MRI of the basement membrane using charged nanoparticles as contrast agents

Bennett, Kevin M.; Zhou, Hua; Sumner, James P.; Dodd, Stephen J.; Bouraoud, Nadia; Doi, Kent; Star, Robert A.; Koretsky, Alan P.

doi:10.1002/mrm.21684

Cited by 96 publications

(105 citation statements)

References 49 publications

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“…T 2* -weighted 3D gradient echo MR images of the kidneys showed a dark MRI signal at the location of glomeruli after CF injections, but not after NF injections. The specific binding of CF, but not NF, was previously confirmed with immunofluorescence and electron microscopy (1). Figure 1 shows the results of an automated 3D segmentation algorithm to identify individual glomeruli.…”

Section: Resultsmentioning

confidence: 54%

Measuring glomerular number and size in perfused kidneys using MRI

Beeman¹,

Zhang

Gubhaju

et al. 2011

American Journal of Physiology-Renal Physiology

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106

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The goal of this work was to nondestructively measure glomerular (and thereby nephron) number in the whole kidney. Variations in the number and size of glomeruli have been linked to many renal and systemic diseases. Here, we develop a robust magnetic resonance imaging (MRI) technique based on injection of cationic ferritin (CF) to produce an accurate measurement of number and size of individual glomeruli. High-field (19 Tesla) gradient-echo MR images of perfused rat kidneys after in vivo intravenous injection of CF showed specific labeling of individual glomeruli with CF throughout the kidney. We developed a three-dimensional image-processing algorithm to count every labeled glomerulus. MRI-based counts yielded 33,786 Ϯ 3,753 labeled glomeruli (n ϭ 5 kidneys). Acid maceration counting of contralateral kidneys yielded an estimate of 30,585 Ϯ 2,053 glomeruli (n ϭ 6 kidneys). Disector/fractionator stereology counting yielded an estimate of 34,963 glomeruli (n ϭ 2). MRI-based measurement of apparent glomerular volume of labeled glomeruli was 4.89 ϫ 10 Ϫ4 mm 3 (n ϭ 5) compared with the average stereological measurement of 4.99 ϫ 10 Ϫ4 mm 3 (n ϭ 2). The MRI-based technique also yielded the intrarenal distribution of apparent glomerular volume, a measurement previously unobtainable in histology. This work makes it possible to nondestructively measure whole-kidney glomerular number and apparent glomerular volumes to study susceptibility to renal diseases and opens the door to similar in vivo measurements in animals and humans. stereology; nephron; glomerulus count; nanoparticles; magnetic resonance imaging THE PURPOSE OF THIS WORK WAS to measure the number and size of all glomeruli in the entire, intact kidney using magnetic resonance imaging (MRI). Changes in the number and size of glomeruli have been linked to a number of renal and systemic diseases (5, 7). However, current techniques for counting and measuring glomeruli, such as acid maceration (4) and the dissector/fractionator stereology technique (3), require the destruction of the entire kidney. Furthermore, conventional histological techniques extrapolate the total number and size of glomeruli from a selected number of histological sections or isolated glomeruli. Current techniques are thus estimates rather than direct measurements and do not allow for localization of identified functioning glomeruli to specific parts of the kidney. A method for directly and nondestructively measuring the number and size of all glomeruli in the kidney would serve as a useful tool in animal studies and potentially in the clinic.Recently we demonstrated that intravenous injections of the iron-binding protein ferritin, functionalized with cationic amine groups (6), can be used to detect individual glomeruli both in vivo and ex vivo with MRI (1). This method is based on the electrostatic binding of cationic ferritin (CF) to the anionic macromolecules of the glomerular basement membrane (GBM) and subsequent perturbation of the magnetic field around the labeled GBM by ferritin, result...

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Section: Resultsmentioning

confidence: 54%

Measuring glomerular number and size in perfused kidneys using MRI

Beeman¹,

Zhang

Gubhaju

et al. 2011

American Journal of Physiology-Renal Physiology

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106

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“…This phenomenon is likely generalizable to most cationic polymer-based nucleic acid delivery systems, or any other delivery vehicles that self-assemble because of electrostatic interactions. For example, 93-nm DNA/PEI polyplexes have been observed to filter through the GBM after direct injection into the renal artery (27), and both Cationic polymers alone (28) and positively charged ferritin nanoparticles (29) have been shown to bind to the GBM after i.v. injection.…”

Section: Discussionmentioning

confidence: 99%

Polycation-siRNA nanoparticles can disassemble at the kidney glomerular basement membrane

Zuckerman

Choi²,

Han³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

323

269

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Despite being engineered to avoid renal clearance, many cationic polymer (polycation)-based siRNA nanoparticles that are used for systemic delivery are rapidly eliminated from the circulation. Here, we show that a component of the renal filtration barrier-the glomerular basement membrane (GBM)-can disassemble cationic cyclodextrin-containing polymer (CDP)-based siRNA nanoparticles and, thereby, facilitate their rapid elimination from circulation. Using confocal and electron microscopies, positron emission tomography, and compartment modeling, we demonstrate that siRNA nanoparticles, but not free siRNA, accumulate and disassemble in the GBM. We also confirm that the siRNA nanoparticles do not disassemble in blood plasma in vitro and in vivo. This clearance mechanism may affect any nanoparticles that assemble primarily by electrostatic interactions between cationic delivery components and anionic nucleic acids (or other therapeutic entities). pharmacokinetics | glomerulusA major challenge with the use of small interfering RNA (siRNA) in mammals is their delivery to intracellular locations in specific tissues (1). The two most investigated approaches to siRNA delivery involve the combination of siRNA with cationic lipids (lipoplexes, liposomes, micelles) or cationic polymers (polyplexes) (2). Polymer-based siRNA delivery vehicles can be tuned to be nonimmunogenic, nononcogenic, nontoxic, and targeted (3). A targeted nanoparticle formulation of siRNA (not chemically modified) with a cationic, cyclodextrin-containing polymer (CDP)-based delivery vehicle (clinical version denoted CALAA-01) was shown to accumulate in human tumors and deliver functional siRNA from a systemic, i.v. infusion (4). This first-in-human study demonstrated the clinical potential for cationic polymerbased siRNA delivery systems.Like most cationic polymer-based siRNA delivery systems (5-9), the siRNA/CDP nanoparticle is rapidly eliminated from circulation (shown in mice, monkeys, and humans) (10-12). In fact, polymer complexation often does not extend the circulation time of siRNA. The rapid clearance of these siRNA nanoparticles is puzzling because they are engineered to be above the size cutoff for single-pass clearance via renal filtration (13). In understanding the mechanism behind the rapid clearance of this type of cancer therapeutic, we can efficiently seek ways to increase their circulation time and, thus, enhance their anticancer efficacy (3).We hypothesize that the paradoxical renal clearance of polycation-nucleic acid nanoparticles results from their binding and disassembly by components of the renal filtration barrier. Three key properties of such nanoparticles (diameters between 10 and 100 nm, positive zeta potentials, and electrostatically driven selfassembly) make them susceptible to this mechanism of clearance.The renal filtration barrier, located within the glomerulus of the nephron, consists of three layers that must be traversed to enter the urinary space. These three layers are the glomerular endothelial fenestrations (≈100 n...

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“…The main advantage of the magnetoferritin described here is the simplicity of its synthesis, monodispersity, homogeneity in size, and their comparably high transverse per-particle and per-iron relaxivity. These characteristics make this synthetic version of magnetoferritin a versatile nanoparticle with various potential applications (8,14,17,22). Inset shows the distribution of pixel intensities in a ROI over the injection of native ferritin or magnetoferritin, normalized to normal tissue (n ¼ 3 rats).…”

Section: Discussionmentioning

confidence: 99%

“…Ferritin is a 13 nm protein nanoparticle with an iron oxide core. Ferritin has been used as a targeted contrast agent, and is small enough to be delivered through fenestrated endothelia (8). Because native ferritin is only partially filled with a weakly superparamagnetic iron core, it has been reconstituted to fully fill the protein core with highly magnetic iron oxide cores to increase its MRI transverse relaxivity (9).…”

mentioning

confidence: 99%

Simplified synthesis and relaxometry of magnetoferritin for magnetic resonance imaging

Jordan

Caplan

Bennett

2010

Magnetic Resonance in Med

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Magnetoferritin nanoparticles have been developed as highrelaxivity, functional contrast agents for MRI. Several previous techniques have relied on unloading native ferritin and reincorporation of iron into the core, often resulting in a polydisperse sample. Here, a simplified technique is developed using commercially available horse spleen apoferritin to create monodisperse magnetoferritin. Iron oxide atoms were incorporated into the protein core via a step-wise Fe(II)Chloride addition to the protein solution under low O 2 conditions; subsequent filtration steps allow for separation of completely filled and superparamagnetic magnetoferritin from the partially filled ferritin. This method yields a monodisperse and homogenous solution of spherical particles with magnetic properties that can be used for molecular magnetic resonance imaging. With a transverse per-iron and per-particle relaxivity of 78 mM 21 sec 21 and 404,045 mM 21 sec 21 , respectively, it is possible to detect~10 nM nanoparticle concentrations in vivo. Magn Reson Med 64:1260-1266, 2010. V C 2010 Wiley-Liss, Inc.Key words: ferritin; magnetoferritin; molecular imaging; MRI Targeted contrast agents have been developed to detect molecules noninvasively with magnetic resonance imaging (MRI). MRI is non-invasive and inherently threedimensional. MRI contrast agents are being detected in increasingly lower concentrations in vivo (1). Typical molecular MRI requires the binding of contrast agents to a specific site and subsequent removal of the unbound agent. Many of the applications of molecular imaging agents require detection in low (

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MRI of the basement membrane using charged nanoparticles as contrast agents

Cited by 96 publications

References 49 publications

Measuring glomerular number and size in perfused kidneys using MRI

Measuring glomerular number and size in perfused kidneys using MRI

Polycation-siRNA nanoparticles can disassemble at the kidney glomerular basement membrane

Simplified synthesis and relaxometry of magnetoferritin for magnetic resonance imaging

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