assessing limitations of ferritin reporters for gene therapy applications. © 2013 Macmillan Publishers Limited All rights reserved. Source


Iordanova B.,Carnegie Mellon University | Iordanova B.,Pittsburgh Center for Biomedical Research | Robison C.S.,Carnegie Mellon University | Robison C.S.,Pittsburgh Center for Biomedical Research | And 2 more authors.
Journal of Biological Inorganic Chemistry | Year: 2010

This paper describes the design and characterization of a novel ferritin chimera. The iron storage protein ferritin forms a paramagnetic ferrihydrite core. This biomineral, when placed in a magnetic field, can decrease the transverse NMR relaxation times (T 2 and T 2*) of nearby mobile water protons. Ferritin nucleic acid constructs have recently been studied as "probeless" magnetic resonance imaging (MRI) reporters. Following reporter expression, ferritin sequesters endogenous iron and imparts hypointensity to 2 and T 2*-weighted images in an amount proportional to the ferritin iron load. Wild-type ferritin consists of various ratios of heavy H and light L subunits, and their ratio affects ferritin's stability and iron storage capacity. We report a novel chimeric ferritin with a fixed subunit stoichiometry obtained by fusion of the L and the H subunits (L *H and H *L) using a flexible linker. We characterize these supramolecular ferritins expressed in human cells, including their iron loading characteristics, hydrodynamic size, subcellular localization, and effect on solvent water T 2 relaxation rate. Interestingly, we found that the L *H chimera exhibits a significantly enhanced iron loading ability and T 2 relaxation compared to wild-type ferritin. We suggest that the L *H chimera may be useful as a sensitive MRI reporter molecule. © SBIC 2010. Source

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