Name: a neurosphere assay to evaluate endogenous neural stem cell activation in a mouse model of minimal spinal cord injury
Uploaded: 2018-09-13T13:00:00
Description: Watch this Scientific Journal Video about A Neurosphere Assay to Evaluate Endogenous Neural Stem Cell Activation in a Mouse Model of Minimal Spinal Cord Injury at JoVE.com

This work is funded by the Krembil Foundation (operating grant CMM). WX was the recipient of the Carlton Marguerite Smith student award. NL received an Ontario Graduate Scholarship.

This protocol was approved by the Animal Care Committee at the University of Toronto and is in accordance with the &#34;Guide to the Care and Use of Experimental Animals&#34; (2nd Edition, Canadian Council on Animal Care, 2017).
1. Minimal Spinal Cord Injury Surgery
NOTE: Prior to surgery make sure that all surgical instruments and materials are sterilized by appropriate methods (Figure 1A).
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	<li>Build a thoracic suppo...

<ol>
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J., Tator, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proliferation,+migration,+and+differentiation+of+endogenous+ependymal+region+stem/progenitor+cells+following+minimal+spinal+cord+injury+in+the+adult+rat.">Proliferation, migration, and differentiation of endogenous ependymal region stem/progenitor cells following minimal spinal cord injury in the adult rat.</a> Neuroscience. 131 (1), 177-187 (2005).</li><li>Thuret, S., Moon, L. D., Gage, F. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Therapeutic+interventions+after+spinal+cord+injury.">Therapeutic interventions after spinal cord injury.</a> Nature Reviews Neuroscience. 7 (8), 628-643 (2006).</li><li>Bethea, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemically+administered+interleukin-10+reduces+tumor+necrosis+factor-alpha+production+and+significantly+improves+functional+recovery+following+traumatic+spinal+cord+injury+in+rats.">Systemically administered interleukin-10 reduces tumor necrosis factor-alpha production and significantly improves functional recovery following traumatic spinal cord injury in rats.</a> Journal of Neurotrauma. 16 (10), 851-863 (1999).</li><li>Donnelly, D. J., Popovich, P. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inflammation+and+its+role+in+neuroprotection,+axonal+regeneration+and+functional+recovery+after+spinal+cord+injury.">Inflammation and its role in neuroprotection, axonal regeneration and functional recovery after spinal cord injury.</a> Experimental Neurology. 209 (2), 378-388 (2008).</li><li>Cummings, B. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+neural+stem+cells+differentiate+and+promote+locomotor+recovery+in+spinal+cord-injured+mice.">Human neural stem cells differentiate and promote locomotor recovery in spinal cord-injured mice.</a> Proceedings of the National Academy of Sciences USA. 102 (39), 14069-14074 (2005).</li><li>Beattie, M. S., Hermann, G. E., Rogers, R. C., Bresnahan, J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+death+in+models+of+spinal+cord+injury.">Cell death in models of spinal cord injury.</a> Progress in Brain Research. 137, 37-47 (2002).</li><li>Metz, G. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+of+the+weight-drop+contusion+model+in+rats:+a+comparative+study+of+human+spinal+cord+injury.">Validation of the weight-drop contusion model in rats: a comparative study of human spinal cord injury.</a> Journal of Neurotrauma. 17 (1), 1-17 (2000).</li><li>Faulkner, J. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reactive+astrocytes+protect+tissue+and+preserve+function+after+spinal+cord+injury.">Reactive astrocytes protect tissue and preserve function after spinal cord injury.</a> Journal of Neuroscience. 24 (9), 2143-2155 (2004).</li><li>Cheriyan, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spinal+cord+injury+models:+a+review.">Spinal cord injury models: a review.</a> Spinal Cord. 52 (8), 588-595 (2014).</li><li>Deleyrolle, L. P., Reynolds, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+expansion,+and+differentiation+of+adult+Mammalian+neural+stem+and+progenitor+cells+using+the+neurosphere+assay.">Isolation, expansion, and differentiation of adult Mammalian neural stem and progenitor cells using the neurosphere assay.</a> Neural Cell Transplantation: Methods and Protocols. , 91-101 (2009).</li><li>Singec, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Defining+the+actual+sensitivity+and+specificity+of+the+neurosphere+assay+in+stem+cell+biology.">Defining the actual sensitivity and specificity of the neurosphere assay in stem cell biology.</a> Nature Methods. 3 (10), (2006).</li><li>Mignone, J. L., Kukekov, V., Chiang, A. S., Steindler, D., Enikolopov, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neural+stem+and+progenitor+cells+in+nestin-GFP+transgenic+mice.">Neural stem and progenitor cells in nestin-GFP transgenic mice.</a> The Journal of Comparative Neurology. 469 (3), 311-324 (2004).</li><li>Xu, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myelin+basic+protein+regulates+primitive+and+definitive+neural+stem+cell+proliferation+from+the+adult+spinal+cord.">Myelin basic protein regulates primitive and definitive neural stem cell proliferation from the adult spinal cord.</a> Stem Cells. 35 (2), 485-496 (2017).</li><li>Sachewsky, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Primitive+neural+stem+cells+in+the+adult+mammalian+brain+give+rise+to+GFAP-expressing+neural+stem+cells.">Primitive neural stem cells in the adult mammalian brain give rise to GFAP-expressing neural stem cells.</a> Stem Cell Reports. 2 (6), 810-824 (2014).</li><li>Mothe, A., Tator, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+neural+stem/progenitor+cells+from+the+periventricular+region+of+the+adult+rat+and+human+spinal+cord.">Isolation of neural stem/progenitor cells from the periventricular region of the adult rat and human spinal cord.</a> Journal of Visualized Experiments. (99), (2015).</li><li>Absher, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemocytometer+counting.">Hemocytometer counting.</a> Tissue Culture. , 395-397 (1973).</li><li>Azari, H., Rahman, M., Sharififar, S., Reynolds, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+expansion+of+the+adult+mouse+neural+stem+cells+using+the+neurosphere+assay.">Isolation and expansion of the adult mouse neural stem cells using the neurosphere assay.</a> Journal of Visualized Experiments. (45), (2010).</li><li>Xiong, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preconditioning+with+isoflurane+produces+dose-dependent+neuroprotection+via+activation+of+adenosine+triphosphate-regulated+potassium+channels+after+focal+cerebral+ischemia+in+rats.">Preconditioning with isoflurane produces dose-dependent neuroprotection via activation of adenosine triphosphate-regulated potassium channels after focal cerebral ischemia in rats.</a> Anesthesia and Analgesia. 96 (1), 233-237 (2003).</li><li>Metz, G. A., Merkler, D., Dietz, V., Schwab, M. E., Fouad, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+testing+of+motor+function+in+spinal+cord+injured+rats.">Efficient testing of motor function in spinal cord injured rats.</a> Brain Research. 883 (2), 165-177 (2000).</li><li>Hamers, F. P., Koopmans, G. C., Joosten, E. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CatWalk-assisted+gait+analysis+in+the+assessment+of+spinal+cord+injury.">CatWalk-assisted gait analysis in the assessment of spinal cord injury.</a> Journal of Neurotrauma. 23 (3-4), 537-548 (2006).</li></ol>

During the surgical procedure, there are a few critical steps where the researcher should pay particular attention to in order to obtain optimal outcomes and minimize variability between animals. Care must be taken with the inhaled anesthesia (isoflurane) during surgery as the anesthetic has been shown to have neuroprotective effects with prolonged exposure27. Accordingly, when studying the regenerative capacity of the spinal cord following injury, make an effort to perform the surgery as quickly ...

The central nervous system contains a subpopulation of self-renewing, multipotent stem cells that have the capacity to give rise to all the different mature neural cell types1,2,3,4. These neural stem cells (NSCs) reside in specialized niches in the brain and spinal cord and can be activated following&#160;injury to proliferate, migrate, and differentiate into mature neural cells. NSCs and their progeny have been shown to migrate to the injury site in cortical injury models5,6. In the brain, NSCs have been shown to migrate from the lateral ventricles to the site of injury where they differentiate into astrocytes that contribute to glial scar formation7. In the spinal cord, however, few studies have been done to ask if these same endogenous NSCs can be harnessed to promote recovery following spinal cord injury. Indeed, there is currently a debate as to whether activation of the stem cell pool in the spinal cord requires a direct physical damage of the periventricular niche lining the central canal8 or if the damage to the spinal cord parenchyma (leaving the stem cell niche intact) is sufficient to activate endogenous NSCs9.
A number of spinal cord injury (SCI) models have been used to study the pathophysiology of acute and chronic injury. These models have also been used to test potential therapies to treat SCI through neuroprotection, immunomodulation, and developing cell transplantation/replacement strategies10,11,13. Current models include compression and/or contusion injuries, which cause large-scale functional deficits as well as extensive lesions and cavitations in the cord14,15. Resultant glial scars can span several spinal segments along with the majority of the width/circumference of the spinal cord16. Thus, while these models are clinically relevant, they afford significant challenges to studying the response of endogenous NSCs following injury. There are chemical models of injury that can be adapted to cause milder forms of injury that can spare the central canal17. However, these types of injury focus on the demyelination associated with SCI and are not clinically relevant models for the physical and/or mechanical damage associated with traumatic SCI.
To address the limitations of current injury models, we have adapted a needle track minimal SCI model, originally developed in the rat9, for the application in an adult mouse model. Our adapted injury model can create a consistent lesion of the dorsolateral region of the mouse spinal cord and spare the central canal at the level(s) of injury. The advantage of this model is that it permits the study of NSC kinetics following injury and their potential radial migration to the site of injury. The use of a mouse model also permits the use of transgenic mice that allow lineage tracking of endogenous NSCs and their progeny following injury. The properties of NSCs can further be assessed using a modified form of the in vitro neurosphere assay that is introduced in this protocol.
The neurosphere assay is an in vitro colony-forming assay that permits the isolation of NSCs in the presence of mitogens. At clonal plating densities, individual NSCs proliferate to give rise to free-floating spherical colonies of cells that are comprised of a small subpopulation of NSCs and a vast majority of progenitors18,19. In our protocol, we demonstrate the isolation of two distinct, lineally-related NSCs from the periventricular region of the spinal cord &#8212; under baseline conditions and following our minimal SCI model. Definitive neural stem cells (dNSCs) express nestin and the glial fibrillary acidic protein (GFAP) and are grown in the presence of epidermal growth factor (EGF), fibroblast growth factor (FGF), and heparin (together termed EFH)20. These dNSCs are rare in the naive spinal cord, giving rise to very few neurospheres in vitro. However, we show that dNSCs are activated following minimal SCI, expanding the numbers of neurospheres isolated from the periventricular region21. Primitive neural stem cells (pNSCs) are upstream of dNSCs in the neural stem cell lineage. pNSCs are exceedingly rare, express low levels of the pluripotency marker Oct4, and are leukemia inhibitory factor (LiF) responsive22. pNSCs do not form neurospheres when isolated from the adult mouse spinal cord due to the presence of myelin basic protein (MBP) in primary cultures; however, pNSC neurospheres can be isolated from MBP deficient mice and their numbers are expanded following injury &#8212; similar to dNSCs21. Finally, we show that dNSC-derived neurospheres can be isolated from the site of injury at early times following minimal SCI. These findings demonstrate that our injury model and assays can assess the activation characteristics of periventricular NSCs such as their ability to proliferate and migrate in response to injury.

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			<td>Any appropriate</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Standard Dissection Tools</td>
			<td style="width:201px;">Fine Science Tools</td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Dissection Microscope</td>
			<td style="width:201px;">Zeiss</td>
			<td style="width:197px;">Stemi 2000</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Counting Microscope</td>
			<td style="width:201px;">Olympus</td>
			<td style="width:197px;">CKX41</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Neural Basal-A Medium</td>
			<td style="width:201px;">Invitrogen</td>
			<td style="width:197px;">10888-022</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">B27</td>
			<td style="width:201px;">Invitrogen</td>
			<td style="width:197px;">17404-044</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Penicillin- Streptomycin</td>
			<td style="width:201px;">Gibco</td>
			<td align="right" style="width:197px;">15070</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">L- Glutamine</td>
			<td style="width:201px;">Gibco</td>
			<td align="right" style="width:197px;">25030</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">DMEM</td>
			<td style="width:201px;">Invitrogen</td>
			<td align="right" style="width:197px;">12100046</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">F12</td>
			<td style="width:201px;">Invitrogen</td>
			<td align="right" style="width:197px;">12700075</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">30% Glucose</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">G6152</td>
			<td>1M- 9.01g in 100mL dH2O</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">1M Glucose</td>
			<td style="width:201px;"></td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">7.5% NaHCO3</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">S5761</td>
			<td>155mM- 1.30g in 100mL dH2O</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">155mM NaHCO3</td>
			<td style="width:201px;"></td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:203px;">1M HEPES</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">H3375</td>
			<td>23.83 g in 100mL dH2O</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Apo-Transferrin</td>
			<td style="width:201px;">R&#38;D Systems</td>
			<td style="width:197px;">3188-AT</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Putrescine&#160;</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">P7505</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Insulin</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">I5500</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Selenium</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">S9133</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Progesterone</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">P6149</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:203px;">Papain Dissociation System&#160;</td>
			<td style="width:201px;">Worthington Biochemical Corporation</td>
			<td style="width:197px;">PDS</td>
			<td>1 vial of papain can be used for 2 samples</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Epidermal Growth Factor</td>
			<td style="width:201px;">Invitrogen</td>
			<td style="width:197px;">PMG8041</td>
			<td>Powder reconstituted with 1mL Hormone Mix and aliquoted into 20uL vials to be stored in freezer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">Fibroblast Growth Factor</td>
			<td style="width:201px;">Invitrogen</td>
			<td style="width:197px;">PHG0226</td>
			<td>Powder reconstituted with 0.5mL Hormone Mix and aliquoted into 20uL vials to be stored in freezer</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Heparin</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">H3149</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Leukemia Inhibitory Factor</td>
			<td style="width:201px;">In House</td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Trypan Blue</td>
			<td style="width:201px;"></td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">Hemocytometer</td>
			<td style="width:201px;"></td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:203px;">24 well Plates</td>
			<td style="width:201px;">NUNC</td>
			<td style="width:197px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">2M NaCl</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">S5886</td>
			<td>11.69g in 100mL dH2O</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">1M KCL</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">P5405</td>
			<td>7.46g in 100mL dH2O</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">1M MgCl2</td>
			<td style="width:201px;">Sigma</td>
			<td style="width:197px;">M2393</td>
			<td>20.33g in 100mL dH2O</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:203px;">108mM CaCl2</td>
			<td style="width:201px;">Sigma&#160;</td>
			<td style="width:197px;">C7902</td>
			<td>1.59g in 100mL dH2O</td>
		</tr>
	</tbody>
</table>

a neurosphere assay to evaluate endogenous neural stem cell activation in a mouse model of minimal spinal cord injury

Neural stem cells (NSCs) in the adult mammalian spinal cord are a relatively mitotically quiescent population of periventricular cells that can be studied in vitro using the neurosphere assay. This colony-forming assay is a powerful tool to study the response of NSCs to exogenous factors in a dish; however, this can also be used to study the effect of in vivo manipulations with the proper understanding of the strengths and limitations of the assay. One manipulation of the clinical interest is the effect of injury on endogenous NSC activation. Current models of spinal cord injury provide a challenge to study this as the severity of common contusion, compression, and transection models cause the destruction of the NSC niche at the site of the injury where the stem cells reside. Here, we describe a minimal injury model that causes localized damage at the superficial dorsolateral surface of the lower thoracic level (T7/8) of the adult mouse spinal cord. This injury model spares the central canal at the level of injury and permits analysis of the NSCs that reside at the level of the lesion at various time points following injury. Here, we show how the neurosphere assay can be utilized to study the activation of the two distinct, lineally-related, populations of NSCs that reside in the spinal cord periventricular region - primitive and definitive NSCs (pNSCs and dNSCs, respectively). We demonstrate how to isolate and culture these NSCs from the periventricular region at the level of injury and the white matter injury site. Our post-surgical spinal cord dissections show increased numbers of pNSC and dNSC-derived neurospheres from the periventricular region of injured cords compared to controls, speaking to their activation via injury. Furthermore, following injury, dNSC-derived neurospheres can be isolated from the injury site &#8212; demonstrating the ability of NSCs to migrate from their periventricular niche to sites of injury.

Following surgery, the mice should experience minimal motor deficits which may include tail and possible hind-limb paresis for up to 24 h. After this time, the mice should experience no hind-limb paralysis and/or paresis and minimal changes in gait.
Figure 3 shows representative results from the neurosphere assay 5 days following the minimal spinal cord injury. The absolute numbers of dNSC-derived n...

Watch this Scientific Journal Video about A Neurosphere Assay to Evaluate Endogenous Neural Stem Cell Activation in a Mouse Model of Minimal Spinal Cord Injury at JoVE.com

A Neurosphere Assay to Evaluate Endogenous Neural Stem Cell Activation in a Mouse Model of Minimal Spinal Cord Injury

Here, we demonstrate the performance of a minimal spinal cord injury model in an adult mouse that spares the central canal niche housing endogenous neural stem cells (NSCs). We show how the neurosphere assay can be used to quantify activation and migration of definitive and primitive NSCs following injury.

Neural stem cells (NSCs) in the adult mammalian spinal cord are a relatively mitotically quiescent population of periventricular cells that can be studied ...

This method can help answer questions related to the role of neural precursor cells in regenerative medicine. Specifically, we can ask how injury affects the behavior of neural precursor cells. The main advantage of this technique is that it provides an approach to study the effect of spinal cord injury on endogenous neural precursor cell kinetics.Visual demonstration of these techniques are critical. As the surgical and dissection steps requires precision, and can be difficult to learn, although they can be perfected with practice. Before beginning the procedure, use hair clippers to remove the fur from the dorsum of an anesthetized mouse from the mid back to the neck and ears.After securing the mouse in a stereotactic device, place four to five pieces of rolled gauze beneath the abdomen, while lightly pulling on the base of the tail to straighten out the body and spine. Push the thoracic gauze roll rostrally from the mouse abdomen toward the upper thorax to support the thoracic spine. And use laboratory tape to secure the tail and limbs in a star-like orientation.After disinfecting the exposed skin with sequential 70%ethanol and povidone iodine swabs, use a number 10 scalpel blade to make a vertical incision parallel to the longitudinal axis of the animal, from the midpoint of both shoulder blades, to the curvature of the thoracic spine. Retract the skin to expose the soft tissue and the spinal column contour. And identify the lower border of the super scapular fat pad.Then, use the scalpel to carefully but forcefully cut along both sides of the vertebral T5 to T8 and nine bones, to detach the back muscle tendons from the spinal column. Reposition retractors so that the teeth of the retractors are inserted into the incision site on either side of the spine. And expand each retractor to adjust the exposure, until the spine is sufficiently elevated without putting too much strain on the retracted muscle layers.Under a surgical microscope, carefully clean the residual muscle and other soft tissue overlying the spine, to expose the vertebral bone. Clasping the spinous process of the vertebrae with toothed forceps, and moving the forceps slightly up and down to identify the vertebrae that will be removed. Next, insert one tip of a pair of curved blunted scissors into either side of the exposed intervertebral foramen, caudal to the vertebral lamina to be excised.And cut the connecting intervertebral joints bilaterally. Then, lift the lamina upwards and cut off the upper attachment of the lamina to isolate and remove the bone. When cutting away and removing the vertebral lamina, take care to always angle the scissors upwards so not as to damage the underlying spinal cord.With the dorsal midline veins serving as a landmark, insert the 45 degree bent shaft of a 30 gage needle tip, bevel side up, one millimeter deep into the dorsal lateral surface of the spinal cord. And approximately 0.5 millimeters lateral to either side of the midline. Move the needle about two millimeters from the caudal to rostral direction, so that the entire length of the bevel is inserted into the cord.Then, retrace the path of the entry to remove the needle. To close the wound, remove the retractor and use a 6-0 absorbable suture to join the back muscles on either side of the injury along the midline. And a 4-0 silk suture to close the overlying skin.To isolate the neurospheres, make a midline incision in the skin along the entire length of the back to expose the muscle and vertebral bone contour. Lift the medial aspect of each scapula and use scissors to cut away the soft tissue between the scapula and vertebrae. When the underlying vertebral column has been exposed, insert the scissors into the upper thoracic aperture, following the curvature of the spinal column, and cut away the attached ribs, muscle and internal organs to isolate the vertebral column.Insert the scissors into the caudal vertebral foramen, and cut the intervertebral joints on either side of the laminae, taking care to not damage the intact cord. When the appropriate length of the cord is exposed, carefully cut any spinal nerves extending laterally from the cord, before transferring the spinal cord tissue into a Petri dish of regular, artificial cerebral spinal fluid on ice. Under a dissection microscope, cut the spinal cord tissue to include about two millimeters of tissue rostral and caudal to the injury site, and use two pairs of fine forceps to gently separate the cord into two longitudinal halves, along the dorsal and ventral fissures.Use the micro scissors to cut out the injured dorsal lateral white matter. And place the injured tissue into a 15 milliliter conical tube. Holding one half of the spinal cord with the forceps, tease and remove the uninjured white matter with two pairs of forceps along the rostral caudal extent of the spinal cord, to isolate the appropriate periventricular region.After isolating the injured white matter and associated periventricular regions from the other half of the spinal cord in the same manner, place the pieces of periventricular tissue into individual 15 milliliter conical tubes. And use the micro scissors to gently mince the tissue against the walls of the tubes. Once the tissue digestion procedure has been completed, and the single cell suspension has been obtained, set up a neurosphere culture by adding 10 milliliters of the appropriate medium into one 25 milliter tissue culture flask per cell condition.And add the isolated neural stem cells up to a clonal density of 10 cells per microliter for their culture in a cell culture incubator. After 24 hours, gently swirl the flasks and decant the contents into individual 15 milliliter conical tubes for centrifugation. Resuspend the pellets in one to two milliliters of fresh neural basal medium for counting.And plate the cells at clonal density in one 24 well tissue culture plate per condition, containing 500 microliters of the appropriate corresponding mitogen supplemented medium per well. Then, grow the neurospheres in the cell culture incubator for seven days. Five days following the minimal spinal cord injury, the absolute numbers of definitive neural stem cell derived neurospheres is greater than the number of primitive neural stem cell derived neurospheres.Definitive neurospheres exhibit a larger diameter and a large dark center. While primitive neurospheres are smaller in size and more tightly packed. Minimal spinal cord injury induces a significant increase in neurospheres grown from the central canal at the level of injury, compared to a relatively modest increase at the central canal, rostral to the level of injury.Definitive neurospheres can also be generated from the lesioned white matter at the level of the injury. A region that does not contain neurosphere forming cells in laminectomy alone animals. A similar increase in primitive neural stem cells is observed post injury, with the exception of primitive neurospheres at the white matter at the level of the lesion site.Once mastered, the surgical technique can be performed in under 40 minutes. And the tissue dissection and isolation can be performed under 30 minutes, if performed properly. Following the surgical procedure, depending on the animal strain, additional methodologies such as immunohistochemistry and lineate shocking, can be used to answer additional questions such as proliferation kinetics, and self fate of the neural precursor cells after injury.After watching this video, you should have a good understanding of how to utilize the neurosphere assay to assess neural stem cell activation, following spinal cord injury.

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Research

JoVE Journal

Neuroscience

Dissection and Culture of Commissural Neurons from Embryonic Spinal Cord

Commissural neurons have been widely used to investigate the mechanisms underlying axon guidance during embryonic spinal cord development. The cell bodies of these neurons are located in the dorsal spinal cord and their axons follow stereotyped trajectories during embryonic development. Commissural axons initially project ventrally towards the floorplate. After crossing the midline, these axons turn anteriorly and project towards the brain. Each of these steps is regulated by the action of several guidance cues. Cultures highly enriched in commissural neurons are ideally suited for many experiments addressing the mechanisms of axon pathfinding, including turning assays, immunochemistry and biochemistry. Here, we describe a method to dissect and culture commissural neurons from E13 rat dorsal spinal cord. First, the spinal cord is isolated and dorsal strips are dissected out. The dorsal tissue is then dissociated into a cell suspension by trypsinization and mechanical disruption. Neurons are plated onto poly-L-lysine-coated glass coverslips or tissue-culture dishes. After 30 hours in vitro, most neurons have extended an axon. The purity of the culture (Yam et al. 2009), typically over 90%, can be assessed by immunolabeling with the commissural neuron markers DCC, LH2 and TAG1 (Helms and Johnson, 1998). This neuronal preparation is a useful tool for in vitro studies of the cellular and molecular mechanisms of commissural axon growth and guidance during spinal cord development.

This video demonstrates a method to dissect and culture commissural neurons from E13 rat dorsal spinal cord. Dissociated commissural neurons are useful to study the cellular and molecular mechanisms of axon growth and guidance.

Commissural neurons have been widely used to investigate the mechanisms underlying axon guidance during embryonic spinal cord development. The cell bodies ...

Isolation and Expansion of the Adult Mouse Neural Stem Cells Using the Neurosphere Assay

Isolation and expansion of the putative neural stem cells (NSCs) from the adult murine brain was first described by Reynolds and Weiss in 1992 employing a chemically defined serum-free culture system known as the neurosphere assay (NSA). In this assay, the majority of differentiated cell types die within a few days of culture but a small population of growth factor responsive precursor cells undergo active proliferation in the presence of epidermal growth factor (EGF) and/ basic fibroblastic growth factor (bFGF). These cells form colonies of undifferentiated cells called neurospheres, which in turn can be subcultured to expand the pool of neural stem cells. Moreover, the cells can be induced to differentiate, generating the three major cell types of the CNS i.e. neurons, astrocytes, and oligodendrocytes. This assay provides an invaluable tool to supply a consistent, renewable source of undifferentiated CNS precursors, which could be used for in vitro studies and also for therapeutic purposes.
This video demonstrates the NSA method to generate and expand NSCs from the adult mouse periventricular region, and provides technical insights to ensure one can achieve reproducible neurosphere cultures. The procedure includes harvesting the brain from the adult mouse, micro-dissection of the periventricular region, tissue preparation and culture in the NSA. The harvested tissue is first chemically digested using trypsin-EDTA and then mechanically dissociated in NSC medium to achieve a single cell suspension and finally plated in the NSA. After 7-10 days in culture, the resulting primary neurospheres are ready for subculture to reach the amount of cells required for future experiments.

This video protocol demonstrates the neurosphere assay method to generate and expand neural stem cells from the adult mouse periventricular region, and provides technical insights to ensure one can achieve reproducible neurosphere cultures.

Isolation and expansion of the putative neural stem cells (NSCs) from the adult murine brain was first described by Reynolds and Weiss in 1992 employing a ...

Establishing Embryonic Mouse Neural Stem Cell Culture Using the Neurosphere Assay

In mammalians, stem cells acts as a source of undifferentiated cells to maintain cell genesis and renewal in different tissues and organs during the life span of the animal. They can potentially replace cells that are lost in the aging process or in the process of injury and disease. The existence of neural stem cells (NSCs) was first described by Reynolds and Weiss (1992) in the adult mammalian central nervous system (CNS) using a novel serum&#8208;free culture system, the neurosphere assay (NSA). Using this assay, it is also feasible to isolate and expand NSCs from different regions of the embryonic CNS. These in vitro expanded NSCs are multipotent and can give rise to the three major cell types of the CNS. While the NSA seems relatively simple to perform, attention to the procedures demonstrated here is required in order to achieve reliable and consistent results. This video practically demonstrates NSA to generate and expand NSCs from embryonic day 14-mouse brain tissue and provides technical details so one can achieve reproducible neurosphere cultures. The procedure includes harvesting E14 mouse embryos, brain microdissection to harvest the ganglionic eminences, dissociation of the harvested tissue in NSC medium to gain a single cell suspension, and finally plating cells in NSA culture. After 5-7 days in culture, the resulting primary neurospheres are passaged to further expand the number of the NSCs for future experiments.

This video protocol demonstrates the application of the neurosphere assay for the isolation and expansion of neural stem cells from the ganglionic eminences of embryonic day 14-mouse brain.

In mammalians, stem cells acts as a source of undifferentiated cells to maintain cell genesis and renewal in different tissues and organs during the life ...

Neural-Colony Forming Cell Assay: An Assay To Discriminate Bona Fide Neural Stem Cells from Neural Progenitor Cells

The neurosphere assay (NSA) is one of the most frequently used methods to isolate, expand and also calculate the frequency of neural stem cells (NSCs). Furthermore, this serum-free culture system has also been employed to expand stem cells and determine their frequency from a variety of tumors and normal tissues. It has been shown recently that a one-to-one relationship does not exist between neurosphere formation and NSCs. This suggests that the NSA as currently applied, overestimates the frequency of NSCs in a mixed population of neural precursor cells isolated from both the embryonic and adult mammalian brain. This video practically demonstrates a novel collagen based semi- solid assay, the neural-colony forming cell assay (N-CFCA), which has the ability to discriminate stem from progenitor cells based on their long-term proliferative potential, and thus provides a method to enumerate NSC frequency. In the N-CFCA, colonies &ge;2 mm in diameter are derived from cells that meet all the functional criteria of a NSC, while colonies &lt; 2mm are derived from progenitors. The N-CFCA procedure can be used for cells prepared from different sources including primary and cultured adult or embryonic mouse CNS cells. Here we use cells prepared from passage one neurospheres generated from embryonic day 14 mice brain to perform N-CFCA. The cultures are replenished with proliferation medium every seven days for three weeks to allow the plated cells to exhibit their full proliferative potential and then the frequency of neural progenitor and bona fide neural stem cells is calculated respectively by counting the number of colonies that are &lt; 2mm and the ones that are &ge;2mm in reference to the number of cells that were initially plated.

This video protocol demonstrates how to discriminate and enumerate bona fide neural stem cells in a mixed population of neural precursor cells using the neural colony-forming cell assay.

The neurosphere assay (NSA) is one of the most frequently used methods to isolate, expand and also calculate the frequency of neural stem cells (NSCs). ...

Lateral Fluid Percussion: Model of Traumatic Brain Injury in Mice

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and mortality. Based on the nature of primary injury following TBI, complex and heterogeneous secondary consequences result, which are followed by regenerative processes 1,2. Primary injury can be induced by a direct contusion to the brain from skull fracture or from shearing and stretching of tissue causing displacement of brain due to movement 3,4. The resulting hematomas and lacerations cause a vascular response 3,5, and the morphological and functional damage of the white matter leads to diffuse axonal injury 6-8. Additional secondary changes commonly seen in the brain are edema and increased intracranial pressure 9. Following TBI there are microscopic alterations in biochemical and physiological pathways involving the release of excitotoxic neurotransmitters, immune mediators and oxygen radicals 10-12, which ultimately result in long-term neurological disabilities 13,14. Thus choosing appropriate animal models of TBI that present similar cellular and molecular events in human and rodent TBI is critical for studying the mechanisms underlying injury and repair.
Various experimental models of TBI have been developed to reproduce aspects of TBI observed in humans, among them three specific models are widely adapted for rodents: fluid percussion, cortical impact and weight drop/impact acceleration 1. The fluid percussion device produces an injury through a craniectomy by applying a brief fluid pressure pulse on to the intact dura. The pulse is created by a pendulum striking the piston of a reservoir of fluid. The percussion produces brief displacement and deformation of neural tissue 1,15. Conversely, cortical impact injury delivers mechanical energy to the intact dura via a rigid impactor under pneumatic pressure 16,17. The weight drop/impact model is characterized by the fall of a rod with a specific mass on the closed skull 18. Among the TBI models, LFP is the most established and commonly used model to evaluate mixed focal and diffuse brain injury 19. It is reproducible and is standardized to allow for the manipulation of injury parameters. LFP recapitulates injuries observed in humans, thus rendering it clinically relevant, and allows for exploration of novel therapeutics for clinical translation 20.
We describe the detailed protocol to perform LFP procedure in mice. The injury inflicted is mild to moderate, with brain regions such as cortex, hippocampus and corpus callosum being most vulnerable. Hippocampal and motor learning tasks are explored following LFP.

Lateral fluid percussion (LFP), an established model of traumatic brain injury in mice, is demonstrated. LFP fulfills three major criteria for animal models: validity, reliability and clinical relevance. The procedure, consisting of surgical craniotomy, fixation of hub followed by induction of injury, resulting in focal and diffuse injuries, is described.

Traumatic brain injury (TBI) research has attained renewed momentum due to the increasing awareness of head injuries, which result in morbidity and ...

Isolation and Culture of Neural Crest Cells from Embryonic Murine Neural Tube

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to mesenchymal transition (EMT) and migrates throughout the embryo, giving rise to diverse cell types 1-3. NC also has the unique ability to influence the differentiation and maturation of target organs4-6. When explanted in vitro, NC progenitors undergo self-renewal, migrate and differentiate into a variety of tissue types including neurons, glia, smooth muscle cells, cartilage and bone. 
NC multipotency was first described from explants of the avian neural tube7-9. In vitro isolation of NC cells facilitates the study of NC dynamics including proliferation, migration, and multipotency. Further work in the avian and rat systems demonstrated that explanted NC cells retain their NC potential when transplanted back into the embryo10-13. Because these inherent cellular properties are preserved in explanted NC progenitors, the neural tube explant assay provides an attractive option for studying the NC in vitro. 
To attain a better understanding of the mammalian NC, many methods have been employed to isolate NC populations. NC-derived progenitors can be cultured from post-migratory locations in both the embryo and adult to study the dynamics of post-migratory NC progenitors11,14-20, however isolation of NC progenitors as they emigrate from the neural tube provides optimal preservation of NC cell potential and migratory properties13,21,22. Some protocols employ fluorescence activated cell sorting (FACS) to isolate a NC population enriched for particular progenitors11,13,14,17. However, when starting with early stage embryos, cell numbers adequate for analyses are difficult to obtain with FACS, complicating the isolation of early NC populations from individual embryos. Here, we describe an approach that does not rely on FACS and results in an approximately 96% pure NC population based on a Wnt1-Cre activated lineage reporter23. 
The method presented here is adapted from protocols optimized for the culture of rat NC11,13. The advantages of this protocol compared to previous methods are that 1) the cells are not grown on a feeder layer, 2) FACS is not required to obtain a relatively pure NC population, 3) premigratory NC cells are isolated and 4) results are easily quantified. Furthermore, this protocol can be used for isolation of NC from any mutant mouse model, facilitating the study of NC characteristics with different genetic manipulations. The limitation of this approach is that the NC is removed from the context of the embryo, which is known to influence the survival, migration and differentiation of the NC2,24-28.

Isolation of embryonic neural crest from the neural tube facilitates the use of in vitro methods for studying migration, self-renewal, and multipotency of neural crest.

The embryonic neural crest (NC) is a multipotent progenitor population that originates at the dorsal aspect of the neural tube, undergoes an epithelial to ...

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal degeneration. Lack of growth cone formation, regeneration, and loss of additional myelinated axonal projections within the spinal cord greatly limits neurological recovery following injury. To assess how central myelinated axons of the spinal cord respond to injury, we developed an ex vivo living spinal cord model utilizing transgenic mice that express yellow fluorescent protein in axons and a focal and highly reproducible laser-induced spinal cord injury to document the fate of axons and myelin (lipophilic fluorescent dye Nile Red) over time using two-photon excitation time-lapse microscopy. Dynamic processes such as acute axonal injury, axonal retraction, and myelin degeneration are best studied in real-time. However, the non-focal nature of contusion-based injuries and movement artifacts encountered during in vivo spinal cord imaging make differentiating primary and secondary axonal injury responses using high resolution microscopy challenging. The ex vivo spinal cord model described here mimics several aspects of clinically relevant contusion/compression-induced axonal pathologies including axonal swelling, spheroid formation, axonal transection, and peri-axonal swelling providing a useful model to study these dynamic processes in real-time. Major advantages of this model are excellent spatiotemporal resolution that allows differentiation between the primary insult that directly injures axons and secondary injury mechanisms; controlled infusion of reagents directly to the perfusate bathing the cord; precise alterations of the environmental milieu (e.g., calcium, sodium ions, known contributors to axonal injury, but near impossible to manipulate in vivo); and murine models also offer an advantage as they provide an opportunity to visualize and manipulate genetically identified cell populations and subcellular structures. Here, we describe how to isolate and image the living spinal cord from mice to capture dynamics of acute axonal injury.

An Ex Vivo Laser-induced Spinal Cord Injury Model to Assess Mechanisms of Axonal Degeneration in Real-time

We present a protocol utilizing two-photon excitation time-lapse microscopy to simultaneously visualize the dynamics of axon and myelin injuries in real time. This proposed protocol permits studies of both intrinsic and extrinsic factors which can influence central myelinated axon fate after injury and contribute to permanent clinical disability.

Injured CNS axons fail to regenerate and often retract away from the injury site. Axons spared from the initial injury may later undergo secondary axonal ...

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in adult mammalian animals remains elusive. In this study, we describe an experimental procedure for measuring calcium dynamics through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy. This method enables recordings and quantifications of neural activity in bilateral mouse brain regions one at a time in the same experiment for a prolonged period in vivo. Key aspects of this method, which can be completed within an hour, include minimally invasive surgery procedures for creating dual optical windows, and the use of 2P imaging. Although we only demonstrate the technique in the S1 area, the method can be applied to other regions of the living brain facilitating the elucidation of structural and functional complexities of brain neural networks.

Imaging Neural Activity in the Primary Somatosensory Cortex Using Thy1-GCaMP6s Transgenic Mice

We describe an experimental procedure for measuring neuronal activity through dual optical windows above bilateral primary somatosensory corticies (S1) in Thy1-GCaMP6s transgenic mice using 2-photon (2P) microscopy in vivo.

The mammalian brain exhibits marked symmetry across the sagittal plane. However, detailed description of neural dynamics in symmetric brain regions in ...

Laminectomy and Spinal Cord Window Implantation in the Mouse

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated digital vaporizer is utilized to achieve a stable plane of anesthesia at a low-flow rate of isoflurane. A single vertebral spine is removed, and a commercially available cover-glass is overlaid on a thin agarose bed. A 3D-printed plastic backplate is then affixed to the adjacent vertebral spines using tissue adhesive and dental cement. A stabilization platform is used to reduce motion artifact from respiration and heartbeat. This rapid and clamp-free method is well-suited for acute multi-photon fluorescence microscopy. Representative data are included for an application of this technique to two-photon microscopy of the spinal cord vasculature in transgenic mice expressing eGFP:Claudin-5 &#8212; a tight junction protein.

This protocol describes implantation of a glass window onto the spinal cord of a mouse to facilitate visualization by intravital microscopy.

This protocol describes a method for spinal cord laminectomy and glass window implantation for in vivo imaging of the mouse spinal cord. An integrated ...

Intra-Arterial Delivery of Neural Stem Cells to the Rat and Mouse Brain: Application to Cerebral Ischemia

Neural stem cell (NSC) therapy is an emerging innovative treatment for stroke, traumatic brain injury and neurodegenerative disorders. As compared to intracranial delivery, intra-arterial administration of NSCs is less invasive and produces a more diffuse distribution of NSCs within the brain parenchyma. Further, intra-arterial delivery allows the first-pass effect in the brain circulation, lessening the potential for trapping of cells in peripheral organs, such as liver and spleen, a complication associated with peripheral injections. Here, we detail the methodology, in both mice and rats, for delivery of NSCs through the common carotid artery (mouse) or external carotid artery (rat) to the ipsilateral hemisphere after an ischemic stroke. Using GFP-labeled NSCs, we illustrate the widespread distribution achieved throughout the rodent ipsilateral hemisphere at 1 d, 1 week and 4 weeks after postischemic delivery, with a higher density in or near the ischemic injury site. In addition to long-term survival, we show evidence of differentiation of GFP-labeled cells at 4 weeks. The intra-arterial delivery approach described here for NSCs can also be used for administration of therapeutic compounds, and thus has broad applicability to varied CNS injury and disease models across multiple species.

A method for delivering neural stem cells, adaptable for injecting solutions or suspensions, through the common carotid artery (mouse) or external carotid artery (rat) after ischemic stroke is reported. Injected cells are distributed broadly throughout the brain parenchyma and can be detected up to 30 d after delivery.

Neural stem cell (NSC) therapy is an emerging innovative treatment for stroke, traumatic brain injury and neurodegenerative disorders. As compared to ...