We have developed a multi-layer approach for the synthesis of water-dispersible superparamagnetic iron oxide nanoparticles for hyperthermia, magnetic resonance imaging (MRI) and drug delivery applications. In this approach, iron oxide core nanoparticles were obtained by precipitation of iron salts in the presence of ammonia and provided β-cyclodextrin and pluronic polymer (F127) coatings. This formulation (F127250) was highly water dispersible which allowed encapsulation of the anti-cancer drug(s) in β-cyclodextrin and pluronic polymer for sustained drug release. The F127250 formulation has exhibited superior hyperthermia effects over time under alternating magnetic field compared to pure magnetic nanoparticles (MNP) and β-cyclodextrin coated nanoparticles (CD200). Additionally, the improved MRI characteristics were also observed for the F127250 formulation in agar gel and in cisplatin resistant ovarian cancer cells (A12780CP) compared to MNP and CD200 formulations. Furthermore, the drug loaded formulation of F127250 exhibited many folds of imaging contrast properties. Due to the internalization capacity of the F127250 formulation, its curcumin loaded formulation (F127250-CUR) exhibited almost equivalent inhibition effects on A2780CP (ovarian), MDA-MB-231 (breast), and PC3 (prostate) cancer cells even though curcumin release was only 40%. The improved therapeutic effects were verified by examining molecular effects using Western blotting and transmission electron microscopic (TEM) studies. F127250-CUR also exhibited haemocompatibility, suggesting a nanochemo-therapuetic agent for cancer therapy.

The objective of tissue engineering (TE) is to create functional replacements for various tissues; the mechanical properties of these engineered constructs are critical to their function. Several techniques have been developed for the measurement of the mechanical properties of tissues and organs; however, current methods are destructive. The field of TE will benefit immensely if biomechanical models developed by these techniques could be combined with existing imaging modalities to enable noninvasive, dynamic assessment of mechanical properties during tissue growth. Specifically, MR elastography (MRE), which is based on the synchronization of a mechanical actuator with a phase contrast imaging pulse sequence, has the capacity to measure tissue strain generated by sonic cyclic displacement. The captured displacement is presented in shear wave images from which the complex shear moduli can be extracted or simplified by a direct measure, termed the shear stiffness. MRE has been extended to the microscopic scale, combining clinical MRE with high-field magnets, stronger magnetic field gradients and smaller, more sensitive, radiofrequency coils, enabling the interrogation of smaller samples, such as tissue-engineered constructs. The following topics are presented in this article: (i) current mechanical measurement techniques and their limitations in TE; (ii) a description of the MRE system, MRE theory and how it can be applied for the measurement of mechanical properties of tissue-engineered constructs; (iii) a summary of in vitro MRE work for the monitoring of osteogenic and adipogenic tissues originating from human adult mesenchymal stem cells (MSCs); (iv) preliminary in vivo studies of MRE of tissues originating from mouse MSCs implanted subcutaneously in immunodeficient mice with an emphasis on in vivo MRE challenges; (v) future directions to resolve current issues with in vivo MRE in the context of how to improve the future role of MRE in TE.

Background:The next generation magnetic nanoparticles (MNPs) with theranostic applications have attracted significant attention and will greatly improve nanomedicine in cancer therapeutics. Such novel MNP formulations must have ultra-low particle size, high inherent magnetic properties, effective imaging, drug targeting, and drug delivery properties. To achieve these characteristic properties, a curcumin-loaded MNP (MNP-CUR) formulation was developed. Methods: MNPs were prepared by chemical precipitation method and loaded with curcumin (CUR) using diffusion method. The physicochemical properties of MNP-CUR were characterized using dynamic light scattering, transmission electron microscopy, and spectroscopy. The internalization of MNP-CUR was achieved after 6 hours incubation with MDA-MB-231 breast cancer cells. The anticancer potential was evaluated by a tetrazolium-based dye and colony formation assays. Further, to prove MNP-CUR results in superior therapeutic effects over CUR, the mitochondrial membrane potential integrity and reactive oxygen species generation were determined. Magnetic resonance imaging capability and magnetic targeting property were also evaluated. Results: MNP-CUR exhibited individual particle grain size of ∼9 nm and hydrodynamic average aggregative particle size of ∼123 nm. Internalized MNP-CUR showed a preferential uptake in MDA-MB-231 cells in a concentration-dependent manner and demonstrated accumulation throughout the cell, which indicates that particles are not attached on the cell surface but internalized through endocytosis. MNP-CUR displayed strong anticancer properties compared to free CUR. MNP-CUR also amplified loss of potential integrity and generation of reactive oxygen species upon treatment compared to free CUR. Furthermore, MNP-CUR exhibited superior magnetic resonance imaging characteristics and significantly increased the targeting capability of CUR. Conclusion: MNP-CUR exhibits potent anticancer activity along with imaging and magnetic targeting capabilities. This approach can be extended to preclinical and clinical use and may have importance in cancer treatment and cancer imaging in the future. Further, if these nanoparticles can functionalize with antibody/ligands, they will serve as novel platforms for multiple biomedical applications.

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Background: Magnetic nanoparticles (MNPs) with theranostic features (diagnosis and treatment) have attracted significant attention and will greatly improve the scope of nanomedicine in cancer applications. The aim of this study is to develop a novel MNPs formulation composed of an iron oxide core coated with α-cyclodextrin and pluronic polymer (F68), to load an anti-cancer drug (curcumin, CUR) and prevent particle aggregation, respectively. The therapeutic efficacy and imaging capabilities of this novel formulation were evaluated in breast cancer cell line models. Methods: The physico-chemical analyses of curcumin loaded MNPs (MNP-CUR) were performed using dynamic light scattering (DLS), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) analyses. MNP-CUR internalization was evaluated after 6 hrs incubation with MDA-MB-231 cancer cells by Prussian blue stain and TEM. Anti-cancer effects of the MNP-CUR formulation was determined by a tetrazolium based dye (MTT) and colony formation assays using “triple negative” MDA-MB-231 cancer cells. Tetramethylrhodamine, ethyl ester, perchlorate (TMRE), red mitochondrial superoxide indicator (Mitosox), and propidium iodide stains were used to evaluate the loss of mitochondrial membrane potential, reactive oxygen species (ROS) generation, and apoptosis/dead cells, respectively, to determine effects MNP-CUR on these cellular features. The imaging capability of this MNP-CUR formulation was analyzed using a magnetic resonance imaging (MRI) system. The magnetic targeting feature of the MNP-CUR formulation was evaluated using fluorescence microscopy. Results: We prepared MNP-CUR with an average aggregative particles size of ∼ 150 nm (individual particle grain size, ∼ 9-11 nm). Prussian blue stain data represent a preferential uptake of MNP-CUR in MDA-MB-231 cells in a dose dependant manner. TEM analysis demonstrates that accumulation of MNP-CUR nanoparticles in cancer cells indicate that particles are not attached on the surface of cells but internalized within the cells. The MNP-CUR formulation showed strong anti-cancer effects in breast cancer cells including “triple negative” MDA-MB-231 cancer cells compared to free curcumin. This formulation also enhanced loss of mitochondrial membrane potential, generation of ROS and apoptosis compared to free curcumin treatment. Additionally, the MNP-CUR formulation exhibits superior T2 imaging characteristics compared to T1. A significant increase of the targeting feature was observed with MNP-CUR in breast cancer cells. Conclusion: These data suggest that our novel MNP-CUR formulation exhibits potent anti-cancer activity along with imaging and magnetic targeting capabilities. This approach can be extended to pre-clinical and clinical use and may have importance in cancer treatment and cancer imaging in the future. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2893. doi:1538-7445.AM2012-2893

Current theory has divided memory into multiple systems, resulting in a fractionated account of human behaviour. By an alternative perspective, memory is a single system. However, debate over the details of different single-system theories has overshadowed the converging agreement among them, slowing the reunification of memory. Evidence in favour of dividing memory often takes the form of dissociations observed in amnesia, where amnesic patients are impaired on some memory tasks but not others. The dissociations are taken as evidence for separate explicit and implicit memory systems. We argue against this perspective. We simulate two key dissociations between classification and recognition in a computational model of memory, A Theory of Nonanalytic Association. We assume that amnesia reflects a quantitative difference in the quality of encoding. We also present empirical evidence that replicates the dissociations in healthy participants, simulating amnesic behaviour by reducing study time. In both analyses, we successfully reproduce the dissociations. We integrate our computational and empirical successes with the success of alternative models and manipulations and argue that our demonstrations, taken in concert with similar demonstrations with similar models, provide converging evidence for a more general set of single-system analyses that support the conclusion that a wide variety of memory phenomena can be explained by a unified and coherent set of principles.

Millions of cases of bone injury or loss due to trauma, osteoporosis, and cancer occur in the United States each year. Because bone is limited in its ability to regenerate, alternative therapy approaches are needed. Bone tissue engineering has the potential to correct musculoskeletal disorders through the development of cell-based substitutes for osteogenic tissue replacement. Multiple medical imaging techniques such as magnetic resonance microscopy (MRM) were investigated recently; these techniques are able to provide useful information on the anatomical and structural changes of developing bone. However, there is a need for noninvasive approaches to evaluate biochemical constituents and consequent compositional development associated with growing osteogenic constructs. In this study, near-infrared (NIR) optical imaging with a bone-specific NIR-targeted probe, IRDye® 800CW BoneTag™ (800CW BT), was applied in this study to longitudinally visualize regions of mineralization of tissue-engineered bone constructs in vivo. A fluorescent cell-based assay was performed to confirm the preferential binding of 800CW BT to the mineralized matrix of differentiated osteogenically driven human mesenchymal stem cells (hMSCs) in vitro. The hMSCs were seeded onto a biocompatible gelatin scaffold, allowed to develop, and implanted into a mouse model. Engineered constructs were examined in vivo using NIR imaging for bone mineralization, paired with MRM for verification of developing tissue. Results showed that NIR imaging with 800CW BT labeling can effectively assess the calcification of the developing osteogenic constructs, which is consistent with the analysis of excised tissue using NIR microscopy and histology. In conclusion, this study evaluated bone-like function of regenerating bone through tracking calcium deposition via NIR optical imaging with a fluorophore-labeled probe in a noninvasive manner.

Traditional mechanical testing often results in the destruction of the sample, and in the case of long term tissue engineered construct studies, the use of destructive assessment is not acceptable. A proposed alternative is the use of an imaging process called magnetic resonance elastography. Elastography is a nondestructive method for determining the engineered outcome by measuring local mechanical property values (i.e., complex shear modulus), which are essential markers for identifying the structure and functionality of a tissue. As a noninvasive means for evaluation, the monitoring of engineered constructs with imaging modalities such as magnetic resonance imaging (MRI) has seen increasing interest in the past decade 1 . For example, the magnetic resonance (MR) techniques of diffusion and relaxometry have been able to characterize the changes in chemical and physical properties during engineered tissue development 2 . The method proposed in the following protocol uses microscopic magnetic resonance elastography (μMRE) as a noninvasive MR based technique for measuring the mechanical properties of small soft tissues 3 . MRE is achieved by coupling a sonic mechanical actuator with the tissue of interest and recording the shear wave propagation with an MR scanner 4 . Recently, μMRE has been applied in tissue engineering to acquire essential growth information that is traditionally measured using destructive mechanical macroscopic techniques 5 . In the following procedure, elastography is achieved through the imaging of engineered constructs with a modified Hahn spin-echo sequence coupled with a mechanical actuator. As shown in Figure 1, the modified sequence synchronizes image acquisition with the transmission of external shear waves; subsequently, the motion is sensitized through the use of oscillating bipolar pairs. Following collection of images with positive and negative motion sensitization, complex division of the data produce a shear wave image. Then, the image is assessed using an inversion algorithm to generate a shear stiffness map 6 . The resulting measurements at each voxel have been shown to strongly correlate (R 2 >0.9914) with data collected using dynamic mechanical analysis 7 . In this study, elastography is integrated into the tissue development process for monitoring human mesenchymal stem cell (hMSC) differentiation into adipogenic and osteogenic constructs as shown in Figure 2. Video LinkThe video component of this article can be found at http://www.jove.com/video/3618/ Protocol Tissue Construct PreparationThe tissue construct preparation process consists of three main stages: expansion of cell population, seeding of cells onto a biomaterial scaffold, and differentiation through the use of chemical signaling molecules. The procedure for construct preparation is based on methods conducted by Dennis et al., Hong et al., and Marion and Mao 8,9,10 . Actuator CharacterizationCharacterization of the actuator is a vital step for the MRE experiment. MRE relies on the propagation of mechanical...