Cell-Based Therapy in TBI: Magnetic Retention of Neural Stem Cells In Vivo

Oxidative Stress Kinase Activation and Impaired Insulin Receptor Signaling Precede Overt Alzheimer’s Disease Neuropathology

Background: The cascade of events that lead to Alzheimer’s disease (AD) consists of several possible underlying signal transduction pathways. Apoptosis signal-regulating kinase 1 (ASK1) and insulin receptor (IR) signaling are implicated in AD. Objective: We aimed to determine whether ASK1 activation and IR signaling impairment occurred prior to and during overt AD. Methods: Immunostaining, immunoblotting, and quantitative PCR were used to assess the levels of ASK1 and IR signaling intermediates. Glucose uptake was determined in AD-patient derived inducible pluripotent stem cells (iPSCs). Results: ASK1 signaling was activated in postmortem brain tissues acquired from APOE4 carriers, a causative heritable factor, and in brain tissues of AD subjects in comparison with those harboring the normal APOE3 variant, which was manifested with an increased phosphorylated ASK1 (p-ASK1) and reduced thioredoxin 1 (TRX1). ASK1 downstream signaling effectors were also significantly elevated in these APOE4 carriers and AD brain tissues. Increased insulin receptor substrate 1 (IRS1) phosphorylation at serine residues, and decreased p-AKT1, p-IRβ, and GLUT3 expression were present in all APOE4 carriers and AD samples, suggesting impaired IR signaling leading to insulin resistance. ASK1 activation, IR signaling impairment, and GLUT3 reduction were also present in young AD transgenic mice prior to AD syndromes, AD mice at AD neuropathology onset, and AD iPSCs and their derived neurons prior to p-Tau aggregation. Conclusion: We conclude that the activation of oxidative stress-responsive kinases and reduced IR signaling precede and are persistent in AD pathogenesis. Our data further suggest possible crosstalk between ASK1 signaling and insulin resistance in AD etiology.

Insulin-incubated palladium clusters promote recovery after brain injury

Traumatic brain injury (TBI) is a cause of disability and death worldwide, but there are currently no specific treatments for this condition. Release of excess reactive oxygen species (ROS) in the injured brain leads to a series of pathological changes; thus, eliminating ROS could be a potential therapeutic strategy. Herein, we synthesized insulin-incubated ultrasmall palladium (Pd@insulin) clusters via green biomimetic chemistry. The Pd@insulin clusters, which were 3.2 nm in diameter, exhibited marked multiple ROS-scavenging ability testified by the theoretical calculation. Pd@insulin could be rapidly excreted via kidney-urine metabolism and induce negligible adverse effects after a long-time treatment in vivo. In a TBI mouse model, intravenously injected Pd@insulin clusters aggregated in the injured cortex, effectively suppressed excessive ROS production, and significantly rescued motor function, cognition and spatial memory. We found that the positive therapeutic effects of the Pd@insulin clusters were mainly attributed to their ROS-scavenging ability, as they inhibited excessive neuroinflammation, reduced cell apoptosis, and prevented neuronal loss. Therefore, the ability of Pd@insulin clusters to effectively eliminate ROS, as well as their simple structure, easy synthesis, low toxicity, and rapid metabolism may facilitate their clinical translation for TBI treatment.

Nanotechnology-Assisted Cell Tracking

The usefulness of nanoparticles (NPs) in the diagnostic and/or therapeutic sector is derived from their aptitude for navigating intra- and extracellular barriers successfully and to be spatiotemporally targeted. In this context, the optimization of NP delivery platforms is technologically related to the exploitation of the mechanisms involved in the NP–cell interaction. This review provides a detailed overview of the available technologies focusing on cell–NP interaction/detection by describing their applications in the fields of cancer and regenerative medicine. Specifically, a literature survey has been performed to analyze the key nanocarrier-impacting elements, such as NP typology and functionalization, the ability to tune cell interaction mechanisms under in vitro and in vivo conditions by framing, and at the same time, the imaging devices supporting NP delivery assessment, and consideration of their specificity and sensitivity. Although the large amount of literature information on the designs and applications of cell membrane-coated NPs has reached the extent at which it could be considered a mature branch of nanomedicine ready to be translated to the clinic, the technology applied to the biomimetic functionalization strategy of the design of NPs for directing cell labelling and intracellular retention appears less advanced. These approaches, if properly scaled up, will present diverse biomedical applications and make a positive impact on human health.

Recent advances in stem cell therapy for neurodegenerative disease: Three dimensional tracing and its emerging use

Neurodegenerative disease is a brain disorder caused by the loss of structure and function of neurons that lowers the quality of human life. Apart from the limited potential for endogenous regeneration, stem cell-based therapies hold considerable promise for maintaining homeostatic tissue regeneration and enhancing plasticity. Despite many studies, there remains insufficient evidence for stem cell tracing and its correlation with endogenous neural cells in brain tissue with three-dimensional structures. Recent advancements in tissue optical clearing techniques have been developed to overcome the existing shortcomings of cross-sectional tissue analysis in thick and complex tissues. This review focuses on recent progress of stem cell treatments to improve neurodegenerative disease, and introduces tissue optical clearing techniques that can implement a three-dimensional image as a proof of concept. This review provides a more comprehensive understanding of stem cell tracing that will play an important role in evaluating therapeutic efficacy and cellular interrelationship for regeneration in neurodegenerative diseases.

Intravenous SPION-labeled adipocyte-derived stem cells targeted to the brain by magnetic attraction in a rat stroke model: An ultrastructural insight into cell fate within the brain

Mesenchymal stem cell therapy after stroke is a promising option investigated in animal models and clinical trials. The intravenous route is commonly used in clinical settings guaranteeing an adequate safety profile although low yields of engraftment. In this report, rats subjected to ischemic stroke were injected with adipose-derived stem cells (ADSCs) labeled with superparamagnetic iron oxide nanoparticles (SPIONs) applying an external magnetic field in the skull to retain the cells. Although most published studies demonstrate viability of ADSCs, only a few have used ultrastructural techniques. In our study, the application of a local magnetic force resulted in a tendency for higher yields of SPION-ADSCs targeting the brain. However, grafted cells displayed morphological signs of death, one day after administration, and correlative microscopy showed active microglia and astrocytes associated in the process of scavenging. Thus, we conclude that, although successfully targeted within the brain, SPION-ADSCs viability was rapidly compromised.

Biodistribution of poly clustered superparamagnetic iron oxide nanoparticle labeled mesenchymal stem cells in aminoglycoside induced ototoxic mouse model

Recently, application of stem cell therapy in regenerative medicine has become an active field of study. Mesenchymal stem cells (MSCs) are known to have a strong ability for homing. MSCs labeled with superparamagnetic iron oxide nanoparticles (SPIONs) exhibit enhanced homing due to magnetic attraction. We have designed a SPION that has a cluster core of iron oxide-based nanoparticles coated with PLGA-Cy5.5. We optimized the nanoparticles for internalization to enable the transport of PCS nanoparticles through endocytosis into MSCs. The migration of magnetized MSCs with SPION by static magnets was seen in vitro. The auditory hair cells do not regenerate once damaged, ototoxic mouse model was generated by administration of kanamycin and furosemide. SPION labeled MSC's were administered through different injection routes in the ototoxic animal model. As result, the intratympanic administration group with magnet had the highest number of cells in the brain followed by the liver, cochlea, and kidney as compared to those in the control groups. The synthesized PCS (poly clustered superparamagnetic iron oxide) nanoparticles, together with MSCs, by magnetic attraction, could synergistically enhance stem cell delivery. The poly clustered superparamagnetic iron oxide nanoparticle labeled in the mesenchymal stem cells have increased the efficacy of homing of the MSC's to the target area by synergetic effect of magnetic attraction and chemotaxis (SDF-1/CXCR4 axis). This technique allows delivery of the stem cells to the areas with limited vasculatures. The nanoparticle in the biomedicine allows drug delivery, thus, the combination of nanomedicince together with the regenerative medicine will provide highly effective therapy.

Artesunate attenuates traumatic brain injury-induced impairments in rats

Background

Blood–brain barrier (BBB) dysfunction and neuroinflammation induced by traumatic brain injuries (TBIs) cause a succession of secondary brain damage events and finally lead to a massive and progressive cerebral neuronal destruction. Artesunate, a semisynthetic artemisinin derivative, is a potential candidate for the management of cerebral damage induced by TBI due to its protective function to BBB and cerebral neurons.

Methods

To demonstrate the effect of artesunate to TBI-induced BBB dysfunction and neural damage, TBI rat model was constructed by cortical impact injury. Behavioral experiments were used to estimate the impact of the combined treatment on rats. Western blotting was performed to demonstrate the protein levels in the brain tissues of rats. Quantitative real-time PCRs were utilized to investigate the alteration in the expression of various RNA levels. The chemokine levels were estimated by ELISA.

Results

Artesunate treatment attenuated the impact caused by TBI on rat brain and improved the long-term neurological recover. Artesunate treatment protected the integrity of BBB and inhibited neuroinflammation. Artesunate treatment promoted the phosphorylation of Akt and inhibited the phosphorylation of glycogen synthase kinase (GSK)-3β in TBI rat model.

Conclusion

Artesunate protected rats from TBI-induced impairments of BBB and improved longer-term neurological outcomes.

Optimizing Stem Cell Therapy after Ischemic Brain Injury

Stem cells have been used for regenerative and therapeutic purposes in a variety of diseases. In ischemic brain injury, preclinical studies have been promising, but have failed to translate results to clinical trials. We aimed to explore the application of stem cells after ischemic brain injury by focusing on topics such as delivery routes, regeneration efficacy, adverse effects, and in vivo potential optimization. PUBMED and Web of Science were searched for the latest studies examining stem cell therapy applications in ischemic brain injury, particularly after stroke or cardiac arrest, with a focus on studies addressing delivery optimization, stem cell type comparison, or translational aspects. Other studies providing further understanding or potential contributions to ischemic brain injury treatment were also included. Multiple stem cell types have been investigated in ischemic brain injury treatment, with a strong literature base in the treatment of stroke. Studies have suggested that stem cell administration after ischemic brain injury exerts paracrine effects via growth factor release, blood-brain barrier integrity protection, and allows for exosome release for ischemic injury mitigation. To date, limited studies have investigated these therapeutic mechanisms in the setting of cardiac arrest or therapeutic hypothermia. Several delivery modalities are available, each with limitations regarding invasiveness and safety outcomes. Intranasal delivery presents a potentially improved mechanism, and hypoxic conditioning offers a potential stem cell therapy optimization strategy for ischemic brain injury. The use of stem cells to treat ischemic brain injury in clinical trials is in its early phase; however, increasing preclinical evidence suggests that stem cells can contribute to the down-regulation of inflammatory phenotypes and regeneration following injury. The safety and the tolerability profile of stem cells have been confirmed, and their potent therapeutic effects make them powerful therapeutic agents for ischemic brain injury patients.

Anti-Inflammatory Effects of Magnetically Targeted Mesenchymal Stem Cells on Laser-Induced Skin Injuries in Rats

Introduction

Mesenchymal stem cells (MSCs) are a promising resource for tissue regeneration and repair. However, their clinical application is hindered by technical limitations related to MSC enrichment at the target sites.

Methods

MSCs were labeled with magnetic Fe₃O₄ nanoparticles (NPs). We analyzed the effects of NP on cell proliferation, stem cell characteristics, and cytokine secretion. Furthermore, we induced NP-labeled MSC migration with an external magnetic field toward laser-induced skin wounds in rats and evaluated the associated anti-inflammatory effects.

Results

Fe₃O₄ NP application did not adversely affect MSC characteristics. Moreover, Fe₃O₄ NP-labeled MSCs presented increased anti-inflammatory cytokine and chemokine production compared with unlabeled MSCs. Furthermore, MSCs accumulated at the injury site and magnetic targeting promoted NP-labeled MSC migration toward burn injury sites in vivo. On day 7 following MSC injection, reduced inflammation and promoted angiogenesis were observed in the magnetically targeted MSC group. In addition, anti-inflammatory factors were upregulated, whereas pro-inflammatory factors were downregulated within the magnetically targeted MSC group compared with those in the PBS group.

Conclusion

This study demonstrates that magnetically targeted MSCs contribute to cell migration to the site of skin injury, improve anti-inflammatory effects and enhance angiogenesis compared with MSC injection alone. Therefore, magnetically targeted MSC therapy may be an effective treatment approach for epithelial tissue injuries.

Endocytic trafficking of polymeric clustered superparamagnetic iron oxide nanoparticles in mesenchymal stem cells

The technology of directing nanoparticles to specific locations in the body continues to be an area of great interest in a myriad of research fields. In the present study, we have developed nanoparticles and a method that allows the nanoparticles to move to specific sites by simultaneously utilizing the homing ability and magnetism of stem cells. Polymeric clustered SPIO (PCS) nanoparticles are composed of a superparamagnetic iron oxide nanoparticle (SPION) cluster core coated with poly lactic-co-glycolic acid (PLGA) and labeled with the fluorescent dye Cy5.5 for tracking. PCS is designed to be internalized by stem cells via endocytosis and then moved to the desired subcellular location through magnetism. Here, we investigated the interactions between SPIONs and mesenchymal stem cells (MSCs), including their absorption mechanism and subcellular localization. Exposure to the nanoparticles at 40 μg/mL for over 96 h did not affect cell survival or differentiation. We used a variety of endocytosis inhibitors and identified the potential cellular internalization pathway of SPIONs to be clathrin-mediated endocytosis. Antibodies to organelles were used to accumulate lysosomes through early and late endosomes. PCS at 40 μg/mL was internalized and stored without significant deleterious effects on stem cells, indicating that MSCs can act as an effective nanoparticle carrier. These findings also demonstrate the successful localization of the novel particles using magnetic attraction.

Amniotic membrane mesenchymal stem cells labeled by iron oxide nanoparticles exert cardioprotective effects against isoproterenol (ISO)-induced myocardial damage by targeting inflammatory MAPK/NF-κB pathway

The aim of the present study is to investigate the protective effects of human amniotic membrane-derived mesenchymal stem cells (hAMSCs) labeled by superparamagnetic iron oxide nanoparticles (SPIONs) against isoproterenol (ISO)-induced myocardial injury in the presence and absence of a magnetic field. ISO was injected subcutaneously for 4 consecutive days to induce myocardial injury in male Wistar rats. The hAMSCs were incubated with 100 μg/ml SPIONs and injected to rats in magnet-dependent and magnet-independent groups via the tail vein. The size and shape of nanoparticles were determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Prussian blue staining was used to determine cell uptake of nanoparticles. Myocardial fibrosis, heart function, characterization of hAMSCs, and histopathological changes were determined using Masson's trichrome, echocardiography, flow cytometry, and H&E staining, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to the expression pro-inflammatory cytokines. Immunohistochemistry assay was used to determine the expression of nuclear factor-κB (NF-κB) and the Ras/mitogen-activated protein kinase (MAPK). SPION-labeled MSCs in the presence of magnetic field significantly improved cardiac function and reduced fibrosis and tissue damage by suppressing inflammation in a NF-κB/MAPK-dependent mechanism (p < 0. 05). Collectively, our findings demonstrate that SPION-labeled MSCs in the presence of magnetic field can be a good treatment option to reduce inflammation following myocardial injury. Graphical abstract.

Homing of Super Paramagnetic Iron Oxide Nanoparticles (SPIONs) Labeled Adipose-Derived Stem Cells by Magnetic Attraction in a Rat Model of Parkinson's Disease

Introduction

Stem cell therapies for neurodegenerative diseases such as Parkinson’s disease (PD) are intended to replace lost dopaminergic neurons. The basis of this treatment is to guide the migration of transplanted cells into the target tissue or injury site. The aim of this study is an evaluation of the homing of superparamagnetic iron oxide nanoparticles (SPIONs) labeled adipose-derived stem cells (ADSC) by an external magnetic field in a rat model of PD.

Methods

ADSCs were obtained from perinephric regions of male adult rats and cultured in a DMEM medium. ADSC markers were assessed by immunostaining with CD90, CD105, CD49d, and CD45. The SPION was coated using poly-L-lysine hydrobromide and transfection was determined in rat ADSC using the GFP reporter gene. For this in vivo study, rats with PD were divided into five groups: a positive control group, a control group with PD (lesion with 6-HD injection), and three treatment groups: the PD/ADSC group (PD transplant with ADSCs transfected by BrdU), PD/ADSC/SPION group (PD transplant with ADSCs labeled with SPION and transfected by GFP), and the PD/ADSC/SPION/EM group (PD transplant with ADSCs labeled with SPION and transfected by GFP induced with external magnet).

Results

ADSCs were immunoreactive to fat markers CD90 (90.73±1.7), CD105 (87.4±2.9) and CD49d (79.6±2.6), with negative immunostaining at the hematopoietic stem cell marker (CD45: 1.4±0.4). The efficiency of cells with SPION/PLL was about 96% of ADSC. The highest number of GFP-positive cells was in the ADSC/SPION/EM group (54.5±1.3), which was significantly different from that in ADSC/SPION group (30.83±3 and P<0.01).

Conclusion

Transfection of ADSC by SPION/PLL is an appropriate protocol for cell therapy. External magnets can be used for the delivery and homing of transplanted stem cells in the target tissue.

Breaking Barriers: Bioinspired Strategies for Targeted Neuronal Delivery to the Central Nervous System

Central nervous system (CNS) disorders encompass a vast spectrum of pathological conditions and represent a growing concern worldwide. Despite the high social and clinical interest in trying to solve these pathologies, there are many challenges to bridge in order to achieve an effective therapy. One of the main obstacles to advancements in this field that has hampered many of the therapeutic strategies proposed to date is the presence of the CNS barriers that restrict the access to the brain. However, adequate brain biodistribution and neuronal cells specific accumulation in the targeted site also represent major hurdles to the attainment of a successful CNS treatment. Over the last few years, nanotechnology has taken a step forward towards the development of therapeutics in neurologic diseases and different approaches have been developed to surpass these obstacles. The versatility of the designed nanocarriers in terms of physical and chemical properties, and the possibility to functionalize them with specific moieties, have resulted in improved neurotargeted delivery profiles. With the concomitant progress in biology research, many of these strategies have been inspired by nature and have taken advantage of physiological processes to achieve brain delivery. Here, the different nanosystems and targeting moieties used to achieve a neuronal delivery reported in the open literature are comprehensively reviewed and critically discussed, with emphasis on the most recent bioinspired advances in the field. Finally, we express our view on the paramount challenges in targeted neuronal delivery that need to be overcome for these promising therapeutics to move from the bench to the bedside.

Strategies to enhance efficacy of SPION-labeled stem cell homing by magnetic attraction: a systemic review with meta-analysis

Stem cells possess a promising potential in the clinical field. The application and effective delivery of stem cells to the desired target organ or site of injury plays an important role. This review describes strategies on understanding the effective delivery of stem cells labeled with superparamagnetic iron oxide nanoparticles (SPION) using an external magnet to enhance stem cell migration in vivo and in vitro. Fourteen total publications among 174 articles were selected. Stem cell type, SPION characteristics, labeling time, and magnetic force in vivo are considered important factors affecting the effective delivery of stem cells to the homing site. Most papers reported that the efficiency was increased when magnet is applied compared to those without. Ten studies analyzed the homing competency of SPION-labeled MSCs in vitro by observing the migration of the cell toward the external magnet. In cell-based experiments, the mechanism of magnetic attraction, the kind of nanoparticles, and various stem cells were studied well. Meta-analysis has shown the mean size of nanoparticles and degree of recovery or regeneration of damaged target organs upon in vivo studies. This strategy may provide a guideline for designing studies involving stem cell homing and further expand stem cell.

Magnetically Assisted Control of Stem Cells Applied in 2D, 3D and In Situ Models of Cell Migration

The success of cell therapy approaches is greatly dependent on the ability to precisely deliver and monitor transplanted stem cell grafts at treated sites. Iron oxide particles, traditionally used in vivo for magnetic resonance imaging (MRI), have been shown to also represent a safe and efficient in vitro labelling agent for mesenchymal stem cells (MSCs). Here, stem cells were labelled with magnetic particles, and their resulting response to magnetic forces was studied using 2D and 3D models. Labelled cells exhibited magnetic responsiveness, which promoted localised retention and patterned cell seeding when exposed to magnet arrangements in vitro. Directed migration was observed in 2D culture when adherent cells were exposed to a magnetic field, and also when cells were seeded into a 3D gel. Finally, a model of cell injection into the rodent leg was used to test the enhanced localised retention of labelled stem cells when applying magnetic forces, using whole body imaging to confirm the potential use of magnetic particles in strategies seeking to better control cell distribution for in vivo cell delivery.

Iron oxide nanoparticles promote the migration of mesenchymal stem cells to injury sites

Background

Developing new methods to deliver cells to the injured tissue is a critical factor in translating cell therapeutics research into clinical use; therefore, there is a need for improved cell homing capabilities.

Materials and methods

In this study, we demonstrated the effects of labeling rat bone marrow-derived mesenchymal stem cells (MSCs) with fabricated polydopamine (PDA)-capped Fe₃O₄ (Fe₃O₄@PDA) superparticles employing preassembled Fe₃O₄ nanoparticles as the cores.

Results

We found that the Fe₃O₄@PDA composite superparticles exhibited no adverse effects on MSC characteristics. Moreover, iron oxide nanoparticles increased the number of MSCs in the S-phase, their proliferation index and migration ability, and their secretion of vascular endothelial growth factor relative to unlabeled MSCs. Interestingly, nanoparticles not only promoted the expression of C-X-C chemokine receptor 4 but also increased the expression of the migration-related proteins c-Met and C-C motif chemokine receptor 1, which has not been reported previously. Furthermore, the MSC-loaded nanoparticles exhibited improved homing and anti-inflammatory abilities in the absence of external magnetic fields in vivo.

Conclusion

These results indicated that iron oxide nanoparticles rendered MSCs more favorable for use in injury treatment with no negative effects on MSC properties, suggesting their potential clinical efficacy.

MRI Tracking of iPS Cells-Induced Neural Stem Cells in Traumatic Brain Injury Rats

Induced pluripotent stem cells (iPS cells) are promising cell source for stem cell replacement strategy applied to brain injury caused by traumatic brain injury (TBI) or stroke. Neural stem cell (NSCs) derived from iPS cells could aid the reconstruction of brain tissue and the restoration of brain function. However, tracing the fate of iPS cells in the host brain is still a challenge. In our study, iPS cells were derived from skin fibroblasts using the four classic factors Oct4, Sox2, Myc, and Klf4. These iPS cells were then induced to differentiate into NSCs, which were incubated with superparamagnetic iron oxides (SPIOs) in vitro. Next, 30 TBI rat models were prepared and divided into three groups (n = 10). One week after brain injury, group A&B rats received implantation of NSCs (labeled with SPIOs), while group C rats received implantation of non-labeled NSCs. After cell implantation, all rats underwent T2*-weighted magnetic resonance imaging (MRI) scan at day 1, and 1 week to 4 weeks, to track the distribution of NSCs in rats' brains. One month after cell implantation, manganese-enhanced MRI (ME-MRI) scan was performed for all rats. In group B, diltiazem was infused during the ME-MRI scan period. We found that (1) iPS cells were successfully derived from skin fibroblasts using the four classic factors Oct4, Sox2, Myc, and Klf4, expressing typical antigens including SSEA4, Oct4, Sox2, and Nanog; (2) iPS cells were induced to differentiate into NSCs, which could express Nestin and differentiate into neural cells and glial cells; (3) NSCs were incubated with SPIOs overnight, and Prussian blue staining showed intracellular particles; (4) after cell implantation, T2*-weighted MRI scan showed these implanted NSCs could migrate to the injury area in chronological order; (5) the subsequent ME-MRI scan detected NSCs function, which could be blocked by diltiazem. In conclusion, using an in vivo MRI tracking technique to trace the fate of iPS cells-induced NSCs in host brain is feasible.

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

Cell transplantation offers a promising approach in many neurological disorders. Neural stem (NS) cells are potential candidates for cell therapy. The ability to track the grafted cells in the host tissue will refine this therapy. Superparamagnetic iron oxide nanoparticles (SPION) have been suggested as a feasible method, but there is no consensus about its safety. Here we investigated the feasibility of label NS cells with SPION and track by MRI after transplantation into mouse striatum with SPION cells and its therapeutic effects by grafting the cells into mouse striatum. We demonstrated that SPION-labeled NS cells display normal patterns of cellular processes including proliferation, migration, differentiation and neurosphere formation. Transmission electron microscopy reveals SPION in the cytoplasm of the cells, which was confirmed by microanalysis. Neurons and astrocytes generated from SPION-labeled NS cells were able to carry nanoparticles after 7 days under differentiation. SPION-labeled NS cells transplanted into striatum of mice were detected by magnetic resonance imaging (MRI) and microscopy 51 days later. In agreement with others reports, we demonstrated that NS cells are able to incorporate SPION in vitro without altering the stemness, and can survive and be tracked by MRI after they have been grafted into mice striatum.

Microarray Expression Profile of lncRNAs and mRNAs in Rats with Traumatic Brain Injury after A2B5+ Cell Transplantation

Traumatic brain injury (TBI) may cause neurological damage, but an effective therapy and the associated mechanisms of action have not yet been elucidated. A TBI model was established using the modified Feeney method. A2B5+ cells, an oligodendroglial progenitor, were acquired from induced pluripotent stem cells (iPSCs) by mouse embryonic fibroblasts and were transplanted into the injured site. The neurological severity score (NSS) was recorded on 3 d, 7 d, 11 d, 15 d, and 19 d. Seven days after transplantation, oligodendrocytes 2 (Olig2) and myelin basic protein (MBP) were detected by immunohistochemistry (IHC) and Western blot (WB), and long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) were screened by microarray technology. Moreover, we took an intersection of the differentially expressed lncRNAs or mRNAs and scanned 10 kb upstream and downstream of the common lncRNAs. Meanwhile, Gene Ontology (GO) and pathway analysis on mRNAs was performed in the A2B5+ iPSC group. A2B5+ iPSCs survived and migrated around the injury site and differentiated into oligodendrocytes. Meanwhile, the increase in Olig2 and MBP were higher in A2B5+ cell-engrafted rats than that in TBI rats. However, the NSSs in the A2B5+ iPSC group were lower than that in the TBI group. Between the TBI and sham groups, 270 lncRNAs and 1,052 mRNAs were differently expressed (P < 0.05, fold change (FC) > 2), while between the A2B5+ iPSC and TBI groups, 83 lncRNAs and 360 mRNAs were differently expressed (P < 0.05, FC > 2). Meanwhile, 37 lncRNAs and 195 mRNAs were simultaneously changed in the 2 parts. Using bioinformatic analysis, we found the crucial lncRNA and mRNA were ENSRNOT00000052577 and Kif2c in the TBI brain with cell transplantation. This study demonstrated that A2B5+ iPSC grafts effectively improved neurological function, and the mechanism of action was associated with lncRNA and mRNA expression. Therefore, A2B5+ iPSC transplantation could be considered as a new method for the treatment of TBI, and ENSRNOT00000052577 and Kif2c may be new molecular targets or markers for functional improvement.

Magnetic Enhancement of Stem Cell-Targeted Delivery into the Brain Following MR-Guided Focused Ultrasound for Opening the Blood-Brain Barrier

Focused ultrasound (FUS)-mediated blood–brain barrier disruption (BBBD) can enable even large therapeutics such as stem cells to enter the brain from the bloodstream. However, the efficiency is relatively low. Our previous study showed that human neural progenitor cells (hNPCs) loaded with superparamagnetic iron oxide nanoparticles (SPIONs) in culture were attracted by an external magnetic field. In vivo, enhanced brain retention was observed near a magnet mounted on the skull in a rat model of traumatic brain injury, where BBBD also occurs. The goal of the current study was to determine whether magnetic attraction of SPION-loaded hNPCs would also enhance their retention in the brain after FUS-mediated BBBD. A small animal magnetic resonance imaging (MRI)-guided FUS system operating at 1.5 MHz was used to treat rats (∼120 g) without tissue damage or hemorrhage. Evidence of successful BBBD was validated with both radiologic enhancement of gadolinium on postsonication TI MRI and whole brain section visualization of Evans blue dye. The procedure was then combined with the application of a powerful magnet to the head directly after intravenous injection of the hNPCs. Validation of cells within the brain was performed by staining with Perls’ Prussian blue for iron and by immunohistochemistry with a human-specific antigen. By injecting equal numbers of iron oxide (SPIONs) and noniron oxide nanoparticles–loaded hNPCs, each labeled with a different fluorophore, we found significantly greater numbers of SPIONs-loaded cells retained in the brain at the site of BBBD as compared to noniron loaded cells. This result was most pronounced in regions of the brain closest to the skull (dorsal cortex) in proximity to the magnet surface. A more powerful magnet and a Halbach magnetic array resulted in more effective retention of SPION-labeled cells in even deeper brain regions such as the striatum and ventral cortex. There, up to 90% of hNPCs observed contained SPIONs compared to 60% to 70% with the less powerful magnet. Fewer cells were observed at 24 h posttreatment compared to 2 h (primarily in the dorsal cortex). These results demonstrate that magnetic attraction can substantially enhance the retention of stem cells after FUS-mediated BBBD. This procedure could provide a safer and less invasive approach for delivering stem cells to the brain, compared to direct intracranial injections, substantially reducing the risk of bleeding and infection.

Enhanced Homing Technique of Mesenchymal Stem Cells Using Iron Oxide Nanoparticles by Magnetic Attraction in Olfactory-Injured Mouse Models

Intranasal delivery of mesenchymal stem cells (MSCs) to the olfactory bulb is a promising approach for treating olfactory injury. Additionally, using the homing phenomenon of MSCs may be clinically applicable for developing therapeutic cell carriers. Herein, using superparamagnetic iron oxide nanoparticles (SPIONs) and a permanent magnet, we demonstrated an enhanced homing effect in an olfactory model. Superparamagnetic iron oxide nanoparticles with rhodamine B (IRBs) had a diameter of 5.22 ± 0.9 nm and ζ-potential of +15.2 ± 0.3 mV. IRB concentration of 15 µg/mL was injected with SPIONs into MSCs, as cell viability significantly decreased when 20 μg/mL was used (p ≤ 0.005) compared to in controls. The cells exhibited magnetic attraction in vitro. SPIONs also stimulated CXCR4 (C-X-C chemokine receptor type 4) expression and CXCR4-SDF-1 (Stromal cell-derived factor 1) signaling in MSCs. After injecting magnetized MSCs, these cells were detected in the damaged olfactory bulb one week after injury on one side, and there was a significant increase compared to when non-magnetized MSCs were injected. Our results suggest that SPIONs-labeled MSCs migrated to injured olfactory tissue through guidance with a permanent magnet, resulting in better homing effects of MSCs in vivo, and that iron oxide nanoparticles can be used for internalization, various biological applications, and regenerative studies.

Treatment of Movement Disorders With Focused Ultrasound

Although the use of ultrasound as a potential therapeutic modality in the brain has been under study for several decades, relatively few neuroscientists or neurologists are familiar with this technology. Stereotactic brain lesioning had been widely used as a treatment for medically refractory patients with essential tremor (ET), Parkinson disease (PD), and dystonia but has been largely replaced by deep brain stimulation (DBS) surgery, with advantages both in safety and efficacy. However, DBS is associated with complications including intracerebral hemorrhage, infection, and hardware malfunction. The occurrence of these complications has spurred interest in less invasive stereotactic brain lesioning methods including magnetic resonance imaging–guided high intensity–focused ultrasound (FUS) surgery. Engineering advances now allow sound waves to be targeted noninvasively through the skull to a brain target. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull, recent Food and Drug Administration approval of unilateral thalamotomy for treatment of ET. Clinical studies of stereotactic FUS for aspects of PD are underway. Moderate intensity, pulsed FUS has also demonstrated the potential to safely open the blood-brain barrier for localized delivery of therapeutics including proteins, genes, and cell-based therapy for PD and related disorders. The goal of this review is to provide basic and clinical neuroscientists with a level of understanding to interact with medical physicists, biomedical engineers, and radiologists to accelerate the application of this powerful technology to brain disease

Focused Ultrasound: An Emerging Therapeutic Modality for Neurologic Disease

Therapeutic ultrasound is only beginning to be applied to neurologic conditions, but the potential of this modality for a wide spectrum of brain applications is high. Engineering advances now allow sound waves to be targeted through the skull to a brain region selected with real time magnetic resonance imaging and thermography, using a commercial array of focused emitters. High intensities of sonic energy can create a coagulation lesion similar to that of older radiofrequency stereotactic methods, but without opening the skull. This has led to the recent Food and Drug Administration approval of focused ultrasound (FUS) thalamotomy for unilateral treatment of essential tremor. Clinical studies of stereotactic FUS for aspects of Parkinson's disease, chronic pain, and refractory psychiatric indications are underway, with promising results. Moderate-intensity FUS has the potential to safely open the blood-brain barrier for localized delivery of therapeutics, while low levels of sonic energy can be used as a form of neuromodulation.

In Vivo Assessment of Stem Cells for Treating Neurodegenerative Disease: Current Approaches and Future Prospects

In recent years, stem cell-related therapies have been widely applied for treating neurodegenerative disease. Despite their potential, stem cell tracking and imaging techniques for the evaluation of in vivo proof-of-concept (PoC) therapies have not been sufficiently represented in the research area. This review summarizes the recent approaches that have been used for tracking and imaging engrafted stem cells in vivo. Furthermore, we introduce tissue clearing technology that can be applied to develop three-dimensional in vivo experiments. Monitoring stem cell survival and migration and graft-host relationships is a useful strategy to evaluate the therapeutic efficacy of regenerative medicine approaches in neurodegenerative disease.

Exosome-like silica nanoparticles: a novel ultrasound contrast agent for stem cell imaging

Ultrasound is critical in many areas of medicine including obstetrics, oncology, and cardiology with emerging applications in regenerative medicine. However, one critical limitation of ultrasound is the low contrast of target tissue over background. Here, we describe a novel cup-shaped silica nanoparticle that is reminiscent of exosomes and that has significant ultrasound impedance mismatch for labelling stem cells for regenerative medicine imaging. These exosome-like silica nanoparticles (ELS) were created through emulsion templating and the silica precursors bis(triethoxysilyl)ethane (BTSE) and bis(3-trimethoxysilyl-propyl)amine (TSPA). We found that 40% TSPA resulted in the exosome like-morphology and a positive charge suitable for labelling mesenchymal stem cells. We then compared this novel structure to other silica structures used in ultrasound including Stober silica nanoparticles (SSN), MCM-41 mesoporous silica nanoparticles (MSN), and mesocellular foam silica nanoparticles (MCF) and found that the ELS offered enhanced stem cell signal due to its positive charge to facilitate cell uptake as well as inherently increased echogenicity. The in vivo detection limits were <500 cells with no detectable toxicity at the concentrations used for labelling. This novel structure may eventually find utility in applications beyond imaging requiring an exosome-like shape including drug delivery.

Effects of the iron oxide nanoparticle Molday ION Rhodamine B on the viability and regenerative function of neural stem cells: relevance to clinical translation

An essential component of developing successful neural stem cell (NSC)-based therapies involves the establishment of methodologies to noninvasively monitor grafted NSCs within brain tissues in real time. In this context, ex vivo labeling with ultrasmall superparamagnetic iron oxide (USPIO) particles has been shown to enable efficient tracking of transplanted NSCs via magnetic resonance imaging (MRI). However, whether and how USPIO labeling affects the intrinsic biology of NSCs is not thoroughly understood, and remains an active area of investigation. Here, we perform a comprehensive examination of rat NSC survival and regenerative function upon labeling with the USPIO, Molday ION Rhodamine B (MIRB), which allows for dual magnetic resonance and optical imaging. After optimization of labeling efficiency, two specific doses of MIRB (20 and 50 μg/mL) were chosen and were followed for the rest of the study. We observed that both MIRB doses supported the robust detection of NSCs, over an extended period of time in vitro and in vivo after transplantation into the striata of host rats, using MRI and post hoc fluorescence imaging. Both in culture and after neural transplantation, the higher 50 μg/mL MIRB dose significantly reduced the survival, proliferation, and differentiation rate of the NSCs. Interestingly, although the lower 20 μg/mL MIRB labeling did not produce overtly negative effects, it increased the proliferation and glial differentiation of the NSCs. Additionally, application of this dose also changed the morphological characteristics of neurons and glia produced after NSC differentiation. Importantly, the transplantation of NSCs labeled with either of the two MIRB doses upregulated the immune response in recipient animals. In particular, in animals receiving the 50 μg/mL MIRB-labeled NSCs, this immune response consisted of an increased number of CD68⁺-activated microglia, which appeared to have phagocytosed MIRB particles and cells contributing to an exaggerated MRI signal dropout in the animals. Overall, these results indicate that although USPIO particles, such as MIRB, may have advantageous labeling and magnetic resonance-sensitive features for NSC tracking, a further examination of their effects might be necessary before they can be used in clinical scenarios of cell-based transplantation.