scholarly journals Adult mouse retina explants: an ex vivo window to explore central nervous system diseases

2020 ◽  
Author(s):  
Julia Schaeffer ◽  
Celine Tardy ◽  
Floriane Albert ◽  
Stephane Belin ◽  
Homaira Nawabi
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Molecular Mechanisms ◽  
Axon Regeneration ◽  
Ex Vivo ◽  
Adult Retina ◽  
Cellular Events ◽  
Embryonic Neurons

ABSTRACTWhen the developing central nervous system (CNS) becomes mature, it loses its ability to regenerate. Therefore, any insult to adult CNS leads to a permanent and irreversible loss of motor and cognitive functions. For a long time, much effort has been deployed to uncover mechanisms of axon regeneration in the CNS. It is now well understood that neurons themselves lose axon regeneration capabilities during development, and also after a lesion or in pathological conditions. Since then, many molecular pathways such as mTOR and JAK/STAT have been associated with axon regeneration. However, no functional recovery has been achieved yet. Today, there is a need not only to identify new molecules implicated in adult CNS axon regeneration, but also to decipher the fine molecular mechanisms associated with regeneration failure. This is critical to make progress in our understanding of neuroprotection and neuroregeneration and for the development of new therapeutic strategies. In this context, it remains particularly challenging to address molecular mechanisms in in vivo models of CNS regeneration. The extensive use of embryonic neurons as in vitro model is a source of bias, as they have the intrinsic competence to grow their axon upon injury, unlike mature neurons. In addition, this type of dissociated neuronal cultures lack a tissue environment to recapitulate properly molecular and cellular events in vitro. Here, we propose to use cultures of adult retina explants to fill this gap. The visual system - which includes the retina and optic nerve - is a gold-standard model to study axon regeneration and degeneration in the mature CNS. Cultures of adult retina explants combine two advantages: they have the simplicity of embryonic neurons cultures and they recapitulate all the aspects of in vivo features in the tissue. Importantly, it is the most appropriate tool to date to isolate molecular and cellular events of axon regeneration and degeneration of the adult CNS in a dish. This ex vivo system allows to set up a large range of experiments to decipher the fine molecular and cellular regulations underlying mature CNS axon growth.

scholarly journals Adult Mouse Retina Explants: From ex vivo to in vivo Model of Central Nervous System Injuries

2020 ◽  
Vol 13 ◽  
Author(s):  
Julia Schaeffer ◽  
Céline Delpech ◽  
Floriane Albert ◽  
Stephane Belin ◽  
Homaira Nawabi
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Molecular Mechanisms ◽  
Axon Regeneration ◽  
Ex Vivo ◽  
Mouse Retina ◽  
In Vivo Model ◽  
Cns Regeneration ◽  
Single Axon

In mammals, adult neurons fail to regenerate following any insult to adult central nervous system (CNS), which leads to a permanent and irreversible loss of motor and cognitive functions. For a long time, much effort has been deployed to uncover mechanisms of axon regeneration in the CNS. Even if some cases of functional recovery have been reported, there is still a discrepancy regarding the functionality of a neuronal circuit upon lesion. Today, there is a need not only to identify new molecules implicated in adult CNS axon regeneration, but also to decipher the fine molecular mechanisms associated with regeneration failure. Here, we propose to use cultures of adult retina explants to study all molecular and cellular mechanisms that occur during CNS regeneration. We show that adult retinal explant cultures have the advantages to (i) recapitulate all the features observed in vivo, including axon regeneration induced by intrinsic factors, and (ii) be an ex vivo set-up with high accessibility and many downstream applications. Thanks to several examples, we demonstrate that adult explants can be used to address many questions, such as axon guidance, growth cone formation and cytoskeleton dynamics. Using laser guided ablation of a single axon, axonal injury can be performed at a single axon level, which allows to record early and late molecular events that occur after the lesion. Our model is the ideal tool to study all molecular and cellular events that occur during CNS regeneration at a single-axon level, which is currently not doable in vivo. It is extremely valuable to address unanswered questions of neuroprotection and neuroregeneration in the context of CNS lesion and neurodegenerative diseases.

Transcription factors Mash-1 and Prox-1 delineate early steps in differentiation of neural stem cells in the developing central nervous system

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 443-456 ◽  
Author(s):  
M.a. Torii ◽  
F. Matsuzaki ◽  
N. Osumi ◽  
K. Kaibuchi ◽  
S. Nakamura ◽  
...  
Keyword(s):  
Stem Cells ◽  
Central Nervous System ◽  
Nervous System ◽  
Transcription Factors ◽  
Cell Differentiation ◽  
Early Development ◽  
Molecular Mechanisms ◽  
Initial Step

Like other tissues and organs in vertebrates, multipotential stem cells serve as the origin of diverse cell types during genesis of the mammalian central nervous system (CNS). During early development, stem cells self-renew and increase their total cell numbers without overt differentiation. At later stages, the cells withdraw from this self-renewal mode, and are fated to differentiate into neurons and glia in a spatially and temporally regulated manner. However, the molecular mechanisms underlying this important step in cell differentiation remain poorly understood. In this study, we present evidence that the expression and function of the neural-specific transcription factors Mash-1 and Prox-1 are involved in this process. In vivo, Mash-1- and Prox-1-expressing cells were defined as a transient proliferating population that was molecularly distinct from self-renewing stem cells. By taking advantage of in vitro culture systems, we showed that induction of Mash-1 and Prox-1 coincided with an initial step of differentiation of stem cells. Furthermore, forced expression of Mash-1 led to the down-regulation of nestin, a marker for undifferentiated neuroepithelial cells, and up-regulation of Prox-1, suggesting that Mash-1 positively regulates cell differentiation. In support of these observations in vitro, we found specific defects in cellular differentiation and loss of expression of Prox-1 in the developing brain of Mash-1 mutant mice in vivo. Thus, we propose that induction of Mash-1 and Prox-1 is one of the critical molecular events that control early development of the CNS.

New Design Of Human T-ALL Transplantation In NSG Mice Uncovers The Major Role Of CD31/PECAM1 In The Central Nervous System Infiltration

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1436-1436
Author(s):  
Sandrine Poglio ◽  
Anne-Laure Bauchet ◽  
José Ramon Pineda ◽  
Caroline Deswarte ◽  
Thierry Leblanc ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Molecular Mechanisms ◽  
Receptor Expression ◽  
Leukemic Cells ◽  
Nsg Mice ◽  
Increased Risk ◽  
Major Player

Abstract T-cell acute lymphoblastic leukemia (T-ALL) is mainly a child and adolescent blood malignancy. T-ALL patients present an increased risk of Central Nervous System (CNS) relapse defined by leukemic cell infiltration in cerebrospinal fluid and brain. Using transgenic mice and T-ALL cell lines previous works have shown that T-ALL migration in CNS depends on CCR7 chemokine receptor expression (S. Buonamici et al., Nature, 2009). VE-cadherin and CD31/PECAM1 also seem implicated, as it has been shown in vitro (S. M. Akers et al., Exp Hematol, 2010). In patients, high level of IL-15 at diagnosis predicts current CNS invasion and sometimes at relapse (G. Cario et al., J Clin Oncol, 2007). So far no study has investigated mechanisms involved in CNS infiltration using T-ALL patient samples in vivo. In the present study we developed a mouse model of CNS infiltration using leukemic cells isolated from patients and transplanted into NOD/SCID IL2Rуc-/- (NSG) mice. Proper conditioning of NSG mice and different routes of injection were tested to define a protocol avoiding non-specific CNS infiltration of leukemic cells. Also bone marrow (BM) engraftment levels of leukemia between 60 to 100% were used to set up the excision time of hematopoietic tissues and brain. Leukemic blasts from 8 patients with or 9 patients without CNS invasion were grafted and brain infiltration was followed up using standard histology and immunohistochemistry techniques. Our data indicate that (1) under specific experimental procedures, leukemic cells from patients with CNS invasion did infiltrate mouse CNS (8/8 samples) whereas the majority of cells from “non-infiltrated” patients did not (7/9 samples), (2) leukemic cells recovered from NSG brain and BM were similar in terms of brain and/or BM infiltration in secondary transplant experiments. Moreover, T-Leukemia Initiating Cell frequency was the same whatever the BM or CNS origin of blasts in the primary recipient. Interestingly, analysis of blasts at diagnosis showed that surface expression of adhesion molecules can not discriminate CNS+ or CNS- leukemic cells. However, blocking of CD31 decreased in vitro migration of blasts from CNS+ compared to CNS- patients through endothelial layer derived from blood brain barrier cells. Pioneered in vivo experiments show that CNS+ blasts pre-treated with CD31 antibody and injected in NSG are less prone to colonize mouse brain. Moreover, knocking down CD31 in CNS+ T-ALL by lentiviral shRNA strategy impairs leukemia development in mice, further decreasing CNS infiltration, whatever injection routes is used including intrafemoral injection. In conclusion, T-ALL xenografts in NSG mice mimic CNS invasion in patients. CD31 is a major player in blast cells migration in vitro and brain infiltration in vivo. This new model opens a new area of investigation to improve our knowledge of the molecular mechanisms of CNS infiltration in T-ALL. Disclosures: No relevant conflicts of interest to declare.

scholarly journals INFLUENCE OF ANESTHESIA ON EXPERIMENTAL NEUROTROPIC VIRUS INFECTIONS

1946 ◽  
Vol 84 (4) ◽  
pp. 277-292 ◽  
Author(s):  
S. Edward Sulkin ◽  
Christine Zarafonetis ◽  
Andres Goth
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Diethyl Ether ◽  
Cervical Region ◽  
Virus Infections ◽  
Ether Anesthesia ◽  
Neurotropic Virus ◽  
Experimental Infections

Anesthesia with diethyl ether significantly alters the course and outcome of experimental infections with the equine encephalomyelitis virus (Eastern or Western type) or with the St. Louis encephalitis virus. No comparable effect is observed in experimental infections produced with rabies or poliomyelitis (Lansing) viruses. The neurotropic virus infections altered by ether anesthesia are those caused by viruses which are destroyed in vitro by this anesthetic, and those infections not affected by ether anesthesia are caused by viruses which apparently are not destroyed by ether in vitro. Another striking difference between these two groups of viruses is their pathogenesis in the animal host; those which are inhibited in vivo by ether anesthesia tend to infect cells of the cortex, basal ganglia, and only occasionally the cervical region of the cord. On the other hand, those which are not inhibited in vivo by ether anesthesia tend to involve cells of the lower central nervous system and in the case of rabies, peripheral nerves. This difference is of considerable importance in view of the fact that anesthetics affect cells of the lower central nervous system only in very high concentrations. It is obvious from the complexity of the problem that no clear-cut statement can be made at this point as to the mechanism of the observed effect of ether anesthesia in reducing the mortality rate in certain of the experimental neurotropic virus infections. Important possibilities include a direct specific effect of diethyl ether upon the virus and a less direct effect of the anesthetic upon the virus through its alteration of the metabolism of the host cell.

scholarly journals Astrocyte-Derived CCL2 is Associated with M1 Activation and Recruitment of Cultured Microglial Cells

2016 ◽  
Vol 38 (3) ◽  
pp. 859-870 ◽  
Author(s):  
Mingfeng He ◽  
Hongquan Dong ◽  
Yahui Huang ◽  
Shunmei Lu ◽  
Shu Zhang ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Microglial Activation ◽  
Culture Media ◽  
Microglial Cells ◽  
Migration Ability ◽  
Migration Assay ◽  
Tnf Α

Background/Aims: Microglia are an essential player in central nervous system inflammation. Recent studies have demonstrated that the astrocytic chemokine, CCL2, is associated with microglial activation in vivo. However, CCL2-induced microglial activation has not yet been studied in vitro. The purpose of the current study was to understand the role of astrocyte-derived CCL2 in microglial activation and to elucidate the underlying mechanism(s). Methods: Primary astrocytes were pre-treated with CCL2 siRNA and stimulated with TNF-α. The culture medium (CM) was collected and added to cultures of microglia, which were incubated with and without CCR2 inhibitor. Microglial cells were analyzed by quantitative RT-PCR to determine whether they polarized to the M1 or M2 state. Microglial migratory ability was assessed by transwell migration assay. Results: TNF-α stimulated the release of CCL2 from astrocytes, even if the culture media containing TNF-α was replaced with fresh media after 3 h. CM from TNF-α-stimulated astrocytes successfully induced microglial activation, which was ascertained by increased activation of M1 and enhanced migration ability. In contrast, CM from astrocytes pretreated with CCL2 siRNA showed no effect on microglial activation, compared to controls. Additionally, microglia pre-treated with RS102895, a CCR2 inhibitor, were resistant to activation by CM from TNF-α-stimulated astrocytes. Conclusion: This study demonstrates that the CCL2/CCR2 pathway of astrocyte-induced microglial activation is associated with M1 polarization and enhanced migration ability, indicating that this pathway could be a useful target to ameliorate inflammation in the central nervous system.

scholarly journals Fishing for Targets of Alien Metabolites: A Novel Peroxisome Proliferator-Activated Receptor (PPAR) Agonist from a Marine Pest

Marine Drugs ◽  
2018 ◽  
Vol 16 (11) ◽  
pp. 431 ◽  
Author(s):  
Rosa Vitale ◽  
Enrico D'Aniello ◽  
Stefania Gorbi ◽  
Andrea Martella ◽  
Cristoforo Silvestri ◽  
...  
Keyword(s):  
Native Species ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Invasion Biology ◽  
In Vitro Assays ◽  
Bioactive Metabolites ◽  
Peroxisome Proliferator ◽  
Invasive Pests

Although the chemical warfare between invasive and native species has become a central problem in invasion biology, the molecular mechanisms by which bioactive metabolites from invasive pests influence local communities remain poorly characterized. This study demonstrates that the alkaloid caulerpin (CAU)—a bioactive component of the green alga Caulerpa cylindracea that has invaded the entire Mediterranean basin—is an agonist of peroxisome proliferator-activated receptors (PPARs). Our interdisciplinary study started with the in silico prediction of the ligand-protein interaction, which was then validated by in vivo, ex vivo and in vitro assays. On the basis of these results, we candidate CAU as a causal factor of the metabolic and behavioural disorders observed in Diplodus sargus, a native edible fish of high ecological and commercial relevance, feeding on C. cylindracea. Moreover, given the considerable interest in PPAR activators for the treatment of relevant human diseases, our findings are also discussed in terms of a possible nutraceutical/pharmacological valorisation of the invasive algal biomasses, supporting an innovative strategy for conserving biodiversity as an alternative to unrealistic campaigns for the eradication of invasive pests.

scholarly journals Polo-Like Kinase 4 (PLK4) Is Overexpressed in Central Nervous System Neuroblastoma (CNS-NB)

2018 ◽  
Vol 5 (4) ◽  
pp. 96 ◽  
Author(s):  
Anders Bailey ◽  
Amreena Suri ◽  
Pauline Chou ◽  
Tatiana Pundy ◽  
Samantha Gadd ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Brain Tumors ◽  
Meta Analysis ◽  
P Value ◽  
Embryonal Tumors ◽  
Expression Levels ◽  
Embryonal Brain

Neuroblastoma (NB) is the most common extracranial solid tumor in pediatrics, with rare occurrences of primary and metastatic tumors in the central nervous system (CNS). We previously reported the overexpression of the polo-like kinase 4 (PLK4) in embryonal brain tumors. PLK4 has also been found to be overexpressed in a variety of peripheral adult tumors and recently in peripheral NB. Here, we investigated PLK4 expression in NBs of the CNS (CNS-NB) and validated our findings by performing a multi-platform transcriptomic meta-analysis using publicly available data. We evaluated the PLK4 expression by quantitative real-time PCR (qRT-PCR) on the CNS-NB samples and compared the relative expression levels among other embryonal and non-embryonal brain tumors. The relative PLK4 expression levels of the NB samples were found to be significantly higher than the non-embryonal brain tumors (p-value < 0.0001 in both our samples and in public databases). Here, we expand upon our previous work that detected PLK4 overexpression in pediatric embryonal tumors to include CNS-NB. As we previously reported, inhibiting PLK4 in embryonal tumors led to decreased tumor cell proliferation, survival, invasion and migration in vitro and tumor growth in vivo, and therefore PLK4 may be a potential new therapeutic approach to CNS-NB.

scholarly journals Microbial enzymes induce colitis by reactivating triclosan in the mouse gastrointestinal tract

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Jianan Zhang ◽  
Morgan E. Walker ◽  
Katherine Z. Sanidad ◽  
Hongna Zhang ◽  
Yanshan Liang ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Metabolic Activation ◽  
Consumer Products ◽  
Environmental Chemicals ◽  
Intestinal Microbes ◽  
Targeted Inhibition

AbstractEmerging research supports that triclosan (TCS), an antimicrobial agent found in thousands of consumer products, exacerbates colitis and colitis-associated colorectal tumorigenesis in animal models. While the intestinal toxicities of TCS require the presence of gut microbiota, the molecular mechanisms involved have not been defined. Here we show that intestinal commensal microbes mediate metabolic activation of TCS in the colon and drive its gut toxicology. Using a range of in vitro, ex vivo, and in vivo approaches, we identify specific microbial β-glucuronidase (GUS) enzymes involved and pinpoint molecular motifs required to metabolically activate TCS in the gut. Finally, we show that targeted inhibition of bacterial GUS enzymes abolishes the colitis-promoting effects of TCS, supporting an essential role of specific microbial proteins in TCS toxicity. Together, our results define a mechanism by which intestinal microbes contribute to the metabolic activation and gut toxicity of TCS, and highlight the importance of considering the contributions of the gut microbiota in evaluating the toxic potential of environmental chemicals.

scholarly journals A genome-wide view of the de-differentiation of central nervous system endothelial cells in culture

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Mark F Sabbagh ◽  
Jeremy Nathans
Keyword(s):  
Central Nervous System ◽  
Endothelial Cells ◽  
Nervous System ◽  
In Vitro Culture ◽  
Vascular Endothelial Cells ◽  
Beta Catenin ◽  
A Genome ◽  
Accessible Chromatin

Vascular endothelial cells (ECs) derived from the central nervous system (CNS) variably lose their unique barrier properties during in vitro culture, hindering the development of robust assays for blood-brain barrier (BBB) function, including drug permeability and extrusion assays. In previous work (Sabbagh et al., 2018) we characterized transcriptional and accessible chromatin landscapes of acutely isolated mouse CNS ECs. In this report, we compare transcriptional and accessible chromatin landscapes of acutely isolated mouse CNS ECs versus mouse CNS ECs in short-term in vitro culture. We observe that standard culture conditions are associated with a rapid and selective loss of BBB transcripts and chromatin features, as well as a greatly reduced level of beta-catenin signaling. Interestingly, forced expression of a stabilized derivative of beta-catenin, which in vivo leads to a partial conversion of non-BBB CNS ECs to a BBB-like state, has little or no effect on gene expression or chromatin accessibility in vitro.

scholarly journals Novel in vitro Experimental Approaches to Study Myelination and Remyelination in the Central Nervous System

2021 ◽  
Vol 15 ◽  
Author(s):  
Davide Marangon ◽  
Nicolò Caporale ◽  
Marta Boccazzi ◽  
Maria P. Abbracchio ◽  
Giuseppe Testa ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Molecular Mechanisms ◽  
Disease Modeling ◽  
Brain Physiology ◽  
Pathological Conditions ◽  
Approaches To Study ◽  
The Central Nervous System ◽  
Experimental Approaches

Myelin is the lipidic insulating structure enwrapping axons and allowing fast saltatory nerve conduction. In the central nervous system, myelin sheath is the result of the complex packaging of multilamellar extensions of oligodendrocyte (OL) membranes. Before reaching myelinating capabilities, OLs undergo a very precise program of differentiation and maturation that starts from OL precursor cells (OPCs). In the last 20 years, the biology of OPCs and their behavior under pathological conditions have been studied through several experimental models. When co-cultured with neurons, OPCs undergo terminal maturation and produce myelin tracts around axons, allowing to investigate myelination in response to exogenous stimuli in a very simple in vitro system. On the other hand, in vivo models more closely reproducing some of the features of human pathophysiology enabled to assess the consequences of demyelination and the molecular mechanisms of remyelination, and they are often used to validate the effect of pharmacological agents. However, they are very complex, and not suitable for large scale drug discovery screening. Recent advances in cell reprogramming, biophysics and bioengineering have allowed impressive improvements in the methodological approaches to study brain physiology and myelination. Rat and mouse OPCs can be replaced by human OPCs obtained by induced pluripotent stem cells (iPSCs) derived from healthy or diseased individuals, thus offering unprecedented possibilities for personalized disease modeling and treatment. OPCs and neural cells can be also artificially assembled, using 3D-printed culture chambers and biomaterial scaffolds, which allow modeling cell-to-cell interactions in a highly controlled manner. Interestingly, scaffold stiffness can be adopted to reproduce the mechanosensory properties assumed by tissues in physiological or pathological conditions. Moreover, the recent development of iPSC-derived 3D brain cultures, called organoids, has made it possible to study key aspects of embryonic brain development, such as neuronal differentiation, maturation and network formation in temporal dynamics that are inaccessible to traditional in vitro cultures. Despite the huge potential of organoids, their application to myelination studies is still in its infancy. In this review, we shall summarize the novel most relevant experimental approaches and their implications for the identification of remyelinating agents for human diseases such as multiple sclerosis.

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