Multicentre dose-ranging study on the efficacy of USPIO ferumoxtran-10 for liver MR imaging

Evaluation of Advanced Nanomaterials for Cancer Diagnosis and Treatment

Cancer is a persistent global disease and a threat to the human species, with numerous cases reported every year. Over recent decades, a steady but slowly increasing mortality rate has been observed. While many attempts have been made using conventional methods alone as a theragnostic strategy, they have yielded very little success. Most of the shortcomings of such conventional methods can be attributed to the high demands of industrial growth and ever-increasing environmental pollution. This requires some high-tech biomedical interventions and other solutions. Thus, researchers have been compelled to explore alternative methods. This has brought much attention to nanotechnology applications, specifically magnetic nanomaterials, as the sole or conjugated theragnostic methods. The exponential growth of nanomaterials with overlapping applications in various fields is due to their potential properties, which depend on the type of synthesis route used. Either top-down or bottom-up strategies synthesize various types of NPs. The top-down only branches out to one method, i.e., physical, and the bottom-up has two methods, chemical and biological syntheses. This review highlights some synthesis techniques, the types of nanoparticle properties each technique produces, and their potential use in the biomedical field, more specifically for cancer. Despite the evident drawbacks, the success achieved in furthering nanoparticle applications to more complex cancer stages and locations is unmatched.

Imaging Characteristics of USPIO Nanoparticles (<5 nm) as MR Contrast Agent In Vitro and in the Liver of Rats

Iron nanoparticles have an increasingly more and more important role in MR molecular imaging due to their novel magnetic and surface chemical properties. They provide new possibilities for noninvasive diagnosis and treatment monitoring, especially for tissues that are rich in macrophages. The smaller size and prolongation of the plasma half-life change the in vivo fate of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles captured by liver in reticuloendothelial system (RES) or mononuclear phagocytic system (MPS). However, there is still a lack of MR imaging studies on the liver assessing USPIO nanoparticles <5 nm in size to reflect its absorption and clearance properties. In this study, we used MRI to study the in vitro phantom and in vivo rat liver imaging characteristics of USPIO nanoparticles (<5 nm). The results showed that USPIO nanoparticles (<5 nm) could potentially reduce longitudinal and transverse relaxation times and showed similar T ₁ relaxation rates compared with commercial gadolinium chelates. In addition, USPIO nanoparticles (<5 nm) in vivo demonstrated both positive (T ₁) and negative (T ₂) liver contrast enhancement in healthy rats' liver. Furthermore, USPIO nanoparticles showed relatively good in vitro biocompatibility and fast clearance (within 45.17 minutes after intravenous injection) in the normal liver. Taken together, these data might inspire a new personalized and precise diagnostic tool and stimulate new applications for specific targeted molecular probes.

Metabolic fate and subchronic biological effects of core-shell structured Fe3O4@SiO2-NH2 nanoparticles

Core-shell structured Fe₃O₄@SiO₂-NH₂ nanoparticles (Fe@Si-NPs) demonstrated outstanding potentials in drug targeting and delivery and medical imaging. However, they have limited clinical applications due to unknown chronic bio-effects and potential bio-related risks. In this study, the subchronic biological effects and metabolic fate of 20 nm Fe@Si-NPs in Sprague-Dawley rats in 12 weeks were investigated by the biochemical assay and NMR-based metabonomic analysis using an intravenous model. Biofluids (plasma and urine) analysis provided the transportation, absorption, and excretion information of Fe@Si-NPs. Urine metabonome displayed a metabolic recovery while self-regulation of plasma metabonome leaded to the parallel metabolic trends between dosed and control groups in 12 weeks. And biological tissues (spleen, liver, kidney, and lung) analysis indicated liver and spleen are the targeted-organs of Fe@Si-NPs. The obvious metabolic variations responding to the biodistribution were induced by Fe@Si-NPs although no visible toxic effects were observed in these tissues. Besides the common energy metabolism response to the xenobiotics, Fe@Si-NPs also disturbed the metabolic pathways in glycerophospholipid and sphingolipid metabolism, metabolisms of purine, pyrimidine, and nicotinate. Our results provide preliminary validation for the potential use of Fe@Si-NPs in clinical medicine and give identifiable ground for the dose selection and bio-nanoagent optimization.

Genotoxic evaluation of different sizes of iron oxide nanoparticles and ionic form by SMART, Allium and comet assay

In this study, the genotoxic potential of <50 nm, <100 nm iron oxide (Fe2O3) nanoparticles (IONPs) and ionic form were investigated using the wing somatic mutation and recombination test (SMART) and Allium and comet assays. In the SMART assay, different concentrations (1, 2, 5 and 10 mM) of NPs and ionic forms were fed to transheterozygous larvae of Drosophila melanogaster. No significant genotoxic effect was observed in <100 nm NPs and ionic form, while <50 nm IONPs showed genotoxicity at 1 and 10 mM concentrations. Allium cepa root meristems were exposed to five concentrations (0.001, 0.01, 0.1, 1 and 10 mM) of <50 nm and ionic forms for 4 h and three concentrations (2.5, 5 and 10 mM) for <100 nm of IONPs for 24 and 96 h. There was a statistically significant effect at 96 h at all concentrations of <100 nm IONPs. Similarly, <50 nm of IONPs and ionic forms also showed a statistically significant effect on mitotic index frequencies for all concentrations at 4 h. There was a dose-dependent increase in chromosomal abnormalities for IONPs and ionic form. Comet assay results showed time- and concentration-dependent increases in <100 nm NPs. There was a concentration-dependent increase in <50 nm NPs and ionic form ( p < 0.05). Consequently, the <50 nm of Fe2O3 was found toxic compared to 100 nm Fe2O3 and ionic form.

Targeted nanoagents for the detection of cancers

Nanotechnology has enabled a renaissance in the diagnosis of cancers. This is due, in part to the ability to develop agents bearing multiple functionalities, including those utilized for targeting, imaging, and therapy, allowing for the tailoring of the properties of the nanomaterials. Whereas many nanomaterials exhibit localization to diseased tissues via intrinsic targeting, the addition of targeting ligands, such as antibodies, peptides, aptamers, and small molecules, facilitates far more sensitive cancer detection. As such, this review focuses upon some of the most poignant examples of the utility of affinity ligand targeted nanoagents in the detection of cancer.

Superparamagnetic hybrid micelles, based on iron oxide nanoparticles and well-defined diblock copolymers possessing beta-ketoester functionalities

The quality of surface coating of magnetic nanoparticles destined as nanoprobes in clinical applications is of utmost significance for their colloidal stability and biocompatibility. A novel approach for the fabrication of such a coating involves the synthesis of well-defined diblock copolymers based on 2-(acetoacetoxy)ethyl methacrylate (chelating) and poly(ethylene glycol)methyl ether methacrylate (water-soluble, thermoresponsive), prepared by reversible addition-fragmentation chain transfer polymerization. Fabrication of magneto-responsive micelles was accomplished via chemical coprecipitation of Fe(III)/Fe(II) in the presence of diblock copolymers. Further to the characterization of micellar morphologies, optical and thermal properties, assessment of magnetic characteristics disclosed superparamagnetic behavior. The hybrid micelles did not compromise cell viability in cultures, while in vitro uptake by macrophage cells was significantly lower in comparison to that of the clinically applicable contrast agent Resovist, suggesting that these systems can evade rapid uptake by the reticuloendothelial system and be useful agents for in vivo applications.

Multifunctional magnetic nanoparticles for targeted imaging and therapy

Magnetic nanoparticles have become important tools for the imaging of prevalent diseases, such as cancer, atherosclerosis, diabetes, and others. While first generation nanoparticles were fairly nonspecific, newer generations have been targeted to specific cell types and molecular targets via affinity ligands. Commonly, these ligands emerge from phage or small molecule screens, or are based on antibodies or aptamers. Secondary reporters and combined therapeutic molecules have further opened potential clinical applications of these materials. This review summarizes some of the recent biomedical applications of these newer magnetic nanomaterials.

Targeted delivery of multifunctional magnetic nanoparticles

Magnetic nanoparticles and their magnetofluorescent analogues have become important tools for in vivo imaging using magnetic resonance imaging and fluorescent optical methods. A number of monodisperse magnetic nanoparticle preparations have been developed over the last decade for angiogenesis imaging, cancer staging, tracking of immune cells (monocyte/macrophage, T cells) and for molecular and cellular targeting. Phage display and data mining have enabled the procurement of novel tissue- or receptor-specific peptides, while high-throughput screening of diversity-oriented synthesis libraries has identified small molecules that permit or prevent uptake by specific cell types. Next-generation magnetic nanoparticles are expected to be truly multifunctional, incorporating therapeutic functionalities and further enhancing an already diverse repertoire of capabilities.

MR contrast probes that trace gene transcripts for cerebral ischemia in live animals

The aim of this research was to validate transcription magnetic resonance (MR) imaging (MRI) for gene transcript targeting in acute neurological disorders in live subjects. We delivered three MR probe variants with superparamagnetic iron oxide nanoparticles (SPION, a T2 susceptibility agent) linked to a phosphorothioate-modified oligodeoxynucleotide (sODN) complementary to c-fos mRNA (SPION-cfos) or beta-actin mRNA (SPION-beta-actin) and to sODN with random sequence (SPION-Ran). Each probe (1 microg Fe in 2 microl) was delivered via intracerebroventricular infusion to the left cerebral ventricle of male C57Black6 mice. We demonstrated SPION retention, measured as decreased T2* signal or increased R2* value (R2* = 1/T2*). Animals that received the SPION-beta-actin probe exhibited the highest R2* values, followed (in descending order) by SPION-cfos and SPION-Ran. SPION-cfos retention was localized in brain regions where SPION-cfos was present and where hybrids of SPION-cfos and its target c-fos mRNA were detected by in situ reverse transcription PCR. In animals that experienced cerebral ischemia, SPION-cfos retention was significantly increased in locations where c-fos mRNA increased in response to the ischemic insult; these elevations were not observed for SPION-beta-actin and SPION-Ran. This study should enable MR detection of mRNA alteration in disease models of the central nervous system.

Imaging cerebral gene transcripts in live animals

To circumvent the limitations of using postmortem brain in molecular assays, we used avidin-biotin binding to couple superparamagnetic iron oxide nanoparticles (SPIONs) (15-20 nm) to phosphorothioate-modified oligodeoxynucleotides (sODNs) with sequence complementary to c-fos and beta-actin mRNA (SPION-cfos and SPION-beta-actin, respectively) (14-22 nm). The Stern-Volmer constant for the complex of SPION and fluorescein isothiocyanate (FITC)-sODN is 3.1 x 10(6)/m. We studied the feasibility of using the conjugates for in vivo magnetic resonance imaging (MRI) to monitor gene transcription, and demonstrated that these complexes at 40 mug of Fe per kilogram of body weight were retained at least 1 d after intracerebroventricular infusion into the left ventricle of C57Black6 mice. SPION retention measured by MRI as T(2)* or R(2)* maps (R(2)* = 1/T(2)*) was compared with histology of iron oxide (Prussian blue) and FITC-labeled sODN. We observed significant reduction in magnetic resonance (MR) T(2)* signal in the right cortex and striatum; retention of SPION-cfos and SPION-beta-actin positively correlated with c-fos and beta-actin mRNA maps obtained from in situ hybridization. Histological examination showed that intracellular iron oxide and FITC-sODN correlated positively with in vivo MR signal reduction. Furthermore, in animals that were administered SPION-cfos and amphetamine (4 mg/kg, i.p.), retention was significantly elevated in the nucleus accumbens, striatum, and medial prefrontal cortex of the forebrain. Control groups that received SPION-cfos and saline or that received a SPION conjugate with a random-sequence probe and amphetamine showed no retention. These results demonstrated that SPION-sODN conjugates can detect active transcriptions of specific mRNA species in living animals with MRI.

Focal liver lesions: SPIO-, gadolinium-, and ferucarbotran-enhanced dynamic T1-weighted and delayed T2-weighted MR imaging in rabbits

PURPOSE

To compare a superparamagnetic iron oxide (SPIO), VSOP-C184, with a gadopentetate dimeglumine with regard to signal-enhancing effects on T1-weighted dynamic magnetic resonance (MR) images and with another SPIO contrast medium with regard to signal-reducing effects on delayed T2-weighted MR images.

MATERIALS AND METHODS

All experiments were approved by the responsible Animal Care Committee. Twenty rabbits (five for each contrast agent and dose) implanted with VX-2 carcinoma were imaged at 1.5 T. VSOP-C184 at 0.015 and 0.025 mmol Fe/kg was compared with gadopentetate dimeglumine at 0.15 mmol Gd/kg and ferucarbotran at 0.015 mmol Fe/kg. The imaging protocol comprised a T1-weighted dynamic gradient-echo (GRE) MR before injection and at 6-second intervals for up to 42 seconds after injection and a T2-weighted turbo spin-echo MR before and 5 minutes after injection. Images were evaluated quantitatively, and contrast media were compared by using nonparametric analysis of variance.

RESULTS

At dynamic T1-weighted GRE MR imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median peak contrast-to-noise ratio (CNR) was 20.7 (25th percentile, 16.3; 75th percentile, 22.6), 24.2 (25th percentile, 19.3; 75th percentile, 28.5), 16.4 (25th percentile, 13.7; 75th percentile, 20.3), and 14.0 (25th percentile, 11.4; 75th percentile, 16.8), respectively. Both doses of VSOP-C184 yielded significantly higher CNR (P < .05) than the other two agents. At T2-weighted turbo spin-echo imaging with 0.015-mmol Fe/kg VSOP-C184, 0.025-mmol Fe/kg VSOP-C184, gadopentetate dimeglumine, and ferucarbotran, the median CNR was 15.0 (25th percentile, 13.4; 75th percentile, 21.3), 15.7 (25th percentile, 14.5; 75th percentile, 19.8), 11.3 (25th percentile, 8.2; 75th percentile, 12.2), and 15.7 (25th percentile, 12.5; 75th percentile, 22.4), respectively. There was no significant difference between VSOP-C184 and ferucarbotran; both had a significantly higher CNR than did gadopentetate dimeglumine.

CONCLUSION

VSOP-C184 produces higher liver-to-tumor contrast at dynamic T1-weighted imaging than does gadopentetate dimeglumine; at delayed T2-weighted imaging, the contrast is comparable to that achieved with ferucarbotran.

Development of functionalized superparamagnetic iron oxide nanoparticles for interaction with human cancer cells

Our goal is to develop, characterize and optimize functionalized super paramagnetic iron oxide nanoparticles (SPION) demonstrating the capacity to be internalized by human cancer cells. SPION (mean diameter 9nm) were coated with various ratios to iron oxide of either polyvinyl alcohol (PVA), carboxylate-functionalized PVA, thiol-functionalized PVA and amino-functionalized PVA (amino-PVA). The interaction with cells and cytotoxicity of the SPION preparations were determined using human melanoma cells. From the four functionalized SPION preparations, only the amino-PVA SPION demonstrated the capacity to interact with, and were not cytotoxic to, human melanoma cells. This interaction with melanoma cells was dependent on the amino-PVA to iron oxide ratio, was an active and saturable mechanism displayed by all cells in a culture. These functionalized SPION were characterized by transmission electron microscopy and electrophoretic mobility. The physical comportment of SPION changed at specific PVAs to iron oxide ratios, and this ratio corresponded to the ratio of optimal interaction with cells. In conclusion, the successful development of functionalized SPION displaying potential cellular uptake by human cancer cells depends both on the presence of amino groups on the coating shell of the nanoparticles and of its ratio to the amount of iron oxide.

Gadopentetate Dimeglumine versus Ultrasmall Superparamagnetic Iron Oxide for Dynamic Contrast-enhanced MR Imaging of Tumor Angiogenesis in Human Colon Carcinoma in Mice

PURPOSE

To compare the kinetic physiologic properties of a clinical contrast agent, gadopentetate dimeglumine, with those of ultrasmall superparamagnetic iron oxide (USPIO) particles for dynamic contrast material-enhanced magnetic resonance (MR) imaging of tumor angiogenesis in human colon carcinoma in mice with a clinical MR imaging unit.

MATERIALS AND METHODS

Thirty-two mice with human colon carcinoma were injected with either gadopentetate dimeglumine (n = 16) or USPIO (n = 16) for dynamic contrast-enhanced MR imaging and pre- and postcontrast T2 and T2* measurements. Dynamic contrast-enhanced MR imaging measurements were analyzed by using a two-compartment model to calculate the endothelial transfer coefficient surface area product (KPS) for the tumor microvasculature, the reflux coefficient (k), and the fractional plasma volume (fPV). KPS, k, and fPV maps were compared with histologic microvessel density (MVD) and used to observe differences between core and rim regions of tumor.

RESULTS

Results in 30 mice (15 in the gadopentetate dimeglumine group and 15 in the USPIO group) could be used. KPS values measured with both agents correlated well with MVD in hot spots (gadopentetate dimeglumine: r = 0.6, P =.02; USPIO: r = 0.6, P =.01). No significant difference (P =.4) in correlation was found between the two agents. Both USPIO and gadopentetate dimeglumine demonstrated higher MVD and KPS values in tumor rim than in tumor core (P <.01). Tumor k values correlated poorly with whole-tumor MVD for both gadopentetate dimeglumine (r = 0.3, P =.4) and USPIO (r = 0.2, P =.6), while fPV values correlated well with whole-tumor MVD for USPIO (r = 0.6, P =.02) but not gadopentetate dimeglumine (r = -0.01, P =.98). T2 and T2* measurements showed small differences between areas of high and low angiogenic activity with both agents.

CONCLUSION

The kinetic physiologic properties of gadopentetate dimeglumine are as good as those of USPIO for dynamic contrast-enhanced MR imaging for calculating KPS as a measurement of angiogenesis in human colon carcinoma. Further studies with patients may reveal whether gadopentetate dimeglumine might be used for this purpose in clinical practice.

Benign liver neoplasms

A variety of benign focal liver lesions are easily characterized with currently available imaging techniques and contrast agents. The most common benign liver lesions, such as hemangioma, bile duct cyst, and FNH, reveal characteristic cross-sectional imaging features that allow an accurate diagnosis. For atypical variants and more uncommon lesions, including HCA, angiomyelioma, infantile hemagioendothelioma, and mesenchymal hamartoma, integration of clinical data can often help in the interpretation of imaging studies. Finally, for the remaining lesions, such as hepatic adenomatosis, the imaging findings may not be specific enough to negate the need for a tissue biopsy.

Heating potential of iron oxides for therapeutic purposes in interventional radiology

RATIONALE AND OBJECTIVES

In addition to their diagnostic applications, iron oxides could be used therapeutically to eliminate tumors with heat if their heating powers are adequate. The authors therefore examined the specific absorption rate (SAR) of different iron oxide (magnetite) samples suspended in water and in liquid or solidified gel.

MATERIALS AND METHODS

The authors compared two ferromagnetic fine powders (total particle size, >350 nm and 100 nm), five superparamagnetic ferrofluidic samples (total particle size, 10-280 nm), and a commercially available contrast medium (ferumoxides injectable solution, Endorem). The SARs of the magnetic material-suspended in distilled water or in liquid or solid agar-were estimated from time-dependent calorimetric measurements during exposure to an alternating current magnetic field (amplitude, 6.5 kA/m; frequency, 400 kHz).

RESULTS

SARs varied considerably between the different iron oxide samples. The highest value was found for a ferrofluidic sample (>93 W/g), while Endorem had little heating power (<0.1 W/g). The SAR was clearly dependent on the aggregation state of the matrix only for the large-particle-size ferromagnetic sample, yielding the highest values for particle suspensions in water (74 W/g) and lowest for solid agar (8 W/g). The heating power of the smaller-particle-size ferromagnetic sample did not exceed 8 W/g.

CONCLUSION

Heating powers differed according to the interaction of multiple physical parameters. Iron oxides should be selected carefully for therapeutic applications in magnetic heating.

Magnetic resonance imaging. Liver-specific contrast agents

MR imaging with new liver-specific contrast agents will probably be the imaging modality used in the future to detect focal liver lesions. The detection of HCC will probably be improved by using specific hepatobiliary agents, but the exact technique remains to be determined. New liver-specific contrast can differentiate some benign lesions from malignant ones and can assist in making a final diagnosis. In certain circumstances, liver-specific contrast agents can be used to evaluate hepatic vessels, the biliary tract, and hepatic function. New applications are also expected.