Name: monitoring astrocyte reactivity and proliferation in vitro under ischemic-like conditions
Uploaded: 2017-10-21T13:00:00
Description: Watch this Scientific Journal Video about Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions at JoVE.com

The authors want to thank Paola L&#243;pez Pieraldi for the technical assistance. A.H.M. is grateful for the grants 8G12MD007600 and U54-NS083924 that supported this publication. We thank NIH-NIMHD-G12-MD007583 grant for the facility support. D.E.R.A. is grateful for the fellowship provided by NIHNIGMS-R25GM110513.We are grateful for the use of the Common Instrumentation Area and the aid of Dr. Priscila Sanabria for the use of the Optical Imaging Facility of the RCMI program by grant G12MD007583. In addition, we want to thank Jose Padilla for his outstanding role in filming and editing the visual protocol.

Postnatal rats (Sprague Dawley) 1-4 days old are used to isolate cortices. The method of euthanasia is decapitation, as approved by NIH guidelines.
1. Preparation of Instruments and Materials for Surgery
<ol>
	<li>Sterilize instruments in an autoclave (temperature: 121 &#186;C, pressure: 15 psi, time: 30 mins) using a steel box or an instant sealing sterilization pouch. See materials in Table of Materials.</li>
</ol>
2. Complete DMEM Preparation
<ol...

<ol>
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This protocol describes the isolation of astrocytes from rat cortices. In this method, it is critical to decrease contamination with other cellular types such as microglia, oligodendrocytes, and fibroblasts. To reduce the number of microglia, several steps can be taken: changing the media, orbital shaking, and chemical treatments. Once culture purity is confirmed by immunofluorescence using selective cellular markers or for the most prominent cell contaminants, experiments can be performed. For instance, antibody against...

Stroke is defined as &#34;an acute neurological dysfunction of vascular origin with either sudden or rapid development of symptoms and signs, corresponding to the involvement of focal areas in the brain&#34;1,2. There are two types of stroke: hemorrhagic and ischemic. When vascular dysfunction is caused either by an aneurysm or an arteriovenous malfunction, accompanied by weakening with posterior rupture of an artery,&#160;this is termed hemorrhagic stroke3 which, in most cases, leads to death. When a thrombus or an embolus obstructs blood flow, causing a temporary deprivation of oxygen and glucose to a brain region, it is called ischemic stroke4. Failure to nourish cells around the affected area or ischemic core leads to a homeostatic and metabolic imbalance, energetic dysfunction, neuronal death, and inflammation5, which can induce a life-long disability for patients6.
Ischemic stroke is a multifactorial injury involving several types of cells that react and exert their effects at different time points. Many interactions create a difficult environment to study the behavior of individual cells. So, how do we study the contribution of a specific cell type under such a complex environment? An accepted in vitro model of ischemia consists of exposing cells to oxygen and glucose deprivation (OGD), for a certain period, followed by the restoration of cells to a normoxic environment. This system simulates an ischemic stroke followed by blood reperfusion. In this method, cells or tissues are exposed to a glucose-free media in an environment purged of oxygen, using a specialized hypoxic chamber. The OGD incubation time can vary from a few minutes up to 24 h, depending on the hypothesis that wants to be tested. Studies have shown that depending on the times of OGD and normoxic environment, specific phenotypes of stroke (i.e., acute or subchronic) can be achieved. Primary isolated astrocytes, exposed to OGD with posterior restoration to normoxic conditions, is a well-studied cellular model to mimic stroke in vitro7. Using OGD is possible to reveal the independent molecular mechanisms of isolated cells under a stroke-like environment.
As our knowledge of astrocyte biology increases, it has become evident that they are crucial for maintaining synapses and sustaining neural repair, development, and plasticity8. Under normal conditions, astrocytes release and respond to cytokines, chemokines, growth factors and gliotransmitters, keeping metabolic balance and homeostasis within synapses5,9. In acute neuroinflammation, such as ischemic stroke, these cells can become reactive, show a long-term overexpression of Glial Fibrillary Acidic Protein (GFAP), and show hypertrophy in their morphology5,10,11,12. As the ischemic infarct develops, the homeostasis provided by astrocytes becomes affected, regarding normal glutamate uptake, energy metabolism, exchange of active molecules, and antioxidant activity13.
Reactivated astrocytes proliferate around the infarct tissue while leukocytes migrate towards the lesioned area14. Astrocytic proliferation can be measured using markers such as proliferating cell nuclear antigen (PCNA), Ki67, and bromodeoxyuridine (BrdU)15. This proliferative response is generated in a time-dependent manner and it helps forming the glial scar, an array of irreversibly reactive astrocytes along the parenchyma of the damaged site after an injury9. One of the initial functions of this scar is to limit the immune cell extravasation from this area. However, studies have shown that the scar becomes a physical impediment for axons to extend, as they release molecules inhibiting axonal growth, and create a physical barrier preventing axons from extending around the injured area16. Nevertheless, there is scientific evidence showing that after a spinal cord injury, completely preventing glial scar formation can impair the regeneration of axons17. Thus, the context in which the specific astrocytic response is measured, must be considered upon the framework of the injury studied.
The presented methodology can be applied to study the individualized function of astrocytes after oxygen glucose deprivation and it can be modified depending on the questions that the investigator wants to answer. For example, besides the morphological change and the markers expressed at different OGD times, the supernatants from astrocytes exposed to OGD can be further analyzed to identify soluble factors released by these cells, or used as a conditioned media to assess its effect in other brain cells. This approach enables studies on astrocyte reactivity that could lead to the elucidation of the factors that govern and modulate their response in an ischemic-stroke scenario.

<table border="0" cellpadding="0" cellspacing="0" width="933">
	<tbody>
		<tr height="34">
			<td height="34" style="height:34px;width:395px;">Instruments for Surgery - Step 1</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Operating scissor 5.5&#8221;</td>
			<td>Roboz Company</td>
			<td style="width:119px;">RS-6812</td>
			<td style="width:253px;">Tools used to decapitate the rats.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Curved forceps 7&#8221;&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5271</td>
			<td style="width:253px;">Holds the skin of the rat while the skull is removed.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Micro-dissecting scissors 4&#8221;&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5882</td>
			<td style="width:253px;">Cuts both the skin and skull of the rat.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Micro-dissecting forceps 4&#8221; angled, fine sharp&#160;</td>
			<td>Roboz Company</td>
			<td>RS-5095</td>
			<td style="width:253px;">Holds the skin of the rat while the skull is removed.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro-dissecting forceps 4&#8221; slightly curved 0.8</td>
			<td>Roboz Company</td>
			<td>RS-5135</td>
			<td>Tool used to separate cortices.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro-dissecting tweezers</td>
			<td>Roboz Company</td>
			<td>RS-4972</td>
			<td>Peels brain meninges.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Dissection microscope</td>
			<td style="width:167px;">Olympus</td>
			<td style="width:119px;">SZX16</td>
			<td style="width:253px;">Important for removing the meninge from the cortices.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">DMEM Preparation - step 2</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Dulbecco&#8217;s Modified Eagle&#8217;s Medium (DMEM)</td>
			<td>GibCo. Company</td>
			<td>11995-065</td>
			<td style="width:253px;">Supports the growth of cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Sodium bicarbonate</td>
			<td>Sigma-Aldrich Company</td>
			<td>S7277</td>
			<td style="width:253px;">Supplement for the cell culture media.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Fetal bovine serum (FBS)</td>
			<td>GibCo. Company</td>
			<td>10437-010</td>
			<td style="width:253px;">Serum-supplement for the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Penicillin-Streptomycin&#160;</td>
			<td>GibCo. Company</td>
			<td>15140-148</td>
			<td style="width:253px;">Inhibits the growth of bacterias in the cell culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Filter System 1L with 0.22um pore</td>
			<td>Corning</td>
			<td>431098</td>
			<td></td>
		</tr>
		<tr height="34">
			<td height="34" style="height:34px;">Astrocyte culture - step 3</td>
			<td></td>
			<td></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 5mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-896</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 10mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-898</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Serological pipets 25mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89130-900</td>
			<td style="width:253px;">To pipette DMEM to containers with cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Centrifuge conical tube 15mL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-200250</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Safe-lock tube 1.5mL</td>
			<td style="width:167px;">Eppendorf</td>
			<td style="width:119px;">022363204</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Barrier Tips 200 uL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td style="width:119px;">sc-201725</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Barrier Tips 1 mL</td>
			<td style="width:167px;">Santa Cruz Biotechnology</td>
			<td>sc-201727</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Biohazard Orange Bag 14 x 19&#34;</td>
			<td>VWR</td>
			<td>14220-048</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">60mm petri dishes</td>
			<td>Falcon</td>
			<td>351007</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Sterile gauze pads</td>
			<td>Honeywell Safety</td>
			<td>89133-086</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Stomacher 80 Biomaster</td>
			<td style="width:167px;">Sewar Lab System</td>
			<td style="width:119px;">030010019</td>
			<td style="width:253px;">Triturate the brain tissue.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Stomacher 80 Blender Sterile Bags</td>
			<td style="width:167px;">Sewar Lab System</td>
			<td style="width:119px;">BA6040</td>
			<td style="width:253px;">Sterile bag for the stomacher cell homogenizer.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Beaker 400mL</td>
			<td style="width:167px;">Pyrex</td>
			<td style="width:119px;">1000</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Sterile cell dissociation sieve, mesh #60&#160;</td>
			<td>Sigma-Aldrich Company</td>
			<td>S1020</td>
			<td style="width:253px;">To obtain a uniform single cell suspension.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Sterile cell dissociation sieve, mesh #100</td>
			<td>Sigma-Aldrich Company</td>
			<td>S3895</td>
			<td style="width:253px;">To obtain a uniform single cell suspension.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Invert phase microscope</td>
			<td style="width:167px;">Nikon</td>
			<td style="width:119px;">Eclypse Ti-S</td>
			<td style="width:253px;">Verify cells for contamination or abnormal cell growth.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">75cm2 sterile flasks</td>
			<td>Falcon</td>
			<td>353136</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Multi-well plate</td>
			<td>Falcon</td>
			<td>353046</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Micro cover glasses (coverslips), 18mm, round</td>
			<td>VWR</td>
			<td>48380-046</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Bright-Line hemacytometer</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">Z359629</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Pasteur pipettes</td>
			<td style="width:167px;">Fisher Scientific</td>
			<td style="width:119px;">13-678-20D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Ethyl alcohol&#160;</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">E7023</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;">L-leucine methyl ester hydrochloride 98% (LME)</td>
			<td>Sigma-Aldrich Company</td>
			<td>L1002</td>
			<td style="width:253px;">Promotes the elimination of microglia cells in the primary cortical astrocyte cultutre.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cytosine &#946;-D-arabinofuranoside (Ara-C)</td>
			<td>Sigma-Aldrich Company</td>
			<td>C1768</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Poly-D-Lysine Hydrobromide, mol wt 70,000-150,000</td>
			<td>Sigma-Aldrich Company</td>
			<td>P0899</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypsin/EDTA</td>
			<td>GibCo. Company</td>
			<td>15400-054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan Blue</td>
			<td>Sigma-Aldrich Company</td>
			<td>T8154</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Sterile Water</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">W3500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">&#160;OGD Medium Preparation - step 5</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Centrifuge conical tube 50 mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89039-658</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s modified Eagle&#8217;s medium-free glucose</td>
			<td>Sigma-Aldrich Company</td>
			<td>D5030</td>
			<td style="width:253px;">Supports the growth of cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Sodium bicarbonate</td>
			<td>Sigma-Aldrich Company</td>
			<td>S7277</td>
			<td style="width:253px;">Supplement for the cell culture media.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Penicillin-Streptomycin&#160;</td>
			<td>GibCo. Company</td>
			<td>15140-148</td>
			<td style="width:253px;">Inhibits the growth of bacterias in the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">200mM&#160; L-glutamine&#160;</td>
			<td>GibCo. Company</td>
			<td>25030-081</td>
			<td style="width:253px;">Amino acid that supplements the growth of cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phospahet buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Filter System 50mL with 0.22um pore</td>
			<td>Corning</td>
			<td>430320</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Centrifuge conical tube 50 mL</td>
			<td style="width:167px;">VWR</td>
			<td style="width:119px;">89039-658</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Single Flow Meter&#160;</td>
			<td>Billups-Rothenberg</td>
			<td>SMF3001</td>
			<td style="width:253px;">Measure gas flow in oxygen purge.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Hypoxia Incubator Chamber&#160;</td>
			<td>StemCell</td>
			<td>27310</td>
			<td style="width:253px;">Generates a hypoxic environment for the cell culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Traceable Dissolved Oxygen Meter</td>
			<td>VWR</td>
			<td>21800-022</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">95% N2/ 5% CO2 Gas Mixture</td>
			<td>Linde</td>
			<td></td>
			<td style="width:253px;">Purges the environment of oxygen.</td>
		</tr>
		<tr height="32">
			<td height="32" style="height:32px;width:395px;">primary astrocyte immunofluorescence - step 6</td>
			<td style="width:167px;"></td>
			<td style="width:119px;"></td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Phosphate buffer saline (PBS) tablets</td>
			<td>Calbiochem</td>
			<td>524650</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Formaline Solution Neutral Buffer 10%</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:119px;">HT501128</td>
			<td style="width:253px;">Solution used to fix cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Methanol&#160;</td>
			<td style="width:167px;">Fisher</td>
			<td style="width:119px;">A4544</td>
			<td style="width:253px;">Solution used to fix cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Non-ionic surfactant (Triton X-100)</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:119px;">T8787</td>
			<td style="width:253px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Fetal bovine serum (FBS)</td>
			<td>GibCo. Company</td>
			<td>10437-010</td>
			<td style="width:253px;">Serum-supplement for the cell culture.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Anti-NeuN</td>
			<td>Cell Signaling</td>
			<td>24307</td>
			<td style="width:253px;">Detects mature neurons, serves to validate the astrocytic culture.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-PCNA</td>
			<td>Cell Signaling</td>
			<td>2586</td>
			<td style="width:253px;">Detects proliferating cells.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Propidium Iodide (PI)</td>
			<td>Sigma-Aldrich Company</td>
			<td>P4170</td>
			<td style="width:253px;">Apoptosis staining.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Olig1</td>
			<td>Abcam</td>
			<td>AB68105</td>
			<td style="width:253px;">Detects mature oligodendrocytes.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Anti-Iba1+</td>
			<td>Wako</td>
			<td>016-20001</td>
			<td style="width:253px;">Detects microglial cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Anti-GFAP Conjugated with Cy3&#160;</td>
			<td>Sigma-Aldrich Company</td>
			<td>C9205</td>
			<td style="width:253px;">Detects reactive astrocytes in the treated cells.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Alexa Fluor 488</td>
			<td style="width:167px;">Molecular Probe Life Technology</td>
			<td style="width:119px;">A1101</td>
			<td style="width:253px;">Anti-Mouse Secondary Antibody</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:395px;">Alexa Fluor 555</td>
			<td style="width:167px;">Molecular Probe Life Technology</td>
			<td style="width:119px;">A21428</td>
			<td style="width:253px;">Anti-Rabbit Secondary Antibody</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">4&#8217;,6&#8217;-diamidino-2-phenylindole (DAPI)</td>
			<td style="width:167px;">Sigma-Aldrich Company</td>
			<td style="width:119px;">D9542</td>
			<td style="width:253px;">Nuclear staining</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Confocal microscope</td>
			<td style="width:167px;">Olympus</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

monitoring astrocyte reactivity and proliferation in vitro under ischemic-like conditions

Ischemic stroke is a complex brain injury caused by a thrombus or embolus obstructing blood flow to parts of the brain. This leads to deprivation of oxygen and glucose, which causes energy failure and neuronal death. After an ischemic stroke insult, astrocytes become reactive and proliferate around the injury site as it develops. Under this scenario, it is difficult to study the specific contribution of astrocytes to the brain region exposed to ischemia. Therefore, this article introduces a methodology to study primary astrocyte reactivity and proliferation under an in vitro model of an ischemia-like environment, called oxygen glucose deprivation (OGD). Astrocytes were isolated from 1-4 day-old neonatal rats and the number of non-specific astrocytic cells was assessed using astrocyte selective marker Glial Fibrillary Acidic Protein (GFAP) and nuclear staining. The period in which astrocytes are subjected to the OGD condition can be customized, as well as the percentage of oxygen they are exposed to. This flexibility allows scientists to characterize the duration of the ischemic-like condition in different groups of cells in vitro. This article discusses the timeframes of OGD that induce astrocyte reactivity, hypertrophic morphology, and proliferation as measured by immunofluorescence using Proliferating Cell Nuclear Antigen (PCNA). Besides proliferation, astrocytes undergo energy and oxidative stress, and respond to OGD by releasing soluble factors into the cell medium. This medium can be collected and used to analyze the effects of molecules released by astrocytes in primary neuronal cultures without cell-to-cell interaction. In summary, this primary cell culture model can be efficiently used to understand the role of isolated astrocytes upon injury.

One of the main concerns of primary astrocytic culture is the presence of other cells such as neurons, oligodendrocytes, fibroblasts, and microglia. In Figure 1, isolated cells from rat cortices had media changes every 3 days and were either untreated or treated with added LME for 1 h. 24 h later, cells were immunostained for GFAP and counterstained with DAPI. Untreated cells showed an average of 39% non-GFAP positive cells, while LME-treated cells showed 8%....

Watch this Scientific Journal Video about Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions at JoVE.com

Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions

Ischemic stroke is a complex event in which the specific contribution of astrocytes to the affected brain region exposed to oxygen glucose deprivation (OGD) is difficult to study. This article introduces a methodology to obtain isolated astrocytes and study their reactivity and proliferation under OGD conditions.

Monitoring Astrocyte Reactivity and Proliferation in Vitro Under Ischemic-Like Conditions

Ischemic stroke is a complex brain injury caused by a thrombus or embolus obstructing blood flow to parts of the brain. This leads to deprivation of ...

The following protocol is intended to show the isolation of a primary astrocytes from brains of pup rats to perform oxygen glucose deprivation or OGD. Exposure of purified astrocytes, to oxygen glucose deprived environment is a module that allows us to test the reaction to some of the conditions found in ischemic strokes. Methodical changes, after exposure to oxygen glucose deprivation can be observed and measured using selective astrocyte markers such as GFAP.In summary, these isolated cells exposed to ischemic-like conditions can be used to test new part ways activated in hypoxic conditions and other drugs that protect against ischemic stroke. In this part of the protocol astrocytes will be isolated from pup rat cortices. The purpose of this procedure is to obtain a primary astrocytic cell culture to perform oxygen glucose deprivation experiments.The materials for this procedure are the following, Autoclave all materials before using them in this procedure. And expose hood to at least 20 minutes of UV lights before starting the protocol. To begin this procedure, pipet three to five milliliters of complete DME media in each plate.It will be divided as following, one for each mouse brain, two for all of the cortices, and three will be for all of the cortices without the meninges. Decapitate a pup after disinfecting with 70%ethanol. Make an incision starting from the back of the head towards the nose.Remove skull with curved forcep and gently scrape out the cerebellum exposing the cortices. Remove the exposed brains with a pair of tweezers and place the brain in the first petri dish with media. Repeat these steps for all of the other pups.Separate the cerebral hemispheres by gently dividing along the midline fissure with the sharp end of the micro dissecting forceps. Peel the cortices by removing the white matter and hippocampus using the tweezers with a pinching movement, leaving them behind. Transfer the peel cortices to the petri dish labeled number two.Repeat the procedure for all the brains combining all the dissected cortices in the petri dish. Gently shake the dish to equally distribute the media between all the cortices. Use the dissection microscope to identify the meninges lining the peeled cortices.Meninges are a very thin transparent layer that can be identified by searching for the small red capillaries surrounding the tissue. Carefully inspect and remove the meninges lining the cortices and gently peel them off from the individual cortical lobes using fine tweezers on both sides of each cortex. Place the clean cortices into a new petri dish labeled number three.For tissue dissociation using the stomach or blender method, pour the clean, peeled cortices and the media from the petri dish into a sterile blender bag. And add enough media to bring the total volume of the bag to five milliliters. Place the bag into the stomacher 80 leaving approximately two centimeters of the bag visible above the closed door.The cell dissociation in this instrument is done after 2.5 minutes at high speed. Alternatively, tissue dissociation can be made by closing the sterile bag and gently pounding the tissue with a beaker in the hood until tissue particles have become a fine suspension. Make sure to use a cloth in between bag and beaker to avoid friction and breaking the bag.Pour the cell suspension into the center of sleeve with a mesh number 60. Pour the filtered cells into the middle of a mesh number 100 allowing it to filter by gravity. Pour the filtered cell suspension into a conical 15 milliliter tube.Center fuge the cell suspension at 200 times G in a center fuge preferably with a swing bucket router for five minutes. Remove the supernatant and discard in a beaker. Add complete fresh media to the cell palette.Using a serological pipet resuspend and dissociate the palette of cells in a maximum of five milliliter of medium. Add the desired amount of cell suspension on a flask and complete with media. Add the resuspended palette into the flask with medium.Distribute cells evenly throughout the flask and place them in an incubator at 37 degrees Celsius with 5%carbon dioxide. Remember to change the media every three days. The following methodology is intended to deprive cells of oxygen and glucose in a controlled environment.The purpose of this model is to study the response of astrocytes in an ischemic-like stroke condition. The materials used for this procedure are, Purge the glucose-free medium by inserting a serological pipet connected to the gas system. Bubble the solution with the gas mixture for 10 minutes at a flow of 10 to 15 litters per minute.After the 10 minutes are done, adjust the pH of the OGD medium to 7.4. Filter the purged glucose-free medium using the 50 milliliter tube filter system. It is important to always make fresh OGD medium for every experiment.This will ensure that the medium is purged of oxygen. Remove astrocyte media and wash with cellular PBS two times to remove glucose from the cells. Add the OGD medium to the wells.Place the multi well dish with the lid open inside the hypoxia chamber. Connect the gas mixture to the entrance valve and leave the exit valve open. Flush the chamber with the gas mixture at 10 to 15 litter per minute, for five to seven minutes.Stop the gas flow and first close the clamp on the exit valve. Then, close the clamp on the gas entrance valve tubing. Place the hypoxic chamber into the cell culture incubator at 37 degrees Celsius for the desired time in OGD.After incubation time is over, aspirate the OGD media and carefully add complete DMEM to the cells for the normoxic condition. Return the cells to the culture incubator for zero 24 and 48 hours of normoxic conditions. This protocol describes the isolation of astrocytes from neonatal rat cortices.After validating the purity of the primary cultures OGD experiments were performed. In this ischemic-like model, glucose and oxygen deprivation induced a more phological change that was monitored by the immunofluorescence using astrocytic markers such as GFAP or proliferation markers such as PCNA. One of the advantages of this model is that is allows us to study a specific cell type response.Although the limitation in this technique is the lack of cell to cell interaction due to the isolation of astrocytes. One of the possible ways to overcome this limitation, is to expose astrocytes to condition media from other cells types or a co-culture. In summary, the oxygen glucose deprivation method in an isolated cell system, allows us to directly test the effects of different neural protective or neurotoxic molecules.Also, it is a valid tool to study astrocyte biology. Finally, this model sets a strong basis to study developmental drugs in experimental conditions using in vivo models.

monitoring-astrocyte-reactivity-proliferation-vitro-under-ischemic

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Neuroscience

Screening Assay for Oxidative Stress in a Feline Astrocyte Cell Line, G355-5

An often-suggested mechanism of virus induced neuronal damage is oxidative stress. Astrocytes have an important role in controlling oxidative stress of the Central Nervous System (CNS). Astrocytes help maintain a homeostatic environment for neurons as well as protecting neurons from Reactive Oxygen Species (ROS). CM-H2DCFDA is a cell-permeable indicator for the presence of ROS. CM-H2DCFDA enters the cell as a non-fluorescent compound, and becomes fluorescent after cellular esterases remove the acetate groups, and the compound is oxidized. The number of cells, measured by flow cytometry, that are found to be green fluorescing is an indication of the number of cells that are in an oxidative state. CM-H2DCFDA is susceptible to oxidation by a large number of different ROS. This lack of specificity, regarding which ROS can oxidize CM-H2DCFDA, makes this compound a valuable regent for use in the early stages of a pathogenesis investigation, as this assay can be used to screen for an oxidative cellular environment regardless of which oxygen radical or combination of ROS are responsible for the cellular conditions. Once it has been established that ROS are present by oxidation of CM-H2DCFDA, then additional experiments can be performed to determine which ROS or combination of ROSs are involved in the particular pathogenesis process. The results of this study demonstrate that with the addition of hydrogen peroxide an increase in CM-H2DCFDA fluoresce was detected relative to the saline controls, indicating that this assay is a valuable test for detecting an oxidative environment within G355-5 cells, a feline astrocyte cell line.

A screening method to detect oxidative cellular environments is to measure the oxidation of CM-H2DCFDA. Once oxidized within a cell, CM-H2DCFDA changes from non-fluorescent into a fluorescent compound. This change in fluorescence is measured by flow cytometry and indicates the number of cells in an oxidative environment.

An often-suggested mechanism of virus induced neuronal damage is oxidative stress. Astrocytes have an important role in controlling oxidative stress of ...

Conditions Affecting Social Space in Drosophila melanogaster

The social space assay described here can be used to quantify social interactions of Drosophila melanogaster &#8212; or other small insects &#8212; in a straightforward manner. As we previously demonstrated 1, in a two-dimensional chamber, we first force the flies to form a tight group, subsequently allowing them to take their preferred distance from each other. After the flies have settled, we measure the distance to the closest neighbor (or social space), processing a static picture with free online software (ImageJ). The analysis of the distance to the closest neighbor allows researchers to determine the effects of genetic and environmental factors on social interaction, while controlling for potential confounding factors. Diverse factors such as climbing ability, time of day, sex, and number of flies, can modify social spacing of flies. We thus propose a series of experimental controls to mitigate these confounding effects. This assay can be used for at least two purposes. First, researchers can determine how their favorite environmental shift (such as isolation, temperature, stress or toxins) will impact social spacing 1,2. Second, researchers can dissect the genetic and neural underpinnings of this basic form of social behavior 1,3. Specifically, we used it as a diagnostic tool to study the role of orthologous genes thought to be involved in social behavior in other organisms, such as candidate genes for autism in humans 4.

Conditions Affecting Social Space in Drosophila melanogaster

The effect of genes and environment on social space of Drosophila melanogaster can be quantified through a powerful but straightforward analytical paradigm. We show here different factors that can affect this social space, and thus need to be taken into consideration when designing experiments in this paradigm.

The social space assay described here can be used to quantify social interactions of Drosophila melanogaster &#8212; or other small insects &#8212; in a ...

The Indirect Neuron-astrocyte Coculture Assay: An In Vitro Set-up for the Detailed Investigation of Neuron-glia Interactions

Proper neuronal development and function is the prerequisite of the developing and the adult brain. However, the mechanisms underlying the highly controlled formation and maintenance of complex neuronal networks are not completely understood thus far. The open questions concerning neurons in health and disease are diverse and reaching from understanding the basic development to investigating human related pathologies, e.g.,&#160;Alzheimer&#39;s disease and&#160;Schizophrenia. The most detailed analysis of neurons can be performed in vitro. However, neurons are demanding cells and need the additional support of astrocytes for their long-term survival. This cellular heterogeneity is in conflict with the aim to dissect the analysis of neurons and astrocytes. We present here a cell-culture assay that allows for the long-term cocultivation of pure primary neurons and astrocytes, which share the same chemically defined medium, while being physically separated. In this setup, the cultures survive for up to four weeks and the assay is suitable for a diversity of investigations concerning neuron-glia interaction.

The Indirect Neuron-astrocyte Coculture Assay: An In Vitro Set-up for the Detailed Investigation of Neuron-glia Interactions

This protocol describes the indirect neuron-astrocyte coculture for compartmentalized analysis of neuron-glia interactions.

Proper neuronal development and function is the prerequisite of the developing and the adult brain. However, the mechanisms underlying the highly ...

A Protocol for Measuring Cue Reactivity in a Rat Model of Cocaine Use Disorder

Cocaine use disorder (CUD) follows a trajectory of repetitive self-administration during which previously neutral stimuli gain incentive value. Cue reactivity, the sensitivity to cues previously linked with the drug-taking experience, plays a prominent role in human craving during abstinence. Cue reactivity can be assessed as the attentional orientation toward drug-associated cues that is measurable as appetitive approach behavior in both preclinical and human studies. Herein describes an assessment of cue reactivity in rats trained to self-administer cocaine. Cocaine self-administration is paired with the presentation of discrete cues that act as conditioned reinforcers (i.e., house light, stimulus light, infusion pump sounds). Following a period of abstinence, lever presses in the cocaine self-administration context accompanied by the discrete cues previously paired with cocaine infusion are measured as cue reactivity. This model is useful to explore neurobiological mechanisms underlying cue reactivity processes as well as to assess pharmacotherapies to suppress cue reactivity and therefore, modify relapse vulnerability. Advantages of the model include its translational relevance, and its face and predictive validities.&#160;The primary limitation of the model is that the cue reactivity task can only be performed infrequently and must only be used in short duration (e.g., 1 hour), otherwise rats will begin to extinguish the pairing of the discrete cues with the cocaine stimulus. The model is extendable to any positively reinforcing stimulus paired with discrete cues; though particularly applicable to drugs of abuse, this model may hold future applications in fields such as obesity, where palatable food rewards can act as positively reinforcing stimuli.

Cue reactivity is conceptualized as sensitivity to cues linked with drug-taking experiences that contribute to craving and relapse in abstinent humans. Cue reactivity is modeled in rats by measuring attentional orientation toward drug-associated cues that results in appetitive approach behavior in a cue reactivity test following self-administration and forced abstinence.

Cocaine use disorder (CUD) follows a trajectory of repetitive self-administration during which previously neutral stimuli gain incentive value. Cue ...

Determining Cell-surface Expression and Endocytic Rate of Proteins in Primary Astrocyte Cultures Using Biotinylation

Cell-surface proteins mediate a wide array of functions. In many cases, their activity is regulated by endocytic processes that modulate their levels at the plasma membrane. Here, we present detailed protocols for 2 methods that facilitate the study of such processes, both of which are based on the principle of the biotinylation of cell-surface proteins. The first is designed to allow for the semi-quantitative determination of the relative levels of a particular protein at the cell-surface. In it, the lysine residues of the plasma membrane proteins of cells are first labeled with a biotin moiety. Once the cells are lysed, these proteins may then be specifically precipitated via the use of agarose-immobilized streptavidin by exploiting the natural affinity of the latter for biotin. The proteins isolated in such a manner may then be analyzed via a standard western blotting approach. The second method provides a means of determining the endocytic rate of a particular cell-surface target over a period of time. Cell-surface proteins are first modified with a biotin derivative containing a cleavable disulfide bond. The cells are then shifted back to normal culture conditions, which causes the endocytic uptake of a proportion of biotinylated proteins. Next, the disulfide bonds of non-internalized biotin groups are reduced using the membrane-impermeable reducing agent glutathione. Via this approach, endocytosed proteins may thus be isolated and quantified with a high degree of specificity.

Two biotinylation-based methods, designed for determining the cell-surface expression and endocytic rate of proteins expressed at the plasma membrane, are presented in this report.

Cell-surface proteins mediate a wide array of functions. In many cases, their activity is regulated by endocytic processes that modulate their levels at ...

A Novel In Vitro Live-imaging Assay of Astrocyte-mediated Phagocytosis Using pH Indicator-conjugated Synaptosomes

Astrocytes are the major cell type in the brain and directly contact synapses and blood vessels. Although microglial cells have been considered the major immune cells and only phagocytes in the brain, recent studies have shown that astrocytes also participate in various phagocytic processes, such as developmental synapse elimination and clearance of amyloid beta plaques in Alzheimer&#39;s disease (AD). Despite these findings, the efficiency of astrocyte engulfment and degradation of their targets is unclear compared with that of microglia. This lack of information is mostly due to the lack of an assay system in which the kinetics of astrocyte- and microglia-mediated phagocytosis are easily comparable. To achieve this goal, we have developed a long-term live-imaging in vitro phagocytosis assay to evaluate the phagocytic capacity of purified astrocytes and microglia. In this assay, real-time detection of engulfment and degradation is possible using pH indicator-conjugated synaptosomes, which emit bright red fluorescence in acidic organelles, such as lysosomes. Our novel assay provides simple and effective detection of phagocytosis through live-imaging. In addition, this in vitro phagocytosis assay can be used as a screening platform to identify chemicals and compounds that can enhance or inhibit the phagocytic capacity of astrocytes. As synaptic pruning malfunction and pathogenic protein accumulation have been shown to cause mental disorders or neurodegenerative diseases, chemicals and compounds that modulate the phagocytic capacity of glial cells should be helpful in treating various neurological disorders.

A Novel In Vitro Live-imaging Assay of Astrocyte-mediated Phagocytosis Using pH Indicator-conjugated Synaptosomes

This protocol presents an in vitro live-imaging phagocytosis assay to measure the phagocytic capacity of astrocytes. Purified rat astrocytes and microglia are used along with pH indicator-conjugated synaptosomes. This method can detect real-time engulfment and degradation kinetics and provides a suitable screening platform to identify factors modulating astrocyte phagocytosis.

Astrocytes are the major cell type in the brain and directly contact synapses and blood vessels. Although microglial cells have been considered the major ...

Diffuse Reflectance Spectroscopy: Getting the Capillary Refill Test Under One's Thumb

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill should occur within 2 s after releasing 5 s of firm pressure (e.g., by the physician&#39;s finger) in the normal healthy supine patient. A slower refill time indicates poor skin perfusion, which can be caused by conditions including sepsis, blood loss, hypoperfusion, and hypothermia. Since its introduction, the clinical usefulness of the test has been debated. Advocates point out its feasibility and simplicity and claim that it can indicate changes in vascular status earlier than changes in vital signs such as heart rate. Critics, on the other hand, stress that the lack of standardization in how the test is performed and the highly subjective nature of the naked eye assessment, as well as the test&#39;s susceptibility to ambient factors, markedly lowers the clinical value. The aim of the present work is to describe in detail the course of the refill event and to suggest potentially more objective and exact endpoint values for the capillary refill test using diffuse polarization spectroscopy.

This protocol describes how the use of diffuse polarization spectroscopy can improve the clinical usefulness of the capillary refill test. We suggest a more detailed analysis of the course of the capillary refill in healthy volunteers using diffuse reflectance spectroscopy videos and new informatic endpoints.

The capillary refill test was introduced in 1947 to help estimate circulatory status in critically ill patients. Guidelines commonly state that refill ...

Levator Auris Longus Preparation for Examination of Mammalian Neuromuscular Transmission Under Voltage Clamp Conditions

This protocol describes a technique to record synaptic transmission from the neuromuscular junction under current-clamp and voltage-clamp conditions. An ex vivo preparation of the levator auris longus (LAL) is used because it is a thin muscle that provides easy visualization of the neuromuscular junction for microelectrode impalement at the motor endplate. This method allows for the recording of spontaneous miniature endplate potentials and currents (mEPPs and mEPCs), nerve-evoked endplate potentials and currents (EPPs and EPCs), as well as the membrane properties of the motor endplate. Results obtained from this method include the quantal content (QC), number of vesicle release sites (n), probability of vesicle release (prel), synaptic facilitation and depression, as well as the muscle membrane time constant (&#964;m) and input resistance. Application of this technique to mouse models of human disease can highlight key pathologies in disease states and help identify novel treatment strategies. By fully voltage-clamping a single synapse, this method provides one of the most detailed analyses of synaptic transmission currently available.

Levator Auris Longus Preparation for Examination of Mammalian Neuromuscular Transmission Under Voltage Clamp Conditions

The protocol described in this paper uses the mouse levator auris longus (LAL) muscle to record spontaneous and nerve-evoked postsynaptic potentials (current-clamp) and currents (voltage-clamp) at the neuromuscular junction. Use of this technique can provide key insights into mechanisms of synaptic transmission under normal and disease conditions.

This protocol describes a technique to record synaptic transmission from the neuromuscular junction under current-clamp and voltage-clamp conditions. An ...

Real-time In Vitro Monitoring of Odorant Receptor Activation by an Odorant in the Vapor Phase

Olfactory perception begins with the interaction of odorants with odorant receptors (OR) expressed by olfactory sensory neurons (OSN). Odor recognition follows a combinatorial coding scheme, where one OR can be activated by a set of odorants and one odorant can activate a combination of ORs. Through such combinatorial coding, organisms can detect and discriminate between a myriad of volatile odor molecules. Thus, an odor at a given concentration can be described by an activation pattern of ORs, which is specific to each odor. In that sense, cracking the mechanisms that the brain uses to perceive odor requires the understanding odorant-OR interactions. This is why the olfaction community is committed to &#34;de-orphanize&#34;&#160;these receptors. Conventional in vitro systems used to identify odorant-OR interactions have utilized incubating cell media with odorant, which is distinct from the natural detection of odors via vapor odorants dissolution into nasal mucosa before interacting with ORs. Here, we describe a new method that allows for real-time monitoring of OR activation via vapor-phase odorants. Our method relies on measuring cAMP release by luminescence using the Glosensor assay. It bridges current gaps between in vivo and in vitro approaches and provides a basis for a biomimetic volatile chemical sensor.

Physiologically, odorant receptors are activated by odorant molecules inhaled in the vapor phase. However, most in vitro systems utilize liquid phase odorant stimulation. Here, we present a method that allows real-time in vitro monitoring of odorant receptor activation upon odorant stimulation in vapor phase.

Olfactory perception begins with the interaction of odorants with odorant receptors (OR) expressed by olfactory sensory neurons (OSN). Odor recognition ...

Visualizing Astrocyte Morphology Using Lucifer Yellow Iontophoresis

Astrocytes are essential components of neural circuits. They tile the entire central nervous system (CNS) and are involved in a variety of functions, which include neurotransmitter clearance, ion regulation, synaptic modulation, metabolic support to neurons, and blood flow regulation. Astrocytes are complex cells that have a soma, several major branches, and numerous fine processes that contact diverse cellular elements within the neuropil. In order to assess the morphology of astrocytes, it is necessary to have a reliable and reproducible method to visualize their structure. We report a reliable&#160;protocol to perform intracellular iontophoresis of astrocytes using fluorescent Lucifer yellow (LY) dye in lightly fixed brain tissue from adult mice. This method has several features that are useful to characterize astrocyte morphology. It allows for three-dimensional reconstruction of individual astrocytes, which is useful to perform morphological analyses on different aspects of their structure. Immunohistochemistry together with LY iontophoresis can also be utilized to understand the interaction of astrocytes with different components of nervous system and to evaluate the expression of proteins within the labelled astrocytes. This protocol can be implemented in a variety of mouse models of CNS disorders to rigorously examine astrocyte morphology with light microscopy. LY iontophoresis provides an experimental approach to evaluate astrocyte structure, especially in the context of injury or disease where these cells are proposed to undergo significant morphological changes.

Astrocytes are morphologically complex cells, exemplified by their multiple processes and bushy territories. To analyze their elaborate morphology, we present a reliable protocol to perform intracellular Lucifer yellow iontophoresis in lightly fixed tissue.

Astrocytes are essential components of neural circuits. They tile the entire central nervous system (CNS) and are involved in a variety of functions, ...