Neurospheres: a potential in vitro model for the study of central nervous system disorders

Establishing Minimum Criteria for Stem Cells from Human Exfoliated Deciduous Teeth (SHEDs) Cultured in Human Platelet Lysate (hPL)-Contained Media as Cell Therapy Candidates: Characterization and Predictive Analysis of Secretome Effects

SHEDs have demonstrated significant potential in cell therapy due to their superior proliferation rate, self-renewal and differentiation capacity (particularly neurogenesis attributed to their neural crest origin), and the less invasive procedure required for tissue collection compared to other stem cells. However, there is no established criterion to verify the minimum qualification to select one from numerous candidates, especially for SHEDs' cultured FBS-free medium for clinic application. For that, we performed a characteristic analysis containing the growth rate, colony-forming unit (CFU) number, average colony size, and migration capacity with hPL-cultured SHEDs from 21 different donors, and we suggest the result as a minimum standard to filter out unqualified candidates. In addition, in the secretome analysis to predict the paracrine effect, it was found that upregulated proteins compared to the control were related to angiogenesis, immune response, and BMP signaling, and this was found to have a strong correlation only with protein concentration. This study presents a minimum standard for selecting cell therapy candidates and suggests the protein concentration of a conditioned medium as a cost-effective tool to expect the paracrine effect of SHEDs.

Pyriproxyfen, villain or good guy? A brief review

Pyriproxyfen (PPF) acts as a juvenile growth regulator, interfering with normal metamorphosis and blocking the development of insects into adulthood. Although the World Health Organization (WHO) considers the use of PPF at a concentration of 0.01 mg/L as unlikely to pose health risks, recent studies have unveiled potential risks associated with PPF exposure to non-target organisms. Exposure to PPF disrupts insect development primarily by mimicking juvenile hormones; therefore, concerns linger over its impact on unintended species. Studies have highlighted the adverse effects of PPF on aquatic invertebrates, fish, and amphibians and revealed mortality and developmental abnormalities in non-target mosquito species exposed to PPF-treated water. Moreover, PPF may act as an endocrine disruptor, interfering with hormonal pathways crucial for growth, reproduction, and behavior in exposed organisms. Amphibians, for instance, display altered reproductive physiology and developmental abnormalities due to disruptions in endocrine signaling pathways caused by PPF. The ecological ramifications of PPF extend beyond direct toxicity to non-target species. Indirect effects include shifts in food web dynamics and ecosystem functioning. Reductions in insect populations, induced by PPF, can disrupt food availability for higher trophic levels, potentially destabilizing community structure and ecosystem equilibrium. Given mounting evidence of unintended consequences, robust risk assessment and regulatory oversight are imperative. Accurate classification of PPF by regulatory bodies is essential to balancing its role in disease control and pest management benefits with the need to safeguard non-target species and maintain ecosystem health. Future research must prioritize comprehensive assessments of PPF's ecological impact across various habitats and taxa to inform evidence-based policymaking.

In vivo mouse models for adult brain tumors: Exploring tumorigenesis and advancing immunotherapy development

Brain tumors, particularly glioblastoma (GBM), are devastating and challenging to treat, with a low 5-year survival rate of only 6.6%. Mouse models are established to understand tumorigenesis and develop new therapeutic strategies. Large-scale genomic studies have facilitated the identification of genetic alterations driving human brain tumor development and progression. Genetically engineered mouse models (GEMMs) with clinically relevant genetic alterations are widely used to investigate tumor origin. Additionally, syngeneic implantation models, utilizing cell lines derived from GEMMs or other sources, are popular for their consistent and relatively short latency period, addressing various brain cancer research questions. In recent years, the success of immunotherapy in specific cancer types has led to a surge in cancer immunology-related research which specifically necessitates the utilization of immunocompetent mouse models. In this review, we provide a comprehensive summary of GEMMs and syngeneic mouse models for adult brain tumors, emphasizing key features such as model origin, genetic alteration background, oncogenic mechanisms, and immune-related characteristics. Our review serves as a valuable resource for the brain tumor research community, aiding in the selection of appropriate models to study cancer immunology.

Overcoming the limits of pediatric brain tumor radiotherapy: The use of preclinical 3D models

Radiotherapy (RT) is an integral part of managing pediatric brain tumors, yet many patients develop tumor radioresistance, leading to recurrence and poor clinical outcomes. In addition, neurocognitive impairment is a common long-term side effect of RT, significantly impairing quality of life. Indeed, increasing evidence suggests that the developing child's brain is particularly vulnerable to the neurotoxic effects of ionizing radiation. Consequently, developing novel preclinical models is crucial for studying radiation's impact on normal brain tissue and predicting patient-specific responses to RT, enabling the development of personalized therapies combined with RT. However, this area remains underexplored, primarily due to the transfer of results gathered from in vitro tumor models from adults to pediatric entities while the location and molecular characteristics of the brain tumor differ. Recent years have seen the emergence of patient-specific 3D in vitro models, which have been established for entities including glioblastoma and medulloblastoma. These models better mimic primary parenteral tumors more closely in their histological, transcriptional, and mutational characteristics, thus approximating their intratumoral heterogeneity more accurately than conventional 2D-models. In this review, we presented the main limits of pediatric brain tumor radiotherapy, including mechanisms of radioresistance, associated tumor relapse, and the side effects of irradiation on the central nervous system. We also conducted an exhaustive review to identify studies utilizing basic or advanced 3D models of pediatric brain tumors combined with irradiation and discussed how these models can overcome the limitations of RT.

Bradykinin promotes immune responses in differentiated embryonic neurospheres carrying APPswe and PS1dE9 mutations

BACKGROUND

Neural progenitor cells (NPCs) can be cultivated from developing brains, reproducing many of the processes that occur during neural development. They can be isolated from a variety of animal models, such as transgenic mice carrying mutations in amyloid precursor protein (APP) and presenilin 1 and 2 (PSEN 1 and 2), characteristic of familial Alzheimer's disease (fAD). Modulating the development of these cells with inflammation-related peptides, such as bradykinin (BK) and its antagonist HOE-140, enables the understanding of the impact of such molecules in a relevant AD model.

RESULTS

We performed a global gene expression analysis on transgenic neurospheres treated with BK and HOE-140. To validate the microarray data, quantitative real-time reverse-transcription polymerase chain reaction (RT-PCR) was performed on 8 important genes related to the immune response in AD such as CCL12, CCL5, CCL3, C3, CX3CR1, TLR2 and TNF alpha and Iba-1. Furthermore, comparative analysis of the transcriptional profiles was performed between treatments, including gene ontology and reactome enrichment, construction and analysis of protein-protein interaction networks and, finally, comparison of our data with human dataset from AD patients. The treatments affected the expression levels of genes mainly related to microglia-mediated neuroinflammatory responses, with BK promoting an increase in the expression of genes that enrich processes, biological pathways, and cellular components related to immune dysfunction, neurodegeneration and cell cycle. B2 receptor inhibition by HOE-140 resulted in the reduction of AD-related anomalies caused in this system.

CONCLUSIONS

BK is an important immunomodulatory agent and enhances the immunological changes identified in transgenic neurospheres carrying the genetic load of AD. Bradykinin treatments modulate the expression rates of genes related to microglia-mediated neuroinflammation. Inhibiting bradykinin activity in Alzheimer's disease may slow disease progression.

Astroglial Cells: Emerging Therapeutic Targets in the Management of Traumatic Brain Injury

Traumatic Brain Injury (TBI) represents a significant health concern, necessitating advanced therapeutic interventions. This detailed review explores the critical roles of astrocytes, key cellular constituents of the central nervous system (CNS), in both the pathophysiology and possible rehabilitation of TBI. Following injury, astrocytes exhibit reactive transformations, differentiating into pro-inflammatory (A1) and neuroprotective (A2) phenotypes. This paper elucidates the interactions of astrocytes with neurons, their role in neuroinflammation, and the potential for their therapeutic exploitation. Emphasized strategies encompass the utilization of endocannabinoid and calcium signaling pathways, hormone-based treatments like 17β-estradiol, biological therapies employing anti-HBGB1 monoclonal antibodies, gene therapy targeting Connexin 43, and the innovative technique of astrocyte transplantation as a means to repair damaged neural tissues.

Neuroprotective Effect of Combined Treatment with Epigallocatechin 3-Gallate and Melatonin on Familial Alzheimer's Disease PSEN1 E280A Cerebral Spheroids Derived from Menstrual Mesenchymal Stromal Cells

Background

Familial Alzheimer's disease (FAD) is caused by mutations in one or more of 3 genes known as AβPP, PSEN1, and PSEN2. There are currently no effective therapies for FAD. Hence, novel therapeutics are needed.

Objective

To analyze the effect of treatment with a combination of epigallocatechin-3-gallate (EGCG) and Melatonin (N-acetyl-5-methoxytryptamine, aMT) in a cerebral spheroid (CS) 3D in vitro model of PSEN 1 E280A FAD.

Methods

We developed a CS in vitro model based on menstrual stromal cells derived from wild-type (WT) and mutant PSEN1 E280A menstrual blood cultured in Fast-N-Spheres V2 medium.

Results

Beta-tubulin III, choline acetyltransferase, and GFAP in both WT and mutant CSs spontaneously expressed neuronal and astroglia markers when grown in Fast-N-Spheres V2 medium for 4 or 11 days. Mutant PSEN1 CSs had significantly increased levels of intracellular AβPP fragment peptides and concomitant appearance of oxidized DJ-1 as early as 4 days, and phosphorylated tau, decreased ΔΨm, and increased caspase-3 activity were observed on Day 11. Moreover, mutant CSs were unresponsive to acetylcholine. Treatment with a combination of EGCG and aMT decreased the levels of all typical pathological markers of FAD more efficiently than did EGCG or aMT alone, but aMT failed to restore Ca2+ influx in mutant CSs and decreased the beneficial effect of EGCG on Ca2+ influx in mutant CSs.

Conclusion

Treatment with a combination of EGCG and aMT can be of high therapeutic value due to the high antioxidant capacity and anti-amyloidogenic effect of both compounds.

Characterization of neural stem cells derived from human stem cells from the apical papilla undergoing three-dimensional neurosphere induction

OBJECTIVES

The endogenous repairing based on the activation of neural stem cells (NSCs) is impaired by neurodegenerative diseases. The present study aims to characterize human stem cells from the apical papilla (hSCAPs) with features of mesenchymal stem cells (MSCs) and to demonstrate the neuronal differentiation of hSCAPs into NSCs through the formation of three-dimensional (3D) neurospheres, verifying the structural, immunophenotyping, self-renewal, gene expression and neuronal activities of these cells to help further improve NSCs transplantation.

METHODOLOGY

The hSCAPs were isolated from healthy impacted human third molar teeth and characterized as MSCs. They were then induced into 3D-neurospheres using a specific neural induction medium. Subsequently, the intra-neurospheral cells were confirmed to be NSCs by the identification of Nissl substance and the analysis of immunofluorescence staining, self-renewal ability, and gene expression of the cells. Moreover, the neuronal activity was investigated using intracellular calcium oscillation.

RESULTS

The isolated cells from the human apical papilla expressed many markers of MSCs, such as self-renewal ability and multilineage differentiation. These cells were thus characterized as MSCs, specifically as hSCAPs. The neurospheres induced from hSCAPs exhibited a 3D-floating spheroidal shape and larger neurospheres, and consisted of a heterogeneous population of intra-neurospheral cells. Further investigation showed that these intra-neurospheral cells had Nissl body staining and also expressed both Nestin and SOX2. They presented a self-renewal ability as well, which was observed after their disaggregation. Their gene expression profiling also exhibited a significant amount of NSC markers (NES, SOX1, and PAX6). Lastly, a large and dynamic change of the fluorescent signal that indicated calcium ions (Ca2+) was detected in the intracellular calcium oscillation, which indicated the neuronal activity of NSCs-derived hSCAPs.

CONCLUSIONS

The hSCAPs exhibited properties of MSCs and could differentiate into NSCs under 3D-neurosphere generation. The present findings suggest that NSCs-derived hSCAPs may be used as an alternative candidates for cell-based therapy, which uses stem cell transplantation to further treat neurodegenerative diseases.

Isolation and Differentiation of Neurons and Glial Cells from Olfactory Epithelium in Living Subjects

The study of psychiatric and neurological diseases requires the substrate in which the disorders occur, that is, the nervous tissue. Currently, several types of human bio-specimens are being used for research, including postmortem brains, cerebrospinal fluid, induced pluripotent stem (iPS) cells, and induced neuronal (iN) cells. However, these samples are far from providing a useful predictive, diagnostic, or prognostic biomarker. The olfactory epithelium is a region close to the brain that has received increased interest as a research tool for the study of brain mechanisms in complex neuropsychiatric and neurological diseases. The olfactory sensory neurons are replaced by neurogenesis throughout adult life from stem cells on the basement membrane. These stem cells are multipotent and can be propagated in neurospheres, proliferated in vitro and differentiated into multiple cell types including neurons and glia. For all these reasons, olfactory epithelium provides a unique resource for investigating neuronal molecular markers of neuropsychiatric and neurological diseases. Here, we describe the isolation and culture of human differentiated neurons and glial cells from olfactory epithelium of living subjects by an easy and non-invasive exfoliation method that may serve as a useful tool for the research in brain diseases.

Differentiation of neurosphere after transplantation into the damaged spinal cord

This study aimed to compare the differentiation and survival of human neural stem/progenitor cells of various origins in vitro and after transplantation into the injured spinal cord of laboratory animals. Rats with simulated spinal cord injury were transplanted with neurosphere cells obtained by directed differentiation of HUES6 cell lines. Fluorescence microscopy was used to visualize the obtained results. HUES6#1 and iPSC#1 neurospheres showed a wide range of markers associated with glial differentiation. The expression of the proliferation marker Ki67 did not exceed 25%, both in the lines of early and late neurospheres. Although neurospheres did not fully differentiate into astrocytes in vitro, they massively approached the GFAP+ astrocyte phenotype when exposed to the transplanted environment. PSC-derived neurospheres transplanted into the site of SM injury without additional growth factors showed only moderate survival, a significant degree of differentiation into astrocytes, and moderate differentiation into neurons. The difference in the survival and differentiation of HUES6#1 and iPSC#1 neurospheres, both in vitro and in vivo, can be explained by the difference in the regulatory behavior of signaling molecules corresponding to the source of origin of PSCs. Derivatives of human PSCs of various origins obtained according to the described differentiation protocol did not mature into astrocytic populations, nor did the glycogenic transition of PSC-derived NSCs occur in vitro. The study demonstrated the impact of the injured spinal cord microenvironment on the differentiation of transplanted HUES6#1 and iPSC#1 into astrocytes. The results showed that HUES6-derived neurospheres generated 90% of GFAP+ astrocytes and 5-10% of early neurons, while iPSC-derived neurospheres generated an average of 74% GFAP+ astrocytes and 5% of early neurons in vivo.

Advanced 3D Models of Human Brain Tissue Using Neural Cell Lines: State-of-the-Art and Future Prospects

Human-relevant three-dimensional (3D) models of cerebral tissue can be invaluable tools to boost our understanding of the cellular mechanisms underlying brain pathophysiology. Nowadays, the accessibility, isolation and harvesting of human neural cells represents a bottleneck for obtaining reproducible and accurate models and gaining insights in the fields of oncology, neurodegenerative diseases and toxicology. In this scenario, given their low cost, ease of culture and reproducibility, neural cell lines constitute a key tool for developing usable and reliable models of the human brain. Here, we review the most recent advances in 3D constructs laden with neural cell lines, highlighting their advantages and limitations and their possible future applications.

Taurine Promotes Differentiation and Maturation of Neural Stem/Progenitor Cells from the Subventricular Zone via Activation of GABAA Receptors

Neurogenesis, the formation of new neurons in the brain, occurs throughout the lifespan in the subgranular zone of the dentate gyrus and subventricular zone (SVZ) lining the lateral ventricles of the mammal brain. In this process, gamma-aminobutyric acid (GABA) and its ionotropic receptor, the GABA_A receptor (GABA_AR), play a critical role in the proliferation, differentiation, and migration process of neural stem/progenitor cells (NPC). Taurine, a non-essential amino acid widely distributed throughout the central nervous system, increases the proliferation of SVZ progenitor cells by a mechanism that may involve GABA_AR activation. Therefore, we characterized the effects of taurine on the differentiation process of NPC expressing GABA_AR. Preincubation of NPC-SVZ with taurine increased microtubule-stabilizing proteins assessed with the doublecortin assay. Taurine, like GABA, stimulated a neuronal-like morphology of NPC-SVZ and increased the number and length of primary, secondary, and tertiary neurites compared with control NPC of the SVZ. Furthermore, neurite outgrowth was prevented when simultaneously incubating cells with taurine or GABA and the GABA_AR blocker, picrotoxin. Patch-clamp recordings revealed a series of modifications in the NPCs' passive and active electrophysiological properties exposed to taurine, including regenerative spikes with kinetic properties similar to the action potentials of functional neurons.

Docosahexaenoic Acid and Melatonin Prevent Impaired Oligodendrogenesis Induced by Intrauterine Growth Restriction (IUGR)

In this study, our aims were to characterize oligodendrogenesis alterations in fetuses with intrauterine growth restriction (IUGR) and to find therapeutic strategies to prevent/treat them using a novel rabbit in vitro neurosphere culture. IUGR was surgically induced in one uterine horn of pregnant rabbits, while the contralateral horn served as a control. Neural progenitor cells (NPCs) were obtained from pup’s whole brain and cultured as neurospheres mimicking the basic processes of brain development including migration and cell differentiation. Five substances, chosen based on evidence provided in the literature, were screened in vitro in neurospheres from untreated rabbits: Docosahexaenoic acid (DHA), melatonin (MEL), zinc, 3,3′,5-Triiodo-L-thyronine (T3), and lactoferrin (LF) or its metabolite sialic acid (SA). DHA, MEL and LF were further selected for in vivo administration and subsequent evaluation in the Neurosphere Assay. In the IUGR culture, we observed a significantly reduced percentage of oligodendrocytes (OLs) which correlated with clinical findings indicating white matter injury in IUGR infants. We identified DHA and MEL as the most effective therapies. In all cases, our in vitro rabbit neurosphere assay predicted the outcome of the in vivo administration of the therapies and confirmed the reliability of the model, making it a powerful and consistent tool to select new neuroprotective therapies.

Spherical Invasion Assay: A Novel Method to Measure Invasion of Cancer Cells

The invasion of tumor cells into the neighboring blood vessels and lymph nodes is a vital step for distant metastasis. Traditionally, the invasive activity of growth factors (or the anti-invasive activity of drugs) is measured with the Boyden chamber assay. However, this assay has a few disadvantages like poor physiological relevance of transwell inserts and an inability to control chemokine gradients. The Boyden chamber assay is one of the most prevalent methods to measure the invasion of cancer cells. It would be advantageous to develop another assay that could validate the results of the Boyden chamber assay. With this in mind, our laboratory developed the spherical invasion assay (SIA) to measure the pro-invasive activity of human cancer cells. The SIA also circumvents some of the drawbacks of the Boyden chamber assay. The present manuscript measures the anti-invasive activity of the Src kinase inhibitor PP2 in A549 human non-small cell lung carcinoma (NSCLC) cells using the SIA. The SIA protocol is comprised of two steps. In the first step, A549 human NSCLC cells (treated or not with PP2) were mixed with Matrigel and seeded in the middle of an eight-well chamber slide. After 24 h, a second layer of Matrigel was overlaid over the first layer. Over the course of the next 24 h, the A549 cells invade from the primary to the secondary Matrigel layers. Subsequently, the cells are visualized by phase-contrast microscopy and the images obtained are quantified using ImageJ to calculate the anti-invasive activity of PP2 in A549 cells. The results of the SIA correlate well with Boyden chamber assays. The SIA may be adapted for multiple experimental designs, such as drug screening (to combat invasion and metastasis), measuring the pro-invasive activity of growth factors, and elucidating the signaling pathways underlying the pro-invasive/anti-invasive activity of biological modifiers. Graphic abstract: Diagrammatic illustration of the spherical invasion assay ( Hurley et al., 2017 ) . A. The first layer is comprised of human cancer cells mixed in a 1:1 suspension with Phenol Red containing Matrigel (represented as LAYER 1 in the figure). After 24 h, the cancer cells grow and extend up to the boundary of this first layer. B. A second layer of 1:1 solution Phenol Red-free Matrigel, in Phenol Red-free RPMI (represented as LAYER 2 in the figure) is added on top of the first Matrigel spot. The cells are incubated for 24 h at 37°C. C. Over these 24 h, the cancer cells invade from the primary layer into the secondary Matrigel layer. The chamber slides are observed by phase-contrast microscopy. D. A representative photograph of the images obtained by the SIA is shown. The black arrow indicates the cancer cells invading into the second layer of Matrigel. The dotted line represents the interface between the two layers. The distance to which the cells have traveled (into the secondary Matrigel layer) is measured at ten sites (for each photograph) in a randomized double-blind fashion by three independent observers, using NIH ImageJ Version 1.47. This process is repeated for three separate photographic fields per sample.

Human mini brains and spinal cords in a dish: Modeling strategies, current challenges, and prospective advances

Engineered three-dimensional (3D) in vitro and ex vivo neural tissues, also known as "mini brains and spinal cords in a dish," can be derived from different types of human stem cells via several differentiation protocols. In general, human mini brains are micro-scale physiological systems consisting of mixed populations of neural progenitor cells, glial cells, and neurons that may represent key features of human brain anatomy and function. To date, these specialized 3D tissue structures can be characterized into spheroids, organoids, assembloids, organ-on-a-chip and their various combinations based on generation procedures and cellular components. These 3D CNS models incorporate complex cell-cell interactions and play an essential role in bridging the gap between two-dimensional human neuroglial cultures and animal models. Indeed, they provide an innovative platform for disease modeling and therapeutic cell replacement, especially shedding light on the potential to realize personalized medicine for neurological disorders when combined with the revolutionary human induced pluripotent stem cell technology. In this review, we highlight human 3D CNS models developed from a variety of experimental strategies, emphasize their advances and remaining challenges, evaluate their state-of-the-art applications in recapitulating crucial phenotypic aspects of many CNS diseases, and discuss the role of contemporary technologies in the prospective improvement of their composition, consistency, complexity, and maturation.

Therapeutic Potential of Human Stem Cell Implantation in Alzheimer's Disease

Alzheimer's disease (AD) is a progressive debilitating neurodegenerative disease and the most common form of dementia in the older population. At present, there is no definitive effective treatment for AD. Therefore, researchers are now looking at stem cell therapy as a possible treatment for AD, but whether stem cells are safe and effective in humans is still not clear. In this narrative review, we discuss both preclinical studies and clinical trials on the therapeutic potential of human stem cells in AD. Preclinical studies have successfully differentiated stem cells into neurons in vitro, indicating the potential viability of stem cell therapy in neurodegenerative diseases. Preclinical studies have also shown that stem cell therapy is safe and effective in improving cognitive performance in animal models, as demonstrated in the Morris water maze test and novel object recognition test. Although few clinical trials have been completed and many trials are still in phase I and II, the initial results confirm the outcomes of the preclinical studies. However, limitations like rejection, tumorigenicity, and ethical issues are still barriers to the advancement of stem cell therapy. In conclusion, the use of stem cells in the treatment of AD shows promise in terms of effectiveness and safety.