This study was supported by grants from the Vanderbilt-Ingram Cancer Center Support Grant (P30 CA068485), the Childhood Brain Tumor Foundation and the National Institutes of Health (NS042205).

1. Micro-dissection of Tumor-bearing Cerebellum and Dissociation of Tumor Tissue
<ol>
<li>Retrieval of tumor tissue
<ol>
<li> Sick mice bearing medulloblastoma are often runted, and display hydrocephaly and typical neurological symptoms, including posterior paralysis and failure to regain posture when overturned. To retrieve tumor tissue, euthanize mice by carbon dioxide inhalation. It is imporant not to perform cervical dislocation, a procedure that generates pressure to the posterior skull and can compromise tumor tissue integrity.</li>
<li> Decapitation is performed immediately after death using a pair of scissors, removing hair and muscle tissue as much as possible for good visualization of the skull. Clean the surface of the skull with Kimwipe soaked with 95% ethanol.</li>
<li>Use fine scissors to cut an opening along the midline of the skull, and remove skull tissue using fine tweezers, at which point the whole brain including tumor-bearing cerebellum is exposed.</li>
<li>While the cerebella of healthy adults display well-defined hemispheres and vermis, the cerebella of tumor-bearing mice are often enlarged, amorphous with a smooth surface and conspicuous blood vessels. Using sterile techniques, retrieve the cerebellar tumor using tweezers and place in ice-cold phosphate buffered saline (PBS) without Mg2+ and Ca2+.</li>
</ol>
</li>
</ol>
Note: all instruments are disinfected in 95% ethanol and steam autoclaved before use.
<ol start="2">
<li>Dissociation of tumor tissue
<ol>
<li> Transfer the tumor tissue from PBS to 50% Accutase (diluted in PBS) that is about 4 times the volume of the tumor tissue, mince the tissue with fine scissors for 3 minutes at room temperature, followed by incubation at 37&deg;C for 4 minutes, after which the tissue undergoes repetitive pipeting with a 1-mL Pipetman for an additional 3 minutes. This method should yield a mixture of single cells and small cellular aggregates.</li>
<li> Dilute the cellular suspension 3-fold with PBS and centrifuge for 5 minutes at 1000xg to pellet the cells. (The procedures above have been described in "Isolation, enrichment and maintenance of medulloblastoma stem cells", JoVE in press)</li></ol></li></ol>
Resuspend the cell pellet in freshly prepared neural stem cell medium consisting of Neurobasal medium with glutamine, Penicillin-Streptomycin, N2, B27, human EGF (25 ng/mL) and basic FGF (25 ng/mL). Calculate the cell density of the solution and make appropriate further dilutions with additional neural stem cell medium such that one can load 4 &mu;L of solution with an appropriate number of dissociated tumor cells, e.g. 5x105, into a sterile bevel-tipped 10&mu;L syringe. The exact number of cells to be inoculated should be determined by the researcher according to specific experimental requirements. Keep the cell solution in a mini 200&mu;L microcentrifuge tube (PCR tube) on ice.
2. Anesthetic Procedures for the Recipient Mice
For the surgical procedure, a disinfected area dedicated to rodent surgery is needed for the duration of the procedure. Ideally, set up a long bench with separate but adjoining areas for animal preparation, operating field and animal recovery. Surgical gloves, not exam gloves, are required for the surgery. Aseptic technique is maintained by holding gloved hands above the waist and used only to handle sterile objects from a dry sterile surface.
<ol>
<li> A mixture of ketamine (100 mg ketamine per 1 kg of mouse weight) and xylazine (10 mg xylazine per 1 kg of mouse weight) is used for anesthesia. Administer the anesthetics intraperitoneally.</li>
<li>It generally takes 3-5 minutes for the anesthetics to take full effect. Determine whether a mouse is fully anesthetized by toe/tail pinch. Place a small amount of ophthalmic ointment on the eyes of the mouse. Bring the fully anesthetized mouse to the operating area, constantly monitoring to make sure that the mouse is breathing normally.</li>
</ol>
3. Intracranial Grafting of the Tumor Cells
<ol>
<li>Shave the dorsal posterior head region of the mouse, using a hair clipper, to reveal the posterior skull above the midbrain and cerebellum.</li>
<li>Apply Betadine solution on the exposed scalp using a cotton tip applicator, followed by wiping with an alcohol pad. Repeat these two sterilizing steps two times.</li>
<li>Make a quarter-inch incision in the posterior scalp using a sterilized scalpel. Drill a 0.5 mm burr hole 2 mm to the right and 2 mm posterior to the lambda using a sterile dental drill.</li>
<li>Place the mouse onto a stereotactic frame by hooking its incisors onto the frame hold. Carefully descend and position the bevel-tipped 10 &mu;L syringe loaded with 4 &mu;L of tumor cell solution into the burr hole. Once the bevel of the syringe needle is below the skull surface, descend for another 3 mm and then ascend for 0.5 mm. Slowly inject the desired amount of tumor cells, with a steady force in a 30 second time frame, into the cerebellum of the recipient. Leave the needle in its place after completion of injection for an additional two minutes. Then remove the needle and syringe. Clip the wound using an autoclip.</li>
<li>Keep the mouse on a warming blanket after the surgery to help maintain its body temperature. 
Mobility and respiratory patterns will be observed continuously. Once the mouse recovers from anesthesia, place it back in a sterile housing cage. Monitor daily for food and water intake, behavior, grooming, and red staining of the eyes. Inspect for signs of infection at the incision site. Remove the autoclips on day 7 post surgery. 
Maintain the mice for an average of 2-6 months and sacrifice those displaying typical medulloblastoma symptoms for further studies.</li>
</ol>
4. Representative Results
Secondary medulloblastomas developed in recipient mice highly resembled those of the primary tumors. The cerebella bearing secondary tumors were often enlarged, amorphous with ectopic blood vessels apparent when viewed as whole-mounts. Immunohistochemical analyses of the secondary tumor tissue revealed that the tumor cells are highly proliferative, express strong SmoM2-YFP and markers of cerebellar granule neuron precursors, such as Math1 and Pax6. When dissociated and cultured using reported methods ("Isolation, enrichment and maintenance of medulloblastoma stem cells", JoVE in press), the secondary medulloblastoma tumor cells can be expanded rapidly, express multiple stem cell markers, are clonogenic and can further initiate tumor formation when transplanted into additional immunocompromised recipients.
 <img src="/files/ftp_upload/2153/2153fig1.jpg" alt="Figure 1" /> 
Figure 1. Typical whole-mount and sectional views of a secondary medulloblastoma tissue 
A typical example of secondary medulloblastoma tissue developed 26 days after injection of 5x105 primary tumor cells. Hematoxylin staining reveals the typical cellular morphology of medulloblastoma, including high nuclear/cytoplasmic ratio and nuclear polymorphism. These secondary tumor cells are highly proliferative as indicated by Ki67 expression and they also robustly express membranous SmoM2-YFP.
 <img src="/files/ftp_upload/2153/2153fig2.jpg" alt="Figure 2" /> 
Figure 2. Secondary medulloblastoma cells can be cultured and expanded in vitro 
Using the protocol described for primary mouse medulloblastoma cells ("Isolation, enrichment and maintenance of medulloblastoma stem cells", JoVE in press), these secondary medulloblastoma cells can be cultured and expanded for multiple passages. The picture shows the same representative tumor colony cultured at 4 days and 14 days. The cultured tumor cells are bipolar, elongated with scant cytoplasm and often radiate from a dense core of cellular aggregate. They do not exhibit growth contact inhibition. The small round cells are red blood cells.

<ol>
	<li>Schuller, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acquisition+of+granule+neuron+precursor+identity+is+a+critical+determinant+of+progenitor+cell+competence+to+form+Shh-induced+medulloblastoma.">Acquisition of granule neuron precursor identity is a critical determinant of progenitor cell competence to form Shh-induced medulloblastoma.</a> Cancer Cell. 14, 123-134 (2008).</li><li>Yang, Z. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Medulloblastoma+can+be+initiated+by+deletion+of+Patched+in+lineage-restricted+progenitors+or+stem+cells.">Medulloblastoma can be initiated by deletion of Patched in lineage-restricted progenitors or stem cells.</a> Cancer Cell. 14, 135-145 (2008).</li><li>Kessler, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-myc+alters+the+fate+of+preneoplastic+cells+in+a+mouse+model+of+medulloblastoma.">N-myc alters the fate of preneoplastic cells in a mouse model of medulloblastoma.</a> Genes Dev. 23, 157-170 (2009).</li><li>Flora, A., Klisch, T. J., Schuster, G., Zoghbi, H. Y., Y, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deletion+of+Atoh1+disrupts+Sonic+Hedgehog+signaling+in+the+developing+cerebellum+and+prevents+medulloblastoma.">Deletion of Atoh1 disrupts Sonic Hedgehog signaling in the developing cerebellum and prevents medulloblastoma.</a> Science. 326, 1424-1427 (2009).</li><li>Salsano, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+the+neurogenic+basic+helix-loop-helix+transcription+factor+NEUROG1+identifies+a+subgroup+of+medulloblastomas+not+expressing+ATOH1.">Expression of the neurogenic basic helix-loop-helix transcription factor NEUROG1 identifies a subgroup of medulloblastomas not expressing ATOH1.</a> Neuro Oncol. 9, 298-307 (2007).</li></ol>

No conflicts of interest declared.

Several critical factors to ensure successful medulloblastoma cell allografting that yields secondary tumor formation are as follows: First, use only 50% Accutase for tissue dissociation and do not over-digest the tissue as prolonged enzyme treatment leads to significant reduction in cell viability. Also use only the 1 mL size Pipetman as smaller tips can also generate physical damage to the dissociated cells. It is fine to have a mixture of single cells and small aggregates for allografting. Second, mix and equilibrate...

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		<th>Comment</th>
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<td>Neurobasal medium</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>21103049</td>
<td>&nbsp;</td>
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<td>hEGF</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>PHG0311</td>
<td>25ng/ml</td>
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<td>&nbsp;</td>
<td>Invitrogen</td>
<td>PHG0023</td>
<td>25ng/ml</td>
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<td>N2</td>
<td>&nbsp;</td>
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<td>1X</td>
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<td>Invitrogen</td>
<td>A1110501</td>
<td>50% </td>
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<td>Invitrogen</td>
<td>25030081</td>
<td>2mM</td>
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<td>Stereotaxic instrument</td>
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<td>Stoelting </td>
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<td>&nbsp;</td>
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<td>Foredom flexible shaft drill, hang-up style</td>
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<td>Large probe holder</td>
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<td>10 &mu;L syringe, 26 ga., bevel tip</td>
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<td>Stoelting </td>
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<td>&nbsp;</td>
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<td>Drill bit .75mm</td>
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intracranial orthotopic allografting of medulloblastoma cells in immunocompromised mice

Medulloblastoma is the most common pediatric tumor of the nervous system. A large body of animal studies has focused on cerebellar granule neuron precursors (CGNPs) as the cell-of-origin for medulloblastoma1-4. However, the diverse clinical presentations of medulloblastoma subtypes in human patients (nodular, desmoplastic, classical and large cell/anaplastic), and the fact that medulloblastoma is found in a subset of human patients with no ectopic expression of CGNP marker5, suggest that the cellular and molecular origins of medulloblastoma are more complex and far from being completely deciphered. Therefore, it is essential to determine whether there is an alternative medulloblastoma tumor cell-of-origin based on which cell-type specific therapeutic modality can be developed. To this end, intracranial orthotopic allografting of genetically marked tumor cell types followed by subsequent analyses of secondary tumor development in recipients will allow determination of the cellular origin of tumor-initiating cells. Here we describe the experimental protocol for intracranial orthotopic allografting of medulloblastoma cells derived from primary tumor tissue, and this procedure can also be used for transplanting cells from established cell lines.

Watch this Scientific Journal Video about Intracranial Orthotopic Allografting of Medulloblastoma Cells in Immunocompromised Mice at JoVE.com

Intracranial Orthotopic Allografting of Medulloblastoma Cells in Immunocompromised Mice

This protocol describes the isolation and dissociation of mouse medulloblastoma tissue, and subsequent allografting of the tumor cells into immunocompromised recipient mice in order to initiate secondary medulloblastoma.

Medulloblastoma is the most common pediatric tumor of the nervous system. A large body of animal studies has focused on cerebellar granule neuron ...

intracranial-orthotopic-allografting-medulloblastoma-cells

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JoVE Journal

Neuroscience

12.1K Views.  Vanderbilt University. This protocol describes the isolation and dissociation of mouse medulloblastoma tissue, and subsequent allografting of the tumor cells into immunocompromised recipient mice in order to initiate secondary medulloblastoma. 

Video: Intracranial Orthotopic Allografting of Medulloblastoma Cells in Immunocompromised Mice

Isolation, Enrichment, and Maintenance of Medulloblastoma Stem Cells

Brain tumors have been suggested to possess a small population of stem cells that are the root cause of tumorigenesis. Neurosphere assays have been generally adopted to study the nature of neural stem cells, including those derived from normal and tumorous tissues. However, appreciable amounts of differentiation and cell death are common in cultured neurospheres likely due to sub-optimal condition such as accessibility of all cells within sphere aggregates to culture medium.
Medulloblastoma, the most common pediatric CNS tumor, is characterized by its rapid progression and tendency to spread along the entire brain-spinal axis with dismal clinical outcome. Medulloblastoma is a neuroepithelial tumor of the cerebellum, accounting for 20% and 40% of intracranial and posterior fossa tumor in childhood, respectively1. It is now well established that Shh signaling stimulates proliferation of cerebellar granule neuron precursors (CGNPs) during cerebellar development 2-4. Numerous studies using mouse models, in which the Shh pathway is constitutively activated, have linked Shh signaling with medulloblastoma 5-9.
A recent report has shown that a subset of medulloblastoma cells derived from Patched1LacZ/+ mice are cancer stem cells, which are capable of initiating and propogating tumors 10. Here we describe an efficient method to isolate, enrich and maintain tumor stem cells derived from several mouse models of medulloblastoma, with constitutively activated Shh pathway due to a mutation in Smoothened (11, hereon referred as SmoM2), a GPCR that is critical for Shh pathway activation. In every isolated medulloblastoma tissue, we were able to establish numerous highly proliferative colonies. These cells robustly expressed several neural stem cell markers such as Nestin and Sox2, can undergo serial passages (greater than 20) and were clonogenic. While these cultured tumor stem cells were relatively small, often bipoar with high nuclear to cytoplasmic ratio when cultured under conditions favoring stem cell growth, they dramatically altered their morphology, extended multiple cellular processes, flattened and withdrew from the cell cycle upon switching to a cell culture medium supplemented with 10% fetal bovine serum. More importantly, these tumor stem cells differentiated into Tuj1+ or NeuN+ neurons, GFAP+ astrocytes and CNPase+ oligodendrocytes, thus highlighting their multi-potency. Furthermore, these cells were capable of propagating secondary medulloblastomas when orthotopically transplanted into host mice.

This protocol describes the isolation, enrichment, and maintenance of medulloblastoma tumor stem cells derived from mutant mice with ectopic Sonic hedgehog pathway activity.

Brain tumors have been suggested to possess a small population of stem cells that are the root cause of tumorigenesis. Neurosphere assays have been ...

Intracranial Injection of Adeno-associated Viral Vectors

Intracranial injection of viral vectors engineered to express a fluorescent protein is a versatile labeling technique for visualization of specific subsets of cells in different brain regions both in vivo and in brain sections. Unlike the injection of fluorescent dyes, viral labeling offers targeting of individual cell types and is less expensive and time consuming than establishing transgenic mouse lines. In this technique, an adeno-associated viral (AAV) vector is injected intracranially using stereotaxic coordinates, a micropipette and an automated pump for precise delivery of AAV to the desired area with minimal damage to the surrounding tissue. Injection parameters can be tailored to individual experiments by adjusting the animal age at injection, injection location, volume of injection, rate of injection, AAV serotype and the promoter driving gene expression. Depending on the conditions chosen, virally-induced transgene expression can allow visualization of groups of cells, individual cells or fine cellular processes, down to the level of dendritic spines. The experiment shown here depicts an injection of double-stranded AAV expressing green fluorescent protein for the labeling of neurons and glia in the mouse primary visual cortex.

Here we present the intracranial injection of AAV vectors for fluorescent labeling of neurons and glia in the visual cortex.

Intracranial injection of viral vectors engineered to express a fluorescent protein is a versatile labeling technique for visualization of specific ...

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding fundamental biological mechanisms. Striking progress has been particularly evident in Drosophila, whose extensive toolkit of mutants and transgenic lines provides a convenient model to study evolutionarily-conserved developmental and cell biological mechanisms. We are interested in understanding the mechanisms that control cell fate specification in the adult peripheral nervous system (PNS) in Drosophila. Bristles that cover the head, thorax, abdomen, legs and wings of the adult fly are individual mechanosensory organs, and have been studied as a model system for understanding mechanisms of Notch-dependent cell fate decisions. Sensory organ precursor (SOP) cells of the microchaetes (or small bristles), are distributed throughout the epithelium of the pupal thorax, and are specified during the first 12 hours after the onset of pupariation. After specification, the SOP cells begin to divide, segregating the cell fate determinant Numb to one daughter cell during mitosis. Numb functions as a cell-autonomous inhibitor of the Notch signaling pathway.
Here, we show a method to follow protein dynamics in SOP cell and its progeny within the intact pupal thorax using a combination of tissue-specific Gal4 drivers and GFP-tagged fusion proteins 1,2.This technique has the advantage over fixed tissue or cultured explants because it allows us to follow the entire development of an organ from specification of the neural precursor to growth and terminal differentiation of the organ. We can therefore directly correlate changes in cell behavior to changes in terminal differentiation. Moreover, we can combine the live imaging technique with mosaic analysis with a repressible cell marker (MARCM) system to assess the dynamics of tagged proteins in mitotic SOPs under mutant or wildtype conditions. Using this technique, we and others have revealed novel insights into regulation of asymmetric cell division and the control of Notch signaling activation in SOP cells (examples include references 1-6,7 ,8).

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding ...

A Simple and Inexpensive Method for Determining Cold Sensitivity and Adaptation in Mice

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life. The cold plantar assay allows the objective and inexpensive assessment of cold sensitivity in mice, and can quantify both analgesia and hypersensitivity. Mice are acclimated on a glass plate, and a compressed dry ice pellet is held against the glass surface underneath the hindpaw. The latency to withdrawal from the cooling glass is used as a measure of cold sensitivity.
Cold sensation is also important for survival in regions with seasonal temperature shifts, and in order to maintain sensitivity animals must be able to adjust their thermal response thresholds to match the ambient temperature. The Cold Plantar Assay (CPA) also allows the study of adaptation to changes in ambient temperature by testing the cold sensitivity of mice at temperatures ranging from 30 &#176;C to 5 &#176;C. Mice are acclimated as described above, but the glass plate is cooled to the desired starting temperature using aluminum boxes (or aluminum foil packets) filled with hot water, wet ice, or dry ice. The temperature of the plate is measured at the center using a filament T-type thermocouple probe. Once the plate has reached the desired starting temperature, the animals are tested as described above.
This assay allows testing of mice at temperatures ranging from innocuous to noxious. The CPA yields unambiguous and consistent behavioral responses in uninjured mice and can be used to quantify both hypersensitivity and analgesia. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

The Cold Plantar Assay (CPA) measures cold responsiveness between 30 &#176;C and 5 &#176;C, and can also measure cold adaptation. This protocol describes how to use the CPA to measure cold hypersensitivity, analgesia, and adaptation in mice.

Cold hypersensitivity is a serious clinical problem, affecting a broad subset of patients and causing significant decreases in quality of life.  The cold ...

Intracranial Pharmacotherapy and Pain Assays in Rodents

Pain is a salient sensory experience with affective and cognitive dimensions. However, central mechanisms for pain remain poorly understood, hindering the development of effective therapeutics. Intracranial pharmacology presents an important tool for understanding the molecular and cellular mechanisms of pain in the brain, as well as for novel treatments. Here we present a protocol that integrates intracranial pharmacology with pain behavior testing. Specifically, we show how to infuse analgesic drugs into a select brain region, which may be responsible for pain modulation. Furthermore, to determine the effect of the candidate drug in the central nerve system, pain assays are performed after intracranial treatment. Our results demonstrate that intracranial administration of analgesic drugs in a targeted region can provide relief of pain in rodents. Thus, our protocol successfully demonstrates that intracranial pharmacology, combined with pain behavior testing, can be a powerful tool for the study of pain mechanisms in the brain.

Here we present a protocol to perform intracranial pharmacological experiments followed by pain behavior assays in rodents. This protocol allows researchers to deliver molecular and cellular targets in the brain, for pharmacologic agents in the treatment of pain.

Pain is a salient sensory experience with affective and cognitive dimensions. However, central mechanisms for pain remain poorly understood, hindering the ...

The Detection of 5-Hydroxymethylcytosine in Neural Stem Cells and Brains of Mice

Multiple&#160;DNA modifications have been identified in the mammalian genome. Of that, 5-methylcytosine and 5-hydroxymethylcytosine-mediated epigenetic mechanisms have been intensively studied. 5-hydroxymethylcytosine displays dynamic features during embryonic and postnatal development of the brain, plays a regulatory function in gene expression, and is involved in multiple neurological disorders. Here, we describe the detailed methods including immunofluorescence staining and&#160;DNA dot-blot to detect 5-hydroxymethylcytosine in cultured cells and brain tissues of mouse.

Here, we present a protocol to detect 5-hydroxymethylcytosine in cells and brain tissues, utilizing immunofluorescence staining and DNA dot-blot methods.

Multiple&#160;DNA modifications have been identified in the mammalian genome. Of that, 5-methylcytosine and 5-hydroxymethylcytosine-mediated epigenetic ...

Quantitative Measurement of Intrathecally Synthesized Proteins in Mice

Cerebrospinal fluid (CSF), a fluid found in the brain and the spinal cord, is of great importance to both basic and clinical science. The analysis of the CSF protein composition delivers crucial information in basic neuroscience research as well as neurological diseases. One caveat is that proteins measured in CSF may derive from both intrathecal synthesis and transudation from serum, and protein analysis of CSF can only determine the sum of these two components. To discriminate between protein transudation from the blood and intrathecally produced proteins in animal models as well as in humans, CSF protein profiling measurements using conventional protein analysis tools must include the calculation of the albumin CSF/serum quotient (Qalbumin), a marker of the integrity of the blood-brain interface (BBI), and the protein index (Qprotein/Qalbumin), an estimate of intrathecal protein synthesis. This protocol illustrates the entire procedure, from CSF and blood collection to quotients and indices calculations, for the quantitative measurement of intrathecal protein synthesis and BBI impairment in mouse models of neurological disorders.

Elevated spinal fluid protein levels can either be the result of diffusion of plasma protein across an altered blood-brain barrier or intrathecal synthesis. An optimized testing protocol is presented in this article that helps to discriminate both cases and provides quantitative measurements of intrathecally synthesized proteins.

Cerebrospinal fluid (CSF), a fluid found in the brain and the spinal cord, is of great importance to both basic and clinical science. The analysis of the ...

Translaminar Autonomous System Model for the Modulation of Intraocular and Intracranial Pressure in Human Donor Posterior Segments

There is a current unmet need for a new preclinical human model that can target disease etiology ex vivo using intracranial pressure (ICP) and intraocular pressure (IOP) which&#160;can identify various pathogenic paradigms related to the glaucoma pathogenesis. Ex vivo human anterior segment perfusion organ culture models have previously been successfully utilized and applied as effective technologies for the discovery of glaucoma pathogenesis and testing of therapeutics. Preclinical drug screening and research performed on ex vivo human organ systems can be more translatable to clinical research. This article describes in detail the generation and operation of a novel ex vivo human translaminar pressure model called the translaminar autonomous system (TAS). The TAS model can independently regulate ICP and IOP using human donor posterior segments. The model allows for studying pathogenesis in a preclinical manner. It can reduce the use of living animals in ophthalmic research. In contrast to in vitro experimental models, optic nerve head (ONH) tissue structure, complexity, and integrity can also be maintained within the ex vivo TAS model.

We describe and detail the use of the translaminar autonomous system. This system utilizes the human posterior segment to independently regulate the pressure inside the segment (intraocular) and surrounding the optic nerve (intracranial) to generate a translaminar pressure gradient that mimics features of glaucomatous optic neuropathy.

There is a current unmet need for a new preclinical human model that can target disease etiology ex vivo using intracranial pressure (ICP) and intraocular ...

A Scalable Model to Study the Effects of Blunt-Force Injury in Adult Zebrafish

Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and heterogenous secondary effects. While there is no mechanism to replace or regenerate the lost neurons following a TBI in humans, zebrafish possess the ability to regenerate neurons throughout their body, including the brain. To examine the breadth of pathologies exhibited in zebrafish following a blunt-force TBI and to study the mechanisms underlying the subsequent neuronal regenerative response, we modified the commonly used rodent Marmarou weight drop for the use in adult zebrafish. Our simple blunt-force TBI model is scalable, inducing a mild, moderate, or severe TBI, and recapitulates many of the phenotypes observed following human TBI, such as contact- and post-traumatic seizures, edema, subdural and intracerebral hematomas, and cognitive impairments, each displayed in an injury severity-dependent manner. TBI sequelae, which begin to appear within minutes of the injury, subside and return to near undamaged control levels within 7 days post-injury. The regenerative process begins as early as 48 hours post-injury (hpi), with the peak cell proliferation observed by 60 hpi. Thus, our zebrafish blunt-force TBI model produces characteristic primary and secondary injury TBI pathologies similar to human TBI, which allows for investigating disease onset and progression, along with the mechanisms of neuronal regeneration that is unique to zebrafish.

We modified the Marmarou weight drop model for adult zebrafish to examine a breadth of pathologies following blunt-force traumatic brain injury (TBI) and the mechanisms underlying subsequent neuronal regeneration. This blunt-force TBI model is scalable, induces a mild, moderate, or severe TBI, and recapitulates injury heterogeneity observed in human TBI.

Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and ...

Shuttle Box Assay as an Associative Learning Tool for Cognitive Assessment in Learning and Memory Studies using Adult Zebrafish

Cognitive deficits, including impaired learning and memory, are a primary symptom of various developmental and age-related neurodegenerative diseases and traumatic brain injury (TBI). Zebrafish are an important neuroscience model due to their transparency during development and robust regenerative capabilities following neurotrauma. While various cognitive tests exist in zebrafish, most of the cognitive assessments that are rapid examine non-associative learning. At the same time, associative-learning assays often require multiple days or weeks. Here, we describe a rapid associative-learning test that utilizes an adverse stimulus (electric shock) and requires minimal preparation time. The shuttle box assay, presented here, is simple, ideal for novice investigators, and requires minimal equipment. We demonstrate that, following TBI, this shuttle box test reproducibly assesses cognitive deficit and recovery from young to old zebrafish. Additionally, the assay is adaptable to examine either immediate or delayed memory. We demonstrate that both a single TBI and repeated TBI events negatively affect learning and immediate memory but not delayed memory. We, therefore, conclude that the shuttle box assay reproducibly tracks the progression and recovery of cognitive impairment.

Learning and memory are potent metrics in studying either developmental, disease-dependent, or environmentally induced cognitive impairments. Most cognitive assessments require specialized equipment and extensive time commitments. However, the shuttle box assay is an associative learning tool that utilizes a conventional gel box for rapid and reliable assessment of adult zebrafish cognition.

Cognitive deficits, including impaired learning and memory, are a primary symptom of various developmental and age-related neurodegenerative diseases and ...