Superparamagnetic iron oxide nanoparticles as a tool to track mouse neural stem cells in vivo

Noninvasive assessment of a bioconductive patch for treating atrial fibrillation with magnetic resonance imaging

Electrical and structural remodeling disrupt atrial electrical conduction, leading to atrial fibrillation (AF). Epicardially delivered conductive biomaterial patches can effectively transmit electrical signals and potentially diminish AF. However, given the progressive nature of AF development, continuous and noninvasive monitoring is essential for assessing the therapeutic efficacy of these patches over time. In this study, superparamagnetic iron oxide nanoparticles (SPIO NPs) are synthesized and used to label a bio-conductive patch made of poly-3-amino-4-methoxybenzoic acid (PAMB) conjugated to gelatin (PAMBG-NP). Incorporating SPIO NPs does not alter the mechanical, electrical, or biocompatible properties of PAMBG. PAMBG-NP restores conduction velocity, suppresses rotor generation, and prevents re-entry currents, thereby relieving AF burden in an in vitro pacing model. In vivo, a bell-shaped PAMBG-NP patch is applied to the right and left atria of KCNE1 knockout mice. Compared to its Gelatin-NP counterpart, PAMBG-NP significantly reduces AF duration and enhances post-AF recovery over a 60-day period. Furthermore, magnetic resonance imaging indicates that PAMBG-NP degrades more slowly than Gelatin-NP, along with having a reduced incidence of AF in PAMBG-NP-treated animals. Therefore, incorporating SPIO NPs into PAMBG enables real-time, in vivo monitoring, potentially facilitating the noninvasive evaluation of its therapeutic efficacy.

Incorporation of Superparamagnetic Magnetic–Fluorescent Iron Oxide Nanoparticles Increases Proliferation of Human Mesenchymal Stem Cells

Mesenchymal stem cells (MSCs) have significant therapeutic potential and their use requires in-depth studies to better understand their effects. Labeling cells with superparamagnetic iron oxide nanoparticles allows real-time monitoring of their location, migration, and fate post-transplantation. This study aimed to investigate the efficacy and cytotoxicity of magnetic–fluorescent nanoparticles in human adipose tissue-derived mesenchymal stem cells (hADSCs). The efficacy of Molday ION rhodamine B (MIRB) labeling in hADSCs was evaluated and their biocompatibility was assessed using various techniques and differentiation assays. Prussian blue and fluorescence staining confirmed that 100% of the cells were labeled with MIRB and this labeling persisted for at least 3 days. Transmission electron microscopy revealed the internalization and clustering of the nanoparticles on the outer surface of the cell membrane. The viability assay showed increased cell viability 3 days after nanoparticle exposure. Cell counts were higher in the MIRB-treated group compared to the control group at 3 and 5 days and an increased cell proliferation rate was observed at 3 days post-exposure. Adipogenic, osteogenic, and chondrogenic differentiation was successfully achieved in all groups, with MIRB-treated cells showing an enhanced differentiation rate into adipocytes and osteocytes. MIRB was efficiently internalized by hADSCs but induced changes in cellular behavior due to the increased cell proliferation rate.

Intricate relationship between cancer stemness, metastasis, and drug resistance

Cancer stem cells (CSCs) are widely acknowledged as the drivers of tumor initiation, epithelial-mesenchymal transition (EMT) progression, and metastasis. Originating from both hematologic and solid malignancies, CSCs exhibit quiescence, pluripotency, and self-renewal akin to normal stem cells, thus orchestrating tumor heterogeneity and growth. Through a dynamic interplay with the tumor microenvironment (TME) and intricate signaling cascades, CSCs undergo transitions from differentiated cancer cells, culminating in therapy resistance and disease recurrence. This review undertakes an in-depth analysis of the multifaceted mechanisms underlying cancer stemness and CSC-mediated resistance to therapy. Intrinsic factors encompassing the TME, hypoxic conditions, and oxidative stress, alongside extrinsic processes such as drug efflux mechanisms, collectively contribute to therapeutic resistance. An exploration into key signaling pathways, including JAK/STAT, WNT, NOTCH, and HEDGEHOG, sheds light on their pivotal roles in sustaining CSCs phenotypes. Insights gleaned from preclinical and clinical studies hold promise in refining drug discovery efforts and optimizing therapeutic interventions, especially chimeric antigen receptor (CAR)-T cell therapy, cytokine-induced killer (CIK) cell therapy, natural killer (NK) cell-mediated CSC-targeting and others. Ultimately use of cell sorting and single cell sequencing approaches for elucidating the fundamental characteristics and resistance mechanisms inherent in CSCs will enhance our comprehension of CSC and intratumor heterogeneity, which ultimately would inform about tailored and personalized interventions.

Mitigating Nanoparticles-induced Neuronal Damage through a Dual Coating Strategy

Magnetic nanoparticles (MNPs) hold significant potential in biomedical applications, including magnetic resonance imaging, cell labeling, drug/gene delivery, and tumor hyperthermia. Understanding interaction between MNPs and cells is fundamental for advancing these biomedical frontiers. Recent studies have highlighted the potential of MNPs in positively influence neural differentiation and proliferation, indicating their utility as a tool for studying neural growing process in vitro. However, emerging evidence underscores the detrimental effects of MNPs on neural cells in terms of morphological and electrophysiological changes, impeding their broader applications. To mitigate the potential neurotoxicity of MNPs, we proposed a dual-coating strategy using bovine serum albumin with polyethylene glycol (BSA-PEG). This strategy aims to enhance the dispersion ability of MNPs while minimizing their adverse effects on neurons. Through comparative analyses between the proposed modified MNPs with solely PEG-coated MNPs across viability, neuromorphology, and electrophysiology, our study offers a pathway to engineer hypo-toxic MNPs structures, thereby fostering their suitability for long-term culture.

Cellular and Molecular Processes Are Differently Influenced in Primary Neural Cells by Slight Changes in the Physicochemical Properties of Multicore Magnetic Nanoparticles

Herein, we use two exemplary superparamagnetic iron oxide multicore nanoparticles (SPIONs) to illustrate the significant influence of slightly different physicochemical properties on the cellular and molecular processes that define SPION interplay with primary neural cells. Particularly, we have designed two different SPION structures, NFA (i.e., a denser multicore structure accompanied by a slightly less negative surface charge and a higher magnetic response) and NFD (i.e., a larger surface area and more negatively charged), and identified specific biological responses dependent on SPION type, concentration, exposure time, and magnetic actuation. Interestingly, NFA SPIONs display a higher cell uptake, likely driven by their less negative surface and smaller protein corona, more significantly impacting cell viability and complexity. The tight contact of both SPIONs with neural cell membranes results in the significant augmentation of phosphatidylcholine, phosphatidylserine, and sphingomyelin and the reduction of free fatty acids and triacylglycerides for both SPIONs. Nonetheless, NFD induces greater effects on lipids, especially under magnetic actuation, likely indicating a preferential membranal location and/or a tighter interaction with membrane lipids than NFA, in agreement with their lower cell uptake. From a functional perspective, these lipid changes correlate with an increase in plasma membrane fluidity, again larger for more negatively charged nanoparticles (NFD). Finally, the mRNA expression of iron-related genes such as Ireb-2 and Fth-1 remains unaltered, while TfR-1 is only detected in SPION-treated cells. Taken together, these results demonstrate the substantial impact that minor physicochemical differences of nanomaterials may exert in the specific targeting of cellular and molecular processes. A denser multicore structure generated by autoclave-based production is accompanied by a slight difference in surface charge and magnetic properties that become decisive for the biological impact of these SPIONs. Their capacity to markedly modify the lipidic cell content makes them attractive as lipid-targetable nanomedicines.

Cancer Stem Cells and the Tumor Microenvironment: Targeting the Critical Crosstalk through Nanocarrier Systems

The physiological state of the tumor microenvironment (TME) plays a central role in cancer development due to multiple universal features that transcend heterogeneity and niche specifications, like promoting cancer progression and metastasis. As a result of their preponderant involvement in tumor growth and maintenance through several microsystemic alterations, including hypoxia, oxidative stress, and acidosis, TMEs make for ideal targets in both diagnostic and therapeutic ventures. Correspondingly, methodologies to target TMEs have been investigated this past decade as stratagems of significant potential in the genre of focused cancer treatment. Within targeted oncotherapy, nanomedical derivates-nanocarriers (NCs) especially-have emerged to present notable prospects in enhancing targeting specificity. Yet, one major issue in the application of NCs in microenvironmental directed therapy is that TMEs are too broad a spectrum of targeting possibilities for these carriers to be effectively employed. However, cancer stem cells (CSCs) might portend a solution to the above conundrum: aside from being quite heavily invested in tumorigenesis and therapeutic resistance, CSCs also show self-renewal and fluid clonogenic properties that often define specific TME niches. Further scrutiny of the relationship between CSCs and TMEs also points towards mechanisms that underly tumoral characteristics of metastasis, malignancy, and even resistance. This review summarizes recent advances in NC-enabled targeting of CSCs for more holistic strikes against TMEs and discusses both the current challenges that hinder the clinical application of these strategies as well as the avenues that can further CSC-targeting initiatives. Central role of CSCs in regulation of cellular components within the TME.

Tracking Neural Stem Cells in vivo: Achievements and Limitations

Neural stem cell (NSC) therapies are developing rapidly and have been proposed as a treatment option for various neurological diseases, such as stroke, Parkinson's disease and multiple sclerosis. However, monitoring transplanted NSCs, exploring their location and migration, and evaluating their efficacy and safety have all become serious and important issues. Two main problems in tracking NSCs have been noted: labeling them for visibility and imaging them. Direct labeling and reporter gene labeling are the two main methods for labeling stem cells. Magnetic resonance imaging and nuclear imaging, including positron emission tomography, single-photon emission computed tomography, and optical imaging, are the most commonly used imaging techniques. Each has its strengths and weaknesses. Thus, multimodal imaging, which combines two or more imaging methods to complement the advantages and disadvantages of each, has garnered increased attention. Advances in image fusion and nanotechnology, as well as the exploration of new tracers and new imaging modalities have substantially facilitated the development of NSC tracking technology. However, the safety issues related to tracking and long-term tracking of cell viability are still challenges. In this review, we discuss the merits and defects of different labeling and imaging methods, as well as recent advances, challenges and prospects in NSC tracking.

Tetraphenylethylene-conjugated polycation covered iron oxide nanoparticles for magnetic resonance/optical dual-mode imaging

Magnetic resonance (MR)/optical dual-mode imaging with high sensitivity and high tissue resolution have attracted many attentions in biomedical applications. To avert aggregation-caused quenching of conventional fluorescence chromophores, an aggregation-induced emission molecule tetraphenylethylene (TPE)-conjugated amphiphilic polyethylenimine (PEI) covered superparamagnetic iron oxide (Alkyl-PEI-LAC-TPE/SPIO nanocomposites) was prepared as an MR/optical dual-mode probe. Alkyl-PEI-LAC-TPE/SPIO nanocomposites exhibited good fluorescence property and presented higher T ₂ relaxivity (352 Fe mM^-1s^-1) than a commercial contrast agent Feridex (120 Fe mM^-1s^-1) at 1.5 T. The alkylation degree of Alkyl-PEI-LAC-TPE effects the restriction of intramolecular rotation process of TPE. Reducing alkane chain grafting ratio aggravated the stack of TPE, increasing the fluorescence lifetime of Alkyl-PEI-LAC-TPE/SPIO nanocomposites. Alkyl-PEI-LAC-TPE/SPIO nanocomposites can effectively labelled HeLa cells and resulted in high fluorescence intensity and excellent MR imaging sensitivity. As an MR/optical imaging probe, Alkyl-PEI-LAC-TPE/SPIO nanocomposites may be used in biomedical imaging for certain applications.

Prospects of Therapeutic Target and Directions for Ischemic Stroke

Stroke is a serious, adverse neurological event and the third leading cause of death and disability worldwide. Most strokes are caused by a block in cerebral blood flow, resulting in neurological deficits through the death of brain tissue. Recombinant tissue plasminogen activator (rt-PA) is currently the only immediate treatment medication for stroke. The goal of rt-PA administration is to reduce the thrombus and/or embolism via thrombolysis; however, the administration of rt-PA must occur within a very short therapeutic timeframe (3 h to 6 h) after symptom onset. Components of the pathological mechanisms involved in ischemic stroke can be used as potential biomarkers in current treatment. However, none are currently under investigation in clinical trials; thus, further studies investigating biomarkers are needed. After ischemic stroke, microglial cells can be activated and release inflammatory cytokines. These cytokines lead to severe neurotoxicity via the overactivation of microglia in prolonged and lasting insults such as stroke. Thus, the balanced regulation of microglial activation may be necessary for therapy. Stem cell therapy is a promising clinical treatment strategy for ischemic stroke. Stem cells can increase the functional recovery of damaged tissue after post-ischemic stroke through various mechanisms including the secretion of neurotrophic factors, immunomodulation, the stimulation of endogenous neurogenesis, and neovascularization. To investigate the use of stem cell therapy for neurological diseases in preclinical studies, however, it is important to develop imaging technologies that are able to evaluate disease progression and to “chase” (i.e., track or monitor) transplanted stem cells in recipients. Imaging technology development is rapidly advancing, and more sensitive techniques, such as the invasive and non-invasive multimodal techniques, are under development. Here, we summarize the potential risk factors and biomarker treatment strategies, stem cell-based therapy and emerging multimodal imaging techniques in the context of stroke. This current review provides a conceptual framework for considering the therapeutic targets and directions for the treatment of brain dysfunctions, with a particular focus on ischemic stroke.

New Insights into Biocompatible Iron Oxide Nanoparticles: A Potential Booster of Gene Delivery to Stem Cells

Gene delivery to stem cells is a critical issue of stem cells-based therapies, still facing ongoing challenges regarding efficiency and safety. Recent advances in the controlled synthesis of biocompatible magnetic iron oxide nanoparticles (IONPs) have provided a powerful nanotool for assisting gene delivery to stem cells. However, this field is still at an early stage, with well-designed and scalable IONPs synthesis highly desired. Furthermore, the potential risks or bioeffects of IONPs on stem cells are not completely figured out. Therefore, in this review, the updated researches focused on the gene delivery to stem cells using various designed IONPs are highlighted. Additionally, the impacts of the physicochemical properties of IONPs, as well as the magnetofection systems on the gene delivery performance and biocompatibility are summarized. Finally, challenges attributed to the potential impacts of IONPs on the biologic behaviors of stem cells and the large-scale productions of uniform IONPs are emphasized. The principles and challenges summarized in this review provide a general guidance for the rational design of IONPs-assisted gene delivery to stem cells.