In Vivo Reprogramming for CNS Repair: Regenerating Neurons from Endogenous Glial Cells

Background: To date, there are no effective treatments for Alzheimer’s disease (AD). Thus, a significant need for research of therapies remains. Objective: One promising pharmacological target is the hormone fibroblast growth factor 21 (FGF21), which is thought to be neuroprotective. A clinical candidate for medical use could be the FGF21 analogue LY2405319 (LY), which has a specificity and potency comparable to FGF21. Methods: The present study investigated the potential neuroprotective effect of LY via PPARγ/apoE/abca1 pathway which is known to degrade amyloid-β (Aβ) plaques by using primary glial cells and hippocampal organotypic brain slice cultures (OBSCs) from 30- and 50-week-old transgenic APPswe/PS1dE9 (tg) mice. By LY treatment of 52-week-old tg mice with advanced Aβ deposition, we further aimed to elaborate the effect of LY on AD pathology in vivo. Results: LY application to primary glial cells caused an upregulation of pparγ, apoE, and abca1 mRNA expression and significantly decreased number and area of Aβ plaques in OBSCs. LY treatment in tg mice increased cerebral [18F] FDG uptake and N-acetylaspartate/creatine ratio indicating enhanced neuronal activity and integrity. Although LY did not reduce the number of Aβ plaques in tg mice, the number of iba1-positive cells was significantly decreased indicating reduced microgliosis. Conclusion: These data identified LY in vitro as an activator of Aβ degrading genes leading to cerebral Aβ load amelioration in early and late AD pathology. Although Aβ plaque reduction by LY failed in vivo, LY may be used as therapeutic agent to treat AD-related neuroinflammation and impaired neuronal integrity.

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Magnetic resonance spectroscopy and metabolism. Applications of proton and 13C NMR to the study of glutamate metabolism in cultured glial cells and human brain in vivo

Biochimie ◽

10.1016/0300-9084(91)90080-k ◽

1991 ◽

Vol 73 (1) ◽

pp. 93-97 ◽

Cited By ~ 22

Author(s):

J.C. Portais ◽

I. Pianet ◽

M. Allard ◽

M. Merle ◽

G. Raffard ◽

...

Keyword(s):

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Human Brain ◽

Glial Cells ◽

13C Nmr ◽

Resonance Spectroscopy ◽

Glutamate Metabolism

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Reaction of ependymal cells to spinal cord injury: a potential role for oncostatin pathway and microglial cells

10.1101/2021.02.12.428106 ◽

2021 ◽

Author(s):

R. Chevreau ◽

H Ghazale ◽

C Ripoll ◽

C Chalfouh ◽

Q Delarue ◽

...

Keyword(s):

Spinal Cord ◽

Spinal Cord Injury ◽

Glial Cells ◽

Mapk Signaling ◽

Central Canal ◽

Microglial Cells ◽

Ependymal Cells ◽

Rna Profiling ◽

Cord Injury

AbstractEpendymal cells with stem cell properties reside in the adult spinal cord around the central canal. They rapidly activate and proliferate after spinal cord injury, constituting a source of new cells. They produce neurons and glial cells in lower vertebrates but they mainly generate glial cells in mammals. The mechanisms underlying their activation and their glial-biased differentiation in mammals remain ill-defined. This represents an obstacle to control these cells. We addressed this issue using RNA profiling of ependymal cells before and after injury. We found that these cells activate STAT3 and ERK/MAPK signaling during injury and downregulate cilia-associated genes and FOXJ1, a central transcription factor in ciliogenesis. Conversely, they upregulate 510 genes, six of them more than 20 fold, namely Crym, Ecm1, Ifi202b, Nupr1, Rbp1, Thbs2 and Osmr. OSMR is the receptor for the inflammatory cytokine oncostatin (OSM) and we studied its regulation and role using neurospheres derived from ependymal cells. We found that OSM induces strong OSMR and p-STAT3 expression together with proliferation reduction and astrocytic differentiation. Conversely, production of oligodendrocyte-lineage OLIG1+ cells was reduced. OSM is specifically expressed by microglial cells and was strongly upregulated after injury. We observed microglial cells apposed to ependymal cells in vivo and co-cultures experiments showed that these cells upregulate OSMR in neurosphere cells. Collectively, these results support the notion that microglial cells and OSMR/OSM pathway regulate ependymal cells in injury. In addition, the generated high throughput data provides a unique molecular resource to study how ependymal cell react to spinal cord lesion.

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Comment on “Rapid and efficient in vivo astrocyte-to-neuron conversion with regional identity and connectivity?”

10.1101/2020.09.02.279273 ◽

2020 ◽

Author(s):

Gong Chen ◽

Wen Li ◽

Zongqin Xiang ◽

Liang Xu ◽

Minhui Liu ◽

...

Keyword(s):

Glial Cells ◽

Viral Vectors ◽

Ectopic Expression ◽

Regional Identity ◽

Neuronal Loss ◽

Critical Factor ◽

Dose Finding ◽

Toxic Dose ◽

Cell Conversion

ABSTRACTRegenerating functional new neurons in the adult mammalian central nervous system (CNS) has been proven to be very challenging due to the inability of neurons to divide and repopulate themselves after neuronal loss. In contrast, glial cells in the CNS can divide and repopulate themselves under injury or disease conditions. Therefore, many groups around the world have been able to utilize internal glial cells to directly convert them into neurons for neural repair. We have previously demonstrated that ectopic expression of NeuroD1 in dividing glial cells can directly convert reactive glial cells into neurons. However, Wang et al. recently posted an article in bioRxiv challenging the entire field of in vivo glia-to-neuron conversion after using one single highly toxic dose of AAV (2×1013 gc/ml, 1 μl) in the mouse cortex, producing artifacts that are very difficult to interpret. We present data here that reducing AAV dosage to safe level will avoid artifacts caused by toxic dosage. We also demonstrate with Aldh1l1-CreERT2 and Ai14 reporter mice that lineage-traced astrocytes can be successfully converted into NeuN+ neurons after infected by AAV5 GFAP::NeuroD1. Retroviral expression of NeuroD1 further confirms our previous findings that dividing glial cells can be converted into neurons. Together, the incidence of Wang et al. sends an alarming signal to the entire in vivo reprogramming field that the dosage of viral vectors is a critical factor to consider when designing proper experiments. For AAV, we recommend a relatively safe dose of 1×1010 - 1×1012 gc/ml (~1 μl) in the rodent brain for cell conversion experiments addressing basic science questions. For therapeutic purpose under injury or diseased conditions, AAV dosage needs to be adjusted through a series of dose finding experiments. Moreover, we recommend that the AAV results are further verified with retroviruses that mainly express transgenes in dividing glial cells in order to draw solid conclusions.

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Purinergic signaling between neurons and satellite glial cells of mouse dorsal root ganglia modulates neuronal excitability in vivo

Pain ◽

10.1097/j.pain.0000000000002556 ◽

2021 ◽

Vol Publish Ahead of Print ◽

Author(s):

Zhiyong Chen ◽

Qian Huang ◽

Xiaodan Song ◽

Neil C. Ford ◽

Chi Zhang ◽

...

Keyword(s):

Glial Cells ◽

Dorsal Root Ganglia ◽

Dorsal Root ◽

Neuronal Excitability ◽

Purinergic Signaling ◽

Satellite Glial Cells

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Cell proliferation in the repairing adult insect central nervous system: incorporation of the thymidine analogue 5-bromo-2-deoxyuridine in vivo

Journal of Cell Science ◽

10.1242/jcs.95.4.599 ◽

1990 ◽

Vol 95 (4) ◽

pp. 599-604

Author(s):

P.J. Smith ◽

E.A. Howes ◽

J.E. Treherne

Keyword(s):

Central Nervous System ◽

Cell Proliferation ◽

Nervous System ◽

Blood Brain Barrier ◽

Glial Cells ◽

Past Research ◽

Thymidine Analogue ◽

Adult Insect ◽

Insect Central Nervous System

Uptake of the thymidine analogue 5-bromo-2-deoxyuridine into non-neuronal cells of the insect central nervous system has been examined following a controlled lesioning of the glial elements. The pattern of BUdR labelling along the penultimate abdominal connective was examined over a period of 17 days. Cell proliferation occurred in and immediately around the site of damage in both perineurial and subperineurial glial cells but at different times post-lesion for the two regions. Proliferation in the perineurial zone was maximal at 6–8 days post-lesion but continued for at least 17 days. Subperineurial proliferation was less dramatic and peaked between days 8–11 post-lesion. In both areas division appears to be confined to the reactive glial cells. These results are discussed in the context of past research on this system, particularly with regard to the restoration of the blood-brain barrier.

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High-Resolution 3D Imaging of Virus Infections in Solvent-Cleared Organs: Novel Insights into Virus Replication and Tropism In Vivo

Proceedings ◽

10.3390/proceedings2020050075 ◽

2020 ◽

Vol 50 (1) ◽

pp. 75

Author(s):

Luca Zaeck ◽

Madlin Potratz ◽

Antonia Klein ◽

Conrad M. Freuling ◽

Thomas Müller ◽

...

Keyword(s):

Rabies Virus ◽

Glial Cells ◽

Virus Replication ◽

3D Visualization ◽

Virus Protein ◽

3D Analysis ◽

Virus Infections ◽

Thin Sections ◽

Cellular Environment

The visualization of infection processes in relevant tissues and organs using microscopy methods reveals a unique link between the distribution, tropism, and abundance of pathogens and the physiological structure of the respective organ. To dissect virus replication and the host reaction in vivo at both a global and a single-cell level, conventional 2D imaging approaches can only provide limited insight. However, pathological studies of infected organ material are still mostly restricted to the immunostaining of thin sections from paraffin-embedded or frozen samples. While the 3D analysis of large tissue volumes is possible via laborious serial sectioning, a variety of problems and artifacts remain. Modern immunostaining-compatible tissue clearing techniques allow for the seamless 3D visualization of infection sites in optically cleared thick tissues sections or even entire organs. Benefiting from pure optical slicing, this approach enables the acquisition of multicolor high-volume 3D image stacks for coherent qualitative and quantitative analyses of the infection and its surrounding cellular environment. Here, we demonstrate the utility and power of this methodology by visualizing virus infections in different target tissues. For instance, we reconstructed the cellular context of rabies virus infection sites in mouse brain tissue, allowing a thorough investigation and quantitative analysis of rabies virus cell tropism. The systematic comparison of different rabies viruses with varying pathogenicity revealed a remarkable difference for highly virulent street rabies viruses and attenuated lab strains. While the virus protein expression was readily detectable at a comparable level in both neurons and non-neuronal glial cells from brains of mice infected with street rabies viruses, it was virtually absent in glial cells of lab strain-infected mice. These data provide novel and detailed insights into the pathogenesis of virus infections and substantially contribute to an improved understanding of virus–host interactions in vivo.

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