Imaging of iron oxide nanoparticles by MR and light microscopy in patients with malignant brain tumours

Response of villin headpiece-capped gold nanoparticles to ultrafast laser heating

The integrity of a small model protein, the 36-residue villin headpiece HP36, attached to gold nanoparticles (AuNP) is examined, and its response to laser excitation of the AuNPs is investigated. To that end, it is first verified by stationary IR and CD spectroscopy, together with denaturation experiments, that the folded structure of the protein is fully preserved when attached to the AuNP surface. It is then shown by time-resolved IR spectroscopy that the protein does not unfold, even upon the highest pump fluences that lead to local temperature jumps on the order of 1000 K of the phonon system of the AuNPs, since that temperature jump persists for too short a time of a few nanoseconds only to be destructive. Judged from a blue shift of the amide I band, indicating destabilized or a few broken hydrogen bonds, the protein either swells, becomes more unstructured from the termini, or changes its degree of solvation. In any case, it recovers immediately after the excess energy dissipates into the bulk solvent. The process is entirely reversible for millions of laser shots without any indication of aggregation of the protein or the AuNPs and with only a minor fraction of broken protein-AuNP thiol bonds. The work provides important cornerstones in designing laser pulse parameters for maximal heating with protein-capped AuNPs without destroying the capping layer.

THE APPLICATION OF NANOMATERIALS IN DIAGNOSIS AND TREATMENT FOR MALIGNANT PRIMARY BRAIN TUMORS

Malignant primary brain tumors have a very high morbidity and mortality. Even though enormous advances have been made in primary brain tumor management, in the case of malignant primary brain tumors, current diagnostic strategies cannot identify exact infiltrating margins, surgery alone cannot achieve total mass resection, and adjuvant therapies cannot improve survivals. Therefore, there is an urgent need to explore novel strategies to diagnose and treat such infiltrating brain tumors. Nanomaterials, particularly zero-dimensional and one-dimensional platforms, can carry various compounds such as contrast agents, anticancer drugs and genes into brain tumor cells specifically. Thus, contrast agent-based nanomaterials can selectively present infiltrating tumor outlines, while anticancer agent-based nanomaterials can specifically kill malignant tumor cells. In addition, dual-targeting nanomaterials, multifunctional nanocarriers, theranostic nanovehicles as well as convection-enhanced delivery technology hold promise to increase drug accumulation in tumor tissues, which could largely improve anticancer efficacy. In this review, we will mainly focus on the application of nanomaterials in preoperative diagnosis, intraoperative diagnosis and adjuvant treatment for malignant primary brain tumors.

Imaging angiogenesis, inflammation, and metastasis in the tumor microenvironment with magnetic resonance imaging

With the development of new imaging techniques, the potential for probing the molecular, cellular, and structural components of the tumor microenvironment in situ has increased dramatically. A multitude of imaging modalities have been successfully employed to probe different aspects of the tumor microenvironment, including expression of molecules, cell motion, cellularity, vessel permeability, vascular perfusion, metabolic and physiological changes, apoptosis, and inflammation. This chapter focuses on the most recent advances in magnetic resonance imaging methods, which offer a number of advantages over other methodologies, including high spatial resolution and the use of nonionizing radiation, as well as the use of such methods in the context of primary and secondary brain tumors. It also highlights how they can be used to assess the molecular and cellular changes in the tumor microenvironment in response to therapy.

Progress on the diagnosis and evaluation of brain tumors

Brain tumors are one of the most challenging disorders encountered, and early and accurate diagnosis is essential for the management and treatment of these tumors. In this article, diagnostic modalities including single-photon emission computed tomography, positron emission tomography, magnetic resonance imaging, and optical imaging are reviewed. We mainly focus on the newly emerging, specific imaging probes, and their potential use in animal models and clinical settings.

Nanotechnology in diagnostics and therapeutics for gastrointestinal disorders

This review describes the state of the art in nanoparticle and nanodevice applications for medical diagnosis and disease treatment. Nanodevices, such as cantilevers, have been integrated into high-sensitivity disease marker diagnostic detectors and devices, are stable over long periods of time, and display reliable performance properties. Nanotechnology strategies have been applied to therapeutic purposes as well. For example, nanoparticle-based delivery systems have been developed to protect drugs from degradation, thereby reducing the required dose and dose frequency, improving patient comfort and convenience during treatment, and reducing treatment expenses. The main objectives for integrating nanotechnologies into diagnostic and therapeutic applications in the context of intestinal diseases are reviewed.

Expression of c-erbB-2 in breast cancer cell lines as experimental receptor of magnetic nanoparticles

High mortality in breast cancer is associated to a late diagnosis and therapy of the disease. Our research group is working on the development of an innovative technology to promote selective ablation of breast cancer in early stages by the use of high frequency magnetic fields assisted by magnetic nanoparticles. The concept behind the technical proposal is to increase the electrical conductivity of tumoral tissue by the use of bioconjugated "magnetic nanoparticle-monoclonal antibody". Is expected that bioconjugated recognizes specific genes on the surface of cancer cells. The aim of this study was to evaluate the expression of the c-erbB-2 gene and c-erbB-2 antigen in breast cancer cells type BT-474, MCF-7 and MDA-MB-231, as previous step to propose the c-erbB-2 protein as receptor of magnetic nanoparticles. The results suggest that the elected breast cancer cell lines show well-differentiated relative expression of the elected gen and antigen, and sems suitable for experimental evaluation of selective targeting by magnetic nanoparticles.

Therapeutic nanomedicine for brain cancer

Malignant brain cancer treatment is limited by a number of barriers, including the blood-brain barrier, transport within the brain interstitium, difficulties in delivering therapeutics specifically to tumor cells, the highly invasive quality of gliomas and drug resistance. As a result, the prognosis for patients with high-grade gliomas is poor and has improved little in recent years. Nanomedicine approaches have been developed in the laboratory, with some technologies being translated to the clinic, in order to address these needs. This review discusses the obstacles to effective treatment that are currently faced in the field, as well as various nanomedicine techniques that have been used or are being explored to overcome them, with a focus on liposomal and polymeric nanoparticles.

Materials characterization of Feraheme/ferumoxytol and preliminary evaluation of its potential for magnetic fluid hyperthermia

Feraheme, is a recently FDA-cleared superparamagnetic iron oxide nanoparticle (SPION)-based MRI contrast agent that is also employed in the treatment of iron deficiency anemia. Feraheme nanoparticles have a hydrodynamic diameter of 30 nm and consist of iron oxide crystallites complexed with a low molecular weight, semi-synthetic carbohydrate. These features are attractive for other potential biomedical applications such as magnetic fluid hyperthermia (MFH), since the carboxylated polymer coating affords functionalization of the particle surface and the size allows for accumulation in highly vascularized tumors via the enhanced permeability and retention effect. This work presents morphological and magnetic characterization of Feraheme by transmission electron microscopy (TEM), Energy dispersive X-ray spectroscopy (EDX), and superconducting quantum interference device (SQUID) magnetometry. Additionally, the results of an initial evaluation of the suitability of Feraheme for MFH applications are described, and the data indicate the particles possess promising properties for this application.

Nanoparticles for brain drug delivery

The central nervous system, one of the most delicate microenvironments of the body, is protected by the blood-brain barrier (BBB) regulating its homeostasis. BBB is a highly complex structure that tightly regulates the movement of ions of a limited number of small molecules and of an even more restricted number of macromolecules from the blood to the brain, protecting it from injuries and diseases. However, the BBB also significantly precludes the delivery of drugs to the brain, thus, preventing the therapy of a number of neurological disorders. As a consequence, several strategies are currently being sought after to enhance the delivery of drugs across the BBB. Within this review, the recently born strategy of brain drug delivery based on the use of nanoparticles, multifunctional drug delivery systems with size in the order of one-billionth of meters, is described. The review also includes a brief description of the structural and physiological features of the barrier and of the most utilized nanoparticles for medical use. Finally, the potential neurotoxicity of nanoparticles is discussed, and future technological approaches are described. The strong efforts to allow the translation from preclinical to concrete clinical applications are worth the economic investments.

Metal-based nanoparticle interactions with the nervous system: the challenge of brain entry and the risk of retention in the organism

This review of metal-based nanoparticles focuses on factors influencing their distribution into the nervous system, evidence they enter brain parenchyma, and nervous system responses. Gold is emphasized as a model metal-based nanoparticle and for risk assessment in the companion review. The anatomy and physiology of the nervous system, basics of colloid chemistry, and environmental factors that influence what cells see are reviewed to provide background on the biological, physical-chemical, and internal milieu factors that influence nervous system nanoparticle uptake. The results of literature searches reveal little nanoparticle research included the nervous system, which about equally involved in vitro and in vivo methods, and very few human studies. The routes of uptake into the nervous system and mechanisms of nanoparticle uptake by cells are presented with examples. Brain nanoparticle uptake inversely correlates with size. The influence of shape has not been reported. Surface charge has not been clearly shown to affect flux across the blood-brain barrier. There is very little evidence for metal-based nanoparticle distribution into brain parenchyma. Metal-based nanoparticle disruption of the blood-brain barrier and adverse brain changes have been shown, and are more pronounced for spheres than rods. Study concentrations need to be put in exposure contexts. Work with dorsal root ganglion cells and brain cells in vitro show the potential for metal-based nanoparticles to produce toxicity. Interpretation of these results must consider the ability of nanoparticles to distribute across the barriers protecting the nervous system. Effects of the persistence of poorly soluble metal-based nanoparticles are of particular concern.

Magnetic particle imaging (MPI) for NMR and MRI researchers

Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the "black blood" contrast generated by SPIOs in MRI due to increased T2* dephasing, SPIOs in MPI generate positive, "bright blood" contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field.

Rapid spectrophotometric technique for quantifying iron in cells labeled with superparamagnetic iron oxide nanoparticles: potential translation to the clinic

Labeling cells with superparamagnetic iron oxide (SPIO) nanoparticles provides the ability to track cells by magnetic resonance imaging. Quantifying intracellular iron concentration in SPIO labeled cells would allow for the comparison of agents and techniques used to magnetically label cells. Here we describe a rapid spectrophotometric technique (ST) to quantify iron content of SPIO-labeled cells, circumventing the previous requirement of an overnight acid digestion. Following lysis with 10% sodium dodecyl sulfate (SDS) of magnetically labeled cells, quantification of SPIO doped or labeled cells was performed using commonly available spectrophotometric instrument(s) by comparing absorptions at 370 and 750 nm with correction for turbidity of cellular products to determine the iron content of each sample. Standard curves demonstrated high linear correlation (R(2) = 0.998) between absorbance spectra of iron oxide nanoparticles and concentration in known SPIO-doped cells. Comparisons of the ST with inductively coupled plasma-mass spectroscopy (ICP-MS) or nuclear magnetic resonance relaxometric (R(2)) determinations of intracellular iron contents in SPIO containing samples resulted in significant linear correlation between the techniques (R(2) vs ST, R(2) > 0.992, p < 0.0001; ST vs ICP-MS, R(2) > 0.995, p < 0.0001) with the limit of detection of ST for iron = 0.66 µg ml(-1) for 10(6) cells ml(-1). We have developed a rapid straightforward protocol that does not require overnight acid digestion for quantifying iron oxide content in magnetically labeled cells using readily available analytic instrumentation that should greatly expedite advances in comparing SPIO agents and protocols for labeling cells.

Correlation between contrast enhancement on intraoperative magnetic resonance imaging and histopathology in glioblastoma

Object:

Glioblastoma is a highly malignant brain tumor, for which standard treatment consists of surgery, radiotherapy, and chemotherapy. Increasing extent of tumor resection (EOTR) is associated with prolonged survival. Intraoperative magnetic resonance imaging (iMRI) is used to increase EOTR, based on contrast enhanced MR images. The correlation between intraoperative contrast enhancement and tumor has not been studied systematically.

Methods:

For this prospective cohort study, we recruited 10 patients with a supratentorial brain tumor suspect for a glioblastoma. After initial resection, a 0.15 Tesla iMRI scan was made and neuronavigation-guided biopsies were taken from the border of the resection cavity. Scores for gadolinium-based contrast enhancement on iMRI and for tissue characteristics in histological slides of the biopsies were used to calculate correlations (expressed in Kendall's tau).

Results:

A total of 39 biopsy samples was available for further analysis. Contrast enhancement was significantly correlated with World Health Organization (WHO) grade (tau 0.50), vascular changes (tau 0.53), necrosis (tau 0.49), and increased cellularity (tau 0.26). Specificity of enhancement patterns scored as “thick linear” and “tumor-like” for detection of (high grade) tumor was 1, but decreased to circa 0.75 if “thin linear” enhancement was included. Sensitivity for both enhancement patterns varied around 0.39-0.48 and 0.61-0.70, respectively.

Conclusions:

Presence of intraoperative contrast enhancement is a good predictor for presence of tumor, but absence of contrast enhancement is a bad predictor for absence of tumor. The use of gadolinium-based contrast enhancement on iMRI to maximize glioblastoma resection should be evaluated against other methods to increase resection, like new contrast agents, other imaging modalities, and “functional neurooncology” – an approach to achieve surgical resection guided by functional rather than oncological-anatomical boundaries.

Superparamagnetic iron oxide based MRI contrast agents: Current status of clinical application

Superparamagnetic iron oxide (SPIO) MR contrast agents are composed of nano-sized iron oxide crystals coated with dextran or carboxydextran. Two SPIO agents are clinically approved, namely: ferumoxides (Feridex in the USA, Endorem in Europe) with a particle size of 120 to 180 nm, and ferucarbotran (Resovist) with a particle size of about 60 nm. The principal effect of the SPIO particles is on T2* relaxation and thus MR imaging is usually performed using T2/T2*-weighted sequences in which the tissue signal loss is due to the susceptibility effects of the iron oxide core. Enhancement on T1-weighted images can also be seen with the smaller Resovist. Both Feridex and Resovist are approved specifically for MRI of the liver. The difference being that Resovist can be administered as a rapid bolus (and thus can be used with both dynamic and delayed imaging), whereas Feridex needs to be administered as a slow infusion and is used solely in delayed phase imaging. In the liver, these particles are sequestered by phagocytic Kupffer cells in normal reticuloendothelial system (RES), but are not retained in lesions lacking Kupffer cells. Consequently, there are significant differences in T2/T2* relaxation between normal tissue and lesions, resulting in increased lesion conspicuity and detectability. SPIO substantially increase the detectability of hepatic metastases. For focal hepatocellular lesions, SPIO-enhanced MR imaging exhibits slightly better diagnostic performance than dynamic CT. A combination of dynamic and static MR imaging technique using T1- and T2 imaging criteria appears to provide clinically more useful patterns of enhancement. Feridex and Resovist are also used for evaluating macrophage activities in some inflammatory lesions, but their clinical values remain to be further confirmed. The clinical development of Ferumoxtran (Combidex in the USA, Sinerem in Europe), designed for lymph node metastasis evaluation, is currently stopped.

Modern micro and nanoparticle-based imaging techniques

The requirements for early diagnostics as well as effective treatment of insidious diseases such as cancer constantly increase the pressure on development of efficient and reliable methods for targeted drug/gene delivery as well as imaging of the treatment success/failure. One of the most recent approaches covering both the drug delivery as well as the imaging aspects is benefitting from the unique properties of nanomaterials. Therefore a new field called nanomedicine is attracting continuously growing attention. Nanoparticles, including fluorescent semiconductor nanocrystals (quantum dots) and magnetic nanoparticles, have proven their excellent properties for in vivo imaging techniques in a number of modalities such as magnetic resonance and fluorescence imaging, respectively. In this article, we review the main properties and applications of nanoparticles in various in vitro imaging techniques, including microscopy and/or laser breakdown spectroscopy and in vivo methods such as magnetic resonance imaging and/or fluorescence-based imaging. Moreover the advantages of the drug delivery performed by nanocarriers such as iron oxides, gold, biodegradable polymers, dendrimers, lipid based carriers such as liposomes or micelles are also highlighted.

Nanotechnology-based approaches in anticancer research

Cancer is a highly complex disease to understand, because it entails multiple cellular physiological systems. The most common cancer treatments are restricted to chemotherapy, radiation and surgery. Moreover, the early recognition and treatment of cancer remains a technological bottleneck. There is an urgent need to develop new and innovative technologies that could help to delineate tumor margins, identify residual tumor cells and micrometastases, and determine whether a tumor has been completely removed or not. Nanotechnology has witnessed significant progress in the past few decades, and its effect is widespread nowadays in every field. Nanoparticles can be modified in numerous ways to prolong circulation, enhance drug localization, increase drug efficacy, and potentially decrease chances of multidrug resistance by the use of nanotechnology. Recently, research in the field of cancer nanotechnology has made remarkable advances. The present review summarizes the application of various nanotechnology-based approaches towards the diagnostics and therapeutics of cancer.

Superparamagnetic iron oxide nanoparticles: magnetic nanoplatforms as drug carriers

A targeted drug delivery system is the need of the hour. Guiding magnetic iron oxide nanoparticles with the help of an external magnetic field to its target is the principle behind the development of superparamagnetic iron oxide nanoparticles (SPIONs) as novel drug delivery vehicles. SPIONs are small synthetic γ-Fe₂O₃ (maghemite) or Fe₃O₄ (magnetite) particles with a core ranging between 10 nm and 100 nm in diameter. These magnetic particles are coated with certain biocompatible polymers, such as dextran or polyethylene glycol, which provide chemical handles for the conjugation of therapeutic agents and also improve their blood distribution profile. The current research on SPIONs is opening up wide horizons for their use as diagnostic agents in magnetic resonance imaging as well as for drug delivery vehicles. Delivery of anticancer drugs by coupling with functionalized SPIONs to their targeted site is one of the most pursued areas of research in the development of cancer treatment strategies. SPIONs have also demonstrated their efficiency as nonviral gene vectors that facilitate the introduction of plasmids into the nucleus at rates multifold those of routinely available standard technologies. SPION-induced hyperthermia has also been utilized for localized killing of cancerous cells. Despite their potential biomedical application, alteration in gene expression profiles, disturbance in iron homeostasis, oxidative stress, and altered cellular responses are some SPION-related toxicological aspects which require due consideration. This review provides a comprehensive understanding of SPIONs with regard to their method of preparation, their utility as drug delivery vehicles, and some concerns which need to be resolved before they can be moved from bench top to bedside.

Therapeutics, imaging and toxicity of nanomaterials in the central nervous system

Treatment and diagnosis of neurodegenerative diseases and other CNS disorders are nowadays considered some of the most challenging tasks in modern medicine. The development of effective strategies for the prevention, diagnosis and treatment of CNS pathologies require better understanding of neurological disorders that is still lacking. The use of nanomaterials is thought to contribute to our further understanding of the CNS and the development of novel therapeutic and diagnostic modalities for neurological interventions. Even though the application of nanoparticles in neuroscience is still embryonic, this article attempts to illustrate the use of different types of nanomaterials and the way in which they have been used in various CNS applications in an attempt to limit or reverse neuropathological processes.

Multiwalled carbon nanotubes interact with macrophages and influence tumor progression and metastasis

Macrophages are one of the most important types of immune effector cells and are closely associated with tumor progression and metastasis. In this work, we investigated the influences of oxidized multiwalled carbon nanotubes (o-MWCNT) on macrophages that are resting in the normal subcutis tissue or in the tumor microenvironment in vivo as well as on the macrophage cell line of RAW 264.7 treated with combination of IL4, IL10 and IL13 in vitro. The o-MWCNT were characterized with SEM, DLS, FTIR, TGA, and UV-vis-NIR spectroscopy, and their effects on the RWA 264.7 cell line and breast cancer tumor-bearing mice were analyzed using the MTS assay, flow cytometry analysis, and histological and immunohistochemical observations. Our experimental results showed that subcutaneously injected o-MWCNT not only induced phagocytosis of the local resident macrophages, but also competitively recruited macrophages from other tissues. These interactions resulted in macrophage reduction and decreased vessel density around the tumor mass, which together inhibited tumor progression and metastasis in the lung. In the cell line model, the o-MWCNT inhibited the ability of the interleukin treated RAW macrophages to promote tumor cell migration as well as decreased their proliferation rate.

Enhanced cellular uptake of aminosilane-coated superparamagnetic iron oxide nanoparticles in mammalian cell lines

Purpose

To compare the cellular uptake efficiency and cytotoxicity of aminosilane (SiO₂-NH₂)-coated superparamagnetic iron oxide (SPIO@SiO₂-NH₂) nanoparticles with three other types of SPIO nanoparticles coated with SiO₂ (SPIO@SiO₂), dextran (SPIO@dextran), or bare SPIO in mammalian cell lines.

Materials and methods

Four types of monodispersed SPIO nanoparticles with a SPIO core size of 7 nm and an overall size in a range of 7–15 nm were synthesized. The mammalian cell lines of MCF-7, MDA-MB-231, HT-29, RAW264.7, L929, HepG2, PC-3, U-87 MG, and mouse mesenchymal stem cells (MSCs) were incubated with four types of SPIO nanoparticles for 24 hours in the serum-free culture medium Dulbecco’s modified Eagle’s medium (DMEM) with 4.5 μg/mL iron concentration. The cellular uptake efficiencies of SPIO nanoparticles were compared by Prussian blue staining and intracellular iron quantification. In vitro magnetic resonance imaging of MSC pellets after SPIO labeling was performed at 3 T. The effect of each SPIO nanoparticle on the cell viability of RAW 264.7 (mouse monocyte/macrophage) cells was also evaluated.

Results

Transmission electron microscopy demonstrated surface coating with SiO₂-NH₂, SiO₂, and dextran prevented SPIO nanoparticle aggregation in DMEM culture medium. MCF-7, MDA-MB-231, and HT-29 cells failed to show notable iron uptake. For all the remaining six cell lines, Prussian blue staining and intracellular iron quantification demonstrated that SPIO@ SiO₂-NH₂ nanoparticles had the highest cellular uptake efficiency. SPIO@SiO₂-NH₂, bare SPIO, and SPIO@dextran nanoparticles did not affect RAW 264.7 cell viability up to 200 μg Fe/mL, while SPIO@SiO₂ reduced RAW 264.7 cell viability from 10 to 200 μg Fe/mL in a dose-dependent manner.

Conclusion

Cellular uptake efficiency of SPIO nanoparticles depends on both the cell type and SPIO surface characteristics. Aminosilane surface coating enhanced the cellular uptake efficiency without inducing cytotoxicity in a number of cell lines.

Comparative analysis of ferumoxytol and gadoteridol enhancement using T1- and T2-weighted MRI in neuroimaging

OBJECTIVE

Ferumoxytol, an ultrasmall superparamagnetic iron oxide particle, has been suggested as a potential alternative MRI contrast agent in patients with renal failure. We compared ferumoxytol to gadoteridol enhancement on T1- and T2-weighted MRI in CNS disorders to explore its diagnostic utility.

SUBJECTS AND METHODS

Data were collected from three protocols in 70 adults who underwent alternate-day gadoteridol- and ferumoxytol-enhanced MRI using identical parameters. Two neuroradiologists measured lesion-enhancing size and intensity on contrast-enhanced T1-weighted images in consensus. T2-weighted images were evaluated for the presence of contrast-enhanced hypointensity. Mixed model repeated measures analysis of variance determined differences between T1-weighted enhancement size and intensity for individual protocols and group.

RESULTS

After exclusions, 49 MRI studies in 29 men and 20 women (mean age, 51 years) were assessed. T1-weighted estimated enhancing sizes were different between agents (p = 0.0456) as a group; however, no differences were observed with untreated gliomas (n = 17) in two protocols (p = 1.0 and p = 0.99, respectively). Differences in T1-weighted enhancement intensity between agents were significant for the group overall (p = 0.0006); however, three-way interactions were not significant (p = 0.1233). T2-weighted images were assessed for contrast-enhanced hypointensity, observed in 26 of 49 (53%) ferumoxytol and zero of 49 (0%) gadoteridol scans.

CONCLUSION

Ferumoxytol may be a useful MRI contrast agent in patients who are unable to receive gadolinium-based contrast agents. Greater experience with a wider variety of disorders is necessary to understand differences in enhancement with ferumoxytol compared with gadolinium-based contrast agents, given their different mechanisms of action.

Toxicology and clinical potential of nanoparticles

In recent years, nanoparticles (NPs) have increasingly found practical applications in technology, research and medicine. The small particle size coupled to their unique chemical and physical properties is thought to underlie their exploitable biomedical activities. Here, we review current toxicity studies of NPs with clinical potential. Mechanisms of cytotoxicity are discussed and the problem of extrapolating knowledge gained from cell-based studies into a human scenario is highlighted. The so-called 'proof-of-principle' approach, whereby ultra-high NP concentrations are used to ensure cytotoxicity, is evaluated on the basis of two considerations; firstly, from a scientific perspective, the concentrations used are in no way related to the actual doses required which, in many instances, discourages further vital investigations. Secondly, these inaccurate results cast doubt on the science of nanomedicine and thus, quite dangerously, encourage unnecessary alarm in the public. In this context, the discrepancies between in vitro and in vivo results are described along with the need for a unifying protocol for reliable and realistic toxicity reports.

The legacy of nanotechnology: revolution and prospects in neurosurgery

Nanotechnology has been an ever-growing field since the discovery of carbon fullerenes, and is being assimilated progressively into a variety of other disciplines including medical science. The association with neurosurgery had initially been less well characterized compared to other organ systems, but has recently offered promising future potential for a wide range of utilities including new therapeutic options for Glioblastoma Multiforme, neurprotection against oxidative stress, nerve nanorepair, nanodiagnosis of Alzheimer's disease, nanoimaging with nanoparticles and quantum dots, nanomanipulation of CNS with surgical nanobots, and nanoneuromodulation with nanofibres & nanowires. This article examines such potentials as well as others, of the utility of nanotechnology in Neurosurgery.

Nanoscale materials for tackling brain cancer: recent progress and outlook

This article reports on recent progress in the development of advanced nanoscale photoreactive, magnetic and multifunctional materials applicable to brain cancer diagnostics, imaging, and therapy, with an emphasis on the latest contributions and the novelty of the approach, along with the most promising emergent trends.

Magnetic resonance imaging of intracranial tumors: intra-patient comparison of gadoteridol and ferumoxytol

This study aims to compare gadoteridol with ferumoxytol for contrast-enhanced and perfusion-weighted (PW) MRI of intracranial tumors. The final analysis included 26 patients, who underwent 3 consecutive days of 3T MRI. Day 1 consisted of anatomical pre- and postcontrast images, and PW MRI was acquired using gadoteridol (0.1 mmol/kg). On Day 2, the same MRI sequences were obtained with ferumoxytol (510 mg) and on Day 3, the anatomical images were repeated to detect delayed ferumoxytol-induced signal changes. The T₁-weighted images were evaluated qualitatively and quantitatively for enhancement volume and signal intensity (SI) changes; PW data were used to estimate the relative cerebral blood volume (rCBV). All 26 lesions showed 24-hour T₁-weighted ferumoxytol enhancement; 16 also had T₂-weighted hypointensities. In 6 patients, ferumoxytol-induced signal changes were noted in areas with no gadoteridol enhancement. Significantly greater (P< .0001) SI changes were seen with gadoteridol, and qualitative analyses (lesion border delineation, internal morphology, contrast enhancement) also showed significant preferences (P= .0121; P = .0015; P < .0001, respectively) for this agent. There was no significant difference in lesion enhancement volumes between contrast materials. The ferumoxytol-rCBV values were significantly higher (P = .0016) compared with the gadoteridol-rCBV values. In conclusion, ferumoxytol provides important information about tumor biology that complements gadoteridol imaging. The rCBV measurements indicate areas of tumor undergoing rapid growth, whereas the 24-hour scans mark the presence of inflammatory cells. Both of these functions provide useful information about tumor response to treatment. We suggest that dynamic and anatomical imaging with ferumoxytol warrant further assessment in brain tumor therapy.

Applications of nanotechnology to imaging and therapy of brain tumors

In the past decade, numerous advances in the understanding of brain tumor physiology, tumor imaging, and tumor therapy have been attained. In some cases, these advances have resulted from refinements of pre-existing technologies (eg, improvements of contrast-enhanced magnetic resonance imaging). In other instances, advances have resulted from development of novel technologies. The development of nanomedicine (ie, applications of nanotechnology to the field of medicine) is an example of the latter. In this review, the authors explain the principles that underlay nanoparticle design and function as well as the means by which nanoparticles can be used for imaging and therapy of brain tumors.

Micro- and nanotechnology approaches for capturing circulating tumor cells

Circulating tumor cells (CTC) are cells that have detached from primary tumors and circulate in the bloodstream where they are carried to other organs, leading to seeding of new tumors and metastases. CTC have been known to exist in the bloodstream for more than a century. With recent progress in the area of micro- and nanotechnology, it has been possible to adopt new approaches in CTC research. Microscale and nanoscale studies can throw some light on the time course of CTC appearance in blood and CTC overexpression profiles for cancer-related markers and galvanize the development of drugs to block metastases. CTC counts could serve as endpoint biomarkers and as prognostic markers for patients with a metastatic disease. This paper reviews some of the recent researches on using micro- and nanotechnology to capture and profile CTC.

Carbon-iron magnetic nanoparticles for agronomic use in plants: promising but still a long way to go

In the recent years, multiple ways of interaction between the fields of nanotechnology and biology have been opened, mainly in the biomedical research, with the development of tools for diagnosis and controlled delivery of substances. (1,2) On the other hand, in the field of plant biology, the interaction between both disciplines has been less frequent. Most of the published work on this field has focus in the environmental impact of nanoparticles on crop growth and development; (3,4) and also on the bio production of nanoparticles using plant extracts (reviewed in (5) , as an example see also (6,7,8)). Much less attention has taken other possible aspects of the interrelationship between nanotechnology and plant biology, such as the development of nanodevices for controlled delivery of drugs or different kind of substances, (9,10) in a similar way to that already developed in the medical research.

EGFRvIII antibody-conjugated iron oxide nanoparticles for magnetic resonance imaging-guided convection-enhanced delivery and targeted therapy of glioblastoma

The magnetic nanoparticle has emerged as a potential multifunctional clinical tool that can provide cancer cell detection by magnetic resonance imaging (MRI) contrast enhancement as well as targeted cancer cell therapy. A major barrier in the use of nanotechnology for brain tumor applications is the difficulty in delivering nanoparticles to intracranial tumors. Iron oxide nanoparticles (IONP; 10 nm in core size) conjugated to a purified antibody that selectively binds to the epidermal growth factor receptor (EGFR) deletion mutant (EGFRvIII) present on human glioblastoma multiforme (GBM) cells were used for therapeutic targeting and MRI contrast enhancement of experimental glioblastoma, both in vitro and in vivo, after convection-enhanced delivery (CED). A significant decrease in glioblastoma cell survival was observed after nanoparticle treatment and no toxicity was observed with treatment of human astrocytes (P < 0.001). Lower EGFR phosphorylation was found in glioblastoma cells after EGFRvIIIAb-IONP treatment. Apoptosis was determined to be the mode of cell death after treatment of GBM cells and glioblastoma stem cell-containing neurospheres with EGFRvIIIAb-IONPs. MRI-guided CED of EGFRvIIIAb-IONPs allowed for the initial distribution of magnetic nanoparticles within or adjacent to intracranial human xenograft tumors and continued dispersion days later. A significant increase in animal survival was found after CED of magnetic nanoparticles (P < 0.01) in mice implanted with highly tumorigenic glioblastoma xenografts (U87DeltaEGFRvIII). IONPs conjugated to an antibody specific to the EGFRvIII deletion mutant constitutively expressed by human glioblastoma tumors can provide selective MRI contrast enhancement of tumor cells and targeted therapy of infiltrative glioblastoma cells after CED.

Novel membrane-permeable contrast agent for brain tumor detection by MRI

One of the key challenges hindering the clinical intervention against brain cancer is defined by the inability to detect brain tumors at an early enough stage to permit effective therapy. Furthermore, the rapid growth and severe lethality of this form of cancer predicate the vital importance of monitoring the development of the pathology and its outcome after therapeutic intervention. With this in mind, we designed a novel membrane-permeant contrast agent, MN-MPAP-Cy5.5, which consists of a superparamagnetic iron oxide core, for MRI conjugated to myristoylated polyarginine peptides, as a membrane translocation module and labeled with the near-infrared dye Cy5.5 for correlative microscopy. This probe showed a remarkable uptake by U-87 human glioma cells in vitro and localized and delineated stereotactically injected tumor in vivo by MRI. Our findings suggest that the agent mediates its effects by translocation of the magnetic nanoparticles label across the leaky tumor vasculature, followed by enhanced accumulation in tumor cells. The noninvasive detection of brain tumors when they are still small represents a formidable challenge from an imaging standpoint. Our study describes an improved strategy to detect brain lesions by utilizing a contrast agent with membrane translocation properties.

Biomaterial-based technologies for brain anti-cancer therapeutics and imaging

Treating malignant brain tumors represents one of the most formidable challenges in oncology. Contemporary treatment of brain tumors has been hampered by limited drug delivery across the blood-brain barrier (BBB) to the tumor bed. Biomaterials are playing an increasingly important role in developing more effective brain tumor treatments. In particular, polymer (nano)particles can provide prolonged drug delivery directly to the tumor following direct intracerebral injection, by making them physiochemically able to cross the BBB to the tumor, or by functionalizing the material surface with peptides and ligands allowing the drug-loaded material to be systemically administered but still specifically target the tumor endothelium or tumor cells themselves. Biomaterials can also serve as targeted delivery devices for novel therapies including gene therapy, photodynamic therapy, anti-angiogenic and thermotherapy. Nanoparticles also have the potential to play key roles in the diagnosis and imaging of brain tumors by revolutionizing both preoperative and intraoperative brain tumor detection, allowing early detection of pre-cancerous cells, and providing real-time, longitudinal, non-invasive monitoring/imaging of the effects of treatment. Additional efforts are focused on developing biomaterial systems that are uniquely capable of delivering tumor-associated antigens, immunotherapeutic agents or programming immune cells in situ to identify and facilitate immune-mediated tumor cell killing. The continued translation of current research into clinical practice will rely on solving challenges relating to the pharmacology of nanoparticles but it is envisioned that novel biomaterials will ultimately allow clinicians to target tumors and introduce multiple, pharmaceutically relevant entities for simultaneous targeting, imaging, and therapy in a unique and unprecedented manner.

Surface activation and targeting strategies of superparamagnetic iron oxide nanoparticles in cancer-oriented diagnosis and therapy

The advanced fabrication and surface engineering of superparamagnetic iron oxide nanoparticles (SPIONs) could offer excellent physiochemical features for noninvasive tumor imaging and drug delivery. The key issues of realization of maximized selective cancer targeting of SPIONs are minimization of uptake by macrophages, preferential binding to cancerous cells over neighboring normal cells, visualization of tumor cells prior to and after treatment and triggered drug release into target cells in a controlled fashion. In this article, we summarize the current status of fabrication of multifunctional SPION-based nanodevices specially designed for cancer-oriented diagnosis and therapy, with a focus on potential malignancy-targeting ligands’ identification and development as nanocarriers. A number of examples of passive and active targeting strategies – lymphoangiogenesis markers, cellular metabolite receptors, extracellular matrix component receptors, neuropeptide receptors and receptor-mediated bypass of the blood–brain barrier – are described in detail.

Superparamagnetic iron oxide nanoparticles: diagnostic magnetic resonance imaging and potential therapeutic applications in neurooncology and central nervous system inflammatory pathologies, a review

Superparamagnetic iron oxide nanoparticles have diverse diagnostic and potential therapeutic applications in the central nervous system (CNS). They are useful as magnetic resonance imaging (MRI) contrast agents to evaluate: areas of blood-brain barrier (BBB) dysfunction related to tumors and other neuroinflammatory pathologies, the cerebrovasculature using perfusion-weighted MRI sequences, and in vivo cellular tracking in CNS disease or injury. Novel, targeted, nanoparticle synthesis strategies will allow for a rapidly expanding range of applications in patients with brain tumors, cerebral ischemia or stroke, carotid atherosclerosis, multiple sclerosis, traumatic brain injury, and epilepsy. These strategies may ultimately improve disease detection, therapeutic monitoring, and treatment efficacy especially in the context of antiangiogenic chemotherapy and antiinflammatory medications. The purpose of this review is to outline the current status of superparamagnetic iron oxide nanoparticles in the context of biomedical nanotechnology as they apply to diagnostic MRI and potential therapeutic applications in neurooncology and other CNS inflammatory conditions.

Chapter 4 - Applications of nanotechnology in molecular imaging of the brain

Rapid advances in the field of nanotechnology promise revolutionary improvements in the diagnosis and therapy of neuroinflammatory disorders. An array of iron oxide nano- and microparticle agents have been developed for in vivo molecular magnetic resonance imaging (mMRI) of cerebrovascular endothelial targets, such as vascular cell adhesion molecule-1 (VCAM-1), E-selectin, and the glycoprotein receptor GP IIb/IIIa expressed on activated platelets. Molecular markers of glioma cells, such as matrix metalloproteinase-2 (MMP-2), and markers for brain tumor angiogenesis, such as alpha (v) beta (3) integrin (alpha(v)beta(3)), have also been successfully targeted using nanoparticle imaging probes. This chapter provides an overview of targeted, iron oxide nano- and microparticles that have been applied for in vivo mMRI of the brain in experimental models of multiple sclerosis (MS), brain ischemia, cerebral malaria (CM), brain cancer, and Alzheimer's disease. The potential of targeted nanoparticle agents for application in clinical imaging is also discussed, including multimodal and therapeutic approaches.

Uses of nanoparticles for central nervous system imaging and therapy

SUMMARY

Applications of nanotechnology to medicine are leading to novel means of imaging living systems and of delivering therapy. Much nanotechnology research is focused on methods for imaging central nervous system functions and disease states. In this review, the principles of nanoparticle design and function are discussed with specific emphasis on applications to neuroradiology. In addition to innovative forms of imaging, this review describes therapeutic uses of nanoparticles, such as drug delivery systems, neuroprotection devices, and methods for tissue regeneration.

Dynamic MRI using iron oxide nanoparticles to assess early vascular effects of antiangiogenic versus corticosteroid treatment in a glioma model

The vascular effects of antiangiogenic treatment may pose problems for evaluating brain tumor response based on contrast-enhanced magnetic resonance imaging (MRI). We used serial dynamic contrast-enhanced MRI at 12 T to assess vascular responses to antiangiogenic versus steroid therapy. Athymic rats with intracerebral U87MG human glioma (n=17) underwent susceptibility-weighted perfusion MRI with ferumoxytol, a solely intravascular ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle, followed by T1-weighted dynamic gadodiamide-enhanced MRI to measure vascular permeability. Rats were imaged before and after 24, 48, and 72 h of treatment with the antiangiogenic agent bevacizumab or the corticosteroid dexamethasone. Contrast agent extravasation was seen rapidly after gadodiamide, but not with ferumoxytol administration. Bevacizumab significantly decreased the blood volume and decreased permeability in tumors as determined by increased time-to-peak enhancement. A single dose of 45 mg/kg bevacizumab resulted in changes analogous to dexamethasone given in an extremely high dose (12 mg/kg per day), and was significantly more effective than dexamethasone at 2 mg/kg per day. We conclude that dynamic perfusion MRI measurements with ferumoxytol USPIO to assess cerebral blood volume, along with dynamic gadodiamide-enhanced MR to assess vascular permeability, hold promise in more accurately detecting therapeutic responses to antiangiogenic therapy.