Labeling of cells with ferumoxides-protamine sulfate complexes does not inhibit function or differentiation capacity of hematopoietic or mesenchymal stem cells

Nanoparticles targeting hematopoietic stem and progenitor cells: Multimodal carriers for the treatment of hematological diseases

Modern-day hematopoietic stem cell (HSC) therapies, such as gene therapy, modify autologous HSCs prior to re-infusion into myelo-conditioned patients and hold great promise for treatment of hematological disorders. While this approach has been successful in numerous clinical trials, it relies on transplantation of ex vivo modified patient HSCs, which presents several limitations. It is a costly and time-consuming procedure, which includes only few patients so far, and ex vivo culturing negatively impacts on the viability and stem cell-properties of HSCs. If viral vectors are used, this carries the additional risk of insertional mutagenesis. A therapy delivered to HSCs in vivo, with minimal disturbance of the HSC niche, could offer great opportunities for novel treatments that aim to reverse disease symptoms for hematopoietic disorders and could bring safe, effective and affordable genetic therapies to all parts of the world. However, substantial unmet needs exist with respect to the in vivo delivery of therapeutics to HSCs. In the last decade, in particular with the development of gene editing technologies such as CRISPR/Cas9, nanoparticles (NPs) have become an emerging platform to facilitate the manipulation of cells and organs. By employing surface modification strategies, different types of NPs can be designed to target specific tissues and cell types in vivo. HSCs are particularly difficult to target due to the lack of unique cell surface markers that can be utilized for cell-specific delivery of therapeutics, and their shielded localization in the bone marrow (BM). Recent advances in NP technology and genetic engineering have resulted in the development of advanced nanocarriers that can deliver therapeutics and imaging agents to hematopoietic stem- and progenitor cells (HSPCs) in the BM niche. In this review we provide a comprehensive overview of NP-based approaches targeting HSPCs to control and monitor HSPC activity in vitro and in vivo, and we discuss the potential of NPs for the treatment of malignant and non-malignant hematological disorders, with a specific focus on the delivery of gene editing tools.

Diagnostic and therapeutic roles of iron oxide nanoparticles in biomedicine

Nanotechnology changed our understanding of physics and chemics and influenced the biomedical field. Iron oxide nanoparticles (IONs) are one of the first emerging biomedical applications of nanotechnology. The IONs are composed of iron oxide core exhibiting magnetism and coated with biocompatible molecules. The small size, strong magnetism, and biocompatibility of IONs facilitate the application of IONs in the medical imaging field. We listed several clinical available IONs including Resovist (Bayer Schering Pharma, Berlin, Germany) and Feridex intravenous (I.V.)/Endorem as magnetic resonance (MR) contrast agents for liver tumor detection. We also illustrated GastroMARK as a gastrointestinal contrast agent for MR imaging. Recently, IONs named Feraheme for treating iron-deficiency anemia have been approved by the Food and Drug Administration. Moreover, tumor ablation by IONs named NanoTherm has also been discussed. In addition to the clinical application, several potential biomedical applications of IONs including cancer-targeting capability by conjugating IONs with cancer-specific ligands, cell trafficking tools, or tumor ablation agents have also been discussed. With the growing awareness of nanotechnology, further application of IONs is still on the horizon that would shed light on biomedicine.

In vivo Cell Tracking Using Non-invasive Imaging of Iron Oxide-Based Particles with Particular Relevance for Stem Cell-Based Treatments of Neurological and Cardiac Disease

Stem cell-based therapeutics is a rapidly developing field associated with a number of clinical challenges. One such challenge lies in the implementation of methods to track stem cells and stem cell-derived cells in experimental animal models and in the living patient. Here, we provide an overview of cell tracking in the context of cardiac and neurological disease, focusing on the use of iron oxide-based particles (IOPs) visualized in vivo using magnetic resonance imaging (MRI). We discuss the types of IOPs available for such tracking, their advantages and limitations, approaches for labeling cells with IOPs, biological interactions and effects of IOPs at the molecular and cellular levels, and MRI-based and associated approaches for in vivo and histological visualization. We conclude with reviews of the literature on IOP-based cell tracking in cardiac and neurological disease, covering both preclinical and clinical studies.

Antibody-siRNA conjugates (ARCs) using multifunctional peptide as a tumor enzyme cleavable linker mediated effective intracellular delivery of siRNA

The tissue-specific targeted delivery and efficient cellular uptake of siRNAs are the main obstacles to their clinical application. Antibody-siRNA-conjugates (ARCs) can deliver siRNA by exploiting the targeting property of antibodies like antibody-drug conjugates (ADCs). However, the effective conjugation of antibodies and siRNAs and the release of siRNAs specifically at target sites have posed challenges to the development of ARCs. In this study, the successful conjugation of antibodies and siRNAs was achieved using a multifunctional peptide as a linker, composed of a cell-penetrating peptide (CPP) and a substrate peptide (SP), which is highly expressed in solid tumors. The resulting antibody-multifunctional peptide (SP-CPP)-siRNA system delivered the siRNA to target tumor cells by the specific binding of the antibody. Once the enzymes on the tumor cell surface hydrolyzed the substrate peptide linker, siRNA-CPP was released from ARCs. The released siRNA-CPP entered the targeted cells via the cellular penetrating ability of CPP, resulting in improved siRNA-mediated gene silencing efficiency, verified both in vitro and in vivo. After intravenous administration, the designed ARCs achieved approximately 66.7% EGFP (Enhanced Green Fluorescent Protein) downregulation efficiency in nude mice xenografted with the HCT116-EGFP tumor model. The proposed system provides a prospective choice for ARC production and the safe and efficient delivery of siRNAs.

Engineering of magnetic nanoparticles as magnetic particle imaging tracers

Magnetic particle imaging (MPI) has recently emerged as a promising non-invasive imaging technique because of its signal linearly propotional to the tracer mass, ability to generate positive contrast, low tissue background, unlimited tissue penetration depth, and lack of ionizing radiation. The sensitivity and resolution of MPI are highly dependent on the properties of magnetic nanoparticles (MNPs), and extensive research efforts have been focused on the design and synthesis of tracers. This review examines parameters that dictate the performance of MNPs, including size, shape, composition, surface property, crystallinity, the surrounding environment, and aggregation state to provide guidance for engineering MPI tracers with better performance. Finally, we discuss applications of MPI imaging and its challenges and perspectives in clinical translation.

Multimodal Tracking of Hematopoietic Stem Cells from Young and Old Mice Labeled with Magnetic-Fluorescent Nanoparticles and Their Grafting by Bioluminescence in a Bone Marrow Transplant Model

This study proposes an innovative way to evaluate the homing and tracking of hematopoietic stem cells from young and old mice labeled with SPION_NIRF-Rh conjugated with two types of fluorophores (NIRF and Rhodamine), and their grafting by bioluminescence (BLI) in a bone marrow transplant (BMT) model. In an in vitro study, we isolated bone marrow mononuclear cells (BM-MNC) from young and old mice, and analyzed the physical-chemical characteristics of SPION_NIRF-Rh, their internalization, cell viability, and the iron quantification by NIRF, ICP-MS, and MRI. The in vivo study was performed in a BMT model to evaluate the homing, tracking, and grafting of young and old BM-MNC labeled with SPION_NIRF-Rh by NIRF and BLI, as well as the hematological reconstitution for 120 days. 5FU influenced the number of cells isolated mainly in young cells. SPION_NIRF-Rh had adequate characteristics for efficient internalization into BM-MNC. The iron load quantification by NIRF, ICP-MS, and MRI was in the order of 10⁴ SPION_NIRF-Rh/BM-MNC. In the in vivo study, the acute NIRF evaluation showed higher signal intensity in the spinal cord and abdominal region, and the BLI evaluation allowed follow-up (11-120 days), achieving a peak of intensity at 30 days, which remained stable around 10⁸ photons/s until the end. The hematologic evaluation showed similar behavior until 30 days and the histological results confirm that iron is present in almost all tissue evaluated. Our results on BM-MNC homing and tracking in the BMT model did not show a difference in migration or grafting of cells from young or old mice, with the hemogram analysis trending to differentiation towards the myeloid lineage in mice that received cells from old animals. The cell homing by NIRF and long term cell follow-up by BLI highlighted the relevance of the multimodal nanoparticles and combined techniques for evaluation.

Melatonin-loaded chitosan nanoparticles endows nitric oxide synthase 2 mediated anti-inflammatory activity in inflammatory bowel disease model

Inflammatory Bowel Disease (IBD) is a complex inflammatory condition arising due to interactions of environmental and genetic factors that lead to dysregulated immune response and inflammation in intestine. Complementary and alternative medicine approaches have been utilized to treat IBD. However, chronic inflammatory diseases are not medically curable. Hence, potent anti-inflammatory therapeutic agents are urgently warranted. Melatonin has emerged as a potent anti-inflammatory and neuroprotective candidate. Although, it's therapeutic efficacy is compromised due to less solubility and rapid clearance. Hence, we have synthesized melatonin loaded chitosan nanoparticle (Mel-CSNPs) to improve drug release profile and evaluate its in-vitro and in-vivo therapeutic efficacy. Mel-CSNPs exhibited better anti-inflammatory response in an in-vitro and in-vivo IBD model. Significant anti-inflammatory activity of Mel-CSNPs is attributed to nitric oxide (NO) reduction, inhibited nuclear translocation of NF-kB p65 and reduced IL-1β and IL-6 expression. In-vivo biodistribution study has shown a good distribution profile. Effective in-vivo therapeutic efficiency of Mel-CSNPs has been confirmed with reduced disease activity index parameters and inhibited neutrophilic infiltration. Histological evaluation has further proved the protective effect of Mel-CSNPs by preventing crypt damage and immune cells infiltration against Dextran Sodium Sulphate induced insults. Immuno-histochemical analysis has confirmed anti-inflammatory action of Mel-CSNPs with reduction of inflammatory markers, Nitric Oxide Synthase-2 (NOS2) and Nitro-tyrosine. Indeed, this study divulges anti-inflammatory activity of Mel-CSNPs by improving the therapeutic potential of melatonin.

Bifunctional Labeling of Rabbit Mesenchymal Stem Cells for MR Imaging and Fluorescence Microscopy

PURPOSE

Longitudinal imaging studies are important in the translational process of stem cell-based therapies. Small animal imaging models are widely available and practical but insufficiently depict important morphologic detail. In contrary, large animal models are logistically challenging and costly but offer greater imaging quality. In order to combine the advantages of both, we developed an intermediate-sized rabbit animal model for cartilage imaging studies.

PROCEDURES

Rabbit mesenchymal stem cells (rMSC) were isolated as primary cultures from the bone marrow of New Zealand white rabbits. rMSC were subsequentially transduced lentivirally with eGFP and magnetically labeled with the iron oxide ferucarbotran. eGFP expression was evaluated by flow cytometry and iron uptake was analyzed by isotope dilution mass spectrometry and Prussian blue staining. Fluorescence microscopy of eGFP-transduced rMSC was performed. Viability and induction of apoptosis were assessed by XTT and caspase-3/-7 measurements. The chondrogenic potential of labeled cells was quantified by glycosaminoglycan contents in TGF-β3 induced pellet cultures. Labeled and unlabeled cells underwent magnetic resonance imaging (MRI) at 1.5 T before and after differentiation using T1-, T2-, and T2*-weighted pulse sequences. Relaxation rates were calculated. rMSCs were implanted in fibrin clots in osteochondral defects of cadaveric rabbit knees and imaged by 7 T MRI. T2* maps were calculated. Statistical analyses were performed using multiple regression models.

RESULTS

Efficiency of lentiviral transduction was greater than 90 %. Fluorescence signal was dose dependent. Cellular iron uptake was significant for all concentrations (p < 0.05) and dose dependent (3.3-56.5 pg Fe/cell). Labeled rMSC showed a strong, dose-dependent contrast on all MR pulse sequences and a significant decrease in T2 and T2* relaxation rates. Compared with non-transduced or unlabeled controls, there were no adverse effects on cell viability, rate of apoptosis, or chondrogenic differentiation. MRI of labeled rMSCs in osteochondral defects showed a significant signal of the transplant with additional high-resolution anatomical information.

CONCLUSIONS

This intermediate-sized rabbit model and its bifunctional labeling technique allow for improved depiction of anatomic detail for noninvasive in vivo rMSC tracking with MRI and for immunohistological correlation by fluorescence microscopy.

Superparamagnetic Iron Oxide Particles (VSOPs) Show Genotoxic Effects but No Functional Impact on Human Adipose Tissue-Derived Stromal Cells (ASCs)

Adipose tissue-derived stromal cells (ASCs) represent a capable source for cell-based therapeutic approaches. For monitoring a cell-based application in vivo, magnetic resonance imaging (MRI) of cells labeled with iron oxide particles is a common method. It is the aim of the present study to analyze potential DNA damage, cytotoxicity and impairment of functional properties of human (h)ASCs after labeling with citrate-coated very small superparamagnetic iron oxide particles (VSOPs). Cytotoxic as well as genotoxic effects of the labeling procedure were measured in labeled and unlabeled hASCs using the MTT assay, comet assay and chromosomal aberration test. Trilineage differentiation was performed to evaluate an impairment of the differentiation potential due to the particles. Proliferation as well as migration capability were analyzed after the labeling procedure. Furthermore, the labeling of the hASCs was confirmed by Prussian blue staining, transmission electron microscopy (TEM) and high-resolution MRI. Below the concentration of 0.6 mM, which was used for the procedure, no evidence of genotoxic effects was found. At 0.6 mM, 1 mM as well as 1.5 mM, an increase in the number of chromosomal aberrations was determined. Cytotoxic effects were not observed at any concentration. Proliferation, migration capability and differentiation potential were also not affected by the procedure. Labeling with VSOPs is a useful labeling method for hASCs that does not affect their proliferation, migration and differentiation potential. Despite the absence of cytotoxicity, however, indications of genotoxic effects have been demonstrated.

Instant labeling of therapeutic cells for multimodality imaging

Autologous therapeutic cells are typically harvested and transplanted in one single surgery. This makes it impossible to label them with imaging biomarkers through classical transfection techniques in a laboratory. To solve this problem, we developed a novel microfluidic device, which provides highly efficient labeling of therapeutic cells with imaging biomarkers through mechanoporation. Methods: Studies were performed with a new, custom-designed microfluidic device, which contains ridges, which compress adipose tissue-derived stem cells (ADSCs) during their device passage. Cell relaxation after compression leads to cell volume exchange for convective transfer of nanoparticles and nanoparticle uptake into the cell. ADSCs were passed through the microfluidic device doped with iron oxide nanoparticles and 18F-fluorodeoxyglucose (FDG). The cellular nanoparticle and radiotracer uptake was evaluated with DAB-Prussian blue, fluorescent microscopy, and inductively coupled plasma spectrometry (ICP). Labeled and unlabeled ADSCs were imaged in vitro as well as ex vivo in pig knee specimen with magnetic resonance imaging (MRI) and positron emission tomography (PET). T2 relaxation times and radiotracer signal were compared between labeled and unlabeled cell transplants using Student T-test with p<0.05. Results: We report significant labeling of ADSCs with iron oxide nanoparticles and 18F-FDG within 12+/-3 minutes. Mechanoporation of ADSCs with our microfluidic device led to significant nanoparticle (> 1 pg iron per cell) and 18F-FDG uptake (61 mBq/cell), with a labeling efficiency of 95%. The labeled ADSCs could be detected with MRI and PET imaging technologies: Nanoparticle labeled ADSC demonstrated significantly shorter T2 relaxation times (24.2±2.1 ms) compared to unlabeled cells (79.6±0.8 ms) on MRI (p<0.05) and 18F-FDG labeled ADSC showed significantly higher radiotracer uptake (614.3 ± 9.5 Bq / 1×104 cells) compared to controls (0.0 ± 0.0 Bq/ 1×104 cells) on gamma counting (p<0.05). After implantation of dual-labeled ADSCs into pig knee specimen, the labeled ADSCs revealed significantly shorter T2 relaxation times (41±0.6 ms) compared to unlabeled controls (90±1.8 ms) (p<0.05). Conclusion: The labeling of therapeutic cells with our new microfluidic device does not require any chemical intervention, therefore it is broadly and immediately clinically applicable. Cellular labeling using mechanoporation can improve our understanding of in vivo biodistributions of therapeutic cells and ultimately improve long-term outcomes of therapeutic cell transplants.

Neurogenin-1 Overexpression Increases the Therapeutic Effects of Mesenchymal Stem Cells through Enhanced Engraftment in an Ischemic Rat Brain

Background and Objectives

Stem cell therapy is a promising strategy for treating neurological diseases but its effectiveness is influenced by the route of administration and the characteristics of the stem cells. We determined whether neural induction of mesenchymal stem cells (MSCs) was beneficial when the cells were delivered intra-arterially through the carotid artery.

Methods and Results

MSCs were neurally induced using a retroviral vector expressing the neurogenic transcription factor neurogenin-1 (Ngn1). The LacZ gene encoding bacterial β-galactosidase was used as a control. Ischemic stroke was induced by transluminal occlusion of the middle cerebral artery and 3 days later the MSCs were delivered intra-arterially through the internal carotid artery. Magnetic resonance imaging analysis indicated that compared to MSCs expressing LacZ (MSCs/LacZ), MSCs expressing Ngn1 (MSCs/Ngn1) exhibited increased recruitment to the ischemic region and populated this area for a longer duration. Immunohistochemical analysis indicated that compared to MSCs/LacZ, MSCs/Ngn1 more effectively alleviated neurological dysfunction by blocking secondary damage associated with neuronal cell death and brain inflammation. Microarray and real-time PCR analysis indicated that MSCs/Ngn1 exhibited increased expression of chemotactic cytokine receptors, adherence to endothelial cells, and migration ability.

Conclusions

Neural induction with Ngn1 increases the homing ability of MSCs, enhancing their engraftment efficiency in the ischemic rat brain. Intra-arterial delivery of neurally induced MSCs/Ngn1 3 days after ischemic injury blocks neuronal cell death and inflammation, and improves functional recovery. Thus, intra-arterial administration of stem cells with neural properties may be a novel therapy for the treatment of ischemic stroke.

Engineered iron oxide nanoparticles to improve regenerative effects of mesenchymal stem cells

Abstract

Mesenchymal stem cells (MSCs) based therapies are a major field of regenerative medicine. However, the success of MSC therapy relies on the efficiency of its delivery and retention, differentiation, and secreting paracrine factors at the target sites. Recent studies show that superparamagnetic iron oxide nanoparticles (SPIONs) modulate the regenerative effects of MSCs. After interacting with the cell membrane of MSCs, SPIONs can enter the cells via the endocytic pathway. The physicochemical properties of nanoparticles, including size, surface charge (zeta-potential), and surface ligand, influence their interactions with MSC, such as cellular uptake, cytotoxicity, homing factors, and regenerative related factors (VEGF, TGF-β1). Therefore, in-depth knowledge of the physicochemical properties of SPIONs might be a promising lead in regenerative and anti-inflammation research using SPIONs mediated MSCs. In this review, recent research on SPIONs with MSCs and the various designs of SPIONs are examined and summarized.

Graphic abstract

A graphical abstract describes important parameters in the design of superparamagnetic iron oxide nanoparticles, affecting mesenchymal stem cells. These physicochemical properties are closely related to the mesenchymal stem cells to achieve improved cellular responses such as homing factors and cell uptake.

The Effect of Uncoated SPIONs on hiPSC-Differentiated Endothelial Cells

Background: Endothelial progenitor cells (EPCs) were indicated in vascular repair, angiogenesis of ischemic organs, and inhibition of formation of initial hyperplasia. Differentiation of endothelial cells (ECs) from human induced pluripotent stem cells (hiPSC)-derived endothelial cells (hiPSC-ECs) provides an unlimited supply for clinical application. Furthermore, magnetic cell labelling offers an effective way of targeting and visualization of hiPSC-ECs and is the next step towards in vivo studies. Methods: ECs were differentiated from hiPSCs and labelled with uncoated superparamagnetic iron-oxide nanoparticles (uSPIONs). uSPION uptake was compared between hiPSC-ECs and mature ECs isolated from patients by software analysis of microscopy pictures after Prussian blue cell staining. The acute and long-term cytotoxic effects of uSPIONs were evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay) and Annexin assay. Results: We showed, for the first time, uptake of uncoated SPIONs (uSPIONs) by hiPSC-ECs. In comparison with mature ECs of identical genetic background hiPSC-ECs showed lower uSPION uptake. However, all the studied endothelial cells were effectively labelled and showed magnetic properties even with low labelling concentration of uSPIONs. uSPIONs prepared by microwave plasma synthesis did not show any cytotoxicity nor impair endothelial properties. Conclusion: We show that hiPSC-ECs labelling with low concentration of uSPIONs is feasible and does not show any toxic effects in vitro, which is an important step towards animal studies.

Nuclear fast red-based colorimetric sensors for sensitive and selective detection of Ag ions

The reduction of nuclear fast red (NFR) stain by sodium tetrahydroboron was catalyzed in the presence of silver ions (Ag⁺ ). The fluorescence properties of reduced NFR differed from that of NFR. The product showed fluorescence emission at 480 nm with excitation at 369 nm. Furthermore, the fluorescence intensity of the mixture increased strongly in the presence of Ag⁺ and Britton-Robinson buffer at pH 4.78. There was a good linear relationship between increased fluorescence intensity (ΔI) and Ag⁺ concentration in the range 5.0 × 10^-9 to 5.0 × 10^-8  M. The correlation coefficient was 0.998, and the detection limit (3σ/k) was 1.5 × 10^-9  M. The colour of the reaction system changed with variation in Ag⁺ concentration over a wide range. Based on the colour change, a visual semiquantitative detection method for recognition and sensing of Ag⁺ was developed for the range 1.0 × 10^-8  to 5.0 × 10^-4  M, with an indicator that was visible to the naked eye. Therefore, a sensitive, simple method for determination of Ag⁺ was developed. Optimum conditions for Ag⁺ detection, the effect of other ions and the analytical application of Ag⁺ detection of synthesized sample were investigated.

In Vitro Safety and Quality of Magnetically Labeled Human Mesenchymal Stem Cells Preparation for Cartilage Repair

IMPACT STATEMENT

This study is very important for a preclinical assessment of the safety and quality of magnetically labeled mesenchymal stem cells (MSCs) for use in cartilage repair. The findings of this study show that magnetic labeling with an appropriate density of magnetic particles has no harmful effects on the safety and quality of MSCs.

Tracking Neural Progenitor Cell Migration in the Rodent Brain Using Magnetic Resonance Imaging

The study of neurogenesis and neural progenitor cells (NPCs) is important across the biomedical spectrum, from learning about normal brain development and studying disease to engineering new strategies in regenerative medicine. In adult mammals, NPCs proliferate in two main areas of the brain, the subventricular zone (SVZ) and the subgranular zone, and continue to migrate even after neurogenesis has ceased within the rest of the brain. In healthy animals, NPCs migrate along the rostral migratory stream (RMS) from the SVZ to the olfactory bulb, and in diseased animals, NPCs migrate toward lesions such as stroke and tumors. Here we review how MRI-based cell tracking using iron oxide particles can be used to monitor and quantify NPC migration in the intact rodent brain, in a serial and relatively non-invasive fashion. NPCs can either be labeled directly in situ by injecting particles into the lateral ventricle or RMS, where NPCs can take up particles, or cells can be harvested and labeled in vitro, then injected into the brain. For in situ labeling experiments, the particle type, injection site, and image analysis methods have been optimized and cell migration toward stroke and multiple sclerosis lesions has been investigated. Delivery of labeled exogenous NPCs has allowed imaging of cell migration toward more sites of neuropathology, which may enable new diagnostic and therapeutic opportunities for as-of-yet untreatable neurological diseases.

Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications

Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.

Magnetic hyperthermia therapy for the treatment of glioblastoma: a review of the therapy's history, efficacy and application in humans

Hyperthermia therapy (HT) is the exposure of a region of the body to elevated temperatures to achieve a therapeutic effect. HT anticancer properties and its potential as a cancer treatment have been studied for decades. Techniques used to achieve a localised hyperthermic effect include radiofrequency, ultrasound, microwave, laser and magnetic nanoparticles (MNPs). The use of MNPs for therapeutic hyperthermia generation is known as magnetic hyperthermia therapy (MHT) and was first attempted as a cancer therapy in 1957. However, despite more recent advancements, MHT has still not become part of the standard of care for cancer treatment. Certain challenges, such as accurate thermometry within the tumour mass and precise tumour heating, preclude its widespread application as a treatment modality for cancer. MHT is especially attractive for the treatment of glioblastoma (GBM), the most common and aggressive primary brain cancer in adults, which has no cure. In this review, the application of MHT as a therapeutic modality for GBM will be discussed. Its therapeutic efficacy, technical details, and major experimental and clinical findings will be reviewed and analysed. Finally, current limitations, areas of improvement, and future directions will be discussed in depth.

The safety and efficacy of magnetic targeting using autologous mesenchymal stem cells for cartilage repair

PURPOSE

A new cell delivery system using magnetic force, termed magnetic targeting, was developed for the accumulation of locally injected cells in a lesion. The aim of this study was to assess the safety and efficacy of mesenchymal stem cell (MSC) magnetic targeting in patients with a focal articular cartilage defect in the knee.

METHODS

MSC magnetic targeting for five patients was approved by the Ministry of Health Labour and Welfare of Japan. Autologous bone marrow MSCs were cultured and subsequently magnetized with ferucarbotran. The 1.0-T compact magnet was attached to a suitable position around the knee joint to allow the magnetic force to be as perpendicular to the surface of the lesion as possible. Then 1 × 10⁷ MSCs were injected into the knee joint. The magnet was maintained in the same position for 10 min after the MSC injection. The primary endpoint was the occurrence of any adverse events. The secondary endpoints were efficacy assessed by magnetic resonance imaging (MRI) T2 mapping and clinical outcomes using the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation and the Knee Injury and Osteoarthritis Outcome Score (KOOS).

RESULTS

No serious adverse events were observed during the treatment or in the follow-up period. Swelling of the treated knee joint was observed from the day after surgery in three of the five patients. The swelling resolved within 2 weeks in two patients. MRI showed that the cartilage defect areas were almost completely filled with cartilage-like tissue. MOCART scores were significantly higher 48 weeks postoperatively than preoperatively (74.8 ± 10.8 vs 27.0 ± 16.8, p = 0.042). Arthroscopy in three patients showed complete coverage of their cartilage defects. Clinical outcome scores were significantly better 48 weeks postoperatively than preoperatively for the IKDC Subjective Knee Evaluation (74.8 ± 17.7 vs 46.9 ± 17.7, p = 0.014) and knee-related quality-of-life (QOL) in the KOOS (53.8 ± 26.4 vs 22.5 ± 30.8, p = 0.012).

CONCLUSION

Magnetic targeting of MSCs was safely performed and showed complete coverage of the defects with cartilage-like tissues and significant improvement in clinical outcomes 48 weeks after treatment. The magnetic targeting of MSCs is useful as a minimally invasive treatment for cartilage repair.

LEVEL OF EVIDENCE

IV.

A Comparison of Iron Oxide Particles and Silica Particles for Tracking Organ Recellularization

Reseeding of decellularized organ scaffolds with a patient’s own cells has promise for eliminating graft versus host disease. This study investigated whether ultrasound imaging or magnetic resonance imaging (MRI) can track the reseeding of murine liver scaffolds with silica-labeled or iron-labeled liver hepatocytes. Mesoporous silica particles were created using the Stöber method, loaded with Alexa Flour 647 fluorophore, and conjugated with protamine sulfate, glutamine, and glycine. Fluorescent iron oxide particles were obtained from a commercial source. Liver cells from donor mice were loaded with the silica particles or iron oxide particles. Donor livers were decellularized and reperfused with silica-labeled or iron-labeled cells. The reseeded livers were longitudinally analyzed with ultrasound imaging and MRI. Liver biopsies were imaged with confocal microscopy and scanning electron microscopy. Ultrasound imaging had a detection limit of 0.28 mg/mL, while MRI had a lower detection limit of 0.08 mg/mL based on particle weight. The silica-loaded cells proliferated at a slower rate compared to iron-loaded cells. Ultrasound imaging, MRI, and confocal microscopy underestimated cell numbers relative to scanning electron microscopy. Ultrasound imaging had the greatest underestimation due to coarse resolution compared to the other imaging modalities. Despite this underestimation, both ultrasound imaging and MRI successfully tracked the longitudinal recellularization of liver scaffolds.

Improved cellular uptake of perfluorocarbon nanoparticles for in vivo murine cardiac 19F MRS/MRI and temporal tracking of progenitor cells

Herein, we maximize the labeling efficiency of cardiac progenitor cells (CPCs) using perfluorocarbon nanoparticles (PFCE-NP) and ¹⁹F MRI detectability, determine the temporal dynamics of single-cell label uptake, quantify the temporal viability/fluorescence persistence of labeled CPCs in vitro, and implement in vivo, murine cardiac CPC MRI/tracking that could be translatable to humans. FuGENE^HD-mediated CPC PFCE-NP uptake is confirmed with flow cytometry/confocal microscopy. Epifluorescence imaging assessed temporal viability/fluorescence (up to 7 days [D]). Nonlocalized murine ¹⁹F MRS and cardiac MRI studied label localization in terminal/longitudinal tracking studies at 9.4 T (D1-D8). A 4-8 fold ¹⁹F concentration increase is evidenced in CPCs for FuGENE vs. directly labeled cells. Cardiac ¹⁹F signals post-CPC injections diminished in vivo to ~31% of their values on D1 by D7/D8. Histology confirmed CPC retention, dispersion, and macrophage-induced infiltration. Intra-cardiac injections of PFCE-NP-labeled CPCs with FuGENE can be visualized/tracked in vivo for the first time with ¹⁹F MRI.

Magnetic Resonance Imaging Evaluation of Cartilage Repair and Iron Particle Kinetics After Magnetic Delivery of Stem Cells

IMPACT STATEMENT

This study is very important as a preclinical study of magnetic resonance imaging (MRI) assessment after magnetic targeting of mesenchymal stem cells. The findings of this study show that MRI is useful for evaluating the regenerative process of cartilage with magnetic targeting and kinetics of iron particles, and is less invasive without any complications.

Safety and Optimization of Metabolic Labeling of Endothelial Progenitor Cells for Tracking

Metabolic labeling is one of the most powerful methods to label the live cell for in vitro and in vivo tracking. However, the cellular mechanisms by modified glycosylation due to metabolic agents are not fully understood. Therefore, metabolic labeling has not yet been widely used in EPC tracking and labeling. In this study, cell functional properties such as proliferation, migration and permeability and gene expression patterns of metabolic labeling agent-treated hUCB-EPCs were analyzed to demonstrate cellular effects of metabolic labeling agents. As the results, 10 μM Ac4ManNAz treatment had no effects on cellular function or gene regulations, however, higher concentration of Ac4ManNAz (>20 μM) led to the inhibition of functional properties (proliferation rate, viability and rate of endocytosis) and down-regulation of genes related to cell adhesion, PI3K/AKT, FGF and EGFR signaling pathways. Interestingly, the new blood vessel formation and angiogenic potential of hUCB-EPCs were not affected by Ac4ManNAz concentration. Based on our results, we suggest 10 μM as the optimal concentration of Ac4ManNAz for in vivo hUCB-EPC labeling and tracking. Additionally, we expect that our approach can be used for understanding the efficacy and safety of stem cell-based therapy in vivo.

Core-shell magnetoelectric nanorobot - A remotely controlled probe for targeted cell manipulation

We have developed a remotely controlled dynamic process of manipulating targeted biological live cells using fabricated core-shell nanocomposites, which comprises of single crystalline ferromagnetic cores (CoFe₂O₄) coated with crystalline ferroelectric thin film shells (BaTiO₃). We demonstrate them as a unique family of inorganic magnetoelectric nanorobots (MENRs), controlled remotely by applied a.c. or d.c. magnetic fields, to perform cell targeting, permeation, and transport. Under a.c. magnetic field excitation (50 Oe, 60 Hz), the MENR acts as a localized electric periodic pulse generator and can permeate a series of misaligned cells, while aligning them to an equipotential mono-array by inducing inter-cellular signaling. Under a.c. magnetic field (40 Oe, 30 Hz) excitation, MENRs can be dynamically driven to a targeted cell, avoiding untargeted cells in the path, irrespective of cell density. D.C. magnetic field (−50 Oe) excitation causes the MENRs to act as thrust generator and exerts motion in a group of cells.

Pursuing meaningful end-points for stem cell therapy assessment in ischemic cardiac disease

Despite optimal interventional and medical therapy, ischemic heart disease is still an important cause of morbidity and mortality worldwide. Although not included in standard of care rehabilitation, stem cell therapy (SCT) could be a solution for prompting cardiac regeneration. Multiple studies have been published from the beginning of SCT until now, but overall no unanimous conclusion could be drawn in part due to the lack of appropriate end-points. In order to appreciate the impact of SCT, multiple markers from different categories should be considered: Structural, biological, functional, physiological, but also major adverse cardiac events or quality of life. Imaging end-points are among the most used - especially left ventricle ejection fraction (LVEF) measured through different methods. Other imaging parameters are infarct size, myocardial viability and perfusion. The impact of SCT on all of the aforementioned end-points is controversial and debatable. 2D-echocardiography is widely exploited, but new approaches such as tissue Doppler, strain/strain rate or 3D-echocardiography are more accurate, especially since the latter one is comparable with the MRI gold standard estimation of LVEF. Apart from the objective parameters, there are also patient-centered evaluations to reveal the benefits of SCT, such as quality of life and performance status, the most valuable from the patient point of view. Emerging parameters investigating molecular pathways such as non-coding RNAs or inflammation cytokines have a high potential as prognostic factors. Due to the disadvantages of current techniques, new imaging methods with labelled cells tracked along their lifetime seem promising, but until now only pre-clinical trials have been conducted in humans. Overall, SCT is characterized by high heterogeneity not only in preparation, administration and type of cells, but also in quantification of therapy effects.

A 3D magnetic tissue stretcher for remote mechanical control of embryonic stem cell differentiation

The ability to create a 3D tissue structure from individual cells and then to stimulate it at will is a major goal for both the biophysics and regenerative medicine communities. Here we show an integrated set of magnetic techniques that meet this challenge using embryonic stem cells (ESCs). We assessed the impact of magnetic nanoparticles internalization on ESCs viability, proliferation, pluripotency and differentiation profiles. We developed magnetic attractors capable of aggregating the cells remotely into a 3D embryoid body. This magnetic approach to embryoid body formation has no discernible impact on ESC differentiation pathways, as compared to the hanging drop method. It is also the base of the final magnetic device, composed of opposing magnetic attractors in order to form embryoid bodies in situ, then stretch them, and mechanically stimulate them at will. These stretched and cyclic purely mechanical stimulations were sufficient to drive ESCs differentiation towards the mesodermal cardiac pathway.

The development of embryoid bodies that are responsive to external stimuli is of great interest in tissue engineering. Here, the authors culture embryonic stem cells with magnetic nanoparticles and show that the presence of magnetic fields could affect their aggregation and differentiation.

In Vivo Tracking of Human Mesenchymal Stem Cells in Experimental Stroke

To understand the fates of human mesenchymal stem cells (hMSCs) following transplantation into a rodent model of middle cerebral artery occlusion (MCAo), magnetic resonance imaging (MRI) techniques were employed. hMSCs were labeled with ferumoxides (Feridex®)-protamine sulfate complexes, which were visualized and examined by MRI up to 10 weeks following transplantation. Migration of the transplanted cells to the infarcted area was further confirmed by histological methods. We found that the hMSCs transplanted in MCAo models possess the capacity to migrate to the infarcted area extensively in both ipsilateral and contralateral injections, exhibiting a pathotropism. We also analyzed the detailed migration patterns of transplanted hMSCs. We speculate that the extensive migratory ability of hMSCs may represent a therapeutic potential for developing efficient cell transplantation strategies in stroke.

High-Yield Synthesis of Monomeric LMWP(CPP)-siRNA Covalent Conjugate for Effective Cytosolic Delivery of siRNA

Because of the unparalleled efficiency and universal utility in treating a variety of disease types, siRNA agents have evolved as the future drug-of-choice. Yet, the inability of the polyanionic siRNA macromolecules to cross the cell membrane remains as the bottleneck of possible clinical applications. With the cell penetrating peptides (CPP) being discovered lately, the most effective tactic to achieve the highest intracellular siRNA delivery deems to be by covalently conjugating the drug to a CPP; for instance, the arginine-rich Tat or low molecular weight protamine (LMWP) peptides. However, construction of such a chemical conjugate has been referred by scientists in this field as the “Holy Grail” challenge due to self-assembly of the cationic CPP and anionic siRNA into insoluble aggregates that are deprived of the biological functions of both compounds. Based on the dynamic motion of PEG, we present herein a concise coupling strategy that is capable of permitting a high-yield synthesis of the cell-permeable, cytosol-dissociable LMWP-siRNA covalent conjugates. Cell culture assessment demonstrates that this chemical conjugate yields by far the most effective intracellular siRNA delivery and its corresponded gene-silencing activities. This work may offer a breakthrough advance towards realizing the clinical potential of all siRNA therapeutics and, presumably, most anionic macromolecular drugs such as anti-sense oligonucleotides, gene compounds, DNA vectors and proteins where conjugation with the CPP encounters with problems of aggregation and precipitation. To this end, the impact of this coupling technique is significant, far-reaching and wide-spread.

Positive contrast from cells labeled with iron oxide nanoparticles: Quantitation of imaging data

PURPOSE

Conventional T₂ -weighted MRI produces a hypointense signal from iron-labeled cells, which renders quantification unfeasible. We tested a SWeep Imaging with Fourier Transformation (SWIFT) MRI pulse sequence to generate a quantifiable hyperintense signal from iron-labeled cells.

METHODS

Mesenchymal stem cells (MSCs) were labeled with different concentrations of iron oxide particles and examined for cell viability, proliferation, and differentiation. The SWIFT sequence was optimized to detect and quantify the amount of iron in the muscle tissue after injection of iron oxide solution and iron-labeled MSCs.

RESULTS

The incubation of MSCs with iron oxide and low concentration of poly-L-lysine mixture resulted in an internalization of up to 22 pg of iron per cell with no adverse effect on MSCs. Phantom experiments showed a dependence of SWIFT signal intensity on the excitation flip angle. The hyperintense signal from iron-labeled cells or solutions was detected, and an amount of the iron oxide in the tissue was quantified with the variable flip angle method.

CONCLUSIONS

The SWIFT sequence can produce a quantifiable hyperintense MRI signal from iron-labeled cells. The graft of 18 x 10⁶ cells was detectable for 19 days after injection and the amount of iron was quantifiable. The proposed protocol simplifies the detection and provides a means to quantify cell numbers. Magn Reson Med 78:1900-1910, 2017. © 2017 International Society for Magnetic Resonance in Medicine.

Transient loading of CD34+ hematopoietic progenitor cells with polystyrene nanoparticles

CD34⁺ hematopoietic progenitor cells (HPCs) offer great opportunities to develop new treatments for numerous malignant and non-malignant diseases. Nanoparticle (NP)-based strategies can further enhance this potential, and therefore a thorough understanding of the loading behavior of HPCs towards NPs is essential for a successful application. The present study focusses on the interaction kinetics of 40 nm sized carboxylated polystyrene (PS) NPs with HPCs. Interestingly, a transient association of the NPs with HPCs is observed, reaching a maximum within 1 hour and declining afterwards. This behavior is not seen in dendritic cells (CD34-DCs) differentiated from HPCs, which display a monotonic increase in NP load. We demonstrate that this transient interaction requires an energy-dependent cellular process, suggesting active loading and release of NPs by HPCs. This novel observation offers a unique approach to transiently equip HPCs. A simple theoretical approach modeling the kinetics of NP loading and release is presented, contributing to a framework of describing this phenomenon.

The cellular magnetic response and biocompatibility of biogenic zinc- and cobalt-doped magnetite nanoparticles

The magnetic moment and anisotropy of magnetite nanoparticles can be optimised by doping with transition metal cations, enabling their properties to be tuned for different biomedical applications. In this study, we assessed the suitability of bacterially synthesized zinc- and cobalt-doped magnetite nanoparticles for biomedical applications. To do this we measured cellular viability and activity in primary human bone marrow-derived mesenchymal stem cells and human osteosarcoma-derived cells. Using AC susceptibility we studied doping induced changes in the magnetic response of the nanoparticles both as stable aqueous suspensions and when associated with cells. Our findings show that the magnetic response of the particles was altered after cellular interaction with a reduction in their mobility. In particular, the strongest AC susceptibility signal measured in vitro was from cells containing high-moment zinc-doped particles, whilst no signal was observed in cells containing the high-anisotropy cobalt-doped particles. For both particle types we found that the moderate dopant levels required for optimum magnetic properties did not alter their cytotoxicity or affect osteogenic differentiation of the stem cells. Thus, despite the known cytotoxicity of cobalt and zinc ions, these results suggest that iron oxide nanoparticles can be doped to sufficiently tailor their magnetic properties without compromising cellular biocompatibility.

Tracking stem cells with superparamagnetic iron oxide nanoparticles: perspectives and considerations

Superparamagnetic iron oxide nanoparticles (SPIONs) have been used for diagnoses in biomedical applications, due to their unique properties and their apparent safety for humans. In general, SPIONs do not seem to produce cell damage, although their long-term in vivo effects continue to be investigated. The possibility of efficiently labeling cells with these magnetic nanoparticles has stimulated their use to noninvasively track cells by magnetic resonance imaging after transplantation. SPIONs are attracting increasing attention and are one of the preferred methods for cell labeling and tracking in preclinical and clinical studies. For clinical protocol approval of magnetic-labeled cell tracking, it is essential to expand our knowledge of the time course of SPIONs after cell incorporation and transplantation. This review focuses on the recent advances in tracking SPION-labeled stem cells, analyzing the possibilities and limitations of their use, not only focusing on myocardial infarction but also discussing other models.

Comparison of MSC-Neurogenin1 administration modality in MCAO rat model

Intracerebral (IC) grafting of mesenchymal stem cells (MSCs) is not currently used in humans due to its potential complications. On the other hand, intra-arterial (IA) administration can be facilitated for engrafting of intensifed MSCs in the injured human brain. The study is designed to compare the two methods of MSC administration using IA and IC routes through the parameters of behavior, infarct volume, cell distribution, and MSC identification. An ischemic stroke model was generated in Sprague Dawley male rats. This experiment used MSCs/Ngn1 that express Neurogenin1 (Ngn1) to ensure grafted MSC maintenance. MSCs/Ngn1 or normal saline was administrated via the IC or IA route on day 3. All animals were randomly assigned into four groups (five rats in each group): IC-control, IA-control, IC-MSCs/Ngn1, or IA-MSCs/Ngn1. Motor behaviors, infarct volume, and distribution of superparamagnetic iron oxide (SPIO)-labeled cells on magnetic resonance imaging (MRI) were compared from each group. There were no baseline differencess in motor behaviors or infarct volume between IC-MSCs/Ngn1 and IA-MSCs/Ngn1. Hovever, the IA-MSCs/Ngn1 group showed the greatest recovery on Rotarod testing and adhesive removal tests (p = 0.003 and p = 0.009 vs. IC-MSCs/Ngn1, respectively). The IA-MSCs/Ngn1 group also had more evenly distributed SPIO-labeled cells on MRI. The results suggest that IA administration is likely to be benefcial for humans based on its ability to improve behavioral outcomes and ensure even MSC engrafting.

Quantifications of in vivo labeled stem cells based on measurements of magnetic moments

Cells labeled by super paramagnetic iron-oxide (SPIO) nanoparticles are more easily seen in gradient echo MR images, but it has not been shown that the amount of nanoparticles or the number of cells can be directly quantified from MR images. This work utilizes a previously developed and improved Complex Image Summation around a Spherical or Cylindrical Object (CISSCO) method to quantify the magnetic moments of several clusters of SPIO nanoparticle labeled cells from archived rat brain images. With the knowledge of mass magnetization of the cell labeling agent and cell iron uptake, the number of cells in each nanoparticle cluster can be determined. Using a high pass filter with a reasonable size has little effect on each measured magnetic moment from the CISSCO method. These procedures and quantitative results may help improve the efficacy of cell-based treatments in vivo.

Magnetic resonance imaging and cell-based neurorestorative therapy after brain injury

Restorative cell-based therapies for experimental brain injury, such as stroke and traumatic brain injury, substantially improve functional outcome. We discuss and review state of the art magnetic resonance imaging methodologies and their applications related to cell-based treatment after brain injury. We focus on the potential of magnetic resonance imaging technique and its associated challenges to obtain useful new information related to cell migration, distribution, and quantitation, as well as vascular and neuronal remodeling in response to cell-based therapy after brain injury. The noninvasive nature of imaging might more readily help with translation of cell-based therapy from the laboratory to the clinic.

Labeling Human Melanoma Cells With SPIO: In Vitro Observations

Objectives:

To use the superparamagnetic iron oxide (SPIO) contrast agent Resovist (±transfection agent) to label human melanoma cells and determine its effects on cellular viability, microstructure, iron quantity, and magnetic resonance imaging (MRI) detectability.

Materials and Methods:

Human SK-Mel28 melanoma cells were incubated with Resovist (±liposomal transfection agent DOSPER). The cellular iron content was measured, and labeled cells were examined at 1.5 T and 3.0 T. The intracellular and extracellular distributions of the contrast agent were assessed by light and electron microscopy.

Results:

The incubation of melanoma cells with SPIO does not interfere with cell viability or proliferation. The iron is located both intracellularly and extracellularly as iron clusters associated with the exterior of the cell membrane. Despite thorough washing, the extracellular SPIO remained associated with the cell membrane. The liposomal transfection agent does not change the maximum achievable cellular iron content but promotes a faster iron uptake. The MRI detectability persists for at least 7 days.

Conclusion:

The transfection agent DOSPER facilitates the efficient labeling of human metastatic melanoma cells with Resovist. Our findings raise the possibility that other Resovist-labeled cells may collect associated extracellular nanoparticles. The SPIO may be available to other iron-handling cells and not completely compartmentalized during the labeling procedure.

Specific detection of CD133-positive tumor cells with iron oxide nanoparticles labeling using noninvasive molecular magnetic resonance imaging

Background

The use of ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles to visualize cells has been applied clinically, showing the potential for monitoring cells in vivo with magnetic resonance imaging (MRI). USPIO conjugated with anti-CD133 antibodies (USPIO-CD133 Ab) that recognize the CD133 molecule, a cancer stem cell marker in a variety of cancers, was studied as a novel and potent agent for MRI contrast enhancement of tumor cells.

Materials and methods

Anti-CD133 antibodies were used to conjugate with USPIO via interaction of streptavidin and biotin for in vivo labeling of CD133-positive cells in xenografted tumors and N-ethyl-N-nitrosourea (ENU)-induced brain tumors. The specific binding of USPIO-CD133 Ab to CD133-positive tumor cells was subsequently detected by Prussian blue staining and MRI with T2-weighted, gradient echo and multiple echo recombined gradient echo images. In addition, the cellular toxicity of USPIO-CD133 Ab was determined by analyzing cell proliferation, apoptosis, and reactive oxygen species production.

Results

USPIO-CD133 Ab specifically recognizes in vitro and labels CD133-positive cells, as validated using Prussian blue staining and MRI. The assays of cell proliferation, apoptosis, and reactive oxygen species production showed no significant differences in tumor cells with or without labeling of USPIO-CD133 Ab. In vivo imaging of CD133-positive cells was demonstrated by intravenous injection of USPIO-CD133 Ab in mice with HT29 xenografted tumors. The MRI of HT29 xenografts showed several clusters of hypotensive regions that correlated with CD133 expression and Prussian blue staining for iron. In rat, brain tumors induced by transplacental ENU mutagenesis, several clusters of hypointensive zones were observed in CD133-expressing brain tumors by MRI and intravenously administered USPIO-CD133 Ab.

Conclusion

Combination of USPIO-CD133 Ab and MRI is valuable in recognizing CD133-expressing tumor cells in vitro, extracellularly labeling for cell tracking and detecting CD133-expressing tumors in xenografted tumors as well as ENU-induced rat brain tumors.

Cell Magnetic Targeting System for Repair of Severe Chronic Osteochondral Defect in a Rabbit Model

The aim of this study was to investigate a cell delivery system for repair of severe chronic osteochondral defects using magnetically labeled mesenchymal stem cells (m-MSCs), with the aid of an external magnetic device, through the accumulation of a small number of m-MSCs into a desired area and to detect the suitable number of autologous m-MSCs needed for repair of the defect. Twenty-six male Japanese white rabbits aged 6 months were used. An osteochondral defect was created bilaterally at the weight-bearing surface of the medial femoral condyle of the rabbits' knees (3 mm diameter; 4 mm depth). At 4 weeks after creation of the defect, autogenic transplantation of the m-MSCs into the defect area was performed, followed by 10-min exposure to an external magnetic device, where animals were divided into four groups: high (1 × 10(6) m-MSCs), medium (2 × 10(5) m-MSCs), low (4 × 10(4) m-MSCs), and control (PBS injection). At 4 and 12 weeks posttransplantation of m-MSCs, repaired tissue was assessed histologically using the Fortier score with toluidine blue staining. Transplantation of a low number of m-MSCs was not enough to improve osteogenesis and chondrogenesis, but the medium and high groups improved repair of the chronic defect with chondrogenic tissues and showed histologically significantly better results than the control and low groups. The use of a magnetic targeting system for delivering m-MSCs has the potential to overcome the clinical hurdles for repair of the severe chronic osteochondral defect. Furthermore, this system is predicted to produce good clinical outcomes for humans, not only to repair osteochondral defects but also to repair a variety of damaged tissues.

Quantitative Assessment of Iron-Labeled Stem-Cell Adhesion at the Vessel Wall in a Vascular Flow Model: Correlation of T2*-Weighted Imaging at 3 T and Histology

PURPOSE

To evaluate the distribution of superparamagnetic iron oxide (SPIO)-labeled cells in a perfused segment of a porcine artery and to estimate the number of adherent cells by means of magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Six vessel specimens (diameters between 0.8 and 1.2 cm) were placed in a bioreactor system, and 2 × 10(4) to 1 × 10(6) SPIO-labeled endothelial colony-forming cells were injected into the artery within the perfused reactor. The area of resulting signal extinctions at the inner wall of the vessels was quantified on MR images by using a high-resolution T2*-weighted sequence with a slice-by-slice approach. After imaging, the labeled cells were quantified histologically.

RESULTS

The total iron load of each cell was 56.5 pg ± 14.4. In the applied range of 2 × 10(4) to 1 × 10(6) cells per vessel, the area of iron-induced signal extinction at the vessel wall on T2*-weighted imaging corresponded to the histologically detected cell number (r = 0.98, P < .001).

CONCLUSIONS

A correlation between the area of signal extinction and the number of labeled cells at the vessel wall was found. This might help to evaluate dose rates in further clinical applications of intravascular cell-based therapies.

Effect of Superparamagnetic Iron Oxide Nanoparticles-Labeling on Mouse Embryonic Stem Cells

OBJECTIVE

Superparamagnetic iron oxide nanoparticles (SPIONs) have been used to label mammalian cells and to monitor their fate in vivo using magnetic resonance imaging (MRI). However, the effectiveness of phenotype of labeled cells by SPIONs is still a matter of question. The aim of this study was to investigate the efficiency and biological effects of labeled mouse embryonic stem cells (mESCs) using ferumoxide- protamine sulfate complex.

MATERIALS AND METHODS

In an experimental study, undifferentiated mESCs, C571 line, a generous gift of Stem Cell Technology Company, were cultured on gelatin-coated flasks. The proliferation and viability of SPION-labeled cells were compared with control. ESCs and embryoid bodies (EBs) derived from differentiated hematopoietic stem cells (HSCs) were analyzed for stage-specific cell surface markers using fluorescence-activated cell sorting (FACS).

RESULTS

Our observations showed that SPIONs have no effect on the self-renewal ability of mESCs. Reverse microscopic observations and prussian blue staining revealed 100% of cells were labeled with iron particles. SPION-labeled mESCs did not significantly alter cell viability and proliferation activity. Furthermore, labeling did not alter expression of representative surface phenotypic markers such as stage-specific embryonic antigen 1 (SSEA1) and cluster of differentiation 117 (CD117) on undifferentiated ESC and CD34, CD38 on HSCs, as measured by flowcytometry.

CONCLUSION

According to the results of the present study, SPIONs-labeling method as MRI agents in mESCs has no negative effects on growth, morphology, viability, proliferation and differentiation that can be monitored in vivo, noninvasively. Noninvasive cell tracking methods are considered as new perspectives in cell therapy for clinical use and as an easy method for evaluating the placement of stem cells after transplantation.

Translational applications of molecular imaging in cardiovascular disease and stem cell therapy

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity worldwide. Molecular imaging techniques provide valuable information at cellular and molecular level, as opposed to anatomical and structural layers acquired from traditional imaging modalities. More specifically, molecular imaging employs imaging probes which interact with specific molecular targets and therefore makes it possible to visualize biological processes in vivo. Molecular imaging technology is now progressing towards preclinical and clinical application that gives an integral and comprehensive guidance for the investigation of cardiovascular disease. In addition, cardiac stem cell therapy holds great promise for clinical translation. Undoubtedly, combining stem cell therapy with molecular imaging technology will bring a broad prospect for the study and treatment of cardiac disease. This review will focus on the progresses of molecular imaging strategies in cardiovascular disease and cardiac stem cell therapy. Furthermore, the perspective on the future role of molecular imaging in clinical translation and potential strategies in defining safety and efficacy of cardiac stem cell therapies will be discussed.

Biological characteristics of adipose tissue-derived stem cells labeled with amine-surface-modified superparamagnetic iron oxide nanoparticles

Cell labeling and tracking are becoming increasingly important areas within the field of stem cell transplantation. The ability to track the migration and distribution of implanted cells is critical to understanding the beneficial effects and mechanisms of stem cell therapy. The present study investigated the effects of amine-surface-modified superparamagnetic iron oxide (SPIO) nanoparticles on the biological properties of human adipose tissue-derived stem cells (hADSCs). Monodisperse hydrophobic magnetite (Fe3 O4 ) nanoparticles were prepared using silicon and surface-modified with amine coating. Cell viability, proliferation, differentiation potential, and surface marker expression were evaluated. The magnetic particles (10-18 nm) displayed high labeling efficiency and stability in hADSCs. SPIO-labeled cells produced a hypointense signal and were effectively visualized by MRI for up to 21 days. The results of MTT proliferation assays and flow cytometry analysis demonstrated that SPIOs were biocompatible, viz. the labeling process did not cause cell death or apoptosis and had no side effects on cell proliferation. In vivo experiments showed that the magnetic particles did not affect liver and kidney function. The successful and stable labeling of hADSCs combined with efficient magnetic tropism demonstrates that SPIOs are promising candidates for hADSC tracking in hADSC-based cell therapy applications.

Chronic spinal cord injury treated with transplanted autologous bone marrow-derived mesenchymal stem cells tracked by magnetic resonance imaging: a case report

INTRODUCTION

Intrathecal transplantation is a minimally invasive method for the delivery of stem cells, however, whether the cells migrate from the lumbar to the injured cervical spinal cord has not been proved in humans. We describe an attempt to track bone marrow-derived mesenchymal stem cells in a patient with a chronic cervical spinal cord injury.

CASE PRESENTATION

A 33-year-old Thai man who sustained an incomplete spinal cord injury from the atlanto-axial subluxation was enrolled into a pilot study aiming to track bone marrow-derived mesenchymal stem cells, labeled with superparamagnetic iron oxide nanoparticles, from intrathecal transplantation in chronic cervical spinal cord injury. He had been dependent on respiratory support since 2005. There had been no improvement in his neurological function for the past 54 months. Bone marrow-derived mesenchymal stem cells were retrieved from his iliac crest and repopulated to the target number. One half of the total cells were labeled with superparamagnetic iron oxide nanoparticles before transplantation to the intrathecal space between L4 and L5. Magnetic resonance imaging studies were performed immediately after the transplantation and at 48 hours, two weeks, one month and seven months after the transplantation. His magnetic resonance imaging scan performed immediately after the transplantation showed hyposignal intensity of paramagnetic substance tagged stem cells in the subarachnoid space at the lumbar spine area. This phenomenon was observed at the surface around his cervical spinal cord at 48 hours. A focal hyposignal intensity of tagged bone marrow-derived stem cells was detected at his cervical spinal cord with magnetic resonance imaging at 48 hours, which faded after two weeks, and then disappeared after one month. No clinical improvement of the neurological function had occurred at the end of this study. However, at 48 hours after the transplantation, he presented with a fever, headache, myalgia and worsening of his motor function (by one grade of all key muscles by the American Spinal Injury Association impairment scale), which lasted for 48 hours.

CONCLUSION

Intrathecal injection of bone marrow-derived stem cells at the lumbar spine level could deliver the cells to the injured cervical spinal cord. Transient complications should be observed closely in the first 48 hours after transplantation. Further study should be carried out to evaluate the result of the treatment.

Effect of HSA coated iron oxide labeling on human umbilical cord derived mesenchymal stem cells

Human umbilical cord derived mesenchymal stem cells (hUC-MSCs) are known for self-renewal and differentiation into cells of various lineages like bone, cartilage and fat. They have been used in biomedical applications to treat degenerative disorders. However, to exploit the therapeutic potential of stem cells, there is a requirement of sensitive non-invasive imaging techniques which will offer the ability to track transplanted cells, bio-distribution, proliferation and differentiation. In this study, we have analyzed the efficacy of human serum albumin coated iron oxide nanoparticles (HSA-IONPs) on the differentiation of hUC-MSCs. The colloidal stability of the HSA-IONPs was tested over a long period of time (≥20 months) and the optimized concentration of HSA-IONPs for labeling the stem cells was 60 μg ml(-1). Detailed in vitro assays have been performed to ascertain the effect of the nanoparticles (NPs) on stem cells. Lactate dehydrogenase (LDH) assay showed minimum release of LDH depicting the least disruptions in cellular membrane. At the same time, mitochondrial impairment of the cells was also not observed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry analysis revealed lesser generation of reactive oxygen species in HSA-IONPs labeled hUC-MSCs in comparison to bare and commercial IONPs. Transmission electron microscopy showed endocytic engulfment of the NPs by the hUC-MSCs. During the process, the gross morphologies of the actin cytoskeleton were found to be intact as shown by immunofluorescence microscopy. Also, the engulfment of the HSA-IONPs did not show any detrimental effect on the differentiation potential of the stem cells into adipocytes, osteocytes and chondrocytes, thereby confirming that the inherent properties of stem cells were maintained.

Optimization of the magnetic labeling of human neural stem cells and MRI visualization in the hemiparkinsonian rat brain

BACKGROUND

Magnetic resonance imaging is the ideal modality for non-invasive in vivo cell tracking allowing for longitudinal studies over time. Cells labeled with superparamagnetic iron oxide nanoparticles have been shown to induce sufficient contrast for in vivo magnetic resonance imaging enabling the in vivo analysis of the final location of the transplanted cells. For magnetic nanoparticles to be useful, a high internalization efficiency of the particles is required without compromising cell function, as well as validation of the magnetic nanoparticles behaviour inside the cells.

RESULTS

In this work, we report the development, optimization and validation of an efficient procedure to label human neural stem cells with commercial nanoparticles in the absence of transfection agents. Magnetic nanoparticles used here do not affect cell viability, cell morphology, cell differentiation or cell cycle dynamics. Moreover, human neural stem cells progeny labeled with magnetic nanoparticles are easily and non-invasively detected long time after transplantation in a rat model of Parkinson's disease (up to 5 months post-grafting) by magnetic resonance imaging.

CONCLUSIONS

These findings support the use of commercial MNPs to track cells for short- and mid-term periods after transplantation for studies of brain cell replacement therapy. Nevertheless, long-term MR images should be interpreted with caution due to the possibility that some MNPs may be expelled from the transplanted cells and internalized by host microglial cells.