Poly-L-ornithine promotes preferred differentiation of neural stem/progenitor cells via ERK signalling pathway

Profiling human iPSC-derived sensory neurons for analgesic drug screening using a multi-electrode array

Chronic pain is a global health issue, yet effective treatments remain limited due to poor preclinical-to-human translation. To address this, we developed a high-content screening (HCS) platform using hiPSC-derived nociceptors to identify analgesics targeting the peripheral nervous system. These cells, cultured on multi-well microelectrode arrays, achieved nearly 100% active electrodes by week 2, maintaining stable activity for at least 2 weeks. After 28 days, we assessed drug effects on neuronal activity, achieving strong assay performance (robust Z' > 0.5). Pharmacological tests confirmed responses to key analgesic targets, including ion channels (Nav, Cav, Kv, and TRPV1), neurotransmitter receptors (AMPAR and GABA-R), and kinase inhibitors (tyrosine and JAK1/2). Transcriptomic analysis validated target expression, though levels differed from primary human DRG cells. The platform was used to screen over 700 natural compounds, demonstrating its potential for analgesic discovery. This HCS platform facilitates the rapid discovery of uncharacterized analgesics, reducing preclinical-to-human translation failure.

Electrospun Polycaprolactone (PCL) Nanofibers Induce Elongation and Alignment of Co-Cultured Primary Cortical Astrocytes and Neurons

Neuromimetic in vitro models, simulating in vivo architecture/organization, are urgently needed to reduce experimental reliance on live animals. Our group recently reported a novel brain tissue derivation protocol, simultaneously deriving all major cortical cell types (including immune cells) in a facile protocol, generating a network of neurons in a single growth medium, which was interfaced with nanomaterials. This represents a significant advance, as tissue engineers overwhelmingly use diverse methods to derive and combine individual brain cells for materials-interfacing. However, this multicellular model lacked cellular directionality/structural organization (unlike the highly organized cortical circuits in vivo). Synthetic nanofiber constructs are of high value in tissue engineering, providing directional cues for cells. Most neuro-nanofiber studies employ simple monocultures of astrocytes/neurons and commonly use peripheral neurons rather than central nervous system populations. Here, we have interfaced our complex brain model (neurons/astrocytes derived simultaneously) with randomly oriented or aligned polycaprolactone (PCL) fiber meshes. Both cell types showed targeted extension along aligned fibers versus coverslips or random fibers. A new analysis method developed in-house demonstrated that peak orientations for astrocytes and neurons correlated with aligned nanofibers. Our data support the concept that nanofiber scaffolds can achieve organized growth of mixed cortical neural cell populations, mimicking neural architecture.

Profiling Human iPSC-Derived Sensory Neurons for Analgesic Drug Screening Using a Multi-Electrode Array

Chronic pain is a major global health issue, yet effective treatments are limited by poor translation from preclinical studies to humans. To address this, we developed a high-content screening (HCS) platform for analgesic discovery using hiPSC-derived nociceptors. These cells were cultured on multi-well micro-electrode arrays to monitor activity, achieving nearly 100% active electrodes by week two, maintaining stable activity for at least two weeks. After maturation (28 days), we exposed the nociceptors to various drugs, assessing their effects on neuronal activity, with excellent assay performance (Z' values >0.5). Pharmacological tests showed responses to analgesic targets, including ion channels (Nav, Cav, Kv, TRPV1), neurotransmitter receptors (AMPAR, GABA-R), and kinase inhibitors (tyrosine, JAK1/2). Transcriptomic analysis confirmed the presence of these drug targets, although expression levels varied compared to primary human dorsal root ganglion cells. This HCS platform facilitates the rapid discovery of novel analgesics, reducing the risk of preclinical-to-human translation failure.

Motivation

Chronic pain affects approximately 1.5 billion people worldwide, yet effective treatments remain elusive. A significant barrier to progress in analgesic drug discovery is the limited translation of preclinical findings to human clinical outcomes. Traditional rodent models, although widely used, often fail to accurately predict human responses, while human primary tissues are limited by scarcity, technical difficulties, and ethical concerns. Recent advancements have identified human induced pluripotent stem cell (hiPSC)-derived nociceptors as promising alternatives; however, current differentiation protocols produce cells with inconsistent and physiologically questionable phenotypes.To address these challenges, our study introduces a novel high-content screening (HCS) platform using hiPSC-derived nociceptors cultured on multi-well micro-electrode arrays (MEAs). The "Anatomic" protocol, used to generate these nociceptors, ensures cells with transcriptomic profiles closely matching human primary sensory neurons. Our platform achieves nearly 100% active electrode yield within two weeks and demonstrates sustained, stable activity over time. Additionally, robust Z' factor analysis (exceeding 0.5) confirms the platform's reliability, while pharmacological validation establishes the functional expression of critical analgesic targets. This innovative approach improves both the efficiency and clinical relevance of analgesic drug screening, potentially bridging the translational gap between preclinical studies and human clinical trials, and offering new hope for effective pain management.

Protocol for evaluating mitochondrial respiration in iPSC-derived neurons by the Seahorse XF analyzer

Here, we present a protocol describing the quantification of oxygen consumption rate (OCR) and maximal respiration rate (MRR) in living induced pluripotent stem cell (iPSC)-derived neurons using the Seahorse analyzer. We guide you through the whole process: culture amplification and seeding of neural progenitor cells (NPCs), their differentiation into neurons, and normalization of the results to cell number in the analytical phase. The assessment of cellular mitochondrial function, by analyzing mitochondrial respiration, could be useful in various diseases as well as in drug screening. For complete details on the use and execution of this protocol, please refer to Aleo et al.1.

Brain Slice Derived Nerve Fibers Grow along Microcontact Prints and are Stimulated by Beta-Amyloid(42)

BACKGROUND

Alzheimer's disease is characterized by extracellular beta-amyloid plaques, intraneuronal tau neurofibrillary tangles and excessive neurodegeneration. The mechanisms of neuron degeneration and the potential of these neurons to form new nerve fibers for compensation remain elusive. The present study aimed to evaluate the impact of beta-amyloid and tau on new formations of nerve fibers from mouse organotypic brain slices connected to collagen-based microcontact prints.

METHODS

Organotypic brain slices of postnatal day 8-10 wild-type mice were connected to established collagen-based microcontact prints loaded with polyornithine to enhance nerve fiber outgrowth. Human beta-amyloid(42) or P301S mutated aggregated tau was co-loaded to the prints. Nerve fibers were immunohistochemically stained with neurofilament antibodies. The physiological activity of outgrown neurites was tested with neurotracer MiniRuby, voltage-sensitive dye FluoVolt, and calcium-sensitive dye Rhod-4.

RESULTS

Immunohistochemical staining revealed newly formed nerve fibers extending along the prints derived from the brain slices. While collagen-only microcontact prints stimulated nerve fiber growth, those loaded with polyornithine significantly enhanced nerve fiber outgrowth. Beta-amyloid(42) significantly increased the neurofilament-positive nerve fibers, while tau had only a weak effect. MiniRuby crystals, retrogradely transported along these newly formed nerve fibers, reached the hippocampus, while FluoVolt and Rhod-4 monitored electrical activity in newly formed nerve fibers.

CONCLUSIONS

Our data provide evidence that intact nerve fibers can form along collagen-based microcontact prints from mouse brain slices. The Alzheimer's peptide beta-amyloid(42) stimulates this growth, hinting at a neuroprotective function when physiologically active. This "brain-on-chip" model may offer a platform for screening bioactive factors or testing drug effects on nerve fiber growth.

Cationic Hydrogels Modulate Neural Stem and Progenitor Cell Proliferation and Differentiation Behavior in Dependence of Cationic Moiety Concentration in 2D Cell Culture

The central nervous system (CNS) has a limited regenerative capacity because a hostile environment prevents tissue regeneration after damage or injury. Neural stem/progenitor cells (NSPCs) are considered a potential resource for CNS repair, which raises the issue of adequate cultivation and expansion procedures. Cationic charge supports the survival and adhesion of NSPCs. Typically, tissue culture plates with cationic coatings, such as poly-l-ornithine (PLO), have been used to culture these cell types (NSPCs). Yet presently, little is known about the impact of cationic charge concentration on the viability, proliferation, and differentiation capacity of NSPCs. Therefore, we have recently developed well-defined, fully synthetic hydrogel systems G1 (gel 1) to G6 (gel 6) that allow for the precise control of the concentration of the cationic trimethylaminoethyl acrylate (TMAEA) molecule associated with the polymer in a range from 0.06 to 0.91 μmol/mg. When murine NSPCs were cultured on these gels under differentiation conditions, we observed a strong correlation of cationic charge concentration with NSPC survival. In particular, neurons were preferentially formed on gels with a higher cationic charge concentration, whereas astrocytes and oligodendrocytes favored weakly charged or even neutral gel surfaces. To test the properties of the gels under proliferative conditions, the NSPCs were cultivated in the presence of fibroblast growth factor 2 (FGF2). The cytokine significantly increased the number of NSPCs but delayed the differentiation toward neurons and glia cells. Thus, the hydrogels are compatible with the survival, expansion, and differentiation of NSPCs and may be useful to create supportive environments in transplantation approaches.

Nanoscale surface coatings and topographies for neural interfaces

With the lack of minimally invasive tools for probing neuronal systems across spatiotemporal scales, understanding the working mechanism of the nervous system and limited assessments available are imperative to prevent or treat neurological disorders. In particular, nanoengineered neural interfaces can provide a solution to this technological barrier. This review covers recent surface engineering approaches, including nanoscale surface coatings, and a range of topographies from the microscale to the nanoscale, primarily focusing on neural-interfaced biosystems. Specifically, the immobilization of bioactive molecules to fertilize the neural cell lineage, topographical engineering to induce mechanotransduction in neural cells, and enhanced cell-chip coupling using three-dimensional structured surfaces are highlighted. Advances in neural interface design will help us understand the nervous system, thereby achieving the effective treatments for neurological disorders. STATEMENT OF SIGNIFICANCE: • This review focuses on designing bioactive neural interface with a nanoscale chemical modification and topographical engineering at multiscale perspective. • Versatile nanoscale surface coatings and topographies for neural interface are summarized. • Recent advances in bioactive materials applicable for neural cell culture, electrophysiological sensing, and neural implants are reviewed.

Mannitol inhibits the proliferation of neural stem cell by a p38 mitogen-activated protein kinase-dependent signaling pathway

PURPOSE

Mannitol is one of the first-line drugs for reducing cerebral edema through increasing the extracellular osmotic pressure. However, long-term administration of mannitol in the treatment of cerebral edema triggers damage to neurons and astrocytes. Given that neural stem cell (NSC) is a subpopulation of main regenerative cells in the central nervous system after injury, the effect of mannitol on NSC is still elusive. The present study aims to elucidate the role of mannitol in NSC proliferation.

METHODS

C57 mice were derived from the animal house of Zunyi Medical University. A total of 15 pregnant mice were employed for the purpose of isolating NSCs in this investigation. Initially, mouse primary NSCs were isolated from the embryonic cortex of mice and subsequently identified through immunofluorescence staining. In order to investigate the impact of mannitol on NSC proliferation, both cell counting kit-8 assays and neurospheres formation assays were conducted. The in vitro effects of mannitol were examined at various doses and time points. In order to elucidate the role of Aquaporin 4 (AQP4) in the suppressive effect of mannitol on NSC proliferation, various assays including reverse transcription polymerase chain reaction, western blotting, and immunocytochemistry were conducted on control and mannitol-treated groups. Additionally, the phosphorylated p38 (p-p38) was examined to explore the potential mechanism underlying the inhibitory effect of mannitol on NSC proliferation. Finally, to further confirm the involvement of the p38 mitogen-activated protein kinase-dependent (MAPK) signaling pathway in the observed inhibition of NSC proliferation by mannitol, SB203580 was employed. All data were analyzed using SPSS 20.0 software (SPSS, Inc., Chicago, IL). The statistical analysis among multiple comparisons was performed using one-way analysis of variance (ANOVA), followed by Turkey's post hoc test in case of the data following a normal distribution using a Shapiro-Wilk normality test. Comparisons between 2 groups were determined using Student's t-test, if the data exhibited a normal distribution using a Shapiro-Wilk normality test. Meanwhile, data were shown as median and interquartile range and analyzed using the Mann-Whitney U test, if the data failed the normality test. A p < 0.05 was considered as significant difference.

RESULTS

Primary NSC were isolated from the mice, and the characteristics were identified using immunostaining analysis. Thereafter, the results indicated that mannitol held the capability of inhibiting NSC proliferation in a dose-dependent and time-dependent manner using cell counting kit-8, neurospheres formation, and immunostaining of Nestin and Ki67 assays. During the process of mannitol suppressing NSC proliferation, the expression of AQP4 mRNA and protein was downregulated, while the gene expression of p-p38 was elevated by reverse transcription polymerase chain reaction, immunostaining, and western blotting assays. Subsequently, the administration of SB203580, one of the p38 MAPK signaling pathway inhibitors, partially abrogated this inhibitory effect resulting from mannitol, supporting the fact that the p38 MAPK signaling pathway participated in curbing NSC proliferation induced by mannitol.

CONCLUSIONS

Mannitol inhibits NSC proliferation through downregulating AQP4, while upregulating the expression of p-p38 MAPK.

A Bioinspired Astrocyte-Derived Coating Promotes the In Vitro Proliferation of Human Neural Stem Cells While Maintaining Their Stemness

The repair of neuronal tissue is a challenging process due to the limited proliferative capacity of neurons. Neural stem cells (NSCs) can aid in the regeneration process of neural tissue due to their high proliferation potential and capacity to differentiate into neurons. The therapeutic potential of these cells can only be achieved if sufficient cells are obtained without losing their differentiation potential. Toward this end, an astrocyte-derived coating (HAc) was evaluated as a promising substrate to promote the proliferation of NSCs. Mass spectroscopy and scanning electron microscopy were used to characterize the HAc. The proliferation rate and the expression of stemness and differentiation markers in NSCs cultured on the HAc were evaluated and compared to the responses of these cells to commonly used coating materials including Poly-L-Ornithine (PLO), and a Human Induced Pluripotent Stem Cell (HiPSC)-based coating. The use of the HAc promotes the in vitro cell growth of NSCs. The expression of the stemness markers Sox2 and Nestin, and the differentiation marker DCX in the HAc group was akin to the expression of these markers in the controls. In summary, HAc supported the proliferation of NSCs while maintaining their stemness and neural differentiation potential.

Plant Cellulose as a Substrate for 3D Neural Stem Cell Culture

Neural stem cell (NSC)-based therapies are at the forefront of regenerative medicine strategies for various neural defects and injuries such as stroke, traumatic brain injury, and spinal cord injury. For several clinical applications, NSC therapies require biocompatible scaffolds to support cell survival and to direct differentiation. Here, we investigate decellularized plant tissue as a novel scaffold for three-dimensional (3D), in vitro culture of NSCs. Plant cellulose scaffolds were shown to support the attachment and proliferation of adult rat hippocampal neural stem cells (NSCs). Further, NSCs differentiated on the cellulose scaffold had significant increases in their expression of neuron-specific beta-III tubulin and glial fibrillary acidic protein compared to 2D culture on a polystyrene plate, indicating that the scaffold may enhance the differentiation of NSCs towards astrocytic and neuronal lineages. Our findings suggest that plant-derived cellulose scaffolds have the potential to be used in neural tissue engineering and can be harnessed to direct the differentiation of NSCs.

Tea polyphenols coated sodium alginate-gelatin 3D edible scaffold for cultured meat

This study aimed to use edible scaffolds as a platform for animal stem cell expansion, thus constructing block-shaped cell culture meat. The tea polyphenols (TP)-coated 3D scaffolds were constructed of sodium alginate (SA) and gelatin (Gel) with good biocompatibility and mechanical support. Initially, the physicochemical properties and mechanical properties of SA-Gel-TP scaffolds were measured, and the biocompatibility of the scaffolds was evaluated by C2C12 cells. SEM results showed that the scaffold had a porous laminar structure with TP particles attached to the surface, while FT-IR results also demonstrated the encapsulation of TP coating on the scaffold. In addition, the porosity of all scaffolds was higher than 40% and the degradation rate during the incubation cycle was less than 40% and the S2-G1-TP0.1-3 h scaffold has excellent cell adhesion and extension. Subsequently, we inoculated rabbit skeletal muscle myoblasts (RbSkMC) on the scaffold and induced differentiation. The results showed good adhesion and extension behavior of RbSkMC on S2-G1-TP0.1-3 h scaffolds with high expression of myogenic differentiation proteins and genes, and SEM results confirmed the formation of myotubes. Additionally, the adhesion rate of cells on scaffolds with TP coating was 1.5 times higher than that on scaffolds without coating, which significantly improved the cell proliferation rate and the morphology of cells with extension on the scaffolds. Furthermore, rabbit-derived cultured meat had similar appearance and textural characteristics to fresh meat. These conclusions indicate the high potential of the scaffolds with TP coating as a platform for the production of cultured meat products.

Structural and functional insights into δ-poly-L-ornithine polymer biosynthesis from Acinetobacter baumannii

Cationic homo-polyamino acid (CHPA) peptides containing isopeptide bonds of diamino acids have been identified from Actinomycetes strains. However, none has been reported from other bacteria. Here, we report a δ-poly-L-ornithine synthetase from Acinetobacter baumannii, which we name PosA. Surprisingly, structural analysis of the adenylation domain and biochemical assay shows L-ornithine as the substrate for PosA. The product from the enzymatic reaction was purified and identified as poly-L-ornithine composed of 7-12 amino acid units. Chemical labeling of the polymer confirmed the isopeptide linkage of δ-poly-L-ornithine. We examine the biological activity of chemically synthesized 12-mer δ-poly-L-ornithine, illustrating that the polymer may act as an anti-fungal agent. Structures of the isolated adenylation domain from PosA are presented with several diamino acids and biochemical assays identify important substrate binding residues. Structurally-guided genome-mining led to the identification of homologs with different substrate binding residues that could activate additional substrates. A homolog from Bdellovibrionales sp. shows modest activity with L-arginine but not with any diamino acids observed to be substrates for previously examined CHPA synthetases. Our study indicates the possibility that additional CHPAs may be produced by various microbes, supporting the further exploration of uncharacterized natural products.

Influence of poly-L-ornithine-bile acid nano hydrogels on cellular bioactivity and potential pharmacological applications

Aim: Cellular bioactivity and pathophysiological changes associated with chronic disorders are considered pivotal detrimental factors when developing novel formulations for biomedical applications. Methods: This paper investigates the use of bile acids and synthetic polypeptide poly-L-ornithine (PLO) in formulations and their impacts on a variety of cell lines, with a particular focus on their cellular bioactivity. Results: The hepatic cell line was the most negatively affected by the presence of PLO, while the muscle and beta-pancreatic cell lines did not show as profound of a negative impact of PLO on cellular viability. PLO was the least disruptive regarding mitochondrial function for muscle and beta cells. Conclusion: The addition of bile acids generally decreased mitochondrial respiration and altered bioenergetic parameters in all cell lines.

Assembling Spheroids of Rat Primary Neurons Using a Stress-Free 3D Culture System

Neural injuries disrupt the normal functions of the nervous system, whose complexities limit current treatment options. Because of their enhanced therapeutic effects, neurospheres have the potential to advance the field of regenerative medicine and neural tissue engineering. Methodological steps can pose challenges for implementing neurosphere assemblies; for example, conventional static cultures hinder yield and throughput, while the presence of the necrotic core, time-consuming methodology, and high variability can slow their progression to clinical application. Here we demonstrate the optimization of primary neural cell-derived neurospheres, developed using a high-throughput, stress-free, 3D bioreactor. This process provides a necessary baseline for future studies that could develop co-cultured assemblies of stem cells combined with endothelial cells, and/or biomaterials and nanomaterials for clinical therapeutic use. Neurosphere size and neurite spreading were evaluated under various conditions using Image J software. Primary neural cells obtained from the hippocampi of three-day-old rat pups, when incubated for 24 h in a reactor coated with 2% Pluronic and seeded on Poly-D-Lysine-coated plates establish neurospheres suitable for therapeutic use within five days. Most notably, neurospheres maintained high cell viability of ≥84% and expressed the neural marker MAP2, neural marker β-Tubulin III, and glial marker GFAP at all time points when evaluated over seven days. Establishing these factors reduces the variability in developing neurospheres, while increasing the ease and output of the culture process and maintaining viable cellular constructs.

Poly (lactic-co-glycolic acid)-encapsulated iodine-131 nanoparticles fabricated with rhTSH induce apoptosis and immobilization of thyroid cancer cells

Background

Aggressive thyroid carcinoma (ATC) usually loses radioiodine avidity to iodine-131 (¹³¹I) due to the downregulation of sodium/iodide symporter (NIS). The expression of thyroid stimulating hormone receptor (TSHR) is more persistent than NIS and the administration of recombinant human thyroid stimulating hormone (rhTSH) promotes de novo NIS synthesis. Hence, exploring methods integrating ¹³¹I with rhTSH might be a feasible therapeutic strategy for selective delivery of ¹³¹I into thyroid cancer to fortify the effect of radioiodine ablation.

Methods

The ¹³¹I, poly (lactic-co-glycolic acid) (PLGA) and rhTSH were used to synthesize of the ¹³¹I-PLGA-rhTSH nanoparticles. The characteristics of the ¹³¹I-PLGA-rhTSH nanoparticles was determined using a light microscopy, scanning electron microscopy (SEM), autoradiography and immunofluorescence (IF) staining. The diameter of the ¹³¹I-PLGA-rhTSH nanoparticles was measured with a Mastersizer 3000, and the encapsulation efficiency (EF) of ¹³¹I in ¹³¹I-PLGA-rhTSH nanoparticles and the radioactivity of a single nanoparticle were determined. Then, the mouse tumor xenograft model was established, and the biodistribution and effect of ¹³¹I-PLGA-rhTSH nanoparticles on apoptosis of thyroid cance cells were investigated in vivo. Thereafter, the role of ¹³¹I-PLGA-rhTSH nanoparticles in cell viability using cell counting kit-8 and lactate dehydrogenase (LDH) release assays. Subsequently, the underlying mechanism of ¹³¹I-PLGA-rhTSH nanoparticles in reducing cell viability was assessed using immunostaining, boyden invasion assays and phalloidin staining.

Results

Our results showed that the method of developing nanoparticles-encapsulated ¹³¹I using poly (lactic-co-glycolic acid) (PLGA) and modified with rhTSH (¹³¹I-PLGA-rhTSH), was a feasible avenue for the integration of ¹³¹I and rhTSH. Meanwhile, the encapsulation efficiency (EF) of ¹³¹I-PLGA-rhTSH nanoparticles was approximately 60%, and the radioactivity of a single nanoparticle was about 1.1×10-2 Bq. Meanwhile, the ¹³¹I-PLGA-rhTSH nanoparticles were selectively delivered into, gradually enriched and slowly downregulated in xenograft tumor after the administration of ¹³¹I-PLGA-rhTSH nanoparticles through tail vein in mouse tumor xenograft model. Thereafter, the tumor weight was significantly reduced after the administration of ¹³¹I-PLGA-rhTSH nanoparticles. Subsequently, the application of ¹³¹I-PLGA-rhTSH nanoparticles facilitated apoptosis and attenuated immobilization via inhibiting F-actin assembling of FTC-133 cells.

Conclusion

The present study develops a suitable approach integrating ¹³¹I and rhTSH, and this strategy is a feasible regimen enhancing the effect of radioiodine ablation for the treatment of thyroid cancer.

Isolate and Culture Mouse Primary Neurons for West Nile Virus Infection

Primary neurons are very valuable cells to study the pathogenesis of neurotropic viruses, such as West Nile virus. The mouse primary neurons can be used to assess viral infection profiles and cellular immune responses to a viral infection. However, successful isolation and culture of mouse neurons can be challenging. Here, we report a step-by-step method to prepare a primary neuron culture from adult mice.

Beneficial Effects of Hyaluronan-Based Hydrogel Implantation after Cortical Traumatic Injury

Traumatic brain injury (TBI) causes cell death mainly in the cerebral cortex. We have previously reported that transplantation of embryonic cortical neurons immediately after cortical injury allows the anatomical reconstruction of injured pathways and that a delay between cortical injury and cell transplantation can partially improve transplantation efficiency. Biomaterials supporting repair processes in combination with cell transplantation are in development. Hyaluronic acid (HA) hydrogel has attracted increasing interest in the field of tissue engineering due to its attractive biological properties. However, before combining the cell with the HA hydrogel for transplantation, it is important to know the effects of the implanted hydrogel alone. Here, we investigated the therapeutic effect of HA on host tissue after a cortical trauma. For this, we implanted HA hydrogel into the lesioned motor cortex of adult mice immediately or one week after a lesion. Our results show the vascularization of the implanted hydrogel. At one month after HA implantation, we observed a reduction in the glial scar around the lesion and the presence of the newly generated oligodendrocytes, immature and mature neurons within the hydrogel. Implanted hydrogel provides favorable environments for the survival and maturation of the newly generated neurons. Collectively, these results suggest a beneficial effect of biomaterial after a cortical traumatic injury.

Neural progenitor cell-derived extracellular matrix as a new platform for neural differentiation of human induced pluripotent stem cells

The culture microenvironment has been demonstrated to regulate stem cell fate and to be a crucial aspect for quality-controlled stem cell maintenance and differentiation to a specific lineage. In this context, extracellular matrix (ECM) proteins are particularly important to mediate the interactions between the cells and the culture substrate. Human induced pluripotent stem cells (hiPSCs) are usually cultured as anchorage-dependent cells and require adhesion to an ECM substrate to support their survival and proliferation in vitro. Matrigel, a common substrate for hiPSC culture is a complex and undefined mixture of ECM proteins which are expensive and not well suited to clinical application. Decellularized cell-derived ECM has been shown to be a promising alternative to the common protein coatings used in stem cell culture. However, very few studies have used this approach as a niche for neural differentiation of hiPSCs. Here, we developed a new stem cell culture system based on decellularized cell-derived ECM from neural progenitor cells (NPCs) for expansion and neural differentiation of hiPSCs, as an alternative to Matrigel and poly-l-ornithine/laminin-coated well plates. Interestingly, hiPSCs were able to grow and maintain their pluripotency when cultured on decellularized ECM from NPCs (NPC ECM). Furthermore, NPC ECM enhanced the neural differentiation of hiPSCs compared to poly-l-ornithine/laminin-coated wells, which are used in most neural differentiation protocols, presenting a statistically significant enhancement of neural gene expression markers, such as βIII-Tubulin and MAP2. Taken together, our results demonstrate that NPC ECM provides a functional microenvironment, mimicking the neural niche, which may have interesting future applications for the development of new strategies in neural stem cell research.

Robust neuronal differentiation of human embryonic stem cells for neurotoxicology

Here, we describe a protocol for rapid neuronal differentiation from human embryonic stem cells (hESCs) toward a heterogenous population of telencephalic progenitors, immature and mature neurons, for drug-screening and early-brain differentiation studies. hESC neuronal differentiation depends on adhesion and minimal cell-passaging to avert monolayer cross-connectivity rupture. In this protocol, we detail optimized cell-seeding densities and coating conditions with high cell viability suitable for neurotoxicology and high-resolution single-cell omics studies. Daily media changes reduce compound instability and degradation for optimal screening. For complete details on the use and execution of this protocol, please refer to Samara et al. (2022).

Copper Modulates Adult Neurogenesis in Brain Subventricular Zone

The subventricular zone (SVZ) in lateral ventricles is the largest neurogenic region in adult brain containing high amounts of copper (Cu). This study aims to define the role of Cu in adult neurogenesis by chelating labile Cu ions using a well-established Cu chelator D-Penicillamine (D-Pen). A neurosphere model derived from adult mouse SVZ tissues was established and characterized for its functionality with regards to neural stem/progenitor cells (NSPCs). Applying D-Pen in cultured neurospheres significantly reduced intracellular Cu levels and reversed the Cu-induced suppression of NSPC’s differentiation and migration. An in vivo intracerebroventricular (ICV) infusion model was subsequently established to infuse D-Pen directly into the lateral ventricle. Metal analyses revealed a selective reduction of Cu in SVZ by 13.1% (p = 0.19) and 21.4% (p < 0.05) following D-Pen infusions at low (0.075 μg/h) and high (0.75 μg/h) doses for 28 days, respectively, compared to saline-infused controls. Immunohistochemical studies revealed that the 7-day, low-dose D-Pen infusion significantly increased Ki67(+)/Nestin(+) cell counts in SVZ by 28% (p < 0.05). Quantification of BrdU(+)/doublecortin (DCX)(+) newborn neuroblasts in the rostral migration stream (RMS) and olfactory bulb (OB) further revealed that the short-term, low-dose D-Pen infusion, as compared with saline-infused controls, resulted in more newborn neuroblasts in OB, while the high-dose D-Pen infusion showed fewer newborn neuroblasts in OB but with more arrested in the RMS. Long-term (28-day) infusion revealed similar outcomes. The qPCR data from neurosphere experiments revealed altered expressions of mRNAs encoding key proteins known to regulate SVZ adult neurogenesis, including, but not limited to, Shh, Dlx2, and Slit1, in response to the changed Cu level in neurospheres. Further immunohistochemical data indicated that Cu chelation also altered the expression of high-affinity copper uptake protein 1 (CTR1) and metallothionein-3 (MT3) in the SVZ as well as CTR1 in the choroid plexus, a tissue regulating brain Cu homeostasis. Taken together, this study provides first-hand evidence that a high Cu level in SVZ appears likely to maintain the stability of adult neurogenesis in this neurogenic zone.

Generation of Human iPSC-Derived Astrocytes with a mature star-shaped phenotype for CNS modeling

The generation of astrocytes from human induced pluripotent stem cells has been hampered by either prolonged differentiation—spanning over two months—or by shorter protocols that generate immature astrocytes, devoid of salient mature astrocytic traits pivotal for central nervous system (CNS) modeling. We directed stable hiPSC-derived neuroepithelial stem cells to human iPSC-derived Astrocytes (hiAstrocytes) with a high percentage of star-shaped cells by orchestrating an astrocytic-tuned culturing environment in 28 days. We employed RT-qPCR and ICC to validate the astrocytic commitment of the neuroepithelial stem cells. To evaluate the inflammatory phenotype, we challenged the hiAstrocytes with the pro-inflammatory cytokine IL-1β (interleukin 1 beta) and quantitatively assessed the secretion profile of astrocyte-associated cytokines and the expression of intercellular adhesion molecule 1 (ICAM-1). Finally, we quantitatively assessed the capacity of hiAstrocytes to synthesize and export the antioxidant glutathione. In under 28 days, the generated cells express canonical and mature astrocytic markers, denoted by the expression of GFAP, AQP4 and ALDH1L1. In addition, the notion of a mature phenotype is reinforced by the expression of both astrocytic glutamate transporters EAAT1 and EAAT2. Thus, hiAstrocytes have a mature phenotype that encompasses traits critical in CNS modeling, including glutathione synthesis and secretion, upregulation of ICAM-1 and a cytokine secretion profile on a par with human fetal astrocytes. This protocol generates a multifaceted astrocytic model suitable for in vitro CNS disease modeling and personalized medicine.

Tetrahydrofolate Alleviates the Inhibitory Effect of Oxidative Stress on Neural Stem Cell Proliferation through PTEN/Akt/mTOR Pathway

Neural stem cell (NSC) proliferation is the initial step for NSC participating in neurorehabilitation after central nervous system (CNS) injury. During this process, oxidative stress is always involved in restricting the regenerative ability of NSC. Tetrahydrofolate (THF) is susceptible to oxidative stress and exhibits a high antioxidant activity. While its effect on NSC proliferation under oxidative stress condition remains obscure. Here, NSC were isolated from embryonic mice and identified using immunofluorescent staining. Meanwhile, the results showed that THF (5 μM and 10 μM) attenuated oxidative stress induced by 50 μM hydrogen peroxide (H₂O₂) in NSC using mitochondrial hydroxyl radical detection and Western blotting assays. Afterward, administration of THF markedly alleviated the inhibitory effect of oxidative stress on NSC proliferation, which was evidenced by Cell Counting Kit-8 (CCK8), neurosphere formation, and immunofluorescence of Ki67 assays. Thereafter, the results revealed that PTEN/Akt/mTOR signaling pathway played a pivotal role in counteracting oxidative stress to rescue the inhibitory effect of oxidative stress on NSC proliferation using Western blotting assays and gene knockdown techniques. Collectively, these results demonstrate that THF mitigates the inhibitory effect of oxidative stress on NSC proliferation via PTEN/Akt/mTOR signaling pathway, which provides evidence for administrating THF to potentiate the neuro-reparative capacity of NSC in the treatment of CNS diseases with the presence of oxidative stress.

A carboxymethyl lentinan layer by layer self-assembly system as a promising drug chemotherapeutic platform

Surface functionalization of mesoporous silica nanoparticles (MSNs) has been proposed as an efficient strategy for enhancing the biocompatibility and efficiency of an MSN-based carrier platform. Herein, natural polyelectrolyte multilayers composed of poly-l-ornithine (PLO) and carboxymethyl lentinan (LC) were coated on the surface of MSNs through a layer-by-layer (LbL) self-assembly technique, and were characterized by ζ-potential, FTIR, ¹³C NMR, SEM, TEM, XRD, and TG. The prepared carrier presented alternating positive and negative potentials when coated with the polyelectrolytes, and the surface of MSN-PLO/LC was rougher compared to the naked MSNs. The biocompatibility tests, including cytocompatibility, hemocompatibility, and histocompatibility, showed that MSNs biocompatibility could be improved by modifying LC. A high loading and sustained release drug delivery system was constructed after loading doxorubicin (DOX) into the prepared MSN-PLO/LC, which exhibited significant anti-proliferative efficiency in human cervical cancer cell lines (Hela). Therefore, the PLO/LC LbL NPs (layer-by-layer self-assembled nanoparticles coated with PLO/LC layers) based on MSNs, which is easily prepared by electrostatic interactions, can be considered a promising drug chemotherapeutic platform and delivery technique for future human cervical cancer therapy.

Neuroprotection by cattle encephalon glycoside and ignotin beyond the time window of thrombolysis in ischemic stroke

Cattle encephalon glycoside and ignotin (CEGI) injection is known as a multi-target neuroprotective drug that contains numerous liposoluble molecules, such as polypeptides, monosialotetrahexosyl ganglioside (GM-1), free amino acids, hypoxanthine and carnosine. CEGI has been approved by the Chinese State Food and Drug Administration and widely used in the treatments of various diseases, such as stroke and Alzheimer's disease. However, the neuroprotective effects of CEGI beyond the time window of thrombolysis (within 4.5 hours) on acute ischemic stroke remain unclear. This study constructed a rat middle cerebral artery occlusion model by suture-occluded method to simulate ischemic stroke. The first daily dose was intraperitoneally injected at 8 hours post-surgery and the CEGI treatments continued for 14 days. Results of the modified five-point Bederson scale, beam balance test and rotameric test showed the neurological function of ischemic stroke rats treated with 4 mL/kg/d CEGI improved significantly, but the mortality within 14 days did not change significantly. Brain MRI and 2,3,5-triphenyltetrazolium chloride staining confirmed that the infarct size in the 4 mL/kg/d CEGI-treated rats was significantly reduced compared with ischemic insult only. The results of transmission electron microscopy and double immunofluorescence staining showed that the hippocampal neuronal necrosis in the ischemic penumbra decreased whereas the immunopositivity of new neuronal-specific protein doublecortin and the percentage of Ki67/doublecortin positive cells increased in CEGI-treated rats compared with untreated rats. Our results suggest that CEGI has an effective neuroprotective effect on ischemic stroke when administered after the time window of thrombolysis. The study was approved by the Animal Ethics Committee of The Third Military Medical University, China.

Ambroxol Upregulates Glucocerebrosidase Expression to Promote Neural Stem Cells Differentiation Into Neurons Through Wnt/β-Catenin Pathway After Ischemic Stroke

Ischemic stroke has been becoming one of the leading causes resulting in mortality and adult long-term disability worldwide. Post-stroke pneumonia is a common complication in patients with ischemic stroke and always associated with 1-year mortality. Though ambroxol therapy often serves as a supplementary treatment for post-stroke pneumonia in ischemic stroke patients, its effect on functional recovery and potential mechanism after ischemic stroke remain elusive. In the present study, the results indicated that administration of 70 mg/kg and 100 mg/kg enhanced functional recovery by virtue of decreasing infarct volume. The potential mechanism, to some extent, was due to promoting NSCs differentiation into neurons and interfering NSCs differentiation into astrocytes through increasing GCase expression to activate Wnt/β-catenin signaling pathway in penumbra after ischemic stroke, which advanced basic knowledge of ambroxol in regulating NSCs differentiation and provided a feasible therapy for ischemic stroke treatment, even in other brain disorders in clinic.

Transplantation of neural stem cells preconditioned with high‑mobility group box 1 facilitates functional recovery after spinal cord injury in rats

Spinal cord injury (SCI) is a devastating disorder that often results in temporary and/or permanent functional impairment below the injured level. To date, few satisfactory therapeutic strategies are available to treat SCI. Hence, exploring novel strategies for SCI is an essential public health concern. Cell transplantation therapy, which is associated with neuroprotection, immunomodulation, axon regeneration, neuronal relay formation and myelin regeneration, provides a promising therapeutic strategy for SCI. The neuronal stem cell (NSC) preconditioning method is an emerging approach, which facilitates NSC survival and neuronal differentiation after implantation. The aim of the present study was to develop a feasible candidate for cell-based therapy following SCI in rats and to investigate the role of high mobility group box-1 (HMGB1) in NSC activation. The results of the present study showed that transplantation of NSCs, preconditioned with 1 ng/ml HMGB1, facilitated functional improvement of injured spinal cords, as indicated by Basso, Beattie and Bresnahan mean scores, mechanical hypersensitivity and cold stimulation. Meanwhile, the histological examination of hematoxylin and eosin staining indicated that engraftment of HMGB1-preconditioned NSCs resulted in decreased atrophy of the injured spinal cord. Meanwhile, the transplantation of HMGB1-preconditioned NSCs resulted in an increased number of functional Nissl bodies in neurons, as detected by Nissl staining, and an increase in the number of βIII-tubulin⁺ cells in the epicenter of injured spinal cords in rats with SCI. In addition, the results also demonstrated that 1 ng/ml HMGB1 promoted the differentiation of NSCs into neurons, and that the ERK signaling pathway played an important role in this process. In conclusion, the present data indicated that the preconditioning strategy with 1 ng/ml HMGB1 may present a feasible candidate for cell-based therapy following SCI in rats, which may enlarge the scope of HMGB1 in NSC activation.

Actin Alpha 2 (ACTA2) Downregulation Inhibits Neural Stem Cell Migration through Rho GTPase Activation

Although neural stem cells (NSCs) could migrate towards lesions after central nervous system (CNS) injury, the migration ability always is restricted due to the disturbed composition and density of the adhesion ligands and extracellular matrix (ECM) gradient after CNS injury. To date, various methods have been developed to enhance NSC migration and a number of factors, which are affecting NSC migration potential, have been identified. Here, primary NSCs were cultured and the expression of actin alpha 2 (ACTA2) in NSCs was determined using reverse transcription polymerase chain reaction (RT-PCR) and immunostaining. Next, the role of ACTA2 in regulating NSC migration and the potential mechanism was explored. Our results demonstrated that ACTA2 expressed in NSCs. Meanwhile, downregulated ACTA2 using siRNA inhibited NSC migration through hindering actin filament polymerization via increasing RhoA expression and decreasing Rac1 expression. The present study might enrich the basic knowledge of ACTA2 in NSC migration and open an avenue for enhancing NSC migration potential, subsequently providing an intervention target for functional recovery after CNS injury.

Artesunate promotes the proliferation of neural stem/progenitor cells and alleviates Ischemia-reperfusion Injury through PI3K/Akt/FOXO-3a/p27kip1 signaling pathway

Stroke is one of the leading causes of death worldwide that also result in long-term disability. Endogenous neural stem/progenitor cells (NSPCs) within subventricular (SVZ) and dentate gyrus (DG) zone, stimulated by cerebral infarction, can promote neural function recovery. However, the proliferation of eNSPCs triggered by ischemia is not enough to induce neural repair, which may contribute to the permanent disability in stroke patients. In this study, our results showed that following the treatment with artesunate (ART, 150 mg/kg), the functional recovery was significantly improved, the infarct volume was notably reduced, and the expression of Nestin, a proliferation marker of NSPCs in the infarcted cortex, was also increased. Additionally, the proliferative activity of NSPCs with or without oxygen-glucose deprivation/reperfusion was significantly promoted by ART treatment, and the therapeutic concentration was 0.8 μmol/L (without OGD/R) or 0.4 μmol/L (with OGD/R) in the in vitro model. Furthermore, the effects of ART can be abolished by the treatment of PI3K inhibitor wortmannin. The expression levels of related molecules in PI3K/Akt/FOXO-3a/p27^kip1 signaling pathway (p-AKT, p-FOXO-3a, p27^kip1) were examined using western blotting. The results suggested ART could inhibit the transcriptional function of FOXO-3a by inducing its phosphorylation, subsequently downregulating p27^kip1 and enhancing neural stem cell proliferation in the infarcted cortex via PI3K/AKT signaling, further alleviating ischemia-reperfusion injury after ischemic stroke.

Coating Materials for Neural Stem/Progenitor Cell Culture and Differentiation

Neural stem/progenitor cells (NSPCs) have a potential to treat various neurological diseases, such as Parkinson's Disease, Alzheimer's Disease, and Spinal Cord Injury. However, the limitation of NSPC sources and the difficulty to maintain their stemness or to differentiate them into specific therapeutic cells are the main hurdles for clinical research and application. Thus, for obtaining a therapeutically relevant number of NSPCs in vitro, it is important to understand factors regulating their behaviors and to establish a protocol for stable NSPC proliferation and differentiation. Coating materials for cell culture, such as Matrigel, laminin, collagen, and other coating materials, can significantly affect NSPC characteristics. This article provides a review of coating materials for NSPC culturing in both two dimensions and three dimensions, and their functions in NSPC proliferation and differentiation, and presents a useful guide to select coating materials for researchers.

Polyornithine-based polyplexes to boost effective gene silencing in CNS disorders

Gene silencing therapies have successfully suppressed the translation of target proteins, a strategy that holds great promise for the treatment of central nervous system (CNS) disorders. Advances in the current knowledge on multimolecular delivery vehicles are concentrated on overcoming the difficulties in delivery of small interfering (si)RNA to target tissues, which include anatomical accessibility, slow diffusion, safety concerns, and the requirement for specific cell uptake within the unique environment of the CNS. The present work addressed these challenges through the implementation of polyornithine derivatives in the construction of polyplexes used as non-viral siRNA delivery vectors. Physicochemical and biological characterization revealed biodegradability and biocompatibility of our polyornithine-based system and the ability to silence gene expression in primary oligodendrocyte progenitor cells (OPCs) effectively. In summary, the well-defined properties and neurological compatibility of this polypeptide-based platform highlight its potential utility in the treatment of CNS disorders.

Interfacing human induced pluripotent stem cell-derived neurons with designed nanowire arrays as a future platform for medical applications

Nanostructured substrates such as nanowire arrays form a powerful tool for building next-generation medical devices.

Progerin-Induced Transcriptional Changes in Huntington's Disease Human Pluripotent Stem Cell-Derived Neurons

Huntington's disease (HD) is a neurodegenerative late-onset genetic disorder caused by CAG expansions in the coding region of the Huntingtin (HTT) gene, resulting in a poly-glutamine (polyQ) expanded HTT protein. Considerable efforts have been devoted for studying HD and other polyQ diseases using animal models and cell culture systems, but no treatment currently exists. Human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) offer an elegant solution for modeling human diseases. However, as embryonic or rejuvenated cells, respectively, these pluripotent stem cells (PSCs) do not recapitulate the late-onset feature of the disease. Here, we applied a robust and rapid differentiation protocol to derive electrophysiologically active striatal GABAergic neurons from human wild-type (WT) and HD ESCs and iPSCs. RNA-seq analyses revealed that HD and WT PSC-derived neurons are highly similar in their gene expression patterns. Interestingly, ectopic expression of Progerin in both WT and HD neurons exacerbated the otherwise non-significant changes in gene expression between these cells, revealing IGF1 and genes involved in neurogenesis and nervous system development as consistently altered in the HD cells. This work provides a useful tool for modeling HD in human PSCs and reveals potential molecular targets altered in HD neurons.

Extracellular Nanomatrix-Induced Self-Organization of Neural Stem Cells into Miniature Substantia Nigra-Like Structures with Therapeutic Effects on Parkinsonian Rats

Substantia nigra (SN) is a complex and critical region of the brain wherein Parkinson's disease (PD) arises from the degeneration of dopaminergic neurons. Miniature SN-like structures (mini-SNLSs) constructed from novel combination of nanomaterials and cell technologies exhibit promise as potentially curative cell therapies for PD. In this work, a rapid self-organization of mini-SNLS, with an organizational structure and neuronal identities similar to those of the SN in vivo, is achieved by differentiating neural stem cells in vitro on biocompatible silica nanozigzags (NZs) sculptured by glancing angle deposition, without traditional chemical growth factors. The differentiated neurons exhibit electrophysiological activity in vitro. Diverse physical cues and signaling pathways that are determined by the nanomatrices and lead to the self-organization of the mini-SNLSs are clarified and elucidated. In vivo, transplantation of the neurons from a mini-SNLS results in an early and progressive amelioration of PD in rats. The sculptured medical device reported here enables the rapid and specific self-organization of region-specific and functional brain-like structures without an undesirable prognosis. This development provides promising and significant insights into the screening of potentially curative drugs and cell therapies for PD.

SVCT2 Promotes Neural Stem/Progenitor Cells Migration Through Activating CDC42 After Ischemic Stroke

Ischemic stroke is one of the most leading diseases causing death/long-term disability worldwide. Activating endogenous neural stem/progenitors cells (NSPCs), lining in the subventricular zone (SVZ) and dentate gyrus, facilitates injured brain tissue recovery in both short and long-term experimental settings. While, only a few proliferated NSPCs migrate toward the lesions to enhance endogenous repair after ischemia. Here, the results indicated that the functional recovery was evidently improved and the infarct volume was significantly reduced with ascorbic acid (AA) treatment in a dose-dependent manner from 125 to 500 mg/Kg, and the suitable therapeutic concentration was 250 mg/Kg. The possible mechanism might be due to activating sodium-vitamin C cotransporter 2 (SVCT2), which was down-regulated in SVZ after ischemia. Furthermore, immunostaining images depicted the number of migrated NSPCs from SVZ were significantly increased with 250 mg/Kg AA treatment or SVCT2 overexpression under the physiological and pathological condition in vivo. Besides, the data also represented that 250 mg/Kg AA or SVCT2 overexpression facilitated NSPCs migration via promoting F-actin assembling in the manner of up-regulating CDC42 expression using oxygen-glucose deprivation in vitro. Collectively, the present study indicates that SVCT2 promotes NSPCs migration through CDC42 activation to facilitate F-actin assembling, which enlarges the therapeutic scope of AA and the role of SVCT2 in NSPCs migration after brain injury.

Isolation and culture of primary embryonic zebrafish neural tissue

BACKGROUND

Primary cell culture is a valuable tool to utilize in parallel with in vivo studies in order to maximize our understanding of the mechanisms surrounding neurogenesis and central nervous system (CNS) regeneration and plasticity. The zebrafish is an important model for biomedical research and primary neural cells are readily obtainable from their embryonic stages viatissue dissociation. Further, transgenic reporter lines with cell type-specific expression allows for observation of distinct cell populations within the dissociated tissue.

NEW METHOD

Here, we define an efficient method for ex vivo quantification and characterization of neuronal and glial tissue dissociated from embryonic zebrafish.

RESULTS

Zebrafish brain dissociated cells have been documented to survive in culture for at least 9 days in vitro (div). Anti-HuC/D and anti-Acetylated Tubulin antibodies were used to identify neurons in culture; at 3 div approximately 48% of cells were HuC/D positive and 85% expressed serotonin, suggesting our protocol can efficiently isolate neurons from whole embryonic zebrafish brains. Live time-lapse imaging was also carried out to analyze cell migration in vitro.

COMPARISON WITH EXISTING METHODS

Primary cultures of zebrafish neural cells typically have low rates of survivability in vitro. We have developed a culture system that has long term cell viability, enabling direct analysis of cell-cell and cell-extracellular matrix interactions.

CONCLUSIONS

These results demonstrate a practical method for isolating, dissociating and culturing of embryonic zebrafish neural tissue. This approach could further be utilized to better understand zebrafish regeneration in vitro.

Photosensitive Hydrogel Creates Favorable Biologic Niches to Promote Spinal Cord Injury Repair

Photochemistry is considered to be a promising strategy for hydrogels to mimic the complex and dynamic properties of natural extracellular matrix. However, it is seldom applied in 3D tissue engineering and regenerative medicine due to the attenuation of light. In this study, phenyl azide photchemistry and optical fiber technology are first used to localize adhesive protein on the inner surface of the nerve guidance conduit in a 3D hydrogel scaffold. In vitro coculture assay of neural stem cells (NSCs) shows that photoimmobilization of collagen significantly improves the adhesion and survival of NSCs in the conduit, and exhibits synergistic effect with the sustainable release of growth factor. After implantation in transected spinal cord, the optimized hydrogel scaffold is found to improve the locomotion recovery of rats 12 weeks after spinal cord injury (SCI). Histological analysis suggests that the designed hydrogel scaffold provides a favorable biological niche for neuronal regeneration, thus producing directional neuron tissue and promoting the repair of SCI. This study demonstrates a promising hydrogel scaffold for SCI repair and provides the first understanding of the photoimmobilization of adhesive protein in a 3D hydrogel conduit concerning its functions on spinal cord tissue restoration.

Chondroitin sulfate proteoglycan represses neural stem/progenitor cells migration via PTPσ/α-actinin4 signaling pathway

Neural stem/progenitor cells (NSPCs) are a promising candidate for the cell-replacement therapy after central nervous system (CNS) injury. However, the short of sufficient NSPCs migration and integration into the lesions is an essential challenge for cell-based therapy after CNS injury due to the disturbance of local environmental homeostasis. Chondroitin sulfate proteoglycan (CSPG) is obviously accumulated at the lesions and destroyed local homeostasis after CNS injury. The previous study has demonstrated that the CSPG is a dominating ingredient inhibiting axonal regrowth of newly born neurons after CNS injury. NSPCs, a strain of special neural subtypes, hold the capacity of leading processes formation to regulate NSPCs migration, which has the same mechanism as axonal regrowth. Hence, it is worth investigating the effect of CSPG on NSPCs migration and its underlying mechanism. Here, different concentration of CSPG was used to evaluate its effect on NSPCs migration. The results showed that the CSPG suppressed NSPCs migration in a dose-dependent manner from 10 to 80 µg/mL with phase-contrast microscopy after 24 hours. Meanwhile, transwell assays were performed to certify the above results. Our data indicated that the 40 µg/mL CSPG obviously suppressed NSPCs migration via decreasing filopodia formation using immunofluorescence staining. Furthermore, data indicated that the 40 µg/mL CSPG upregulated protein tyrosine phosphatase receptor σ (PTPσ) expression and decreased α-actinin4 (ACTN4) expression through immunofluorescence, reverse transcription polymerase chain reaction, and Western blot assays. While the inhibitory effect was attenuated using PTPσ-specific small interfering RNA. In addition, data demonstrated that the 40 µg/mL CSPG facilitated NSPCs differentiation into glial fibrillary acidic protein-positive cells and inhibited NSPCs directing into MAP2- and MBP-positive cells. Collectively, these data demonstrated that the CSPG suppressed NSPCs migration through PTPσ/ACTN4 signaling pathway. Meanwhile, CSPG facilitated NSPCs differentiation into astrocytes and inhibited NSPCs directing into neurons and oligodendrocytes.

Organs to Cells and Cells to Organoids: The Evolution of in vitro Central Nervous System Modelling

With 100 billion neurons and 100 trillion synapses, the human brain is not just the most complex organ in the human body, but has also been described as "the most complex thing in the universe." The limited availability of human living brain tissue for the study of neurogenesis, neural processes and neurological disorders has resulted in more than a century-long strive from researchers worldwide to model the central nervous system (CNS) and dissect both its striking physiology and enigmatic pathophysiology. The invaluable knowledge gained with the use of animal models and post mortem human tissue remains limited to cross-species similarities and structural features, respectively. The advent of human induced pluripotent stem cell (hiPSC) and 3-D organoid technologies has revolutionised the approach to the study of human brain and CNS in vitro, presenting great potential for disease modelling and translational adoption in drug screening and regenerative medicine, also contributing beneficially to clinical research. We have surveyed more than 100 years of research in CNS modelling and provide in this review an historical excursus of its evolution, from early neural tissue explants and organotypic cultures, to 2-D patient-derived cell monolayers, to the latest development of 3-D cerebral organoids. We have generated a comprehensive summary of CNS modelling techniques and approaches, protocol refinements throughout the course of decades and developments in the study of specific neuropathologies. Current limitations and caveats such as clonal variation, developmental stage, validation of pluripotency and chromosomal stability, functional assessment, reproducibility, accuracy and scalability of these models are also discussed.

G protein-coupled estrogen receptor 1 negatively regulates the proliferation of mouse-derived neural stem/progenitor cells via extracellular signal-regulated kinase pathway

G protein-coupled estrogen receptor 1 (GPER1, also known as GPR30) has been reported to play a wide range of function in the central nervous system (CNS). However, whether GPER1 is expressed by neural stem/progenitor cells (NSPCs) and its role has not been established. Here, we found the expression of GPER1 in mouse-derived NSPCs via western blot and immunofluorescent staining. Moreover, we revealed that specific activation of GPER1 by the agonist G1 decreased the proliferation of NSPCs in a dose-dependent manner. The neurosphere formation assay and Ki67 staining further demonstrated that activation of GPER1 inhibited the proliferation of NSPCs. Additionally, the inhibitory effect of G1 on the proliferation of NSPCs could be blocked by the specific GPER1 antagonist G15. Intriguingly, ERK pathway was involved in the negative effect of GPER1 on the proliferation of NSPCs, because the phosphorylation level of ERK in NSPCs was remarkably decreased during G1 treatment. However, the antagonist G15 reversed the down-regulated level of p-ERK. Knock-down GPER1 also reversed the inhibitory effect of G1 on NSPCs proliferation. Together, our results provide the first evidence that GPER1 is expressed by NSPCs and its activation negatively modulates the proliferation of NSPCs, highlighting the importance of GPER1 in regulating NSPC behaviors.

An accessible and high-throughput strategy of continuously monitoring apoptosis by fluorescent detection of caspase activation

We present a real-time, high-throughput, and cost-effective method of detecting apoptosis in vitro using a previously developed reagent that detects caspase activation by fluorescence. Current methods of assessing apoptosis fail to account for the dimension of time, and thus are limited in data yielded per sample. This reagent allows real-time detection of apoptosis, but until now has been restricted to a costly automated detection system. Here, we describe apoptosis detection with the Essen Bioscience IncuCyte^® Caspase-3/7 Reagent using a multimode microplate reader, a common instrument in biological laboratories, which may be used prior to or in lieu of the automated system. This modified microplate reader apoptosis assay was validated against the established automated system, and was shown to detect a strong dose-response relationship (automated system r² = 0.9968, microplate reader r² = 0.9924). We also propose a quick and reliable method of quantifying cell density by Hoechst 33342 nuclear staining in microplates (r² = 0.8812 between Hoechst signal and cell density). We assert that the dimension of time should not be overlooked, and that the method presented here is an accessible strategy for many researchers due to low startup cost and precise detection of apoptosis in real time.

Primary biocompatibility tests of poly(lactide-co-glycolide)-(poly-L-orithine/fucoidan) core-shell nanocarriers

Layer-by-layer (LbL) self-assembly is the technology used in intermolecular static electricity, hydrogen bonds, covalent bonds and other polymer interactions during film assembling. This technology has been widely studied in the drug carrier field. Given their use in drug delivery systems, the biocompatibility of these potential compounds should be addressed. In this work, the primary biocompatibility of poly(lactide-co-glycolide)-(poly-L-orithine/fucoidan) [PLGA-(PLO/fucoidan)] core-shell nanoparticles (NPs) was investigated. Atomic force microscopy revealed the PLGA-(PLO/Fucoidan)₄ NPs to be spherical, with a uniform size distribution and a smooth surface, and the NPs were stable in physiological saline. The residual amount of methylene chloride was further determined by headspace gas chromatography, in which the organic solvent can be volatilized during preparation. Furthermore, cell viability, acridine orange/ethidium bromide staining, haemolysis and mouse systemic toxicity were all assessed to show that PLGA-(PLO/fucoidan)₄ NPs were biocompatible with cells and mice. Therefore, these NPs are expected to have potential applications in future drug delivery systems.

Hereditary multiple exostoses: are there new plausible treatment strategies?

Introduction

Hereditary multiple exostoses (HME) is a rare congenital pediatric disorder characterized by osteochondromas forming next to the growth plates in young patients. The osteochondromas cause multiple health problems that include skeletal deformities and chronic pain. Surgery is used to remove the most symptomatic osteochondromas but because of their large number, many are left in place, causing life-long problems and increasing the probability of malignant transformation. There is no other treatment to prevent or reduce osteochondromas formation at present.

Areas covered

Recent studies reviewable through PubMed are providing new insights into cellular and molecular mechanisms of osteochondroma development. The resulting data are suggesting rational and plausible new therapeutic strategies for osteochondroma prevention some of which are being tested in HME animal models and one of which is part of a just announced clinical trial.

Expert Commentary

This section summarizes and evaluates such strategies and points also to possible future alternatives.

2D versus 3D human induced pluripotent stem cell-derived cultures for neurodegenerative disease modelling

Neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and amyotrophic lateral sclerosis (ALS), affect millions of people every year and so far, there are no therapeutic cures available. Even though animal and histological models have been of great aid in understanding disease mechanisms and identifying possible therapeutic strategies, in order to find disease-modifying solutions there is still a critical need for systems that can provide more predictive and physiologically relevant results. One possible avenue is the development of patient-derived models, e.g. by reprogramming patient somatic cells into human induced pluripotent stem cells (hiPSCs), which can then be differentiated into any cell type for modelling. These systems contain key genetic information from the donors, and therefore have enormous potential as tools in the investigation of pathological mechanisms underlying disease phenotype, and progression, as well as in drug testing platforms. hiPSCs have been widely cultured in 2D systems, but in order to mimic human brain complexity, 3D models have been proposed as a more advanced alternative. This review will focus on the use of patient-derived hiPSCs to model AD, PD, HD and ALS. In brief, we will cover the available stem cells, types of 2D and 3D culture systems, existing models for neurodegenerative diseases, obstacles to model these diseases in vitro, and current perspectives in the field.

Transplantation of hypoxic preconditioned neural stem cells benefits functional recovery via enhancing neurotrophic secretion after spinal cord injury in rats

Spinal cord injury (SCI) is a debilitating, costly, and common pathological condition that affects the function of central nervous system (CNS). To date, there are few promising therapeutic strategies available for SCI. To look for a suitable therapeutic strategy, we have developed a sublethal hypoxic preconditioning procedure using Fluorescence-activated cell sorting (FACS) analysis, LDH releasing, and cell viability assays in vitro. Meanwhile, we have examined the benefits of neural stem cells (NSCs) transplantation prior to hypoxic preconditioning on functional recovery and potential mechanism via MRI screening, H&E, and Nissl staining, immunofluorescence staining and Elisa assays. Our data showed that transplantation of hypoxic prconditioned NSCs could enhance neuronal survival, especially 5-TH⁺ and ChAT⁺ neurons, in the injured spinal cord to reinforce functional benefits. The hypoxia exposure upregulated HIF-1α, neurotrophic and growth factors including neurotrophin-3 (NT-3), glial cell-derived neurotrophic factor (GDNF), and brain-derived neurotrophic factor (BDNF) in vitro and in vivo. Furthermore, functional recovery, including locomotor and hypersensitivities to mechanical and thermal stimulation assessed via behavioral and sensory tests, improved significantly in rats with engraftment of NSCs after hypoxia exposure from day 14 post-SCI, compared with the control and N-NSCs groups. In short, the approach employed in this study could result in functional recovery via upregulating neurotrophic and growth factors, which implies that hypoxic preconditioning strategy could serve as an effective and feasible strategy for cell-based therapy in the treatment of SCI in rats.

Cell density-dependent differential proliferation of neural stem cells on omnidirectional nanopore-arrayed surface

Recently, the importance of surface nanotopography in the determination of stem cell fate and behavior has been revealed. In the current study, we generated polystyrene cell-culture dishes with an omnidirectional nanopore arrayed surface (ONAS) (diameter: 200 nm, depth: 500 nm, center-to-center distance: 500 nm) and investigated the effects of nanotopography on rat neural stem cells (NSCs). NSCs cultured on ONAS proliferated better than those on the flat surface when cell density was low and showed less spontaneous differentiation during proliferation in the presence of mitogens. Interestingly, NSCs cultured on ONAS at clonal density demonstrated a propensity to generate neurospheres, whereas those on the flat surface migrated out, proliferated as individuals, and spread out to attach to the surface. However, the differential patterns of proliferation were cell density-dependent since the distinct phenomena were lost when cell density was increased. ONAS modulated cytoskeletal reorganization and inhibited formation of focal adhesion, which is generally observed in NSCs grown on flat surfaces. ONAS appeared to reinforce NSC-NSC interaction, restricted individual cell migration and prohibited NSC attachment to the nanopore surface. These data demonstrate that ONAS maintains NSCs as undifferentiated while retaining multipotency and is a better topography for culturing low density NSCs.

M2 microglia promotes neurogenesis and oligodendrogenesis from neural stem/progenitor cells via the PPARγ signaling pathway

Neural stem/progenitor cells (NSPCs) are an important source of cells for cell replacement therapy after nerve injury. How to induce NSPCs differentiation towards neurons and oligodendrocytes is a challenging issue in neuroscience research. In the present study, we polarized microglia into M1 and M2 phenotype, used their supernatants to induce NSPCs differentiation, and investigated the effects of different microglia phenotypes on NSPCs differentiation and their mechanisms. We discovered that, after exposure to M1 phenotype supernatant, NSPCs differentiated into fewer Tuj-1+ and Olig2+ cells, but more GFAP+ cells. Meanwhile, a significantly increased number of Tuj-1+ and Olig2+ cells and smaller number of GFAP+ cells were generated by M2 microglia supernatant-induced NSPCs differentiation. We also observed that 15d-PGJ₂, an endogenous ligand of PPARγ, was elevated in M2 phenotype supernatant and could activate PPARγ expression in NSPCs, whereas use of the PPARγ inhibitor GW9662, could reduce the percentage of differentiated neurons and oligodendrocytes. Our study results confirm that M2 microglia supernatant can activate the PPARγ signaling pathway and promote neurogenesis and oligodendrogenesis from NSPCs differentiation. The present study provides a further theoretical basis for induction of NSPCs oriented differentiation.