Name: a drosophila in vivo injury model for studying neuroregeneration in the peripheral and central nervous system
Uploaded: 2018-05-05T14:30:00
Description: Watch this Scientific Journal Video about A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System at JoVE.com

We thank Jessica Goldshteyn for technical support. Work in the Song lab is funded by the NIH grant R00NS088211, and the Intellectual and Developmental Disabilities Research Center (IDDRC) New Program Development Award.

1. Preparation of Culture Plates and Bottles
<ol>
	<li>Preparation of grape juice agar plates
	<ol>
		<li>Add 10 g of agar powder, 200 mL grape juice, and 192 mL ddH2O into a beaker and microwave for about 4-5 min, stirring intermittently until the agar is completely dissolved.</li>
		<li>In a fume hood, cool down the solution to approx. 60 &#176;C. Add 4.2 mL 95% ethanol and 4.0 mL glacial acetic acid. Adjust the total volume of the solution to 400 mL with ddH2O. Mix well.</li>
		<li>For each 35-...

<ol>
	<li>Yakura, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Recovery following spinal cord injury. , (1996).</li><li>Harel, N. Y., Strittmatter, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+regenerating+axons+recapitulate+developmental+guidance+during+recovery+from+spinal+cord+injury?.">Can regenerating axons recapitulate developmental guidance during recovery from spinal cord injury?.</a> Nature reviews. Neuroscience. 7, 603-616 (2006).</li><li>Jurewicz, A., Matysiak, M., Raine, C. 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P., Cafferty, W. B., Budel, S. O., Strittmatter, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Extracellular+regulators+of+axonal+growth+in+the+adult+central+nervous+system.">Extracellular regulators of axonal growth in the adult central nervous system.</a> Philos Trans R Soc Lond B Biol Sci. 361, 1593-1610 (2006).</li><li>Liu, K., Tedeschi, A., Park, K. K., He, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+intrinsic+mechanisms+of+axon+regeneration.">Neuronal intrinsic mechanisms of axon regeneration.</a> Annu Rev Neurosci. 34, 131-152 (2011).</li><li>Schwab, M. E., Strittmatter, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nogo+limits+neural+plasticity+and+recovery+from+injury.">Nogo limits neural plasticity and recovery from injury.</a> Curr Opin Neurobiol. 27, 53-60 (2014).</li><li>He, Z., Jin, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+Control+of+Axon+Regeneration.">Intrinsic Control of Axon Regeneration.</a> Neuron. 90, 437-451 (2016).</li><li>Park, K. K., 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=Promoting+axon+regeneration+in+the+adult+CNS+by+modulation+of+the+PTEN/mTOR+pathway.">Promoting axon regeneration in the adult CNS by modulation of the PTEN/mTOR pathway.</a> Science. 322, 963-966 (2008).</li><li>Geoffroy, C. G., Hilton, B. 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M., 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=The+Drosophila+cell+corpse+engulfment+receptor+Draper+mediates+glial+clearance+of+severed+axons.">The Drosophila cell corpse engulfment receptor Draper mediates glial clearance of severed axons.</a> Neuron. 50, 869-881 (2006).</li><li>Song, Y., 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=Regeneration+of+Drosophila+sensory+neuron+axons+and+dendrites+is+regulated+by+the+Akt+pathway+involving+Pten+and+microRNA+bantam.">Regeneration of Drosophila sensory neuron axons and dendrites is regulated by the Akt pathway involving Pten and microRNA bantam.</a> Genes Dev. 26, 1612-1625 (2012).</li><li>Song, Y., 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=Regulation+of+axon+regeneration+by+the+RNA+repair+and+splicing+pathway.">Regulation of axon regeneration by the RNA repair and splicing pathway.</a> Nat Neurosci. 18, 817-825 (2015).</li><li>Kato, K., Forero, M. G., Fenton, J. C., Hidalgo, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+glial+regenerative+response+to+central+nervous+system+injury+is+enabled+by+pros-notch+and+pros-NFkappaB+feedback.">The glial regenerative response to central nervous system injury is enabled by pros-notch and pros-NFkappaB feedback.</a> PLoS Biol. 9, e1001133 (2011).</li><li>Fang, Y., Soares, L., Teng, X., Geary, M., Bonini, N. 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J., DiAntonio, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Models+of+axon+regeneration+in+Drosophila.">Models of axon regeneration in Drosophila.</a> Exp Neurol. 287, 310-317 (2017).</li><li>Hao, Y., Collins, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intrinsic+mechanisms+for+axon+regeneration:+insights+from+injured+axons+in+Drosophila.">Intrinsic mechanisms for axon regeneration: insights from injured axons in Drosophila.</a> Curr Opin Genet Dev. 44, 84-91 (2017).</li><li>Galbraith, J. A., Terasaki, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+damage+in+thick+specimens+by+multiphoton+excitation.">Controlled damage in thick specimens by multiphoton excitation.</a> Mol Biol Cell. 14, 1808-1817 (2003).</li><li>Sugimura, K., 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=Distinct+developmental+modes+and+lesion-induced+reactions+of+dendrites+of+two+classes+of+Drosophila+sensory+neurons.">Distinct developmental modes and lesion-induced reactions of dendrites of two classes of Drosophila sensory neurons.</a> J Neurosci. 23, 3752-3760 (2003).</li><li>Yanik, M. F., 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=Neurosurgery:+functional+regeneration+after+laser+axotomy.">Neurosurgery: functional regeneration after laser axotomy.</a> Nature. 432, 822 (2004).</li><li>Wu, Z., 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=Caenorhabditis+elegans+neuronal+regeneration+is+influenced+by+life+stage,+ephrin+signaling,+and+synaptic+branching.">Caenorhabditis elegans neuronal regeneration is influenced by life stage, ephrin signaling, and synaptic branching.</a> Proc Natl Acad Sci U S A. 104, 15132-15137 (2007).</li><li>Stone, M. C., Nguyen, M. M., Tao, J., Allender, D. L., Rolls, M. 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B., 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=Projections+of+Drosophila+multidendritic+neurons+in+the+central+nervous+system:+links+with+peripheral+dendrite+morphology.">Projections of Drosophila multidendritic neurons in the central nervous system: links with peripheral dendrite morphology.</a> Development. 134, 55-64 (2007).</li><li>Buss, 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=NG2+and+phosphacan+are+present+in+the+astroglial+scar+after+human+traumatic+spinal+cord+injury.">NG2 and phosphacan are present in the astroglial scar after human traumatic spinal cord injury.</a> BMC Neurol. 9, 32 (2009).</li><li>McKeon, R. J., Jurynec, M. J., Buck, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+chondroitin+sulfate+proteoglycans+neurocan+and+phosphacan+are+expressed+by+reactive+astrocytes+in+the+chronic+CNS+glial+scar.">The chondroitin sulfate proteoglycans neurocan and phosphacan are expressed by reactive astrocytes in the chronic CNS glial scar.</a> J Neurosci. 19, 10778-10788 (1999).</li><li>Raabe, I., Vogel, S. K., Peychl, J., Tolic-Norrelykke, I. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracellular+nanosurgery+and+cell+enucleation+using+a+picosecond+laser.">Intracellular nanosurgery and cell enucleation using a picosecond laser.</a> J Microsc. 234, 1-8 (2009).</li><li>Hutson, M. S., Ma, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plasma+and+cavitation+dynamics+during+pulsed+laser+microsurgery+in+vivo.">Plasma and cavitation dynamics during pulsed laser microsurgery in vivo.</a> Phys Rev Lett. 99, 158104 (2007).</li><li>Venugopalan, V., Guerra, A., Nahen, K., Vogel, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+laser-induced+plasma+formation+in+pulsed+cellular+microsurgery+and+micromanipulation.">Role of laser-induced plasma formation in pulsed cellular microsurgery and micromanipulation.</a> Phys Rev Lett. 88, 078103 (2002).</li><li>Bourgeois, F., Ben-Yakar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femtosecond+laser+nanoaxotomy+properties+and+their+effect+on+axonal+recovery+in+C.+elegans.">Femtosecond laser nanoaxotomy properties and their effect on axonal recovery in C. elegans.</a> Opt Express. 16, 5963 (2008).</li><li>O'Brien, G. 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When setting up fly crosses, the number of females and males used can vary depending on the genotypes and the number of larvae needed for specific experiments. For WT flies, typical cross uses 10 females and 5 males. The collection window may be narrowed, depending on the accuracy of the larvae age required. For example, a 2-h collection period will yield larvae of a more homogenous population. In this case, using 20 or more virgin females to set up the crosses will help yield sufficient eggs. The yield from the first da...

The inability of axons to regenerate after an injury to the central nervous system (CNS), may lead to permanent disabilities in patients, and also plays a role in the irreversible neurological deficits in neurodegenerative diseases1,2,3,4,5. The CNS environment, as well as the intrinsic growth ability of neurons, determines whether axons are able to regenerate after trauma. Extracellular factors from oligodendrocyte, astroglial, and fibroblastic sources have been shown to impede neuronal growth4,6,7,8, but the elimination of these molecules only allows for limited sprouting5. Intrinsic regeneration signals can influence regenerative success5,9 and represent potential therapeutic targets, but these processes are still not well-defined at the molecular level. Increases in trophic factor signaling or elimination of endogenous brakes, such as the Pten phosphatase10, can result in axonal regeneration in certain circumstances. Combinations of different methods found to be individually effective also only provide limited overall recovery to date11,12,13,14. Therefore, there is a desperate need to identify additional pathways for targeted therapy. In addition to the initiation of axon regrowth, whether and how axons re-wire to the correct target, reform synapse specificity, and achieve functional recovery are important unanswered questions.
In summary, current understanding of the machinery dictating axon regeneration is still very fragmentary. Part of the problem is the technical difficulty of studying axon regeneration in mammals in real-time, an approach that is costly, time-consuming, and challenging for conducting large-scale genetic screens. Drosophila melanogaster, on the other hand, has proven to be an exceptionally powerful system for the study of complex biological questions. The fruit fly has been instrumental in defining genes and signaling pathways that are strikingly conserved in humans and has been a successful model for the study of human conditions, such as neurodegenerative diseases, through the vast molecular genetics tools available to manipulate gene function15. In particular, fruit flies are considered to be an ideal tool for the discovery of genes involved in neural injury and regrowth15,16. Several fly neural injury models have been developed, including adult-head or larval ventral nerve cord (VNC) stabbing with needles, larval VNC or nerve crush with forceps, larval neuron laser axotomy, olfactory receptor neuron removal, brain explants injury, and peripheral nerve lesion by wing severance15,17,18,19,20,21,22,23. Excitingly, recent work utilizing Drosophila injury models have&#160;advanced our understanding of the cellular and genetic pathways used by the nervous system to respond to neural injuries, some of which have been shown to be conserved in mammals24,25. Again, this emphasizes the utility of this model organism for identifying novel mechanisms of neural repair.
Described here is a two-photon laser-based Drosophila larval sensory neuron injury model. A two-photon laser was first used to cut axons in zebrafish in vivo in 200326. In the same year, the first laser dendriotomy was performed in Drosophila using a pulsed nitrogen laser27. Shortly afterward, several C. elegans labs used femtosecond lasers to establish models of axon regeneration28. In 2007, Wu and colleagues compared and reported the differences between laser injuries in C. elegans induced by various types of lasers29. In 2010, axon regeneration after laser axotomy was first shown to occur in Drosophila30. Building on this extensive laser injury literature, we have developed a fly neural injury model using the two-photon laser, which allows precise induction of injury to targeted sites with minimal perturbation of neighboring tissues, providing a relatively clean system to study both the intrinsic and extrinsic properties of neuroregeneration with single-cell resolution. Specifically, we have established a set of injury methods for dendritic arborization (da) sensory neurons in both the peripheral nervous system (PNS) and CNS. Da neurons can be grouped into four distinct classes distinguished primarily by their dendrite branching complexities: class I to IV31. Our published work shows that da neuron regeneration resembles mammalian injury models at the phenotypic and molecular level: da neurons display class specific regeneration properties, with class IV but not class I or III da neurons exhibiting regeneration in the PNS; class IV da neuron axons regenerate robustly in the periphery, but their regenerative potential is dramatically reduced in the CNS, thus resembling dorsal root ganglion (DRG) neurons in mammals; enhancing mTOR activity via Pten deletion or Akt overexpression enhances axon regeneration in the fly CNS19. Utilizing this injury model, we have been performing genetic screens and have identified the RNA processing enzyme Rtca as an evolutionarily conserved inhibitory factor for axon regeneration, linking axon injury to cellular stress and RNA modification20.
In the presented paradigm, the injury is induced via laser axotomy/dendriotomy of larval class IV or III da neurons, labeled by ppk-CD4-tdGFP or 19-12-Gal4, UAS-CD4-tdGFP, repo-Gal80, respectively. The injury is performed on 2nd to 3rd instar larvae at around 48 - 72 h after egg laying (h AEL). For PNS axotomy the lesion is targeted to the section of axon ~20 - 50 &#181;m away from the cell body, for CNS axotomy to an area of ~20 &#181;m in diameter at the commissure junction in the VNC, and for dendriotomy to the primary dendritic branch points. The same neuron is imaged at 8 - 24 h after injury (AI) to confirm complete transection, and at 48 - 72 h AI to assess regeneration. Through time-lapse confocal imaging, the degeneration and regeneration of individual axons/dendrites that have been injured in vivo can be monitored over time.

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			<td height="63" style="height:63px;width:444px;">Diethyl ether, ACS reagent, anhydrous</td>
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			<td style="width:153px;">AC615080010</td>
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			<td height="84" style="height:84px;width:444px;">Halocarbon 27 Oil</td>
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			<td height="21" style="height:21px;">Phosphate buffered saline (PBS), 20x Concentrate, pH 7.5, supplier # E703-1L</td>
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			<td>97062-948&#160;</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Agar powder, Alfa Aesar, 500GM</td>
			<td style="width:155px;">VWR</td>
			<td>AAA10752-36</td>
			<td></td>
		</tr>
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			<td height="21" style="height:21px;">Grape juice</td>
			<td>Welch&#8217;s</td>
			<td style="width:153px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:444px;">Ethanol 95% (Reagent Alcohol 95%)</td>
			<td style="width:155px;">VWR</td>
			<td style="width:153px;">64-17-5</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:444px;">Acetic acid</td>
			<td style="width:155px;">Sigma-Aldrich</td>
			<td style="width:153px;">A6283</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:444px;">Propionic Acid</td>
			<td style="width:155px;">J.T.Baker</td>
			<td style="width:153px;">U33007</td>
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		<tr height="63">
			<td height="63" style="height:63px;width:444px;">Cover Glasses: Rectangles</td>
			<td style="width:155px;">Fisher Scientific</td>
			<td style="width:153px;">12-544-D</td>
			<td>50 mm X 22 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:444px;">Zeiss LSM 880 laser scanning microscope</td>
			<td style="width:155px;">Zeiss</td>
			<td style="width:153px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:444px;">Zen software</td>
			<td style="width:155px;">Zeiss</td>
			<td style="width:153px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:444px;">Chameleon Ultra II</td>
			<td style="width:155px;">Coherent</td>
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</table>

a drosophila in vivo injury model for studying neuroregeneration in the peripheral and central nervous system

The regrowth capacity of damaged neurons governs neuroregeneration and functional recovery after nervous system trauma. Over the past few decades, various intrinsic and extrinsic inhibitory factors involved in the restriction of axon regeneration have been identified. However, simply removing these inhibitory cues is insufficient for successful regeneration, indicating the existence of additional regulatory machinery. Drosophila melanogaster, the fruit fly, shares evolutionarily conserved genes and signaling pathways with vertebrates, including humans. Combining the powerful genetic toolbox of flies with two-photon laser axotomy/dendriotomy, we describe here the Drosophila sensory neuron &#8211; dendritic arborization (da) neuron injury model as a platform for systematically screening for novel regeneration regulators. Briefly, this paradigm includes a) the preparation of larvae, b) lesion induction to dendrite(s) or axon(s) using a two-photon laser, c) live confocal imaging post-injury and d) data analysis. Our model enables highly reproducible injury of single labeled neurons, axons, and dendrites of well-defined neuronal subtypes, in both the peripheral and central nervous system.

Da neurons show differential regeneration potential between the peripheral and central nervous system, as well as class specificity. This provides unique opportunities to screen for novel factors that are required for axon regeneration (using class IV PNS injury), as well as those that are inhibitory for regeneration (with class IV CNS injury and class III PNS injury).
Axon regeneration in the PNS
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Watch this Scientific Journal Video about A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System at JoVE.com

A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System

Here, we present a protocol using the Drosophila sensory neuron - dendritic arborization (da) neuron injury model, which combines in vivo live imaging, two-photon laser axotomy/dendriotomy, and the powerful fly genetic toolbox, as a platform for screening potential promoters and inhibitors of neuroregeneration.

A Drosophila In Vivo Injury Model for Studying Neuroregeneration in the Peripheral and Central Nervous System

The regrowth capacity of damaged neurons governs neuroregeneration and functional recovery after nervous system trauma. Over the past few decades, various ...

The overall goal of this Drosophila larval sensory neuron injury model is to combine in vivo live imaging, two-photon laser axotomy/dendriotomy, and the powerful fly genetic toolbox into a platform for screening potential promoters and inhibitors of neuroregeneration. This method will help address key questions in a field of neurogeneration, such as by identifying new intrinsic and extrinsic regulator for neurogeneration, both in a peripheral and central nerve system. The main advantage of this technique is that novel candidates for neuroregeneration can be screened in an easy, fast and cheap way.Though this system can provide insight into neuroregeneration, it can also be applied to other systems, such as neurodegenerative diseases and neuron-glia interactions. Generally, individuals new to this method will struggle because different experimental setups that utilize different types of neurons are used to model axon versus dendritic regeneration. For the larvae collection, prepare culture bottles as follows.Use a blade to punch a 1.5-centimeter hole in one wall of a Drosophila culture bottle, and fill the hole with a cotton ball for ventilation. Then put a dab of yeast paste on a grape juice agar plate, and use the plate to plug the main opening of the bottle. In such a bottle, set up a cross of 10 virgin females and five males, and change the plate daily while culturing at 25 degrees Celsius.Culture the collected plates with a wet tissue soaked in mild propionic acid to prevent contamination. From the cultured plates, harvest larvae at the required stage using forceps. Gently transfer the picked larvae to a new grape juice agar plate without yeast paste.After they have cleaned themselves off by crawling around, they can be imaged. To begin each imaging session, turn on the imaging lasers and the microscope. For the injury, use a two-photon microscope.In the imaging software, set the laser to view GFP at 930 nanometers with a maximum power of 1950 milliwatts. Select Line Scan Mode, and open the pinhole all the way. Then increase the laser intensity to about 20%of full power to make a PNS injury, or to 50%to 100%of full power to make a VNC injury.Next, select 512 square pixel frame for scanning, and use the highest possible scanning speed. Use an average number of one, and a bit depth of eight bits. Then set the gain to about 750, and set the offset to zero.Now save this preset experimental protocol as 2P GFP 930 Ablation, allowing for easy reuse in further experiments. For post-injury imaging, use a confocal microscope. First set up the argon laser at 488 nanometers.Select the Acquisition tab and then select Z Stack. Under Laser, turn on the 488 nanometer argon laser. Next go to Channels, select the 488 nanometer laser, and increase the laser power to five to 10%For the pinhole, use the option for one to two area units.Then adjust the gain to 650. Now in Acquisition Mode, select the 1024 square pixels as the frame scan. Use the maximum scan speed.Use an average number of two and a bit depth of eight bits. Save this pre-experimental protocol as GFP Imaging. Begin with anesthetizing the larvae.In a fume hood, place a 60-millimeter glass dish into a 15-centimeter plastic petri dish. Then fold a piece of tissue paper and place it in the glass dish. Place the grape agar plate on the tissue, after the diethyl ether is added.Next, onto a glass slide, place one drop of Halocarbon 27 oil at the center, and place a spot of vacuum grease on each of the four corners. Then use forceps to transfer one larva onto the agar plate, and cover the glass dish to anesthetize the larva. As soon as the larva stops moving, carefully transfer it to the Halocarbon oil, with its head upright.Then place a cover slip over the slide and press it down gently until it touches the larva. Next, use gentle force to slide the cover slip to roll the cells to be ablated to where the two-photon laser will most easily hit them. The location will vary, depending on what neurons are being targeted.Now secure the assembly on the two-photon microscope stage, and focus on the cells of interest, using a 40X oil immersion objective. In the software, switch to the scanning mode and load the saved protocol. Make sure the pinhole is opened all the way.Then in Live Mode, get a good image of the region of interest. Next, stop the live scan so that the Crop button will become available. Using the Crop function, adjust the scan window to focus the target area on just the prospective site of injury.Then open a new imaging window. Now reduce the scan speed and increase the laser intensity. Then toggle the Continuous button to start and stop the scan.Watch carefully. As soon as there is a drastic increase in florescence, end the scan. Next switch back to the original imaging window and select the Live Mode, and find the region that was just targeted by adjusting the focus.A good indication of successful injury is the appearance of a small crater, ring-like structure, or localized debris right on the injury site. If the laser power was too high, a large damaged area will be visible, which can be lethal. Now carefully remove the cover slip, and transfer the injured larva onto a new plate with yeast paste.Put the plate into a 60-millimeter dish, along with a propionic acid soaked tissue. Then return the plate to culturing temperature. For subsequent imaging of the larva, make use of the saved confocal setup, and collect Z stack images with a 25X objective.Be sure to include the normalization point, so the regeneration can be quantified. Using the described protocol, regeneration of class three and four DA neurons was investigated. Typically, three or four neurons on the right side of abdominal segments A7 to A2 were injured.Specifically, class three DDAF and class four V Prime ADA neurons were targeted. Larvae were imaged at 24, 48, and 72 hours post-injury. At 24 hours, the distal axons usually completed degeneration, and the axon stem was readily visible.At 48 hours, it was possible to assess regeneration in the class four DA neurons. About 70%of these neurons regenerated beyond the injury site. Even after 72 hours, it was clear that class three DA neurons, however, failed to regrow.This was assessed based on repeated observations of stalled growth cones. After watching this video, you should have a good understanding of how to set up the experiment, perform two-photon injury, and assess the results. Once mastered, this technique takes 15 minutes per larvae, if it's performed properly.While attempting this procedure, it's important to remember to compare the experimental growth with the corresponding controls, side by side. Following this procedure, a method like immunostaining can be performed in order to answer more questions, like whether axon injury can cause protein translocation, resulting in a pathway alteration. Since its development, this technique paved the way for the researchers in the field of neuroscience to explore neuroregeneration in Drosophila larval sensory neurons.Finally, don't forget that working with diethyl ether can be extremely hazardous, and precautions, such as performing larval anesthesia in a fume hood, should always be taken while performing this procedure.

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An in vivo Rodent Model of Contraction-induced Injury and Non-invasive Monitoring of Recovery

Muscle strains are one of the most common complaints treated by physicians. A muscle injury is typically diagnosed from the patient history and physical exam alone, however the clinical presentation can vary greatly depending on the extent of injury, the patient's pain tolerance, etc. In patients with muscle injury or muscle disease, assessment of muscle damage is typically limited to clinical signs, such as tenderness, strength, range of motion, and more recently, imaging studies. Biological markers, such as serum creatine kinase levels, are typically elevated with muscle injury, but their levels do not always correlate with the loss of force production. This is even true of histological findings from animals, which provide a "direct measure" of damage, but do not account for all the loss of function. Some have argued that the most comprehensive measure of the overall health of the muscle in contractile force. Because muscle injury is a random event that occurs under a variety of biomechanical conditions, it is difficult to study. Here, we describe an in vivo animal model to measure torque and to produce a reliable muscle injury. We also describe our model for measurement of force from an isolated muscle in situ. Furthermore, we describe our small animal MRI procedure.

An in vivo Rodent Model of Contraction-induced Injury and Non-invasive Monitoring of Recovery

An in vivo animal model of injury is described. The method takes advantage of the subcutaneous position of the fibular nerve. Velocity, timing of muscle activation, and arc of motion are all pre-determined and synchronized using commercial software. Post injury changes are monitored in vivo using MR imaging/spectroscopy.

Muscle strains are one of the most  common complaints treated by physicians. A muscle injury is typically diagnosed from the patient history and  physical ...

In vivo 19F MRI for Cell Tracking

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.

In vivo 19F MRI for Cell Tracking

We describe a general protocol for in vivo cell tracking using MRI in a mouse model with ex vivo labeled cells. A typical protocol for cell labeling, image acquisition processing and quantification is included.

In vivo 19F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. ...

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic cerebrovascular accidents account for 80% of all strokes. A common cause of IR injury is the rapid inflow of fluids following an acute/chronic occlusion of blood, nutrients, oxygen to the tissue triggering the formation of free radicals.
Ischemic stroke is followed by blood-brain barrier (BBB) dysfunction and vasogenic brain edema. Structurally, tight junctions (TJs) between the endothelial cells play an important role in maintaining the integrity of the blood-brain barrier (BBB). IR injury is an early secondary injury leading to a non-specific, inflammatory response. Oxidative and metabolic stress following inflammation triggers secondary brain damage including BBB permeability and disruption of tight junction (TJ) integrity.
Our protocol presents an in vitro example of oxygen-glucose deprivation and reoxygenation (OGD-R) on rat brain endothelial cell TJ integrity and stress fiber formation. Currently, several experimental in vivo models are used to study the effects of IR injury; however they have several limitations, such as the technical challenges in performing surgeries, gene dependent molecular influences and difficulty in studying mechanistic relationships. However, in vitro models may aid in overcoming many of those limitations. The presented protocol can be used to study the various molecular mechanisms and mechanistic relationships to provide potential therapeutic strategies. However, the results of in vitro studies may differ from standard in vivo studies and should be interpreted with caution.

Oxygen-Glucose Deprivation and Reoxygenation as an In Vitro Ischemia-Reperfusion Injury Model for Studying Blood-Brain Barrier Dysfunction

Ischemia-Reperfusion (IR) injury is associated with a high rate of morbidity and mortality. The goal of the in vitro model of oxygen-glucose deprivation and reoxygenation (OGD-R) described here is to assess the effects of ischemia reperfusion injury on a variety of cells, particularly in blood-brain barrier (BBB) endothelial cells.

Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic ...

Studying Pancreatic Cancer Stem Cell Characteristics for Developing New Treatment Strategies

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor initiation, metastasis and resistance to radio- and chemotherapy. Here we describe a specific methodology for culturing primary human pancreatic CSCs as tumor spheres in anchorage-independent conditions. Cells are grown in serum-free, non-adherent conditions in order to enrich for CSCs while their more differentiated progenies do not survive and proliferate during the initial phase following seeding of single cells. This assay can be used to estimate the percentage of CSCs present in a population of tumor cells. Both size (which can range from 35 to 250 micrometers) and number of tumor spheres formed represents CSC activity harbored in either bulk populations of cultured cancer cells or freshly harvested and digested tumors 1,2. Using this assay, we recently found that metformin selectively ablates pancreatic CSCs; a finding that was subsequently further corroborated by demonstrating diminished expression of pluripotency-associated genes/surface markers and reduced in vivo tumorigenicity of metformin-treated cells. As the final step for preclinical development we treated mice bearing established tumors with metformin and found significantly prolonged survival. Clinical studies testing the use of metformin in patients with PDAC are currently underway (e.g., NCT01210911, NCT01167738, and NCT01488552). Mechanistically, we found that metformin induces a fatal energy crisis in CSCs by enhancing reactive oxygen species (ROS) production and reducing mitochondrial transmembrane potential. In contrast, non-CSCs were not eliminated by metformin treatment, but rather underwent reversible cell cycle arrest. Therefore, our study serves as a successful example for the potential of in vitro sphere formation as a screening tool to identify compounds that potentially target CSCs, but this technique will require further in vitro and in vivo validation to eliminate false discoveries.

Pancreatic cancer stem cells (CSCs) can be expanded in vitro using the anchorage-independent sphere culture technique, which represents a powerful tool to study CSC biology and can serve as the first step to develop novel CSC-targeting therapies. Here the methodology for expanding, analyzing and targeting of pancreatic CSCs is provided.

Pancreatic ductal adenocarcinoma (PDAC) contains a subset of exclusively tumorigenic cancer stem cells (CSCs) which have been shown to drive tumor ...

Depletion of Mouse Cells from Human Tumor Xenografts Significantly Improves Downstream Analysis of Target Cells

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic patient tumors in different assays1. Human tumor xenografts represent the gold standard with respect to tumor biology, drug discovery, and metastasis research 2-4. Tumor xenografts can be derived from different types of material like tumor cell lines, tumor tissue from primary patient tumors4 or serially transplanted tumors. When propagated in vivo, xenografted tissue is infiltrated and vascularized by cells of mouse origin. Multiple factors such as the tumor entity, the origin of xenografted material, growth rate and region of transplantation influence the composition and the amount of mouse cells present in tumor xenografts. However, even when these factors are kept constant, the degree of mouse cell contamination is highly variable.
Contaminating mouse cells significantly impair downstream analyses of human tumor xenografts. As mouse fibroblasts show high plating efficacies and proliferation rates, they tend to overgrow cultures of human tumor cells, especially slowly proliferating subpopulations. Mouse cell derived DNA, mRNA, and protein components can bias downstream gene expression analysis, next-generation sequencing, as well as proteome analysis 5. To overcome these limitations, we have developed a fast and easy method to isolate untouched human tumor cells from xenografted tumor tissue. This procedure is based on the comprehensive depletion of cells of mouse origin by combining automated tissue dissociation with the benchtop tissue dissociator and magnetic cell sorting. Here, we demonstrate that human target cells can be can be obtained with purities higher than 96% within less than 20 min independent of the tumor type.

Human tumor xenografts are vascularized and infiltrated by cells of mouse origin during the growth phase in vivo. To circumvent the bias caused by these contaminating cells during downstream analysis, we developed a method allowing for comprehensive depletion of all mouse cells by magnetic cell sorting.

The use of in vitro cell line models for cancer research has been a useful tool. However, it has been shown that these models fail to reliably mimic ...

A Repetitive Concussive Head Injury Model in Mice

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of knowledge on the injury and its effects. To develop a better understanding of concussions, animals are often used because they provide a controlled, rigorous, and efficient model. Studies have adapted traditional animal models to perform mTBI to stimulate mild injury severity by changing the injury parameters. These models have been used because they can produce morphologically similar brain injuries to the clinical condition and provide a spectrum of injury severities. However, they are limited in their ability to present the identical features of injuries in patients. Using a traditional impact system, a repetitive concussive injury (rCHI) model can induce mild to moderate human-like concussion. The injury degree can be determined by measuring the period of loss of consciousness (LOC) with a sign of a transient termination of breathing. The rCHI model is beneficial to use for its accuracy and simplicity in determining mTBI effects and potential treatments.

Concussion presents the most common type of traumatic brain injury. Therefore, a repetitive concussive animal model, which replicates the important features of an injury in patients, may provide a means to study concussion in a rigorous, controlled, and efficient manner.

Despite the concussion/ mild traumatic brain injury (mTBI) being the most frequent occurrence of traumatic brain injury, there is still a lack of ...

Induction of Accelerated Atherosclerosis in Mice: The "Wire-Injury" Model

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. Moreover, by rupture of the defective vascular wall, atherosclerosis induces occlusive thrombus formation, which represents the main cause of myocardial infarction or stroke and the most frequent cause of death. Despite the advances in the cardiovascular field, many questions remain unanswered, and additional basic research is essential to improve our understanding of the molecular mechanisms during atherosclerosis and its effects. Due to limited clinical studies, there is a need for representative animal models recreating atherosclerotic conditions such as neointima formation after stent implantation, balloon angioplasty, or endarterectomy. Since the mouse presents many advantages and is the most frequently used model for studying molecular processes, the current study proposes an invasive procedure of endothelial denudation, also known as the wire-injury model, which is representative of the human condition of neointima formation in arteries after revascularization procedures.

Induction of Accelerated Atherosclerosis in Mice: The &quot;Wire-Injury&quot; Model

This study describes an invasive procedure for the induction of accelerated atherosclerosis in mice. In comparison to other methods using electric- or cryo-induced injury, mechanical-induced injury mimics the human condition of restenosis after revascularization therapies and is ideal for the study of the molecular mechanisms involved.

Atherosclerosis is a proliferative fibro-inflammatory disease developing in the arterial wall, inducing a deficient blood flow or a lack of blood flow. ...

Open Tracheostomy Gastric Acid Aspiration Murine Model of Acute Lung Injury Results in Maximal Acute Nonlethal Lung Injury

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute respiratory distress syndrome (ARDS), characterized by neutrophilic alveolitis, and injury to both alveolar epithelium and vascular endothelium. Clinically, ARDS is defined by acute onset of hypoxemia, bilateral patchy pulmonary infiltrates and non-cardiogenic pulmonary edema. Human studies have provided us with valuable information about the physiological and inflammatory changes in the lung caused by ARDS, which has led to various hypotheses about the underling mechanisms. Unfortunately, difficulties determining the etiology of ARDS, as well as a wide range of pathophysiology have resulted in a lack of critical information that could be useful in developing therapeutic strategies.
Translational animal models are valuable when their pathogenesis and pathophysiology accurately reproduce a concept proven in both in vitro and clinical settings. Although large animal models (e.g., sheep) share characteristics of the anatomy of human trachea-bronchial tree, murine models provide a host of other advantages including: low cost; short reproductive cycle lending itself to greater data acquisition; a well understood immunologic system; and a well characterized genome leading to the availability of a variety of gene deletion and transgenic strains. A robust model of low pH induced ARDS requires a murine ALI that targets mainly the alveolar epithelium, secondarily the vascular endothelium, as well as the small airways leading to the alveoli. Furthermore, a reproducible injury with wide differences between different injurious and non-injurious insults is important.
The murine gastric acid aspiration model presented here using hydrochloric acid employs an open tracheostomy and recreates a pathogenic scenario that reproduces the low pH pneumonitis injury in humans. Additionally, this model can be used to examine interaction of a low pH insult with other pulmonary injurious entities (e.g., food particles, pathogenic bacteria).

This protocol induces acute lung injury in a mouse that has close fidelity to the pathogenesis of acid pneumonitis observed in humans. We generate a maximal acute nonlethal low pH lung injury and account for differences in rodent-human anatomic respiratory structure using an open tracheostomy coupled with circumferential pressure release.

Acid pneumonitis is a major cause of sterile acute lung injury (ALI) in humans. Acid pneumonitis spans the clinical spectrum from asymptomatic to acute ...

Studying the Hypothalamic Insulin Signal to Peripheral Glucose Intolerance with a Continuous Drug Infusion System into the Mouse Brain

Insulin regulates systematic metabolism in the hypothalamus and the peripheral insulin response. An inflammatory reaction in peripheral adipose tissues contributes to type 2 diabetes mellitus (T2DM) development and appetite regulation in the hypothalamus. Chemokine CCL5 and C-C chemokine receptor type 5 (CCR5) levels have been suggested to mediate arteriosclerosis and glucose intolerance in type 2 diabetes mellitus (T2DM). In addition, CCL5 plays a neuroendocrine role in the hypothalamus by regulating food intake and body temperature, thus, prompting us to investigate its function in hypothalamic insulin signaling and the regulation of peripheral glucose metabolism.
The micro-osmotic pump brain infusion system is a quick and precise way to manipulate CCL5 function and study its effect in the brain. It also provides a convenient alternative approach to generating a transgenic knockout animal. In this system, CCL5 signaling was blocked by intracerebroventricular (ICV) infusion of its antagonist, MetCCL5, using a micro-osmotic pump. The peripheral glucose metabolism and insulin responsiveness was detected by the Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT). Insulin signaling activity was then analyzed by protein blot from tissue samples derived from the animals.
After 7-14 days of MetCCL5 infusion, the glucose metabolism and insulin responsiveness was impaired in mice, as seen in the results of the OGTT and ITT. The IRS-1 serine302 phosphorylation was increased and the Akt activity was reduced in mice hypothalamic neurons following CCL5 inhibition. Altogether, our data suggest that blocking CCL5 in the mouse brain increases the phosphorylation of IRS-1 S302 and interrupts hypothalamic insulin signaling, leading to a decrease in insulin function in peripheral tissues as well as the impairment of glucose metabolism.

This protocol studies the role of chemokine (C-C motif) ligand 5 (CCL5) in the hypothalamus by delivering an antagonist, MetCCL5, into the mouse brain using a micro-osmotic pump brain infusion system. This transient inhibition of CCL5 activity interrupted hypothalamic insulin signaling, leading to glucose intolerance and peripheral systemic insulin sensitivity.

Insulin regulates systematic metabolism in the hypothalamus and the peripheral insulin response. An inflammatory reaction in peripheral adipose tissues ...

Severe Burn Injury in a Swine Model for Clinical Dressing Assessment

Wound healing is a dynamic repair process and is the most complex biological process in human life. In response to burn injury, alterations in biological pathways impair the inflammation response, resulting in delayed wound healing. Impaired wound healing frequently occurs in patients with diabetes leading to unfavorable outcomes such as amputation. Hence, dressings having beneficial effect in promoting burn wound repair are needed. However, studies on burn wound treatment are limited due to lack of proper animal models. Our previous study demonstrated wound-healing performance in rat and swine models using a minimally invasive surgical technique. This study aimed to demonstrate a swine model of severe burn injury that eliminates wound contraction and more closely approximates the human processes of re-epithelialization and new tissue formation. This protocol provides a detailed procedure for creating consistent burn wounds and examining the wound-healing performance under the treatment of an experimental dressing in a swine model. Six burn wounds were created symmetrically on the dorsum, which were covered with a clinical dressing composed of four layers: an inner contact layer of experimental materials, an inner intermediate layer of waterproof film, an outer intermediate layer of gauze, and an outer layer of adhesive plaster. Upon the completion of experiments, wound closure, wound area, and Vancouver Scar Scale score were examined. The samples of skin resected from each animal post-sacrifice were histologically prepared and stained using hematoxylin and eosin staining. Antibacterial activity of each dressing in the context of wound healing was also examined. The application of the clinical dressing to the wounds in swine model mimics the biological processes of human wound healing with respect to the processes of epithelialization, cellular proliferation, and angiogenesis. Therefore, this swine model provides an easy-to-learn, cost-effective, and robust method to assess the effect of clinical dressings in severe burn injury.

To closely mimic the mode of burn injuries requires the interplay between clinical observation and studies in animal models. In this study, a swine model of severe burn injury was established to assess an experimental dressing in physiological and pathophysiological settings.

Wound healing is a dynamic repair process and is the most complex biological process in human life. In response to burn injury, alterations in biological ...