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Hu F, MacRenaris KW, Waters EA, Liang T, Schultz-Sikma EA, Eckermann AL, Meade TJ. Ultrasmall, Water-Soluble Magnetite Nanoparticles with High Relaxivity for Magnetic Resonance Imaging. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2009; 113:20855-20860. [PMID: 24991303 PMCID: PMC4076104 DOI: 10.1021/jp907216g] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Ultrasmall (3, 4, 5, and 6 nm), water-soluble Fe3O4 magnetic nanoparticles were synthesized in diethylene glycol (DEG) via a facile one-pot reaction. Hydrodynamic size and relaxation time measurements did not show particle aggregation when Fe3O4 nanoparticles were dispersed in phosphate buffered saline, fetal bovine serum, or calf bovine serum for 1 week. Furthermore, the new Fe3O4 nanoparticles tolerated high salt concentrations (≤1 M NaCl) and a wide pH range from 5 to 11. Surface modification of the nanoparticles with poly(ethylene glycol) bis(carboxymethyl) ether (HOOC-PEG-COOH, 600 g/mol) was accomplished through a ligand-exchange reaction. The effects of PEG modification on magnetization and relaxivity of the Fe3O4 nanoparticles were investigated, and the results indicate that the increase in transverse relaxivity after PEG modification may be due to the increased volume of slowly diffusing water surrounding each nanoparticle. In vitro experiments showed that the DEG- and PEG-coated Fe3O4 nanoparticles have little effect on NIH/3T3 cell viability.
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102
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Hu F, Macrenaris KW, Waters EA, Schultz-Sikma EA, Eckermann AL, Meade TJ. Highly dispersible, superparamagnetic magnetite nanoflowers for magnetic resonance imaging. Chem Commun (Camb) 2009; 46:73-5. [PMID: 20024297 DOI: 10.1039/b916562b] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A one-pot reaction process was developed to synthesize highly dispersible, superparamagnetic Fe(3)O(4) nanoflowers; the potential of these nanoflowers as MRI contrast agents was investigated.
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103
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Barker KD, Eckermann AL, Sazinsky MH, Hartings MR, Abajian C, Georganopoulou D, Ratner MA, Rosenzweig AC, Meade TJ. Protein Binding and the Electronic Properties of Iron(II) Complexes: An Electrochemical and Optical Investigation of Outer Sphere Effects. Bioconjug Chem 2009; 20:1930-9. [DOI: 10.1021/bc900270a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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104
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Bertin PA, Meade TJ. Novel redox active bifunctional crosslinkers from unsymmetrical 1,1′-disubstituted ferrocenes. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.07.056] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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105
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106
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Abstract
Magnetic resonance imaging (MRI) has become increasingly popular in experimental molecular imaging and clinical radiology because it is non-invasive and capable of producing three-dimensional representations of opaque organisms with high spatial and temporal resolution. Approximately 35% of all clinical MR scans utilize contrast media, however a primary limitation of MR imaging is the sensitivity of contrast agents that require high concentrations (0.1-0.6 mM). A number of strategies have been employed to amplify the observed in vivo signal of MR contrast agents. Approaches include attachment of Gd(III) chelates to polymers, proteins and particles, encapsulation into micelles and caged structures, and targeting to receptors. While each of these approaches has yielded significant increases in the relaxivity of MR contrast agents (and therefore sensitivity), all of these classes of complexes possess intrinsic background signal and function solely as anatomical reporters. In order to reduce the background signal and simultaneously create probes that are modulated by biochemical processes, caged complexes were designed to coordinatively saturate the paramagnetic ion. Coupled with amplification strategies, these agents represent a means to selectively modulate the observed MR signal and function as in vivo biochemical reporters. For example, to create an in vivo MR assay of enzymatic activities and secondary messengers, agents have been designed and synthesized with removable protection groups that largely prevent access of water to a paramagnetic center. By limiting the access of bulk water (q-modulation) the unprocessed agent is designed to be an ineffective contrast agent, and hence serves as a reliable marker for regions of enzyme activity or the presence of secondary messengers. Further, we have focused on designing multimodal contrast agents that are simultaneously detectable by more than one imaging technique. For example, attaching an optical probe to a MR contrast agent provides the means to detect the probe in a whole animal and subsequently validate the results by histological methods. Finally, we describe strategies for signal amplification, and cell delivery vehicles attached to imaging probes for in vivo long-term fate mapping experiments.
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107
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Lin W, Hyeon T, Lanza GM, Zhang M, Meade TJ. Magnetic Nanoparticles for Early Detection of Cancer by Magnetic Resonance Imaging. MRS BULLETIN 2009; 34:441-448. [PMID: 26166945 PMCID: PMC4495966 DOI: 10.1557/mrs2009.120] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This article provides a brief overview of recent progress in the synthesis and functionalization of magnetic nanoparticles and their applications in the early detection of malignant tumors by magnetic resonance imaging (MRI). The intrinsic low sensitivity of MRI necessitates the use of large quantities of exogenous contrast agents in many imaging studies. Magnetic nanoparticles have recently emerged as highly efficient MRI contrast agents because these nanometer-scale materials can carry high payloads while maintaining the ability to move through physiological systems. Superparamagnetic ferrite nanoparticles (such as iron oxide) provide excellent negative contrast enhancement. Recent refinement of synthetic methodologies has led to ferrite nanoparticles with narrow size distributions and high crystallinity. Target-specific tumor imaging becomes possible through functionalization of ferrite nanoparticles with targeting agents to allow for site-specific accumulation. Nanoparticulate contrast agents capable of positive contrast enhancement have recently been developed in order to overcome the drawbacks of negative contrast enhancement afforded by ferrite nanoparticles. These newly developed magnetic nanoparticles have the potential to enable physicians to diagnose cancer at the earliest stage possible and thus can have an enormous impact on more effective cancer treatment.
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108
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Abstract
Cell transplantation is a promising approach to improve the life of patients with liver disease. At present, however, techniques to track and visualise transplanted cells in patients are fairly limited and further development of non-invasive imaging technology is needed to advance the monitoring of liver cell grafts. Magnetic resonance imaging (MRI) is a non-invasive imaging technology that already allows the visualisation of particular cell fractions in the liver by using MR contrast agents. The use of contrast agents to pre-label liver cells prior to transplantation will potentially provide a method to identify, track and study the integration of engrafted cells non-invasively by MRI. Before this technique can find its clinical application, in vitro and pre-clinical in vivo studies need to be conducted to determine the safety and specificity of this approach.
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109
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Song Y, Xu X, MacRenaris KW, Zhang XQ, Mirkin CA, Meade TJ. Multimodal gadolinium-enriched DNA-gold nanoparticle conjugates for cellular imaging. Angew Chem Int Ed Engl 2009; 48:9143-7. [PMID: 19882611 PMCID: PMC2917899 DOI: 10.1002/anie.200904666] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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110
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Major JL, Boiteau RM, Meade TJ. Mechanisms of ZnII-activated magnetic resonance imaging agents. Inorg Chem 2008; 47:10788-95. [PMID: 18928280 DOI: 10.1021/ic801458u] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report on the mechanism of a series of Zn (II)-activated magnetic resonance contrast agents that modulate the access of water to a paramagnetic Gd (III) ion to create an increase in relaxivity upon binding of Zn (II). In the absence and presence of Zn (II), the coordination at the Gd (III) center is modulated by appended Zn (II) binding groups. These groups were systematically varied to optimize the change in coordination upon Zn (II) binding. We observe that at least one appended aminoacetate must be present as a coordinating group to bind Gd (III) and effectively inhibit access of water. At least two binding groups are required to efficiently bind Zn (II), creating an unsaturated complex and allowing access of water. (13)C isotopic labeling of the acetate binding groups for NMR spectroscopy provides evidence of a change in the metal coordination of these groups upon the addition of Zn (II) supporting our proposed mechanism of activation as presented.
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111
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Endres PJ, MacRenaris KW, Vogt S, Meade TJ. Cell-permeable MR contrast agents with increased intracellular retention. Bioconjug Chem 2008; 19:2049-59. [PMID: 18803414 DOI: 10.1021/bc8002919] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Magnetic resonance imaging (MRI) is a technique used in both clinical and experimental settings to produce high-resolution images of opaque organisms without ionizing radiation. Currently, MR imaging is augmented by contrast agents, and the vast majority these small molecule Gd(III) chelates are confined to the extracellular regions. As a result, contrast agents are confined to vascular regions reducing their ability to provide information about cell physiology or molecular pathology. We have shown that polypeptides of arginine have the capacity to transport Gd(III) contrast agents across cell membranes. However, this transport is not unidirectional, and once inside the cell, the arginine-modified contrast agents efflux rapidly, decreasing the intracellular Gd(III) concentration and corresponding MR image intensity. By exploiting the inherent disulfide reducing environment of cells, thiol compounds, Gd(III)-DOTA-SS-Arg 8 and Gd(III)-DTPA-SS-Arg 8, are cleaved from their cell-penetrating peptide transduction domains upon cell internalization. This reaction prolongs the cell-associated lifetime of the chelated Gd(III) by cleaving it from the cell transduction domain.
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112
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Bertin PA, Georganopoulou D, Liang T, Eckermann AL, Wunder M, Ahrens MJ, Blackburn GF, Meade TJ. Electroactive self-assembled monolayers on gold via bipodal dithiazepane anchoring groups. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:9096-9101. [PMID: 18627193 DOI: 10.1021/la801165b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Novel dithiazepane-functionalized ferrocenyl-phenylethynyl oligomers 1 and 2 have been synthesized. Self-assembled monolayers (SAMs) of these ferrocene derivatives have been studied by X-ray photoelectron spectroscopy, ellipsometry, and cyclic voltammetry. It has been shown by XPS that monolayers of the dithiazepane-anchored molecules on gold electrodes contain gold-thiolate species. Cyclic voltammetry of the SAMs were characteristic of stable electroactive monolayers even for single-component SAMs of 1 and 2, with the more ideal responses recorded for the two-component SAMs diluted with undecanethiol. The small variation in peak splittings at progressively higher scan rates in these SAMs makes dithiazepane-bridged redox species promising candidates for further studies on molecular wires with bipodal anchoring.
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113
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Cilliers R, Song Y, Kohlmeir EK, Larson AC, Omary RA, Meade TJ. Modification of embolic-PVA particles with MR contrast agents. Magn Reson Med 2008; 59:898-902. [PMID: 18383280 DOI: 10.1002/mrm.21518] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
We report the synthesis and characterization of polyvinyl alcohol (PVA) embolic particles modified with a clinically approved magnetic resonance (MR) contrast agent. PVA particles are used during transcatheter arterial embolization (TAE) procedures and this minimally invasive technique is a widely employed treatment for inoperable tumors. The PVA particles are injected into tumor vessels and prevent blood flow which results in tumor attenuation. An accurate assessment of the endpoint of embolization is critical to successful TAE procedures. Recent reports suggest that 20% of endpoint determination of TAE procedures by angiographic techniques are erroneous. Real time, in vivo imaging of the embolic particles would overcome this limitation. The contrast-modified PVA particles described here show an 80% decrease in T(1) relaxation times compared to unmodified particles. Images of particles in capillary tubes of similar size to catheters used in TAE procedures are clearly visible by MRI.
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114
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Song Y, Kohlmeir EK, Meade TJ. Synthesis of multimeric MR contrast agents for cellular imaging. J Am Chem Soc 2008; 130:6662-3. [PMID: 18452288 DOI: 10.1021/ja0777990] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We have prepared a series of molecular multimeric MR contrast agents for cell labeling that are easy to synthesize, relatively low molecular weight, and biocompatible. The relaxivities of the agents range from 17 to 85 mM(-1) s(-1). Cellular uptake is concentration dependent and viability is excellent. MR images of cell pellets reveal a marked increase in observed signal intensity.
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115
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Bull SR, Palmer LC, Fry NJ, Greenfield MA, Messmore BW, Meade TJ, Stupp SI. A templating approach for monodisperse self-assembled organic nanostructures. J Am Chem Soc 2008; 130:2742-3. [PMID: 18266371 PMCID: PMC2538364 DOI: 10.1021/ja710749q] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The precise structural control is known for self-assembly into closed spherical structures (e.g., micelles), but similar control of open structures is much more challenging. Inspired by natural tobacco mosaic virus, we present the use of a rigid-rod template to control the size of a one-dimensional self-assembly. We believe that this strategy is novel for organic self-assembly and should provide a general approach to controlling size and dimension.
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116
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Urbanczyk-Pearson LM, Meade TJ. Preparation of magnetic resonance contrast agents activated by β-galactosidase. Nat Protoc 2008; 3:341-50. [DOI: 10.1038/nprot.2007.529] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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117
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Urbanczyk-Pearson LM, Femia FJ, Smith J, Parigi G, Duimstra JA, Eckermann AL, Luchinat C, Meade TJ. Mechanistic Investigation of β-Galactosidase-Activated MR Contrast Agents. Inorg Chem 2007; 47:56-68. [DOI: 10.1021/ic700888w] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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118
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Endres PJ, Paunesku T, Vogt S, Meade TJ, Woloschak GE. DNA−TiO2 Nanoconjugates Labeled with Magnetic Resonance Contrast Agents. J Am Chem Soc 2007; 129:15760-1. [DOI: 10.1021/ja0772389] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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119
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Wang P, Miller JE, Henling LM, Stern CL, Frank NL, Eckermann AL, Meade TJ. Synthesis and Characterization of Ruthenium and Rhenium Nucleosides. Inorg Chem 2007; 46:9853-62. [DOI: 10.1021/ic701250r] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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120
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Karfeld LS, Bull SR, Davis NE, Meade TJ, Barron AE. Use of a genetically engineered protein for the design of a multivalent MRI contrast agent. Bioconjug Chem 2007; 18:1697-700. [PMID: 17927227 DOI: 10.1021/bc700149u] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The majority of clinically used contrast agents (CAs) for magnetic resonance imaging have low relaxivities and thus require high concentrations for signal enhancement. Research has turned to multivalent, macromolecular CAs to increase CA efficiency. However, previously developed macromolecular CAs do not provide high relaxivities, have limited biocompatibility, and/or do not have a structure that is readily modifiable to tailor to particular applications. We report a new family of multivalent, biomacromolecular, genetically engineered protein polymer-based CAs; the protein backbone contains evenly spaced lysines that are derivatized with gadolinium (Gd(III)) chelators. The protein's length and repeating amino acid sequence are genetically specified. We reproducibly obtained conjugates with an average of 8-9 Gd(III) chelators per protein. These multivalent CAs reproducibly provide a high relaxivity of 7.3 mM (-1) s (-1) per Gd(III) and 62.6 mM (-1) s (-1) per molecule. Furthermore, they can be incorporated into biomaterial hydrogels via chemical cross-linking of the remaining free lysines, and provide a dramatic contrast enhancement. Thus, these protein polymer CAs could be a useful tool for following the evolution of tissue engineering scaffolds.
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121
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Major JL, Parigi G, Luchinat C, Meade TJ. The synthesis and in vitro testing of a zinc-activated MRI contrast agent. Proc Natl Acad Sci U S A 2007; 104:13881-6. [PMID: 17724345 PMCID: PMC1955783 DOI: 10.1073/pnas.0706247104] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Zinc(II) plays a vital role in normal cellular function as an essential component of numerous enzymes, transcription factors, and synaptic vesicles. While zinc can be linked to a variety of physiological processes, the mechanisms of its cellular actions are less discernible. Here, we have synthesized and tested a Zn(II)-activated magnetic resonance imaging (MRI) contrast agent in which the coordination geometry of the complex rearranges upon binding of Zn(II). In the absence of Zn(II) water is restricted from binding to a chelated Gd(III) ion by coordinating acetate arms resulting in a low relaxivity of 2.33 mM(-1) x s(-1) at 60 MHz. Upon addition of Zn(II) the relaxivity of the Gd(III)-Zn(II) complex increases to 5.07 mM(-1) x s(-1) and is consistent with one water molecule bound to Gd(III). These results were confirmed by nuclear magnetic relaxation dispersion analysis. There was no observed change in relaxivity of the Gd(III) complex when physiologically competing cations Ca(II) and Mg(II) were added. A competitive binding assay gave a dissociation constant of 2.38 x 10(-4) M for the Gd(III)-Zn(II) complex. In vitro magnetic resonance images confirm that Zn(II) concentrations as low as 100 microM can be detected by using this contrast agent.
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122
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Frullano L, Meade TJ. Multimodal MRI contrast agents. J Biol Inorg Chem 2007; 12:939-49. [PMID: 17659368 DOI: 10.1007/s00775-007-0265-3] [Citation(s) in RCA: 193] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 05/10/2007] [Indexed: 02/04/2023]
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123
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Lee J, Burdette JE, MacRenaris KW, Mustafi D, Woodruff TK, Meade TJ. Rational Design, Synthesis, and Biological Evaluation of Progesterone-Modified MRI Contrast Agents. ACTA ACUST UNITED AC 2007; 14:824-34. [PMID: 17656319 DOI: 10.1016/j.chembiol.2007.06.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2007] [Revised: 05/29/2007] [Accepted: 06/18/2007] [Indexed: 12/30/2022]
Abstract
A series of contrast agents for magnetic resonance imaging (MRI) aimed at noninvasively determining the hormone receptor status of cancer in vitro was developed. These MRI contrast agents were prepared by conjugating progesterone to clinically used Gd(III) chelates. These agents exhibited higher progesterone receptor binding affinities in the nanomolar range and intracellular accumulation. High logP values of the modified compounds suggested that the lipophilicity of the steroid conjugates may have contributed to membrane permeability. Synchrotron radiation X-ray fluorescence microscopy and magnetic resonance images revealed that the synthesized conjugates showed the greatest cellular accumulation and significant increase in relaxivity in vitro compared to the previously developed steroid-modified agent. Transcriptional assays using the progesterone response element linked to luciferase indicated that the contrast agents entered the cell, interacted with the biological target, and drove specific progesterone-mediated transcription.
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124
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Brekke C, Morgan SC, Lowe AS, Meade TJ, Price J, Williams SCR, Modo M. The in vitro effects of a bimodal contrast agent on cellular functions and relaxometry. NMR IN BIOMEDICINE 2007; 20:77-89. [PMID: 16952123 DOI: 10.1002/nbm.1077] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The in vivo monitoring of cell survival and migration will be essential to the translation of cell-based therapies from the laboratory to clinical studies. The pre-labeling of cells with magnetic resonance imaging (MRI) contrast agents renders them visible in vivo for serial cellular imaging. However, little is known about the impact of the presence of these metal particles inside transplanted cells. The use of the bimodal contrast agent GRID made it possible to demonstrate by means of fluorescent microscopy and inductively coupled plasma mass spectrometry (ICP-MS) that, after 16 h of incubation (without the use of a transfection agent), neural stem cells (NSCs) were saturated and no longer incorporated particles. With this maximal uptake, no significant effect on cell viability was observed. However, a significant decrease in proliferation was evident in cells that underwent 24 h of labeling. A significant increase in reactive oxygen species was observed for all GRID labeling, with a very significant increase with 24 h of labeling. GRID labeling did not affect cell motility in comparison with PKH26-labeled NSCs in a glioma-based migration assay and also allowed differentiation into all major cell types of the brain. GRID-labeled cells induced a signal change of 47% on T(2) measurements and allows a detection of cell clusters of approximately 220 cells/microl. Further in vivo testing will be required to ensure that cell labeling with gadolinium-based MRI contrast agents does not impair their ability to repair.
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125
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