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While the size-dependent optical properties of BSA-stabilized gold nanoclusters are well known, the time-dependent growth mechanism remains to be described. Herein, we systematically compare two synthesis methods with and without ascorbic acid, and show that tuning of BSA-stabilized gold nanoclusters (AuNCs) of different sizes can be performed without the aid of an extrinsic reducing agent and with good reproducibility. We also show that adding ascorbic acid yields larger BSA-stabilized gold nanoparticles (AuNPs), and that AuNPs can only form above a threshold gold precursor concentration. Using computed tomography, we describe how these biomineralized AuNPs show size-dependent X-ray attenuation. Growth of BSA-stabilized AuNCs and AuNPs, over a range of gold precursor concentrations, was followed with steady-state fluorescence and UV-vis spectroscopy for one week, constituting the first study of its kind. Based on our results, we propose a mechanism for BSA-stabilization of AuNCs and AuNPs that can further aid in selective growth of discrete AuNCs and AuNPs.

Transferrin (Tf) conjugated to gold nanoparticles and clusters combine the protein's site-specific receptor targeting capabilities with the optical properties imparted by the nano-sized gold. We have described two different synthesis protocols, one yielding fluorescent Tf-stabilized gold nanoclusters (AuNCs) and one yielding Tf-stabilized gold nanoparticles that exhibit localized surface plasmon resonance. We demonstrate that the synthetic route employed has a large influence both on the gold nanostructure formed, and also on the structural integrity of the protein. A slight protein unfolding allows stronger interaction with lipids, and was found to significantly perturb lipid monolayers. Interactions between the protein-gold nanostructures and three different cell types were also assessed, indicating that the enhanced membrane affinity may be attributed to intercellular membrane differences.

Brain-computer interface (BCI) systems can provide people with ability to communicate and control real world systems using neural activities. Therefore, it makes sense to develop an assistive framework for command and control of a future robotic system which can assist the human robot collaboration. In this paper, we have employed electroencephalographic (EEG) signals recorded by electrodes placed over the scalp. The human-hand movement based motor imagery mentalization is used to collect brain signals over the motor cortex area. The collected µ-wave (8–13 Hz) EEG signals were analyzed with event-related desynchronization/synchronization (ERD/ERS) quantification to extract a threshold between hand grip and release movement and this information can be used to control forestry crane grasping and release functionality. The experiment was performed with four healthy persons to demonstrate the proof-of concept BCI system. From this study, it is demonstrated that the proposed method has potential to assist the manual operation of crane operators performing advanced task with heavy cognitive work load.

Background The artery of Percheron is a rare anatomic variant of arterial supply to the paramedian thalamus and rostral midbrain, and occlusion of the artery of Percheron results in bilateral paramedian thalamic infarcts with or without midbrain involvement. Acute artery of Percheron infarcts represent 0.1 to 2% of total ischemic stroke. However, of thalamic strokes, occlusion of artery of Percheron is the cause in 4 to 35% of cases. Early diagnosis of artery of Percheron infarction can be challenging because it is infrequent and early computed tomography or magnetic resonance imaging may be negative. Thus, it can be confused with other neurological conditions such as tumors and infections. Case presentation This is a retrospective case study of a 56-year-old white man admitted to Umeå University Hospital and diagnosed with an artery of Percheron infarction. Medical records and the neuroradiological database were reviewed, and the diagnosis was made based on typical symptoms and radiological findings of artery of Percheron infarction. We report the case of a 56-year-old man with a history of overconsumption of alcohol who was found in his home unconscious and hypothermic. He had a Reaction Level Scale-85 score of 4. He developed ventricular fibrillation on arrival at our emergency department, and cardiopulmonary resuscitation successfully restored sinus rhythm within an estimated 2 minutes of onset. He was then put on cardiopulmonary bypass for rewarming. The initial head computed tomography performed on admission was wrongly assessed as unremarkable. Bilateral ischemia in the paramedian thalamic nuclei and pons were first documented on a follow-up computed tomography on day 24 after hospitalization. He died on day 35 after hospitalization. Conclusions Artery of Percheron infarcts are rare. The radiological diagnosis can initially often be judged as normal and in combination with variability in the neurological symptoms it is a rather difficult condition to diagnose. For these reasons few clinicians have much experience with this type of infarct, which may delay diagnosis and initiation of appropriate treatment.

The human brain is a remarkable computing machine, i.e. vastly parallel, self-organizing, robust, and energy efficient. To gain a better understanding into how the brain works, a cyborg (cybernetic organism, a combination of machine and living tissue) is currently being made in an interdisciplinary effort, known as the Cyborg project. In this paper we describe how living cultures of neurons (biological neural networks) are successfully grown in-vitro over Micro-Electrode Arrays (MEAs), which allow them to be interfaced to a robotic body through electrical stimulation and neural recordings. Furthermore, we describe the bio- and nano-technological procedures utilized for the culture of such dissociated neural networks and the interface software and hardware framework used for creating a closed-loop hybrid neuro-system. A Reservoir Computing (RC) approach is used to harness the computational power of the neuronal culture. © 2017 Massachusetts Institute of Technology Published under a Creative Commons Attribution 4.0 International (CC BY 4.0) license

The coordinated development of the nervous system requires fidelity in the expression of specific genes determining the different neural cell phenotypes. Stem cell fate decisions during neurodevelopment are strictly correlated with their epigenetic status. The epigenetic regulatory processes, such as DNA methylation and histone modifications discussed in this review article, may impact both neural stem cell (NSC) self-renewal and differentiation and thus play an important role in neurodevelopment. At the same time, stem cell decisions regarding fate commitment and differentiation are highly dependent on the temporospatial expression of specific genes contingent on the developmental stage of the nervous system. An interplay between the above, as well as basic cell processes, such as transcription regulation, DNA replication, cell cycle regulation and DNA repair therefore determine the accuracy and function of neuronal connections. This may significantly impact embryonic health and development as well as cognitive processes such as neuroplasticity and memory formation later in the adult. Copyright © 2017 Podobinska, Szablowska-Gadomska, Augustyniak, Sandvig, Sandvig and Buzanska. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution and reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Effective transplant-mediated repair of ischemic brain lesions entails extensive tissue remodeling, especially in the ischemic core. Neural stem cells (NSCs) are promising reparative candidates for stroke induced lesions, however, their survival and integration with the host-tissue post-transplantation is poor. In this study, we address this challenge by testing whether co-grafting of NSCs with olfactory ensheathing cells (OECs), a special type of glia with proven neuroprotective, immunomodulatory, and angiogenic effects, can promote graft survival and host tissue remodelling. Transient focal cerebral ischemia was induced in adult rats by a 60-min middle cerebral artery occlusion (MCAo) followed by reperfusion. Ischemic lesions were verified by neurological testing and magnetic resonance imaging. Transplantation into the globus pallidus of NSCs alone or in combination with OECs was performed at two weeks post-MCAo, followed by histological analyses at three weeks post-transplantation. We found evidence of extensive vascular remodelling in the ischemic core as well as evidence of NSC motility away from the graft and into the infarct border in severely lesioned animals co-grafted with OECs. These findings support a possible role of OECs as part of an in situ tissue engineering paradigm for transplant mediated repair of ischemic brain lesions. This is the authors' manuscript to the article (preprint). The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs11064-016-2098-3

One of the main challenges in tissue engineering and regenerative medicine is the ability to maintain optimal cell function and survival post-transplantation. Biomaterials such as alginates are commonly used for immunoisolation, while they may also provide structural support to the cell transplants by mimicking the extracellular matrix. In this study, arginine-glycine-aspartate (RGD)-peptide-coupled alginates of tailored composition were produced by adopting a unique chemoenzymatic strategy for substituting the nongelling mannuronic acid on the alginate. Alginates with and without RGD were produced with high and low content of G. Using carbodiimide chemistry 0.1-0.2% of the sugar units were substituted by peptide. Furthermore, the characterization by (1)H-nuclear magnetic resonance (NMR) revealed by-products from the coupling reaction that partly could be removed by coal filtration. Olfactory ensheathing cells (OECs) and myoblasts were grown in two-dimensional (2D) and 3D cultures of RGD-peptide modified or unmodified alginates obtained by the chemoenzymatically strategy and compared to native alginate. Both OECs and myoblasts adhered to the RGD-peptide modified alginates in 2D cultures, forming bipolar protrusions. OEC encapsulation resulted in cell survival for up to 9 days, thus demonstrating the potential for short-term 3D culture. Myoblasts showed long-term survival in 3D cultures, that is, up to 41 days post encapsulation. The RGD modifications did not result in marked changes in cell viability in 3D cultures. We demonstrate herein a unique technique for tailoring peptide substituted alginates with a precise and flexible composition, conserving the gel forming properties relevant for the use of alginate in tissue engineering.

Lab-on-chip platforms, such as microfluidic chips and micro-electrode arrays (MEAs) are powerful tools that allow us to manipulate and study neurons in vitro. Microfluidic chips provide a controlled extracellular environment that structures neural networks and facilitates isolation and manipulation at a sub-cellular level. Furthermore, MEAs enable measurement of extracellular electrophysiological activity from single neurons to entire networks. Here, we demonstrate the design, fabrication and application of a 3-nodal microfluidic chip integrated with MEAs as a versatile study platform for neurobiology and pathophysiology. In this work, we evaluate the use of the microfluidic chip to structure a neural network into three separate nodes, interconnected through tunnels that isolate and guide axons into a channel, thus facilitating synaptic contacts between neurons originating from opposite nodes. Furthermore, we demonstrate the utility of the MEA for monitoring developing activity and intra-/inter nodal connectivity of the structured neural network. Finally, we demonstrate the versatility of the platform in two separate experiments. First, we demonstrate the ability to measure intra- and inter-nodal dynamic responses to a fluidically isolated chemical stimulation. Then, we demonstrate the feature of the microfluidic chip enabling the disruption of functional connectivity between nodes and examination of the immediate activity response of the neural network. The platform enables in vitro modelling of neural networks to study their functional connectomes in the context of neurodegenerative disease and CNS trauma, including spinal cord injury.

Introduction: Spontaneous spinal epidural hematomas are rare. However, in patients on anticoagulant treatment the risk may increase. Symptomatically patients may present with radiculopathy and even progressive neurological deficits. Case description: We present a case of a warfarin treated patient with left L5 radiculopathy. MRI was evaluated as showing a lumbar disc prolapse or synovial cyst at L4-L5 level. The patient was operated and an organized material was removed and analysed as a hematoma. No prolapsed disc or synovial cyst was found. The patient was neurologically restored following the operation. Discussion and Evaluation: This case illustrates how spontaneous epidural spinal hematomas can present with symptoms of radiculopathy and radiologically be misinterpreted as a protruding disc or cyst. Conclusion: Warfarin treated patients may have an increased risk of spontaneous spinal epidural hematomas.

Restoration of lost neuronal function after spinal cord injury (SCI) still remains a big challenge for current medicine. One important repair strategy is bridging the SCI lesion with a supportive and stimulatory milieu that would enable axonal rewiring. Injectable extracellular matrix (ECM)-derived hydrogels have been recently reported to have neurotrophic potential in vitro. In this study, we evaluated the presumed neuroregenerative properties of ECM hydrogels in vivo in the acute model of SCI. ECM hydrogels were prepared by decellularization of porcine spinal cord (SC) or porcine urinary bladder (UB), and injected into a spinal cord hemisection cavity. Histological analysis and real-time qPCR were performed at 2, 4, and 8 weeks postinjection. Both types of hydrogels integrated into the lesion and stimulated neovascularization and axonal ingrowth into the lesion. On the other hand, massive infiltration of macrophages into the lesion and rapid hydrogel degradation did not prevent cyst formation, which progressively developed over 8 weeks. No significant differences were found between SC-ECM and UB-ECM. Gene expression analysis revealed significant downregulation of genes related to immune response and inflammation in both hydrogel types at 2 weeks post SCI. A combination of human mesenchymal stem cells with SC-ECM did not further promote ingrowth of axons and blood vessels into the lesion, when compared with the SC-ECM hydrogel alone. In conclusion, both ECM hydrogels bridged the lesion cavity, modulated the innate immune response, and provided the benefit of a stimulatory substrate for in vivo neural tissue regeneration. However, fast hydrogel degradation might be a limiting factor for the use of native ECM hydrogels in the treatment of acute SCI.

Manganese oxide nanoparticles (MONPs) are capable of time-dependent magnetic resonance imaging contrast switching as well as releasing a surface-bound drug. MONPs give T2/T2* contrast, but dissolve and release T1-active Mn2+ and L-3,4-dihydroxyphenylalanine. Complementary images are acquired with a single contrast agent, and applications toward Parkinson's disease are suggested. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. This is the peer reviewed version the article, which has been published in final form at http://dx.doi.org/10.1002/smll.201502545. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Labelling of olfactory ensheathing cells (OECs) with micron-sized particles of iron oxide (MPIO) and detection by MRI

The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.

To assess optic nerve (ON) regeneration after injury by applying manganese-enhanced MRI (MEMRI) in a study of comparative physiology between nonregenerating rat and mouse species and regenerating frog and fish species.The normal visual projections of rats, mice, frogs, and fish was visualized by intravitreal MnCl(2) injection followed by MRI. Rats and mice with ON crush (ONC) were divided into nonregenerating (ONC only), and regenerating animals with peripheral nerve graft (ONC+PNG; rats) or lens injury (ONC+LI; mice) and monitored by MEMRI at 1 and 20 days post-lesion (dpl). Frog and fish with ON transection (ONT) were monitored by MEMRI up to 6 months postlesion (mpl).Signal intensity profiles of the Mn(2+)-enhanced ON were consistent with ON regeneration in the ONC+PNG and ONC+LI rat and mice groups, respectively, compared with the nonregenerating ONC groups. Furthermore, signal intensity profiles of the Mn(2+)-enhanced ON obtained between 1 mpl and 6 mpl in the fish and frog groups, respectively, were consistent with spontaneous, complete ON regeneration.Taken together, these results demonstrate that MEMRI is a viable method for serial, in vivo monitoring of normal, induced, and spontaneously regenerating optic nerve axons in different species.

Purpose 1) To evaluate a novel theoretical model for in vivo axonal Mn(2+) transport with MRI data from the rat optic nerve (ON); and 2) to compare predictions from the new model with previously reported experimental data. Materials and methods Time-resolved in vivo T(1)-weighted magnetic resonance imaging (MRI) of adult female Sprague-Dawley rat (n = 9) ON was obtained at different timepoints after intravitreal MnCl(2) injection. A concentration-dependent and a rate-dependent function for the Mn(2+) retinal ganglion cell (RGC) axon entrance was convolved with three different transport functions and each model system was optimized to fit the ON data. Results The rate-limited input function gave a better fit to the data than the concentration-limited input. Simulations showed that the rate-limited input leads to a semilogarithmic relationship between injected dose and Mn(2+) concentration in the ON, which is in agreement with previously reported in vivo experiments. A random walk transport model and an anterograde predominant slow model gave a similar fit to the data, both better than an anterograde predominant fast model. Conclusion The results indicate that Mn(2+) input into RGC axons is limited by a maximum entrance rate into the axons. Also, a wide range of apparent Mn(2+) transport rates seems to be involved, different from synaptic vesicle transport rates, meaning that manganese does not depict synaptic vesicle transport rates directly.

To evaluate manganese (Mn(2+))-enhanced MRI (MEMRI) and diffusion tensor imaging (DTI) as tools for detection of axonal injury and regeneration after intravitreal peripheral nerve graft (PNG) implantation in the rat optic nerve (ON).In adult Fischer rats, retinal ganglion cell (RGC) survival was evaluated in Flurogold (FG) back-filled retinal whole mounts after ON crush (ONC), intravitreal PNG, and intravitreal MnCl(2) injection (150 nmol) at 0 and 20 days post lesion (dpl). MEMRI and echo-planar DTI (DTI-EPI) was obtained of noninjured ON one day after intravitreal MnCl(2) injection, and at 1 and 21 dpl after ONC, intravitreal PNG, and intravitreal MnCl(2) injections given at 0 and 20 dpl. GAP-43 immunohistochemistry was performed after the last MRI.ONC reduced RGC density in retina by 94% at 21 dpl compared to noninjured ON without MnCl(2) injections. Both intravitreal PNG and intravitreal MnCl(2) injections improved RGC survival in retina, which was reduced by 90% (ONC+MnCl(2)), 82% (ONC+PNG), and 74% (ONC+PNG+MnCl(2)) compared to noninjured ON. DTI-derived parameters (fractional anisotropy [FA], mean diffusivity, axial diffusivity lambda( parallel), and radial diffusivity lambda( perpendicular)) were unaffected by the presence of Mn(2+) in the ON. At 1 dpl, CNR(MEMRI) and lambda( parallel) were reduced at the injury site, while at 21 dpl they were increased at the injury site compared to values measured at 1 dpl. GAP-43 immunoreactive axons were present in the ON distal to the ONC injury site.MEMRI and DTI enabled detection of functional and structural degradation after rat ON injury, and there was correlation between the MRI-derived and immunohistochemical measures of axon regeneration.

To provide dose-response data for the safe and effective use of MnCl(2) for manganese (Mn(2+)) -enhanced MRI (MEMRI) of the visual pathway.Retinal ganglion cell (RGC) toxicity, CNR in MEMRI, axon density resolution for MEMRI, mode of axonal transport and clearance of Mn(2+) from the vitreous after ivit were investigated. After 0, 30, 150, 300, 1500, and 3000 nmol ivit MnCl(2), neural toxicity was measured by counting surviving RGC back-filled with FluroGold (FG), CNR of the vitreous body and visual pathway by three-dimensional (3D) MEMRI, resolution of ON axon density by correlating CNR with axon density, and axonal transport of Mn(2+) by studying CNR in 3D MEMRI of the ON after ion of 200 nmol MnCl(2).There were no changes in RGC density after ivit MnCl(2)or= 150 nmol, and reductions of 12%, 57%, and 94% occurred after 300, 1500, and 3000 nmol MnCl(2). CNR increased in the visual pathway with MnCl(2)or= 300 nmol, and decreased when the dose was raised further. Minimum detectable ON axon densities were 125,000/mm(2). After 200 nmol ion MnCl(2), CNR0 were recorded distally from the ion site, but there was no signal in the retina. At ivit doses1500 nmol, clearance from the vitreous body was impaired.The optimal dose for MEMRI of the rat visual pathway was found to be 150-300 nmol ivit MnCl(2). Higher doses are toxic, causing RGC death, impair active clearance from the vitreous, and loss of Mn(2+) enhancement throughout the visual pathway. Mn(2+) traffic within RGC axons is mediated mainly by anterograde transport.

The blood–brain barrier (BBB) constitutes a significant obstacle for the delivery of drugs into the central nervous system (CNS). Nanoparticles have been able to partly overcome this obstacle and can thus improve drug delivery across the BBB. Furthermore, focused ultrasound in combination with gas filled microbubbles has opened the BBB in a temporospatial manner in animal models, thus facilitating drug delivery across the BBB. In the current study we combine these two approaches in our quest to develop a novel, generic method for drug delivery across the BBB and into the CNS. Nanoparticles were synthesized using the polymer poly(butyl cyanoacrylate) (PBCA), and such nanoparticles have been reported to cross the BBB to some extent. Together with proteins, these nanoparticles self-assemble into microbubbles. Using these novel microbubbles in combination with focused ultrasound, we successfully and safely opened the BBB transiently in healthy rats. Furthermore, we also demonstrated that the nanoparticles could cross the BBB and deliver a model drug into the CNS. This is a submitted manuscript of an article published by Elsevier in Journal of Controlled Release, 28 October 2015

Experimental visual pathway lesion in the form of optic nerve (ON) crush or transection injury results in massive death of retinal ganglion cells (RGCs) and permanent loss of synaptic connections (Berkelaar et al., J Neurosci 14:4368-4374, 1994). Despite the fact that RGC axon regeneration is inhibited in a manner typical of other CNS lesions, the rodent ON injury model is one of the few models where robust axon regeneration has been achieved after therapeutic intervention (Berry et al., Restor Neurol Neurosci 26:147-174, 2008). However, assessment of the efficacy of therapeutic approaches in promoting ON regeneration has traditionally relied on histological methods, which necessitate the sacrifice of experimental animals and thus preclude longitudinal in vivo monitoring of individual subjects. Manganese-enhanced MRI (MEMRI) utilizes the paramagnetic properties and uptake and transport mechanisms of manganese ions (Mn(2+)) by neurons, thus enabling serial in vivo monitoring of the entire axonal projections (Sandvig et al., J Magn Reson Imaging 34:670-675, 2011; Thuen et al., J Magn Reson Imaging 4:492-500, 2005; Pautler et al., Magn Res Med 50:33-39, 2003; Saleem et al., Neurotechnique 34:685-700, 2000). The above properties of Mn(2+) render MEMRI a highly suitable technique for assessment of ON regeneration after injury, especially with a view to in vivo monitoring of neuronal connectivity and axon-regenerative responses to treatment. In this chapter, we provide a generic protocol for ON lesioning and MEMRI application for assessment of ON regeneration in rodents.

Experimental visual pathway lesion in the form of optic nerve (ON) crush or transection injury results in massive death of retinal ganglion cells (RGCs) and permanent loss of synaptic connections (Berkelaar et al., J Neurosci 14:4368-4374, 1994). Despite the fact that RGC axon regeneration is inhibited in a manner typical of other CNS lesions, the rodent ON injury model is one of the few models where robust axon regeneration has been achieved after therapeutic intervention (Berry et al., Restor Neurol Neurosci 26:147-174, 2008). However, assessment of the efficacy of therapeutic approaches in promoting ON regeneration has traditionally relied on histological methods, which necessitate the sacrifice of experimental animals and thus preclude longitudinal in vivo monitoring of individual subjects. Manganese-enhanced MRI (MEMRI) utilizes the paramagnetic properties and uptake and transport mechanisms of manganese ions (Mn(2+)) by neurons, thus enabling serial in vivo monitoring of the entire axonal projections (Sandvig et al., J Magn Reson Imaging 34:670-675, 2011; Thuen et al., J Magn Reson Imaging 4:492-500, 2005; Pautler et al., Magn Res Med 50:33-39, 2003; Saleem et al., Neurotechnique 34:685-700, 2000). The above properties of Mn(2+) render MEMRI a highly suitable technique for assessment of ON regeneration after injury, especially with a view to in vivo monitoring of neuronal connectivity and axon-regenerative responses to treatment. In this chapter, we provide a generic protocol for ON lesioning and MEMRI application for assessment of ON regeneration in rodents.

Fe@Au core–shell nanoparticles (NPs) exhibit multiple functionalities enabling their effective use in applications such as medical imaging and drug delivery. In this work, a novel synthetic method was developed and optimized for the synthesis of highly stable, monodisperse Fe@Au NPs of average diameter ∼24 nm exhibiting magneto-plasmonic characteristics. Fe@Au NPs were characterized by a wide range of experimental techniques, including scanning (transmission) electron microscopy (S(T)EM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS) and UV–vis spectroscopy. The formed particles comprise an amorphous iron core with a crystalline Au shell of tunable thickness, and retain the superparamagnetic properties at room temperature after formation of a crystalline Au shell. After surface modification, PEGylated Fe@Au NPs were used for in vitro studies on olfactory ensheathing cells (OECs) and human neural stem cells (hNSCs). No adverse effects of the Fe@Au particles were observed post-labeling, both cell types retaining normal morphology, viability, proliferation, and motility. It can be concluded that no appreciable toxic effects on both cell types, coupled with multifunctionality and chemical stability make them ideal candidates for therapeutic as well as diagnostic applications. © 2014. This is the authors’ accepted and refereed manuscript to the article. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

A crucial issue in transplant-mediated repair of the damaged central nervous system (CNS) is serial non-invasive imaging of the transplanted cells, which has led to interest in the application of magnetic resonance imaging (MRI) combined with designated intracellular magnetic labels for cell tracking. Micron-sized particles of iron oxide (MPIO) have been successfully used to track cells by MRI, yet there is relatively little known about either their suitability for efficient labelling of specific cell types, or their effects on cell viability. The purpose of this study was to develop a suitable MPIO labelling protocol for olfactory ensheathing cells (OECs), a type of glia used to promote the regeneration of CNS axons after transplantation into the injured CNS. Here, we demonstrate an OEC labelling efficiency of90% with an MPIO incubation time as short as 6 h, enabling intracellular particle uptake for single-cell detection by MRI without affecting cell proliferation, migration and viability. Moreover, MPIO are resolvable in OECs transplanted into the vitreous body of adult rat eyes, providing the first detailed protocol for efficient and safe MPIO labelling of OECs for non-invasive MRI tracking of transplanted OECs in real time for use in studies of CNS repair and axon regeneration.

The purpose of the present study was to use magnetic resonance imaging (MRI) as a tool for monitoring transplant-mediated repair of the adult rat visual pathway. We labelled rat olfactory ensheathing cells (OECs) using micron-sized particles of iron oxide (MPIO) and transplanted them by: i) intravitreal injection (ivit) and ii) intra-optic nerve (ON) injection (iON) in adult rats with ON crush (ONC) injury. We applied T(2)-weighted MRI and manganese-enhanced MRI (MEMRI) to visualise transplanted cells and ON axons at specific times after injury and cell engraftment. Our findings demonstrate that ivit MPIO-labelled OECs are unequivocally detected by T(2)-weighted MRI in vivo and that the T(1)-weighted 3D FLASH sequence applied for MEMRI facilitates simultaneous visualisation of Mn(2+-) enhanced regenerating retinal ganglion cell (RGC) axons and MPIO-labelled OEC grafts. Furthermore, analysis of MRI data and ultrastructural findings supports the hypothesis that iON OEC transplants mediate regeneration and remyelination of RGC axons post injury.

To develop and validate an objective technique for 3D segmentation of manganese-enhanced MR images of the optic nerve/tract (ON) in adult rats to improve contrast-to-noise (CNR) calculations and use the technique to ascertain if manganese dipyridoxyl diphosphate (MnDPDP) gives sufficient Mn(2+) enhancement compared to MnCl(2) when used for functional imaging of the visual pathway.Intravitreous injection of the manganese-releasing MR contrast agent MnDPDP (30 nmol Mn(2+)) was performed to trace the ON in adult rats (n = 4). A positive control group of rats (n = 5) received a standard preparation of MnCl(2) (200 nmol Mn(2+)), while gadodiamide (1500 nmol Gd(3+)) was administered in negative control rats (n = 2). An objective technique for 3D segmentation of the enhanced ON was developed. CNR profiles along the ON were calculated by resampling the 3D image-volume in 2D planes perpendicular to the Mn(2+) enhanced ON in 0.2 mm steps, 4 mm along the segmented ON measured from the lamina cribrosa.The ON was successfully segmented and CNR calculated accurately within 2 minutes in a representative 3D MR image volume. Intravitreal MnDPDP injection resulted in significant MRI contrast enhancement of the retina and ON after 12-24 hours similar to that of MnCl(2) injection.3D semiautomated image segmentation and the use of MnDPDP can improve in vivo axon tracing based on MRI. Mn(2+) was found to be released from MnDPDP after intravitreal injection in sufficient amounts to obtain functional tracing of the adult rat primary visual pathway.

Purpose To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visual projections. Materials and Methods MRI was performed 24 hours after unilateral intravitreal injection of MnCl2 (150 nmol) into adult Fischer rats that were divided into four groups: 1) controls (N = 5), 2) dose-response (N = 10, 0.2–200 nmol), 3) time-response with repeated MRI during 24–168 hours post injection (N = 4), and 4) optic nerve crush (ONC) immediately preceding the MnCl2 injection (N = 7). Control and ONC animals were reinjected with MnCl2 20 days after the first injection, and MRI was performed 24 hours later. Results In the control group, the optic projection was visualized from the retina to the superior colliculus, with indications of transsynaptic transport to the cortex. There was a semilogarithmic relationship between the Mn2+ dose and Mn2+ enhancement from 4 to 200 nmol, and the enhancement decayed gradually to 0 by 168 hours. No Mn2+-enhanced signal was detected distal to the ON crush site. In the control group, similar enhancement was obtained after the first and second MnCl2 injections, while in the ONC group the enhancement proximal to the crush site was reduced 20 days post lesion (20dpl). Conclusion Mn2+-enhanced MRI is a viable method for temporospatial visualization of normal and injured ON in the adult rat. The observed reduction in the Mn2+ signal proximal to the ONC is probably a result of retrograde damage to the retinal ganglion cells, and not of Mn2+ toxicity. J. Magn. Reson. Imaging 2005. © 2005 Wiley-Liss, Inc.

Axon regeneration is arrested in the injured central nervous system (CNS) by axon growth-inhibitory ligands expressed in oligodendrocytes/myelin, NG2-glia, and reactive astrocytes in the lesion and degenerating tracts, and by fibroblasts in scar tissue. Growth cone receptors (Rc) bind inhibitory ligands, activating a Rho-family GTPase intracellular signaling pathway that disrupts the actin cytoskeleton inducing growth cone collapse/repulsion. The known inhibitory ligands include the chondroitin sulfate proteoglycans (CSPG) Neurocan, Brevican, Phosphacan, Tenascin, and NG2, as either membrane-bound or secreted molecules; Ephrins expressed on astrocyte/fibroblast membranes; the myelin/oligodendrocyte-derived growth inhibitors Nogo, MAG, and OMgp; and membrane-bound semaphorins (Sema) produced by meningeal fibroblasts invading the scar. No definitive CSPG Rc have been identified, although intracellular signaling through the Rho family of G-proteins is probably common to all the inhibitory ligands. Ephrins bind to signalling Ephs. The ligand-binding Rc for all the myelin inhibitors is NgR and requires p75(NTR) for transmembrane signaling. The neuropilin (NP)/plexin (Plex) Rc complex binds Sema. Strategies for promoting axon growth after CNS injury are thwarted by the plethora of inhibitory ligands and the ligand promiscuity of some of their Rc. There is also paradoxical reciprocal expression of many of the inhibitory ligands/Rc in normal and damaged neurons, and NgR expression is restricted to a limited number of neuronal populations. All these factors, together with an incomplete understanding of the normal functions of many of these molecules in the intact CNS, presently confound interpretive acumen in regenerative studies.